U.S. patent application number 15/197988 was filed with the patent office on 2016-10-20 for golf balls having a foam center.
This patent application is currently assigned to Acushnet Company. The applicant listed for this patent is Acushnet Company. Invention is credited to Steven Aoyama, Mark L. Binette, Michael J. Sullivan.
Application Number | 20160303430 15/197988 |
Document ID | / |
Family ID | 53173868 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160303430 |
Kind Code |
A1 |
Sullivan; Michael J. ; et
al. |
October 20, 2016 |
GOLF BALLS HAVING A FOAM CENTER
Abstract
Large diameter golf balls having a foam core are provided.
Inventors: |
Sullivan; Michael J.; (Old
Lyme, CT) ; Binette; Mark L.; (Mattapoisett, MA)
; Aoyama; Steven; (Marion, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Acushnet Company |
Fairhaven |
MA |
US |
|
|
Assignee: |
Acushnet Company
Fairhaven
MA
|
Family ID: |
53173868 |
Appl. No.: |
15/197988 |
Filed: |
June 30, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14467089 |
Aug 25, 2014 |
9381403 |
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15197988 |
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14145648 |
Dec 31, 2013 |
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14467089 |
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14017979 |
Sep 4, 2013 |
9327166 |
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14145648 |
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13872354 |
Apr 29, 2013 |
9302156 |
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14017979 |
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13913670 |
Jun 10, 2013 |
9126083 |
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14145648 |
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13611376 |
Sep 12, 2012 |
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13913670 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A63B 37/0051 20130101;
A63B 37/0064 20130101; A63B 37/0024 20130101; A63B 37/0075
20130101; A63B 37/0092 20130101; A63B 37/0063 20130101; A63B
37/0039 20130101; A63B 37/0044 20130101; A63B 45/00 20130101; A63B
37/0091 20130101; A63B 37/0076 20130101; A63B 37/0058 20130101;
A63B 37/0045 20130101; A63B 37/06 20130101; A63B 37/008 20130101;
A63B 2037/065 20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00 |
Claims
1. A golf ball having a diameter of 1.70 inches or greater and
comprising: an inner core layer having a diameter of 1.60 inches or
greater and formed from a foamed polyurethane composition, the
inner core layer having an outer surface hardness (H.sub.inner core
surface) and a center hardness (H.sub.inner core center), the
H.sub.inner core surface being the same or less than the
H.sub.inner core center to provide a zero or negative hardness
gradient; and a cover layer formed from a composition comprising:
an acid copolymer of ethylene and an .alpha.,.beta.-unsaturated
carboxylic acid, optionally including a softening monomer selected
from the group consisting of alkyl acrylates and methacrylates; an
organic acid or salt thereof; a cation source present in an amount
sufficient to neutralize greater than 80% of all acid groups
present in the composition; and optionally a non-acid polymer
selected from the group consisting of polyolefins, polyamides,
polyesters, polyethers, polyurethanes, metallocene-catalyzed
polymers, single-site catalyst polymerized polymers, ethylene
propylene rubber, ethylene propylene diene rubber, styrenic block
copolymer rubbers, alkyl acrylate rubbers, and functionalized
derivatives thereof.
2. The golf ball of claim 1, wherein the golf ball has a diameter
of 1.80 inches or greater.
3. The golf ball of claim 1, wherein the golf ball has a diameter
of 2.00 inches or greater.
4. A golf ball having a diameter of greater than 1.70 inches and
comprising: an inner core layer having a diameter of 1.30 inches or
greater and formed from a foamed polyurethane composition, the
inner core layer having an outer surface hardness (H.sub.inner core
surface) and a center hardness (H.sub.inner core center), the
H.sub.inner core surface being greater than the H.sub.inner core
center to provide a positive hardness gradient; and an outer core
layer having a thickness of 0.20 inches or greater and formed from
a thermoset composition, the outer core layer having an outer
surface hardness (H.sub.outer surface of OC) and an inner surface
hardness (H.sub.inner surface of OC), the H.sub.outer surface of OC
being the same or less than the H.sub.inner surface of OC to
provide a zero or negative hardness gradient; and a cover
layer.
5. The golf ball of claim 4, wherein the golf ball has a diameter
of 1.80 inches or greater.
