U.S. patent application number 15/498883 was filed with the patent office on 2017-08-10 for multi-layered cores for golf balls based on ionomers.
This patent application is currently assigned to Acushnet Company. The applicant listed for this patent is Acushnet Company. Invention is credited to Mark L. Binette, Michael J. Sullivan.
Application Number | 20170225044 15/498883 |
Document ID | / |
Family ID | 47262112 |
Filed Date | 2017-08-10 |
United States Patent
Application |
20170225044 |
Kind Code |
A1 |
Sullivan; Michael J. ; et
al. |
August 10, 2017 |
Multi-Layered Cores For Golf Balls Based On Ionomers
Abstract
Multi-piece golf balls having a solid core of at least one layer
and cover of at least one layer are provided. Thermoplastic
ethylene acid copolymer ionomer compositions are used to form the
core layers. Preferably, the ball contains a dual-core having an
inner core and surrounding outer core layer. Low modulus and high
modulus ionomer compositions may be used in the core structure. In
one embodiment, a first ionomer composition is used to form the
inner core and a second ionomer composition is used to form the
outer core, and the flex modulus of the first composition is
greater than the flex modulus of the second composition. The
ionomer compositions have varying levels of hardness. The resulting
ball has high resiliency and rebounding properties.
Inventors: |
Sullivan; Michael J.; (Old
Lyme, CT) ; Binette; Mark L.; (Mattapoisett,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Assignee: |
Acushnet Company
Fairhaven
MA
|
Family ID: |
47262112 |
Appl. No.: |
15/498883 |
Filed: |
April 27, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14852857 |
Sep 14, 2015 |
9636546 |
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15498883 |
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13152577 |
Jun 3, 2011 |
9132319 |
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14852857 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 1/00 20130101; A63B
37/06 20130101; A63B 37/0069 20130101; A63B 37/0063 20130101; A63B
37/0037 20130101; B32B 7/02 20130101; C08L 23/08 20130101; A63B
37/0039 20130101; A63B 37/12 20130101; A63B 37/0059 20130101; A63B
37/0076 20130101; A63B 37/0064 20130101; C08L 23/0869 20130101;
A63B 37/0075 20130101; C08L 23/0876 20130101; C08L 23/0876
20130101; A63B 37/0033 20130101; A63B 37/0049 20130101; C08L 23/025
20130101; A63B 37/0092 20130101; C08L 23/04 20130101; A63B 37/02
20130101; A63B 37/0003 20130101; A63B 37/0044 20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00; B32B 1/00 20060101 B32B001/00; A63B 37/12 20060101
A63B037/12; B32B 7/02 20060101 B32B007/02; A63B 37/02 20060101
A63B037/02; A63B 37/06 20060101 A63B037/06 |
Claims
1. A golf ball, comprising: a) an inner core layer formed from a
first ionomer composition comprising an ethylene acid copolymer,
the first ionomer composition containing acid groups such that
greater than 70% of the acid groups are neutralized; b) an outer
core layer formed from a second ionomer composition comprising an
ethylene acid copolymer, the second ionomer composition containing
acid groups such that 70% or less of the acid groups are
neutralized; and c) a cover having at least one layer.
2. The golf ball of claim 1, wherein the first ionomer composition
has a flex modulus of 1,000 to 50,000 psi and the second ionomer
composition has a flex modulus of 20,000 psi to 150,000 psi, the
flex modulus of the first ionomer composition being less than the
flex modulus of the second ionomer composition.
3. The golf ball of claim 1, wherein the first ionomer composition
has a flex modulus of 20,000 psi to 150,000 psi and the second
ionomer composition has a flex modulus of 1,000 to 50,000 psi, the
flex modulus of the first ionomer composition being greater than
the flex modulus of the second ionomer.
4. The golf ball of claim 1, wherein the center of the inner core
and surface of the outer core layer each has a hardness, and the
surface hardness of the outer core layer is greater than the center
hardness of the inner core.
5. The golf ball of claim 4, wherein the center hardness of the
inner core is about 25 Shore D units or greater and the surface
hardness of the outer core is about 40 Shore D units or
greater.
6. The golf ball of claim 4, wherein the center hardness of the
inner core is in the range of about 25 to about 82 Shore D units
and the surface hardness of the outer core is in the range of about
30 to about 97 Shore D units.
7. The golf ball of claim 1, wherein the center of the inner core
and surface of the outer core layer each has a hardness, and the
center hardness of the inner core is greater than the surface
hardness of the outer core layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending, co-assigned
U.S. patent application Ser. No. 14/852,857 having a filing date of
Sep. 14, 2015, now allowed, which is a divisional of co-assigned
U.S. patent application Ser. No. 13/152,577 having a filing date of
Jun. 3, 2011, now issued as U.S. Pat. No. 9,132,319 having an issue
date of Sep. 15, 2017, the entire disclosures of which are hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Field of the Invention
[0003] The present invention generally relates to multi-piece golf
balls having a solid core of at least one layer and cover of at
least one layer. A thermoplastic ionomer composition is used to
form at least one of the core layers. Preferably, the ball contains
a dual-core having an inner core and surrounding outer core layer
or a multi-layered core having an inner core, intermediate core
layer, and outer core layer. Low modulus and high modulus ionomer
compositions may be used in the core structure. The resulting ball
has high resiliency and rebounding properties.
[0004] Brief Review of the Related Art
[0005] Golf ball manufacturers are continuously looking to improve
the properties and playing performance of golf balls. One way for
improving the quality of golf balls is by designing and developing
new ball materials and structures. Multi-piece, solid golf balls
having a solid inner core protected by a cover are used today.
Normally, the inner core is made of a natural or synthetic rubber
material such as, for example, styrene butadiene, polybutadiene,
poly(cis-isoprene), or poly(trans-isoprene); and the outer cover is
made of a durable material such as , for example, ethylene acid
copolymer ionomer resins, polyamides, polyesters, polyurethanes, or
polyureas. The core and cover may be single or multi-layered.
Intermediate (casing) layers may be disposed between the core and
cover layers to form four-piece and five-piece balls and the like.
Today, the industry is interested, among other things, in making
balls that can rebound faster, retain more total energy when struck
with a club, and have longer flight distance.
[0006] In general, the rebounding performance of a golf ball is
based on its initial velocity after being struck by the face of a
golf club and its outgoing velocity after making impact with a hard
surface. More particularly, the "coefficient of restitution" or
"COR" of a golf ball refers to the ratio of a ball's rebound
velocity to its initial incoming velocity when the ball is fired
out of an air cannon into a rigid vertical plate. The COR for a
golf ball is written as a decimal value between zero and one. A
golf ball may have different COR values at different initial
velocities. The United States Golf Association (USGA) sets limits
on the initial velocity of the ball so one objective of golf ball
manufacturers is to maximize COR under these conditions. Balls with
a higher rebound velocity have a higher COR value. To improve the
resiliency and rebounding performance of the golf ball, the
industry has focused primarily on the material and construction of
the ball's core.
[0007] Golf balls having single-layered and multi-layered cores
have been developed. For example, Bulpett et al, US Patent
Application Publication US 2009/0227394 discloses multi-layered
core construction comprising: a) an inner core formed from a first
thermoset rubber composition; b) an intermediate core layer formed
from a partially-neutralized or highly-neutralized ionomer
composition; and c) an outer core formed from a second thermoset
rubber composition. A cover layer having a thickness of about 0.01
t o0.05 inches and a surface hardness of about 60 Shore D or less
is formed around the core.
[0008] Sullivan et al., US Patent Application Publication No. US
2009/0017940 discloses golf balls having a dual-core and a
single-layered cover. The dual-core includes an inner core formed
from a rubber composition and an outer core layer formed from a
highly neutralized polymer (HNP) composition comprising an ethylene
acid copolymer. In the HNP composition, at least 80% of all acid
groups are neutralized. The inner core has an outer surface
hardness of less than 80 Shore C; the outer core layer has an outer
surface hardness of 56 Shore D or greater; and the cover layer has
a material hardness of 60 Shore D or less.
[0009] Sullivan et al., U.S. Pat. Nos. 7,357,736 and 7,211,008
disclose golf balls comprising: a) an inner core layer formed from
a diene rubber composition; (b) an outer core layer formed from a
high modulus highly neutralized polymer (HNP) comprising a highly
neutralized ethylene/(meth)acrylic acid copolymer having a modulus
of from 45,000 psi to 150,000 psi; (c) an intermediate core layer
disposed between the inner core layer and the outer core layer and
formed from a low modulus HNP composition comprising a highly
neutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate
copolymer having a modulus of from 1,000 psi to 50,000 psi. In the
HNP compositions, at least 80% of all acid groups are
neutralized.
[0010] Although some conventional multi-layered core constructions
are generally effective in providing high resiliency golf balls,
there is a continuing need for improved core constructions in golf
balls. Particularly, it would be desirable to have multi-layered
core constructions that could be manufactured efficiently, have
relatively low material costs, and provide the ball with high
quality and performance properties. In particular, the core should
provide the ball with good flight distance along with a comfortable
and soft feel. The present invention provides core constructions
and golf balls having such properties as well as other advantageous
features, and benefits.
SUMMARY OF THE INVENTION
[0011] The present invention provides a multi-piece golf ball
comprising a solid core having at least one layer and a cover
having at least one layer. The golf ball may have different
constructions. For instance, in one version, a golf ball having a
dual-core is made; while in another version, a golf ball having a
three-layered core is made. In preferred embodiment "A", a first
ionomer composition comprising an ethylene acid copolymer and
containing acid groups such that 70% or less of the acid groups are
neutralized is used to form an inner core, and a second ionomer
composition comprising an ethylene acid copolymer and containing
acid groups such that greater than 70%, preferably 90% or greater,
of the acid groups are neutralized is used to form an outer core
layer.
[0012] Different materials can be used as the neutralizing agent.
For example, the neutralizing agent can be a metal cation salt,
wherein the metal cation is selected preferably from Zn, Na, Li, K,
Ca, Mg, Ni, Mn, Cu, Ti, and Al, and mixtures thereof. More
preferably, Ca or Mg cations are used in the composition. In one
preferred version, the first ionomer composition does not contain a
fatty acid or salt thereof, while the second ionomer composition
does contain a fatty acid or salt thereof. The fatty acid is
selected preferably from the group of stearic acid, behenic acid,
erucic acid, oleic acid, linoelic acid, and dimerized derivatives,
and mixtures thereof. More preferably, behenic acid or erucic acid
is used in the composition.
[0013] In one version, the first ionomer composition may have a
flex modulus of 1,000 to 50,000 psi and the second ionomer
composition may have a flex modulus of 20,000 to 150,000 psi,
wherein the modulus of the first ionomer composition is preferably
at least 10% less than the modulus of the second ionomer
composition. More particularly, in one embodiment, the flex modulus
of the first ionomer composition is 30,000 or less and the flex
modulus of the second ionomer composition is 40,000 or greater. In
an alternative version, the first ionomer composition may have a
flex modulus of 20,000 to 150,000 psi and the second ionomer
composition may have a flex modulus of 1,000 to 50,000 psi, wherein
the modulus of the first ionomer composition is preferably at least
10% greater than the modulus of the second ionomer composition.
More particularly, in one embodiment, the flex modulus of the first
ionomer composition is 40,000 or greater and the flex modulus of
the second ionomer composition is 30,000 or less. The center of the
inner core and surface of the outer core each has a hardness and
preferably the surface hardness of the outer core layer (for
example, 40 Shore D or greater) is greater than the center hardness
of the inner core (for example, 25 Shore D or greater). In
alternative versions, the center hardness of the inner core is
greater than the surface hardness of the outer core layer. The
cover may be single or multi-layered. For example, a single-layered
cover having a thickness of about 0.020 to about 0.090 inches may
be made from a thermoplastic or thermoset polymer material. In
another instance, a dual-cover having inner and outer layers,
wherein the hardness of the outer cover layer (for example, 65
Shore D or less) is less than the hardness of the inner cover layer
may be prepared. The dual-core normally has a compression in the
range of about 50 to about 130, preferably about 70 to about
110.
[0014] In preferred embodiment "B", the first ionomer composition
is relatively highly neutralized, containing greater than 70% of
the acid groups neutralized, and is used to form the inner core,
while the second ionomer composition is relatively lowly
neutralized, containing less than 70% of the acid groups
neutralized, is used to form the outer core layer. In one version,
the first ionomer composition has a flex modulus of 1,000 to 50,000
psi, preferably 30,000 or less and the second ionomer composition
has a flex modulus of 20,000 to 150,000 psi, preferably 40,000 or
greater. Alternatively, the first ionomer composition has a flex
modulus of 20,000 to 150,000 psi, preferably 40,000 or greater and
the second ionomer composition has a flex modulus of 1,000 to
50,000 psi, preferably 30,000 or less.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The novel features that are characteristic of the present
invention are set forth in the appended claims. However, the
preferred embodiments of the invention, together with further
objects and attendant advantages, are best understood by reference
to the following detailed description in connection with the
accompanying drawings in which:
[0016] FIG. 1 is a cross-sectional view of a three-piece golf ball
having a dual-core comprising an inner core/outer core, and a cover
layer made in accordance with the present invention;
[0017] FIG. 2 is a cross-sectional view of a four-piece golf ball
having a dual-core comprising an inner core/outer core; and inner
cover layer; and outer cover layer made in accordance with the
present invention;
[0018] FIG. 3 is a cross-sectional view of another three-piece golf
ball having a dual-core made in accordance with the present
invention; and
[0019] FIG. 4 is a cross-sectional view of another four-piece golf
ball having a dual-core made in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention relates generally to golf balls
containing at least one component made from a thermoplastic
ionomeric composition. In one preferred version, a first ionomer
composition comprising an ethylene acid copolymer and containing
acid groups such that 70% or less of the acid groups are
neutralized is used to form an inner core, and a second ionomer
composition comprising an ethylene acid copolymer and containing
acid groups such that greater than 70% of the acid groups,
preferably 90% or greater, is used to form an outer core layer. In
a second preferred version, the first ionomer composition contains
acid groups neutralized to greater than 70% and is used to form the
inner core, while the second ionomer composition contains acid
groups neutralized to 70% or less and is used to form the outer
core layer.
[0021] Golf balls having various constructions may be made in
accordance with this invention. For example, golf balls having
three-piece, four-piece, and five-piece constructions with single
or multi-layered cover materials may be made The term, "layer" as
used herein means generally any spherical portion of the golf ball.
More particularly, in one version, a three-piece golf ball having a
dual-core and a cover is made. The dual-core includes an inner core
(center) and surrounding outer core layer. In another version, a
four-piece golf ball comprising a dual-core and dual-cover
comprising an inner cover and outer cover is made. In yet another
construction, a four-piece or five-piece golf ball having a
multi-layered core comprising an inner core (center), intermediate
core layer, and outer core layer, may be made. The golf balls of
this invention may further contain an intermediate layer(s). As
used herein, the term, "intermediate layer" means a layer of the
ball disposed between the core and cover. The intermediate layer
also may be referred to as a casing or mantle layer. The diameter
and thickness of the different layers along with properties such as
hardness and compression may vary depending upon the construction
and desired playing performance properties of the golf ball.
[0022] Low Modulus and High Modulus Core Layers
[0023] As discussed above, the present invention provides a golf
ball comprising an inner core formed from a first ionomer
composition comprising an ethylene acid copolymer containing acid
groups neutralized to 70% or less; and an outer core layer formed
from a second ionomer composition comprising an ethylene acid
copolymer containing acid groups neutralized to greater than 70%;
along with a cover that may be single or multi-layered. The present
invention also provides a golf ball comprising an inner core formed
from a first ionomer composition comprising an ethylene acid
copolymer containing acid groups neutralized to greater than 70%;
and an outer core layer formed from a second ionomer composition
comprising an ethylene acid copolymer containing acid groups
neutralized to 70% or less; along with a cover that may be single
or multi-layered.
[0024] In some versions, the first ionomer composition is
relatively flexible having a relatively low flex modulus of 1,000
to 50,000 psi and the second ionomer composition is relatively
stiff having a relatively high flex modulus of 20,000 to 150,000
psi. That is, in this version, the modulus of the first ionomer
composition is less than the modulus of the second ionomer
composition. In alternative versions, the first ionomer composition
has a relatively high flex modulus of 20,000 to 150,000 psi and the
second ionomer composition has a relatively low flex modulus of
1,000 to 50,000 psi. That is, in this version, the modulus of the
first ionomer composition is greater than the modulus of the second
ionomer composition. More particularly, the low modulus ionomer
material generally has a modulus with a lower limit of 1,000 or
5,000 or 10,000 psi or 15,000 psi and an upper limit of 17,000 or
25,000 or 28,000 or 30,000 or 35,000 or 45,000 or 50,000. The
hardness of the low modulus material is generally 30 Shore C or
greater; or 40 Shore C or greater; or 50 Shore C or greater, or
preferably within a range having a lower limit of 30 or 40 or 50
Shore C and an upper limit of 60 or 70 or 80 or 87 Shore C. On the
other hand, the high modulus ionomer material preferably has a
modulus within the range having a lower limit of 20,000 or 30,000
or 40,000 or 45,000 or 50,000 or 55,000 or 60,000 psi and an upper
limit of 72,000 or 75,000 or 100,000 or 150,000 and a hardness of
80 Shore C or greater, or 87 Shore C or greater, or 90 Shore C or
greater, or within a range having a lower limit of 80 or 87 or 90
Shore C and an upper limit of 90 or 95 or 100 Shore C. In a
preferred embodiment, the modulus of the relatively low modulus
ionomer material is at least 10% less, or at least 20% less, or at
least 30% less than the modulus of the relatively high modulus
ionomer material.
[0025] By the term, "modulus" as used herein, it is meant flexural
modulus which is the ratio of stress to strain within the elastic
limit (when measured in the flexural mode) and is similar to
tensile modulus. This property is used to indicate the bending
stiffness of a material. The flexural modulus, which is a modulus
of elasticity, is determined by calculating the slope of the linear
portion of the stress-strain curve during the bending test. The
formula used to calculate the flexural modulus from the recorded
load (F) and deflection (D) is:
E B = 3 4 FL 3 bd 3 D ##EQU00001##
[0026] wherein,
[0027] L=span of specimen between supports (m);
[0028] b=width (m); and
[0029] d=thickness (m)
If the slope of the stress-strain curve is relatively steep, the
material has a relatively high flexural modulus meaning the
material resists deformation. The material is more rigid. If the
slope is relatively flat, the material has a relatively low
flexural modulus meaning the material is more easily deformed. The
material is more flexible. Flexural modulus can be determined in
accordance with ASTM D790 standard among other testing
procedures.
[0030] Ethylene Acid Copolymers
[0031] Suitable ethylene acid copolymers that may be used to form
the compositions of this invention are generally referred to as
copolymers of ethylene; C.sub.3 to C.sub.8.alpha.,
.beta.-ethylenically unsaturated mono-or dicarboxylic acid; and
optional softening monomer. Copolymers may include, without
limitation, ethylene acid copolymers, such as
ethylene/(meth)acrylic acid, ethylene/(meth)acrylic acid/maleic
anhydride, ethylene/(meth)acrylic acid/maleic acid mono-ester,
ethylene/maleic acid, ethylene/maleic acid mono-ester,
ethylene/(meth)acrylic acid/n-butyl (meth)acrylate,
ethylene/(meth)acrylic acid/iso-butyl (meth)acrylate,
ethylene/(meth)acrylic acid/methyl (meth)acrylate,
ethylene/(meth)acrylic acid/ethyl (meth)acrylate terpolymers, and
the like. 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 a,
P-ethylenically unsaturated mono- or dicarboxylic acids are (meth)
acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric
acid, itaconic acid. (Meth) acrylic acid is most preferred. As used
herein, "(meth) acrylic acid" means methacrylic acid and/or acrylic
acid. Likewise, "(meth) acrylate" means methacrylate and/or
acrylate.
[0032] When a softening monomer is included, such copolymers are
referred to herein as E/X/Y-type copolymers, wherein E is ethylene;
X is a C.sub.3 to C.sub.8.alpha., .beta.-ethylenically unsaturated
mono- or dicarboxylic acid; and Y is a softening monomer. The
softening monomer is typically an alkyl (meth) acrylate, wherein
the alkyl groups have from 1 to 8 carbon atoms. Preferred
E/X/Y-type copolymers are those wherein X is (meth) acrylic acid
and/or Y is selected from (meth) acrylate, n-butyl (meth) acrylate,
isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth)
acrylate. More preferred E/X/Y-type copolymers are ethylene/(meth)
acrylic acid/n-butyl acrylate, ethylene/(meth) acrylic acid/methyl
acrylate, and ethylene/(meth) acrylic acid/ethyl acrylate.
[0033] The amount of ethylene in the acid copolymer is typically at
least 15 wt. %, preferably at least 25 wt. %, more preferably least
40 wt. %, and even more preferably at least 60 wt. %, based on
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 from 1 wt. %
to 35 wt. %, preferably from 5 wt. % to 30 wt. %, more preferably
from 5 wt. % to 25 wt. %, and even more preferably from 10 wt. % to
20 wt. %, based on total weight of the copolymer. The amount of
optional softening comonomer in the acid copolymer is typically
from 0 wt. % to 50 wt. %, preferably from 5 wt. % to 40 wt. %, more
preferably from 10 wt. % to 35 wt. %, and even more preferably from
20 wt. % to 30 wt. %, based on total weight of the copolymer. "Low
acid" and "high acid" ionomeric polymers, as well as blends of such
ionomers, may be used. In general, low acid ionomers are considered
to be those containing 16 wt. % or less of acid moieties, whereas
high acid ionomers are considered to be those containing greater
than 16 wt. % of acid moieties.
[0034] The acidic groups in the copolymeric ionomers are partially
or totally neutralized with a cation source. Suitable cation
sources include 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. The metal cation salts provide the cations
capable of neutralizing (at varying levels) the carboxylic acids of
the ethylene acid copolymer and fatty acids, if present, as
discussed further below. These include, for example, the sulfate,
carbonate, acetate, oxide, or hydroxide salts of lithium, sodium,
potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum,
manganese, nickel, chromium, copper, or a combination thereof.
Preferred metal cation salts are calcium and magnesium-based salts.
High surface area cation particles such as micro and nano-scale
cation particles are preferred. The amount of cation used in the
composition is readily determined based on desired level of
neutralization.
[0035] For example, ionomeric resins having acid groups that are
neutralized from about 10 percent to about 100 percent may be used.
In one ionomer composition, the acid groups are partially
neutralized. That is, the neutralization level is from about 10% to
about 70%, more preferably 20% to 60%, and most preferably 30 to
50%. These ionomer compositions, containing acid groups neutralized
to 70% or less, may be referred to ionomers having relatively low
neutralization levels.
[0036] As discussed above, ethylene acid copolymer ionomer resins,
having relatively low neutralization levels, may be used in
accordance with this invention and suitable examples of these
polymers are described in the following Tables I and II.
TABLE-US-00001 TABLE I Composition of Ethylene Acid Copolymers with
Relatively Low Levels of Neutralization % Ester Grade Co- Metal
Weight Mole Melt Weight % Mol % Names Monomer Type % Acid % Acid
Index Metal Neutralization 6320 23.5 Mg 9.0 3.11 0.95 0.63 49.6
7940 -- Li 15.0 5.44 2.6 0.51 42.2 8020 10 Na 10.0 3.48 1.2 1.05
39.3 8150 -- Na 19.0 7.10 4.5 2.30 45.3 8320 23.5 Na 9.0 3.11 1.0
1.25 52.0 8528 -- Na 10.0 3.48 1.3 1.47 55.0 8660 -- Na 11.0 3.86
10.0 1.05 35.7 8920 -- Na 15.0 5.44 0.93 2.25 56.2 8940 -- Na 15.0
5.44 2.8 1.21 30.2 8945 -- Na 15.0 5.44 4.5 2.05 51.2 9020 10 Zn
10.0 3.48 1.0 2.54 66.9 9120 -- Zn 19.0 7.10 1.3 2.57 35.6 9150 --
Zn 19.0 7.10 4.5 2.73 37.8 9320 23.5 Zn 9.0 3.11 0.75 1.41 41.3
9520 -- Zn 10.5 3.67 1.05 2.75 69.0 9650 -- Zn 11.0 3.86 5.2 2.58
61.8 9721 -- Zn 12.0 4.25 1.0 2.17 47.6 9730 -- Zn 12.0 4.25 1.8
1.69 37.1 9910 -- Zn 15.0 5.44 0.7 3.45 60.6 9945 -- Zn 15.0 5.44
4.2 3.10 54.4 9950 -- Zn 15.0 5.44 5.0 1.11 19.5 AD1022 Zn 4.5
AD1043 Mg 4.5 AD1092 -- Mg 19.0 2.8 Med.
TABLE-US-00002 TABLE II Properties of Ethylene Acid Copolymers with
Relatively Low Levels of Neutralization Vicat Flex Stiffness
Softening Solid Sphere Grade Modulus (Kg- Shore D Point MP Atti
Names (ksi) f/cm.sup.2) Hardness (.degree. C.) (.degree. C.) FP
(.degree. C.) Comp. CoR 6320 7.7 404 43 49 70 34 76 0.637 7940 61
3380 68 63 91 48 161 0.745 8020 14 1006 56 61 82 67 8150 71 65 53
84 40 189 0.785 8320 4.4 251 36 47 70 38 76 0.590 8528 32 1608 60
73 93 66 153 0.646 8660 34 1710 62 71 95 74 156 0.638 8920 51 66 58
88 48 156 0.752 8940 51 2875 65 63 94 59 165 0.720 8945 65 3005 65
71 88 47 162 0.745 9020 14 1101 55 57 81 64 125 0.587 9120 62 66 60
86 53 159 0.709 9150 52 3703 63 57 82 42 159 0.707 9320 4.3 40 48
70 37 56 0.567 9520 38 60 74 96 76 150 0.622 9650 32 1624 63 71 92
73 149 0.614 9721 32 61 71 92 76 153 0.625 9730 30 1616 63 73 90 76
9910 48 2820 64 62 86 46 163 0.690 9945 47 61 60 87 51 162 0.674
9950 37 62 66 87 73 AD1022 4.5 37 77 26 0.500 AD1043 8 40 77 68
0.670 AD1092 89 64 56 86 163 0.771
[0037] Conversely, the ionomer composition may contain acid groups
that are highly or fully-neutralized. That is, the neutralization
level is greater than 70%, preferably at least 90% and even more
preferably at least 100%. In another embodiment, an excess amount
of neutralizing agent, that is, an amount greater than the
stoichiometric amount needed to neutralize the acid groups, may be
used. That is, the acid groups may be neutralized to 100% or
greater, for example 110% or 120% or greater. In one preferred
embodiment, a high acid ethylene acid copolymer containing about 19
to 20 wt. % methacrylic or acrylic acid is neutralized with zinc
and sodium cations to a 95% neutralization level.
[0038] As discussed above, ethylene acid copolymer ionomer resins,
which are highly neutralized, may be used in accordance with this
invention and suitable examples of these highly neutralized
polymers (HNPs) are described in the following Table III
(dipolymers) and Tables IV and V (terpolymers). Examples of
suitable HNPs are further described in Degaravilla, US Patent
Application Publications US 2009/0118040 and US 20101/0304893, the
disclosures of which are hereby incorporated by reference.
TABLE-US-00003 TABLE III Ethylene Acid Copolymers with Relatively
High Levels of Neutralization HNP Properties Base Resin Flex Props.
% Fatty/ % Atti Sphere Shore D Mod. Melt Ex # Resin % Acid/Type
Type* Neut. Comp. CoR Sphere Plaque (Kpsi) Index 1 R-17 21% AA
36.8% Ol 125% 129 0.884 58.7 -- -- 0.03 2 R-14 20% MAA 35.9% Ol
139% 130 0.864 56.0 60 24.5 0.63 3 R-14 20% MAA 36.7% Ol 162% 128
0.862 50.6 57 20.9 0.45 4 R-14 20% MAA 38.3% Ol 170% 120 0.866 52.0
57 21.5 0.59 5 R-14 20% MAA 39.9% Ol 178% 119 0.867 48.5 55 20.4
0.72 6 R-15 19% MAA 41% Ol 134% 115 0.868 48.0 54 16.8 1.2 7 R-15
19% MAA 41% Ol 134% 116 0.866 51.3 57 20 0.6 8 R-15 19% MAA 36.9%
Ol 146% 119 0.863 49.6 57 21.5 0.5 9 R-15 19% MAA 39% Ol 160% 128
0.865 51.0 57 20.9 0.61 10 R-15 19% MAA 46% Ol 160% 115 0.862 49.2
54 18.3 0.62 11 R-15 19% MAA 41.4% Ol 174% 116 0.867 47.1 56 20.1
0.75 12 R-16 19% MAA 35% Ol 126% 96 0.860 53.0 57 20.8 1.2 13 R-16
19% MAA 39.9% Ol 174% 109 0.862 47.4 56 17.2 0.96 14 R-18 18% AA
36% Ol 81% 122 0.819 -- 57 20.6 0.8 15 R-18 18% AA 40% Ol 97% 125
0.818 -- -- -- 0.75 16 R-18 18% AA 34.8% Ol 150% 108 0.867 55.9 --
-- 0.22 17 R-18 18% AA 40.4% Er 153% 97 0.872 50.1 -- -- 0.46 18
R-19 15.4% AA 40% Ol 98% 115 0.821 -- -- -- 0.38 R-14: An ethylene
methacrylic acid (MAA) dipolymer with 20 weight % of MAA, and a
Melt Index of 500. R-15: An ethylene methacrylic acid (MAA)
dipolymer with 19 weight % of MAA, and a Melt Index of 305. R-16:
An ethylene methacrylic acid (MAA) dipolymer with 19 weight % of
MAA, and a Melt Index of 250. R-17: An ethylene acrylic acid (AA)
dipolymer with 21 weight % of AA, and a Melt Index of 300. R-18: An
ethylene acrylic acid (AA) dipolymer with 18 weight % of AA, and a
Melt Index of 60. R-19: An ethylene acrylic acid (AA) dipolymer
with 15.4 weight % of AA, and a Melt Index of 80. *Fatty Acid Type:
Ol--Oleic acid and Er--Erucic Acid
[0039] As shown above in above Table III, the flex modulus of some
relatively highly neutralized ethylene acid copolymers may fall
within the range of about 10,000 to about 40,000 psi, preferably
15,000 to 35,000 psi, in some instances. Such ionomer compositions
may be used to form a low modulus (or high modulus) core layer in
accordance with this invention.
TABLE-US-00004 TABLE IV Ethylene Acid Terpolymers with Relatively
High Levels of Neutralization Base Resin Properties HNP Properties
% Acid/ % Fatty/ % Atti Sphere Shore D HNP Ex # Resin Type/% Ester
Type Neut. Comp CoR Sphere Plaque MI 19 R-11 21.3% AA/2% nBA 40.5%
50/50 103% 124 0.886 55.3 -- 0.29 O/E 20 R-11 21.3% AA/2% nBA 44%
50/50 O/E 123% 118 0.889 51.5 -- 0.34 21 R-11 21.3% AA/2% nBA 30.7%
oleic 105% 141 0.884 58.1 -- 0.01 22 R-11 21.3% AA/2% nBA 42.6%
oleic 105% 131 0.889 54.5 -- 0.37 23 R-12 21.4% AA/4% nBA 31.6%
oleic 99% 140 0.866 59.1 -- 0.17 24 R-12 21.4% AA/4% nBA 41.9%
oleic 105% 127 0.888 53.3 -- 0.48 25 R-12 21.4% AA/4% nBA 34.3%
oleic 134% 131 0.872 57 -- 0.06 26 R-12 21.4% AA/4% nBA 39.3% 50/50
102% 123 0.884 55.1 -- 0.25 O/E 27 R-2 20.8% AA/2% nBA 36.7 oleic
124% 127 0.880 59.6 -- 0.06 28 R-7 19.5% MAA/4% nBA 29.5% oleic
150% 122 0.835 53.6 -- 0.31 29 R-7 19.5% MAA/4% nBA 32.1% oleic
142% 115 0.835 52.6 -- 0.89 30 R-7 19.5% MAA/4% nBA 38.7% oleic
143% 111 0.853 49.7 -- 2.58 31 R-7 19.5% MAA/4% nBA 38% oleic 195%
112 0.853 48.2 -- 0.93 32 R-9 17.6% AA/4% nBA 30.5% oleic 122% 123
0.865 54.2 -- 0.16 33 R-9 17.6% AA/4% nBA 32.1% oleic 104% 125
0.866 52.7 -- 0.46 34 R-9 17.6% AA/4% nBA 40% oleic 104% 116 0.882
49.5 -- 1.12 35 R-9 17.6% AA/4% nBA 31% oleic 154% 121 0.862 58.1
-- 0.01 36 R-9 17.6% AA/4% nBA 39.6% oleic 135% 120 0.880 50.7 --
0.35 37 R-8 17.5% MAA/8% nBA 30.8% oleic 138% 107 0.828 47.3 --
2.21 38 R-8 17.5% MAA/8% nBA 29.4% oleic 152% 112 0.842 51.1 --
0.01 39 R-8 17.5% MAA/8% nBA 36.8% oleic 160% 102 0.844 46.8 --
6.85 40 R-8 17.5% MAA/8% nBA 38.2% oleic 215% 104 0.847 47 -- 4.55
41 R-6 15.7% MAA/7.8% 40% oleic 153% 97 0.868 47.8 -- 0.95 nBA 42
R-6 15.7% MAA/7.8% 37.5% oleic 129% 97 0.866 48.6 -- 1.05 nBA R-2:
A 50/50 blend by weight of the following: i) an ethylene/acrylic
acid (AA)/n-butyl acrylate (nBA) terpolymer with 20.5 weight % of
AA and 4.0 weight % of nBA, and a Melt Index of about 750; and ii)
an ethylene/AA copolymer with 21.0 weight % of AA and a Melt Index
of 300. R-6: An ethylene/methacrylic acid (MAA)/nBA terpolymer with
15.7 weight % of MAA and 7.8 weight % of nBA, and a Melt Index of
122. R-7: An ethylene/MAA/nBA terpolymer with 19.5 weight % of MAA
and 4.0 weight % of nBA, and a Melt Index of 265. R-8: An
ethylene/MAA/nBA terpolymer with 17.5 weight % of MAA and 8.0
weight % of nBA, and a Melt Index of 280. R-9: An ethylene/AA/nBA
terpolymer with 17.6 weight % of AA and 4.0 weight % of nBA, and a
Melt Index of 285. R-11: An ethylene/AA/nBA terpolymer with 21.3
weight % of AA and 2.0 weight % of nBA, and a Melt Index of 275.
R-12: An ethylene/AA/nBA terpolymer with 21.4 weight % of AA and
4.0 weight % of nBA, and a Melt Index of 275. *Fatty Acid Type:
Oleic Acid and Erucic Acid O--Oleic acid and E--Erucic Acid.
TABLE-US-00005 TABLE V Ethylene Acid Terpolymers with Relatively
High Levels of Neutralization Base Resin Properties HNP Properties
% Acid/ % Fatty/ % Atti Sphere Shore D HNP Ex # Resin Type/% Ester
Type Neut. Comp CoR Sphere Plaque MI 43 R-10 15.4% AA/8% nBA 30%
oleic 114% 117 0.870 53.6 -- 0.29 44 R-10 15.4% AA/8% nBA 39.8%
oleic 138% 111 0.875 48.3 -- 0.75 45 R-10 15.4% AA/8% nBA 36.5%
oleic 142% 101 0.875 49.6 -- 0.21 46 R-1 12% AA/17.6% nBA 36.5%
oleic 135% 118 0.868 47.7 -- 0.35 47 R-3 10.5% AA/15.5% 35% oleic
102% 101 0.859 45.8 -- 1 nBA 48 R-3 10.5% AA/15.5% 34.9% oleic 124%
82 0.850 47.8 -- 0.91 nBA 49 R-3 10.5% AA/15.5% 37.5% oleic 127% 75
0.850 48.6 -- 1.05 nBA 50 R-13 9% MAA/15.5% nBA 35.1% oleic 120% 62
0.817 39.2 -- 3.68 51 R-13 9% MAA/15.5% nBA 38.7% erucic 125% 57
0.817 36.4 -- 7.74 52 R-4 6.2% AA/28% nBA 35% oleic 145% 75 0.826
41.8 -- 1 53 R-4 6.2% AA/28% nBA 35% oleic 124% 51 0.807 35.8 --
2.63 54 R-4 6.2% AA/28% nBA 39.8% erucic 121% 41 0.805 33.6 -- 5.94
55 R-5 6.2% AA/28% nBA 35% oleic 115% NA NA NA NA NA HPF 1000 9%
AA/15.5% nBA ~40% St.A ~100 110 0.833 55 52 -- HPF 2000 10.5%
AA/15.5% ~40% oleic acid ~100 123 0.863 47 -- -- nBA AD 1030 NA NA
~100 73 0.824 -- -- -- AD 1035 NA NA ~100 66 0.826 -- -- -- AD 1040
NA NA ~100 123 0.852 -- -- -- R-1: An ethylene/acrylic acid
(AA)/n-butyl acrylate (nBA) terpolymer with 12 weight % of AA and
17.6 weight % of nBA, and a Melt Index of 95. R-3: An
ethylene/AA/nBA terpolymer with 10.5 weight % of AA and 15.5 weight
% of nBA, and a Melt Index of 60. R-4: An ethylene/AA/nBA
terpolymer with 6.2 weight % of AA and 28.0 weight % of nBA, and a
Melt Index of 60. R-5: An ethylene/AA/nBA terpolymer with 6.2
weight % of AA and 28.0 weight % of nBA, and a Melt Index of 300.
R-10: An ethylene/AA/nBA terpolymer with 15.4 weight % of AA and
8.0 weight % of nBA, and a Melt Index of 300. R-13: An
ethylene/MAA/nBA terpolymer with 9.0 weight % of MAA and 15.5
weight % of nBA, and a Melt Index of 60. HPF-1000, HPF-2000,
AD-1030, AD-1035, and AD-1040: formulations unavailable -
compositions are commercially available from DuPont.
[0040] The above-described ethylene acid copolymer compositions in
Tables III-V were prepared according to the following general
procedure. The organic acid, ethylene acid copolymer, and
neutralizing agent (Mg(OH).sub.2 concentrate) were melt-blended in
a Werner & Pfleiderer twin screw extruder. The amounts of the
acid and copolymer were added so that the resulting blend contained
25 to 45 weight % of the organic acid. The blend was treated with
sufficient neutralizing agent so that the acid moieties of the
organic acid and the acid copolymer were neutralized to the level
indicated in above Tables III-V.
[0041] The highly neutralized ethylene acid copolymer compositions
described in Tables IV-V have other physical properties, some of
which are described below in Table VI. In particular, the flex
modulus of some relatively highly neutralized ethylene acid
copolymers may fall within the range of about 1,000 to about 20,000
psi, preferably 3,000 to 10,000 in some instances. Such ionomer
compositions may be used to form a low modulus (or high modulus)
core layer in accordance with this invention.
TABLE-US-00006 TABLE VI Properties of Highly Neutralized Ethylene
Acid Copolymers (Flex Modulus of 5,000 PSI or Less) Tensile
Elongation Shore D Flex Modulus Resin Strength (psi)* (%)* Hardness
(psi)** HPF 1000 2,600 430% 55 31,000 HPF 2000 1,800 330% 47 12,000
*Tensile Strength and Elongation were measured according to ASTM
D638. *** Flex Modulus was measured according to ASTM D790.
[0042] Other highly neutralized ethylene acid copolymer
compositions, examples of which are described below in Table VII,
may be used in accordance with this invention. In particular, the
flex modulus of the relatively highly neutralized ethylene acid
copolymers may fall within the range of about 10,000 to about
80,000 psi, preferably 20,000 to 70,000 in some instances. Such
ionomer compositions may be used to form a low modulus (or high
modulus) core layer. Examples of suitable HNPs are further
described in Sullivan et al., U.S. Pat. No. 7,468,006, the
disclosure of which is hereby incorporated by reference.
TABLE-US-00007 TABLE VII Properties of Highly Neutralized Ethylene
Acid Copolymers (Flex Modulus of 10,000 PSI or Greater) Flex Cation
Fatty Modulus** Shore D Example Copolymer* Source Acid (psi)
Hardness*** 56 dipolymer Ca/Mg Stearic 71,600 57 57 dipolymer Ca/Li
Stearic 70,300 58 58 dipolymer Ca Stearic 70,100 60 59 dipolymer
Ca/Zn Stearic 60,400 58 60 terpolymer Mg Stearic 38,300 52 61
dipolymer Mg Oleic 27,600 52 62 terpolymer Mg Oleic 16,300 45 63
Terpolymer Mg Oleic 10,600 40 64 terpolymer Mg Oleic 10,400 39 65
dipolymer Ca Stearic 60,300 37 66 dipolymer Ca Stearic 69,300 60 67
terpolymer Mg Erucic 7,300 37 *Copolymer Type: dipolymer -
poly(ethylene-acrylic acid) terpolymer - Poly(ethylene-n-butyl
acrylate-acrylic acid) **Flex Modulus was measured according to
ASTM D790-03, Procedure B. ***Hardness was measured according to
ASTM D-2240.
[0043] Additional Materials in lonomer Compositions
[0044] In the present invention, it is not necessary that any
"ionic plasticizer" such as organic acids or salts of organic
acids, particularly fatty acids, be added to the ionomer resin.
Such ionic plasticizers are used to make conventional ionomer
composition more processable as described in Rajagopalan et al.,
U.S. Pat. No. 6,756,436, the disclosure of which is hereby
incorporated by reference. In the present invention such ionic
plasticizers are optional. In one preferred embodiment, the
thermoplastic ionomer composition, containing acid groups
neutralized to 70% or less, does not include a fatty acid or salt
thereof, or any other ionic plasticizer. On the other hand, the
thermoplastic ionomer composition, containing acid groups
neutralized to greater than 70%, includes an ionic plasticizer,
particularly a fatty acid or salt thereof. For example, the ionic
plasticizer may be added in an amount of 0.5 to 10 pph, more
preferably 1 to 5 pph. The organic acids may be aliphatic, mono- or
multi-functional (saturated, unsaturated, or multi-unsaturated)
organic acids. Salts of these organic acids may also be employed.
Suitable fatty acid salts include, for example, metal stearates,
laureates, oleates, palmitates, pelargonates, and the like. For
example, fatty acid salts such as zinc stearate, calcium stearate,
magnesium stearate, barium stearate, and the like can be used. The
salts of fatty acids are generally fatty acids neutralized with
metal ions. The metal cation salts provide the cations capable of
neutralizing (at varying levels) the carboxylic acid groups of the
fatty acids. Examples include the sulfate, carbonate, acetate and
hydroxide salts of metals such as barium, lithium, sodium, zinc,
bismuth, chromium, cobalt, copper, potassium, strontium, titanium,
tungsten, magnesium, cesium, iron, nickel, silver, aluminum, tin,
or calcium, and blends thereof. It is preferred the organic acids
and salts be relatively non-migratory (they do not bloom to the
surface of the polymer under ambient temperatures) and non-volatile
(they do not volatilize at temperatures required for
melt-blending).
[0045] The final ionomeric compositions of this invention may
contain additional materials such as, for example, a small amount
of ionic plasticizer, which is particularly effective at improving
the processability of highly-neutralized ionomers. For example, the
ionic plasticizer may be added in an amount of 0.5 to 10 pph, more
preferably 1 to 5 pph. In addition to the fatty acids and salts of
fatty acids discussed above, other suitable ionic plasticizers
include, for example, polyethylene glycols, waxes, bis-stearamides,
minerals, and phthalates. In another embodiment, an amine or
pyridine compound is used, preferably in addition to a metal
cation. Suitable examples include, for example, ethylamine,
methylamine, diethylamine, tert-butylamine, dodecylamine, and the
like.
[0046] Fillers, fibers, flakes also may be included in the final
ionomeric composition. 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.
[0047] Other additives and fillers include, but are not limited to,
chemical blowing and foaming agents, optical brighteners, coloring
agents, fluorescent agents, whitening agents, UV absorbers, light
stabilizers, defoaming agents, processing aids, antioxidants,
stabilizers, softening agents, fragrance components, plasticizers,
impact modifiers, TiO.sub.2, acid copolymer wax, surfactants, and
fillers, such as zinc oxide, tin oxide, barium sulfate, zinc
sulfate, calcium oxide, calcium carbonate, zinc carbonate, barium
carbonate, tungsten, tungsten carbide, silica, lead silicate,
regrind (recycled material), clay, mica, talc, nano-fillers, carbon
black, glass flake, milled glass, and mixtures thereof. Suitable
additives are more fully described in, for example, Rajagopalan et
al., U.S. Patent Application Publication No. 2003/0225197, the
entire disclosure of which is hereby incorporated herein by
reference. In a particular embodiment, the total amount of
additive(s) and filler(s) present in the final thermoplastic
ionomeric composition is 15 wt % or less, or 12 wt % or less, or 10
wt % or less, or 9 wt % or less, or 6 wt % or less, or 5 wt % or
less, or 4 wt % or less, or 3 wt % or less, based on the total
weight of the ionomeric composition. In a particular aspect of this
embodiment, the final thermoplastic ionomeric composition includes
filler(s) selected from carbon black, nanoclays (e.g.,
Cloisite.RTM. and Nanofil.RTM. nanoclays, commercially available
from Southern Clay Products, Inc., and Nanomax.RTM. and
Nanomer.RTM. nanoclays, commercially available from Nanocor, Inc.),
talc (e.g., Luzenac HAR.RTM. high aspect ratio talcs, commercially
available from Luzenac America, Inc.), glass (e.g., glass flake,
milled glass, and microglass), mica and mica-based pigments (e.g.,
Iriodin.RTM. pearl luster pigments, commercially available from The
Merck Group), and combinations thereof. In a particular embodiment,
the final thermoplastic ionomeric composition is modified with
organic fiber micropulp, as disclosed, for example, in Chen, U.S.
Pat. No. 7,504,448, the entire disclosure of which is hereby
incorporated herein by reference. In another version, the ionomer
compositions may contain carbon fibers or carbon fiber sheets
comprising a weave of thin carbon fibers held together in a resin.
In yet another version, the ionomer compositions may contain forged
composite material composed of bundles of microscopic carbon fibers
held together in a resin. These turbostratic carbon fibers are
randomly dispersed in the resin. The structure of the forged
composite material differs over traditional carbon fiber sheets.
The forged composite material contains discontinuous fibers
intertwined in the resin; while ordinary carbon fiber sheets are
woven--they contain a weave of fibers. As a result, the forged
composite material is very lightweight and has high mechanical
strength.
[0048] Other suitable thermoplastic polymers that may be included
in the final ionomer composition of this invention include, but are
not limited to, the following polymers (including homopolymers,
copolymers, and derivatives thereof.)
[0049] (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;
[0050] (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;
[0051] (c) polyurethanes, polyureas, polyurethane-polyurea hybrids,
and blends of two or more thereof;
[0052] (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;
[0053] (e) polystyrenes, such as poly(styrene-co-maleic anhydride),
acrylonitrile-butadiene-styrene, poly(styrene sulfonate),
polyethylene styrene, and blends of two or more thereof;
[0054] (f) polyvinyl chlorides and grafted polyvinyl chlorides, and
blends of two or more thereof;
[0055] (g) polycarbonates, blends of
polycarbonate/acrylonitrile-butadiene-styrene, blends of
polycarbonate/polyurethane, blends of polycarbonate/polyester, and
blends of two or more thereof;
[0056] (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;
[0057] (i) polyimides, polyetherketones, polyamideimides, and
blends of two or more thereof; and
[0058] (j) polycarbonate/polyester copolymers and blends.
[0059] Furthermore, the resulting thermoplastic ionomer composition
may contain natural and synthetic rubbers such as, for example,
polybutadiene, polyisoprene, ethylene propylene rubber (EPR),
ethylene propylene diene rubber (EPDM), 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), polyalkenamers such as, for example,
polyoctenamer, butyl rubber, halobutyl rubber, and polystyrene
elastomers.
[0060] The ionomer compositions may contain a blend of two or more
ionomers. For example, the composition may contain a 50/50 wt. %
blend of two different highly-neutralized ethylene/methacrylic acid
copolymers. In another version, the composition may contain a blend
of one or more ionomers and a maleic anhydride-grafted
non-ionomeric polymer. The non-ionomeric polymer may be a
metallocene-catalyzed polymer. In another version, the composition
contains a blend of a highly-neutralized ethylene/methacrylic acid
copolymer and a maleic anhydride-grafted metallocene-catalyzed
polyethylene. In yet another version, the composition contains a
material 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.
[0061] In accordance with the present invention, golf balls
containing dual-cores formed from thermoplastic ionomer
compositions containing acid groups neutralized to 70% or less and
thermoplastic ionomer compositions containing acid groups
neutralized to greater than 70% have several advantageous
properties. For example, the ionomer compositions can be used to
make a dual-core that provides the golf ball with good rebounding
properties (distance) without sacrificing a nice feel to the ball.
The resulting ball has a relatively high COR allowing it to reach
high velocity when struck by a golf club. Thus, the ball tends to
travel a greater distance which is particularly important for
driver shots off the tee. At the same time, the ionomer composition
is not excessively hard and it helps provide the ball with a soft
and comfortable feel. The golf player experiences a better sense of
control and natural feeling ball when making the shot. In general,
the cores of this invention typically have a COR of about 0.76 or
greater; and preferably about 0.80 or greater. The compression of
the core preferably is about 50 to about 130 and more preferably in
the range of about 70 to about 110.
[0062] Core Structure
[0063] As discussed above, the core is preferably a dual-core
comprising an inner core (center) and surrounding outer core layer.
In one preferred embodiment, the inner core is formed from a first
ionomer composition comprising an ethylene acid copolymer
containing acid groups such that the acid groups are neutralized to
70% or less; and an outer core layer formed from a second ionomer
composition comprising an ethylene acid copolymer containing acid
groups such that the acid groups are neutralized to greater than
70%. In a second preferred embodiment, the relatively highly
neutralized ionomer composition (acid groups neutralized to greater
than 70%) is used to form the inner core; and the relatively lowly
neutralized ionomer composition (acid groups neutralized to 70% or
less) is used to form the outer core.
[0064] Preferably, the inner core has a center hardness (CH) within
a range having a lower limit of 20 or 25 or 30 or 35 or 40 or 45 or
50 or 55 Shore D and an upper limit of 60 or 65 or 70 or 75 or 80
or 85 or 90 Shore D. The inner core (center) also preferably has a
surface hardness (ICSH) within a range having a lower limit of 20
or 25 or 30 or 35 or 40 or 45 or 50 or 55 Shore D and an upper
limit of 60 or 65 or 70 or 75 or 80 or 85 or 90 Shore D. Meanwhile,
the outer core layer preferably has a surface hardness (OCLSH)
within a range having a lower limit of 20 or 25 or 30 or 35 or 40
or 45 or 50 or 55 Shore D and an upper limit of 60 or 65 or 70 or
75 or 80 or 85 or 90 Shore D. In one embodiment, the surface
hardness of the outer core layer is greater than the center
hardness of the inner core. In an alternative embodiment, the
center hardness of the inner core is greater than the surface
hardness of the outer core layer.
[0065] Particularly, in one preferred instance, the center hardness
of the inner core is in the range of about 25 to about 82 Shore D
units and the surface hardness of the outer core is in the range of
about 30 to about 87 Shore C units. More particularly, the center
hardness of the inner core is about 25 Shore D units or greater and
the surface hardness of the outer core is about 40 Shore D units or
greater. In these instances, the surface hardness (outer core) is
preferably at least 5 Shore D units greater than the center
hardness (inner core).
[0066] In another instance, the center hardness of the inner core
is about 40 Shore D units or greater and the surface hardness of
the outer core is about 25 Shore D units or greater. In these
instances, the center hardness (inner core) is preferably at least
5 Shore D units greater than the surface hardness (outer core).
[0067] In one preferred golf ball, the inner core (center) has a
"positive" hardness gradient (that is, the outer surface of the
inner core is harder than its geometric center) and the outer core
layer has a "positive" hardness gradient (that is, the outer
surface of the outer core layer is harder than the inner surface of
the outer core layer.) In cases where both the inner core and outer
core layer have "positive" hardness gradients, the outer surface
hardness of the outer core layer is still preferably greater than
the material hardness of the inner core (center).
[0068] In another version, the inner core (center) has a positive
hardness gradient, while the outer core layer has a "negative"
hardness gradient (that is, the outer surface of the outer core
layer is softer than the inner surface of the outer core layer.) In
yet another version, the outer core layer may have a "zero"
hardness gradient. (That is, the hardness values of the outer
surface of the outer core layer and the inner surface of the outer
core layer are substantially the same.) Particularly, the term,
"zero hardness gradient" as used herein, means a surface to center
(or second surface) Shore C hardness gradient of less than 8,
preferably less than 5 and most preferably less than 3 and may have
a value of zero or negative 1 to negative 25. The term, "negative
hardness gradient" as used herein, means a surface to center (or
second surface) Shore C hardness gradient of less than zero. The
terms, "zero hardness gradient" and "negative hardness gradient,"
may be used herein interchangeably to refer to hardness gradients
of negative 1 to negative 25. The term, "positive hardness
gradient" as used herein, means a surface to center (or second
surface) Shore C hardness gradient of 8 or greater, preferably 10
or greater, and most preferably 20 or greater. By the term, "steep
positive hardness gradient" as used herein, it is meant surface to
center (or second surface) Shore C hardness gradient of 20 or
greater, more preferably 25 or greater, and most preferably 30 or
greater. For example, the core may have a steep positive hardness
gradient of 35, 40, or 45 Shore C or greater.
[0069] Preferably, the hardness gradient from geometric center of
the inner core to the surface of the outer core layer is a positive
hardness gradient. That is, the outer surface of the outer core
layer is harder than the center of the inner core. Methods for
measuring the hardness of the core and cover layers and determining
the hardness gradients are discussed in further detail below.
[0070] As discussed above, the dual-core constitutes an inner core
(center) and an outer core layer. The inner core preferably has a
diameter within a range having a lower limit of 0.45 or 0.50 or
0.60 or 0.75 or 0.85 or 0.875 inches and an upper limit of 1.125 or
1.15 or 1.39 or 1.55 inches. The outer core layer encloses the
inner core such that the two-layered core has an overall diameter
within a range having a lower limit of 1.20 or 1.30 or 1.40 or 1.50
or 1.51 or 1.52 or 1.525 inches and an upper limit of 1.54 or 1.55
or 1.555 or 1.56 or 1.59 or 1.62 or 1.64 inches.
[0071] The inner core or center preferably has a compression within
a range having a lower limit of 10 or less, 20 or less, 30 or less,
40 or less, 50 or less; and an upper limit of 55 or greater, 65 or
greater, 75 or greater, 80 or greater, 90 or greater, 100 or
greater, 110 or greater, 120 or greater, 130 or greater, or 150 or
greater.
[0072] Cover Structure
[0073] The golf ball cores of this invention may be enclosed with
one or more cover layers. A wide variety of materials may be used
for forming the outer cover including, for example, polyurethanes;
polyureas; copolymers, blends and hybrids of polyurethane and
polyurea; ethylene acid copolymer ionomer resins (for example,
Surlyn.RTM. ionomer resins and HPF.RTM. 1000 and HPF.RTM. 2000,
commercially available from DuPont; lotek.RTM. ionomers,
commercially available from ExxonMobil Chemical Company;
Amplify.RTM. IO ionomers of ethylene acrylic acid copolymers,
commercially available from The Dow Chemical Company; and
.sup.Clarix.RTM. ionomer resins, commercially available from A.
Schulman Inc.); polyethylene, including, for example, low density
polyethylene, linear low density polyethylene, and high density
polyethylene; polypropylene; rubber-toughened olefin polymers; acid
copolymers, for example, poly(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; copolymers of ethylene and vinyl acetates;
copolymers of ethylene and methyl acrylates; polyvinyl chloride
resins; polyamides, poly(amide-ester) elastomers, and graft
copolymers of ionomer and polyamide including, for example,
Pebax.RTM. thermoplastic polyether block amides, commercially
available from Arkema Inc; cross-linked trans-polyisoprene and
blends thereof; polyester-based thermoplastic elastomers, such as
Hytrel.RTM., commercially available from DuPont; polyurethane-based
thermoplastic elastomers, such as Elastollan.RTM., commercially
available from BASF; synthetic or natural vulcanized rubber; and
combinations thereof. Castable polyurethanes, polyureas, and
hybrids of polyurethanes-polyureas are particularly desirable
because these materials can be used to help make a golf ball having
high resiliency and a soft feel. By the term, "hybrids of
polyurethane and polyurea," it is meant to include copolymers and
blends thereof.
[0074] Polyurethanes, polyureas, and blends, copolymers, 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.
[0075] In one preferred embodiment, the ball includes a dual-cover
comprising inner and outer cover layers. The inner cover layer is
preferably formed from a composition comprising an ionomer or a
blend of two or more ionomers that helps impart hardness to the
ball. The inner cover layer preferably has a material hardness of
95 Shore C or less, or less than 95 Shore C, or 92 Shore C or less,
or 90 Shore C or less, or a material hardness within a range having
a lower limit of 60 or 65 or 70 or 75 or 80 or 84 or 85 Shore C and
an upper limit of 90 or 92 or 95 Shore C. The thickness of the
inner cover layer is preferably within a range having a lower limit
of 0.010 or 0.015 or 0.020 or 0.030 inches and an upper limit of
0.035 or 0.045 or 0.080 or 0.120 inches. The outer cover layer
preferably has a material hardness of 85 Shore C or less. The
thickness of the outer cover layer is preferably within a range
having a lower limit of 0.010 or 0.015 or 0.025 inches and an upper
limit of 0.035 or 0.040 or 0.055 or 0.080 inches.
[0076] In a particular embodiment, the inner cover layer is formed
from a composition comprising a high acid ionomer. A particularly
suitable high acid ionomer is Surlyn 8150.RTM. (DuPont). Surlyn
8150.RTM. is a copolymer of ethylene and methacrylic acid, having
an acid content of 19 wt %, which is 45% neutralized with sodium.
In another particular embodiment, the inner cover layer is formed
from a composition comprising a high acid ionomer and a maleic
anhydride-grafted non-ionomeric polymer. A particularly suitable
maleic anhydride-grafted polymer is Fusabond 525D.RTM. (DuPont),
which is a maleic anhydride-grafted, metallocene-catalyzed
ethylene-butene copolymer having about 0.9 wt % maleic anhydride
grafted onto the copolymer. A particularly preferred blend of high
acid ionomer and maleic anhydride-grafted polymer is a 84 wt %/16
wt % blend of Surlyn 8150.RTM. and Fusabond 525D.RTM.. Blends of
high acid ionomers with maleic anhydride-grafted polymers are
further disclosed, for example, in U.S. Pat. Nos. 6,992,135 and
6,677,401, the entire disclosures of which are hereby incorporated
herein by reference.
[0077] In one embodiment, the inner cover layer is formed from a
composition comprising a 50/45/5 blend of Surlyn.RTM.
8940/Surlyn.RTM. 9650/Nucrel.RTM. 960, and, in a particularly
preferred embodiment, has a material hardness of from 80 to 85
Shore C. In another particular embodiment, the inner cover layer is
formed from a composition comprising a 50/25/25 blend of
Surlyn.RTM. 8940/Surlyn.RTM. 9650/Surlyn.RTM. 9910, preferably
having a material hardness of about 90 Shore C. In another version,
a blend of 50% Surlyn.RTM. 7940 and 50% Surlyn.RTM. 8940 is used to
form the inner cover. In yet another particular embodiment, the
inner cover layer is preferably formed from a composition
comprising a 50/50 blend of Surlyn.RTM. 8940/Surlyn.RTM. 9650,
preferably having a material hardness of about 86 Shore C.
Surlyn.RTM. 8940 is an ethylene/methacrylic acid copolymer in which
the MAA acid groups have been partially neutralized with sodium
ions. Surlyn.RTM. 9650 and Surlyn.RTM. 9910 are two different
grades of ethylene/methacrylic acid copolymer in which the MAA acid
groups have been partially neutralized with zinc ions. Surlyn.RTM.
7940 is a copolymer of about 85% ethylene and 15% methacrylic acid
that has been neutralized with lithium ions. Nucrel.RTM. 960 is an
ethylene/methacrylic acid copolymer resin nominally made with 15 wt
% methacrylic acid, and available from DuPont.
[0078] As discussed above, the dual-core of the golf ball may be
enclosed with a single-layered or multi-layered covers. In one
embodiment, a single-layered cover having a thickness in the range
of about 0.020 to about 0.090 inches, more preferably about 0.030
to about 0.070 inches, is formed. The cover has a hardness of about
Shore D 80 or less, more preferably 70 or less, and most preferably
about 60 or less. In another embodiment, a multi-layered cover
comprising inner and outer cover layers is formed, where the inner
cover layer has a thickness of about 0.01 inches to about 0.06
inches, more preferably about 0.015 inches to about 0.040 inches,
and most preferably about 0.02 inches to about 0.035 inches. In
this version, the inner cover layer is formed from a partially- or
fully-neutralized ionomer having a Shore D hardness of greater than
about 55, more preferably greater than about 60, and most
preferably greater than about 65. The outer cover layer, in this
embodiment, preferably has a thickness of about 0.015 inches to
about 0.055 inches, more preferably about 0.02 inches to about 0.04
inches, and most preferably about 0.025 inches to about 0.035
inches, with a hardness of about Shore D 80 or less, more
preferably 70 or less, and most preferably about 60 or less. The
inner cover layer is harder than the outer cover layer in this
version. A preferred outer cover layer is a castable or reaction
injection molded polyurethane, polyurea or copolymer, blend, or
hybrid thereof having a Shore D hardness of about 40 to about 50.
In another multi-layer cover, dual-core embodiment, the outer cover
and inner cover layer materials and thickness are the same but, the
hardness range is reversed, that is, the outer cover layer is
harder than the inner cover layer.
[0079] Golf Ball Constructions
[0080] As discussed above, the thermoplastic ionomer compositions
of this invention may be used to form a core for any suitable ball
construction, including, for example, three-piece, four-piece, and
five-piece designs.
[0081] The core and cover compositions may be prepared using
conventional mixing techniques. The core composition can be formed
into an inner core structure by ordinary techniques such as, for
example, injection or compression molding. After molding, the core
structure is removed from the mold and its surface may be treated
using techniques such as corona discharge, sand blasting, or
grinding to improve adhesion of the surrounding layers. Injection
molding or compression molding can be used to form an outer core
layer and inner cover layer about the inner core to produce an
intermediate golf ball. The cover layer(s) is subsequently molded
over the inner/outer core to produce a final golf ball.
[0082] In compression molding, the outer core and/or inner cover
composition is formed into smooth surfaced hemispherical shells
which are then positioned around the inner core in a mold having
the desired inner cover thickness and subjected to compression
molding under heat followed by cooling. This process fuses the
shells together to form a unitary intermediate ball. Alternatively,
the intermediate balls may be produced by injection molding,
wherein the outer core and/or inner cover layer is injected
directly around the core placed at the center of an intermediate
ball mold under heat and pressure. After molding, the golf balls
produced may undergo various further processing steps such as
buffing, painting and marking using conventional techniques.
[0083] Referring to FIG. 1, one version of a golf ball that can be
made in accordance with this invention is generally indicated at
(6). The ball (6) contains a dual-core (8) having an inner core
(center) (8a) and outer core layer (8b) surrounded by a
single-layered cover (10). The center (8a) is formed from a first
ionomer composition containing acid groups neutralized to 70% or
less. The outer core layer (8b) is formed from a second ionomer
composition containing acid groups neutralized to greater than 70%.
In FIG. 2, a golf ball (11) containing the above-described
dual-core (8) is surrounded by a dual-cover (12) having an inner
cover layer (12a) and outer cover layer (12b), which may be formed
from any of the cover materials described above. Referring to FIG.
3, in another version, the golf ball (14) contains a dual-core (16)
having an inner core (center) (16a) and outer core layer (16b)
surrounded by a single-layered cover (18). The center (16a) is
formed from a first ionomer composition containing acid groups
neutralized to greater than 70%. The outer core layer (16b) is
formed from a second ionomer composition containing acid groups
neutralized to 70% or less. In FIG. 4, a golf ball (19) containing
the above-described dual-core (16) is surrounded by a dual-cover
(20) having an inner cover layer (20a) and outer cover layer
(20b),
[0084] The surfaces of the golf balls shown in FIGS. 1-4 may have
various dimple patterns to modify the aerodynamic properties of the
ball. It should be understood the golf balls shown in FIGS. 1-4 are
for illustrative purposes only and not meant to be restrictive.
Other golf ball constructions can be made in accordance with this
invention.
[0085] For example, a golf ball containing an inner core (center);
an intermediate core layer; and an outer core layer may be made.
The center preferably has a diameter within a range having a lower
limit of 0.100 or 0.125 or 0.250 inches and an upper limit of 0.375
or 0.500 or 0.750 or 1.00 inches. The intermediate core layer
preferably has a thickness within a range having a lower limit of
0.050 or 0.100 or 0.150 or 0.200 inches and an upper limit of 0.300
or 0.350 or 0.400 or 0.500 inches. The outer core layer encloses
the center and intermediate core layer structure such that the
multi-layer core has an overall diameter within a range having a
lower limit of 1.40 or 1.45 or 1.50 or 1.55 inches and an upper
limit of 1.58 or 1.60 or 1.62 or 1.66 inches.
[0086] In one embodiment, the center is made of a rubber material
such as, for example, polybutadiene, polyisoprene, ethylene
propylene rubber (EPR), ethylene propylene diene rubber (EPDM),
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), polyalkenamers
such as, for example, polyoctenamer, butyl rubber, halobutyl
rubber, and polystyrene elastomers; b) the intermediate core layer
is made of a first ionomer composition containing acid groups
neutralized to 70% or less; and c) the outer core layer is made of
a second ionomer composition containing acid groups neutralized to
greater than 70%.
[0087] In one embodiment, the center has an outer surface hardness
of 70 Shore C or greater, more preferably a surface hardness of 80
Shore C or greater, and most preferably a surface hardness of 85
Shore C or greater. For example, the center may have an outer
surface hardness within a range having a lower limit of 70 or 75 or
80 Shore C and an upper limit of 90 or 95 Shore C. The outer core
layer may have an outer surface hardness that is less than that of
the center and is preferably 50 Shore C or less; or 60 Shore C or
less; or 70 Shore C or less; or 75 Shore C or less; or 80 Shore C
or less. The intermediate layer preferably has an outer surface
greater than that of the center and outer core layer. Preferably,
the intermediate layer has a surface hardness of 80 Shore C or
greater.
[0088] In another embodiment, the center is made of a rubber
material as described above; b) the intermediate core layer is made
of a first ionomer composition containing acid groups neutralized
to greater than 70%; and c) the outer core layer is made of a
second ionomer composition containing acid groups neutralized to
70% or less.
[0089] It is recognized that additional golf ball constructions can
be made without departing from the spirit and scope of the present
invention. For example, in one version, the inner core is made of a
first ionomer composition containing acid groups neutralized to 70%
or less; b) the intermediate core layer is made of a second ionomer
composition containing acid groups neutralized to greater than 70%;
and c) the outer core layer is made of a rubber material as
described above. In yet another version, the inner core is made of
a first ionomer composition containing acid groups neutralized to
greater than 70%; b) the intermediate core layer is made of a
second ionomer composition containing acid groups neutralized to
70% or less; and c) the outer core layer is made of a rubber
material as described above.
[0090] Test Methods
[0091] Hardness. 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.
[0092] The outer surface hardness of a golf ball layer is measured
on the actual outer surface of the layer and 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
ensure that the golf ball or golf ball subassembly is centered
under the durometer indenter before a surface hardness reading is
obtained. A calibrated, digital durometer, capable of reading to
0.1 hardness units is used for the hardness measurements. 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 conforms to ASTM D-2240.
[0093] In certain embodiments, a point or plurality of points
measured along the "positive" or "negative" gradients may be above
or below a line fit through the gradient and its outermost and
innermost hardness values. In an alternative preferred embodiment,
the hardest point along a particular steep "positive" or "negative"
gradient may be higher than the value at the innermost portion of
the inner core (the geometric center) or outer core layer (the
inner surface)-as long as the outermost point (i.e., the outer
surface of the inner core) is greater than (for "positive") or
lower than (for "negative") the innermost point (i.e., the
geometric center of the inner core or the inner surface of the
outer core layer), such that the "positive" and "negative"
gradients remain intact.
[0094] As discussed above, the direction of the hardness gradient
of a golf ball layer is defined by the difference in hardness
measurements taken at the outer and inner surfaces of a particular
layer. The center hardness of an inner core and hardness of the
outer surface of an inner core in a single-core ball or outer core
layer are readily determined according to the test procedures
provided above. The outer surface of the inner core layer (or other
optional intermediate core layers) in a dual-core ball are also
readily determined according to the procedures given herein for
measuring the outer surface hardness of a golf ball layer, if the
measurement is made prior to surrounding the layer with an
additional core layer. Once an additional core layer surrounds a
layer of interest, the hardness of the inner and outer surfaces of
any inner or intermediate layers can be difficult to determine.
Therefore, for purposes of the present invention, when the hardness
of the inner or outer surface of a core layer is needed after the
inner layer has been surrounded with another core layer, the test
procedure described above for measuring a point located 1 mm from
an interface is used.
[0095] Also, 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 invention,
material hardness is measured according to ASTM D2240 and generally
involves measuring the hardness of a flat "slab" or "button" formed
of the material. Surface hardness as measured directly on a golf
ball (or other spherical surface) typically results in a different
hardness value. The difference in "surface hardness" and "material
hardness" values is due to several factors including, but not
limited to, ball construction (that is, core type, number of cores
and/or cover layers, and the like); ball (or sphere) diameter; and
the material composition of adjacent layers. It also should be
understood that the two measurement techniques are not linearly
related and, therefore, one hardness value cannot easily be
correlated to the other. Shore hardness (for example, Shore C or
Shore D hardness) was measured according to the test method ASTM
D-2240.
[0096] Compression. As disclosed in Jeff Dalton's Compression by
Any Other Name, Science and Golf IV, Proceedings of the World
Scientific Congress of Golf (Eric Thain ed., Routledge, 2002) ("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 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. 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 J. Dalton.
Compression may be measured as described in McNamara et al., U.S.
Pat. No. 7,777,871, the disclosure of which is hereby incorporated
by reference.
[0097] Coefficient of Restitution ("COR"). The COR is determined
according to a known procedure, wherein a golf ball or golf ball
subassembly (for example, a golf ball core) is fired from an air
cannon at two given velocities and a velocity of 125 ft/s is used
for the calculations. Ballistic light screens are located between
the air cannon and 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 ball's time period at each light screen
is measured. This provides an incoming transit time period which is
inversely proportional to the ball's incoming velocity. The ball
makes impact with the steel plate and rebounds so it passes again
through the light screens. As the rebounding ball activates each
light screen, the ball's time period at each screen is measured.
This provides an outgoing transit time period which is inversely
proportional to the ball's outgoing velocity. The COR is then
calculated as the ratio of the ball's outgoing transit time period
to the ball's incoming transit time period
(COR=V.sub.out/V.sub.in=T.sub.in/T.sub.out).
[0098] When numerical lower limits and numerical upper limits are
set forth herein, it is contemplated that any combination of these
values may be used. Other than in the operating examples, or unless
otherwise expressly specified, all of the numerical ranges,
amounts, values and percentages such as those for amounts of
materials and others in the specification may be read as if
prefaced by the word "about" even though the term "about" may not
expressly appear with the value, amount or range. Accordingly,
unless indicated to the contrary, the numerical parameters set
forth in the specification and attached claims are approximations
that may vary depending upon the desired properties sought to be
obtained by the present invention.
[0099] 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.
[0100] It is understood that the compositions and golf ball
products described and illustrated herein represent only some
embodiments of the invention. It is appreciated by those skilled in
the art that various changes and additions can be made to
compositions and products without departing from the spirit and
scope of this invention. It is intended that all such embodiments
be covered by the appended claims.
* * * * *