6. A golf ball having a diameter of greater than 1.70 inches and
comprising: an inner core layer having a diameter of 1.30 inches or
greater and formed from a foamed polyurethane composition, the
inner core layer having an outer surface hardness (H.sub.inner core
surface) and a center hardness (H.sub.inner core center), the
H.sub.inner core surface being the same or less than the
H.sub.inner core center to provide a zero or negative hardness
gradient; and an outer core layer having a thickness of 0.20 inches
or greater and formed from a thermoset composition, the outer core
layer having an outer surface hardness (H.sub.outer surface of OC)
and an inner surface hardness (H.sub.inner surface of OC), the
H.sub.outer surface of OC being greater than the H.sub.inner
surface of OC to provide a positive hardness gradient; and a cover
layer.
7. The golf ball of claim 6, wherein the golf ball has a diameter
of 1.80 inches or greater.
8. A golf ball having a diameter of greater than 1.70 inches and
comprising: an inner core layer having a diameter of 1.30 inches or
greater and formed from a foamed polyurethane composition, the
inner core layer having an outer surface hardness (H.sub.inner core
surface) and a center hardness (H.sub.inner core center), the
H.sub.inner core surface being the same or less than the
H.sub.inner core center to provide a zero or negative hardness
gradient; and an outer core layer having a thickness of 0.20 inches
or greater and formed from a thermoset composition, the outer core
layer having an outer surface hardness (H.sub.outer surface of OC)
and an inner surface hardness (H.sub.inner surface of OC), the
H.sub.outer surface of OC being the same or less than the
H.sub.inner surface of OC to provide a zero or negative hardness
gradient; and a cover layer.
9. The golf ball of claim 8, wherein the golf ball has a diameter
of 1.80 inches or greater.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 14/467,089, filed Aug. 25, 2014, which is a
continuation-in-part of U.S. patent application Ser. No.
14/145,648, filed Dec. 31, 2013, the entire disclosures of which
are hereby incorporated herein by reference.
[0002] U.S. patent application Ser. No. 14/145,648 is a
continuation-in-part of U.S. patent application Ser. No.
14/017,979, filed Sep. 4, 2013, now U.S. Pat. No. 9,327,166, which
is a continuation-in-part of U.S. patent application Ser. No.
13/872,354, filed Apr. 29, 2013, now U.S. Pat. No. 9,302,156, the
entire disclosures of which are hereby incorporated herein by
reference.
[0003] U.S. patent application Ser. No. 14/145,648 is also a
continuation-in-part of U.S. patent application Ser. No.
13/913,670, filed Jun. 10, 2013, now U.S. Pat. No. 9,126,083, the
entire disclosure of which is hereby incorporated herein by
reference.
[0004] U.S. patent application Ser. No. 14/145,648 is also a
continuation-in-part of U.S. patent application Ser. No.
13/611,376, filed Sep. 12, 2012, the entire disclosure of which is
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0005] The present invention relates generally to one-piece and
multi-piece golf balls having a solid core formed from a foamed
composition. Particularly, the core has a foamed inner core
(center) and optionally at least one outer core layer formed from a
thermoset or a thermoplastic composition.
BACKGROUND OF THE INVENTION
[0006] Both professional and amateur golfer use multi-piece, solid
golf balls today. Basically, a two-piece solid golf ball includes a
solid inner core protected by an outer cover. The inner core is
made of a natural or synthetic rubber such as polybutadiene,
styrene butadiene, or polyisoprene. The cover surrounds the inner
core and may be made of a variety of materials including ethylene
acid copolymer ionomers, polyamides, polyesters, polyurethanes, and
polyureas.
[0007] In recent years, three-piece, four-piece, and even
five-piece balls have become more popular. New manufacturing
technologies, lower material costs, and desirable ball playing
performance properties have contributed to these multi-piece balls
becoming more popular. Many golf balls used today have
multi-layered cores comprising an inner core and at least one
surrounding outer core layer. For example, the inner core may be
made of a relatively soft and resilient material, while the outer
core may be made of a harder and more rigid material. The
"dual-core" sub-assembly is encapsulated by a cover of at least one
layer to provide a final ball assembly. Different materials can be
used to manufacture the core and cover and impart desirable
properties to the final ball.
[0008] In general, dual-cores comprising an inner core (or center)
and a surrounding outer core layer are known in the industry. For
example, Sugimoto, U.S. Pat. No. 6,390,935 discloses a three-piece
golf ball comprising a core having a center and outer shell and a
cover disposed about the core. The specific gravity of the outer
shell is greater than the specific gravity of the center. The
center has a JIS-C hardness (X) at the center point thereof and a
JIS-C hardness (Y) at a surface thereof satisfying the equation:
(Y-X).gtoreq.8. The core structure (center and outer shell) has a
JIS-C hardness (Z) at a surface of 80 or greater. The cover has a
Shore D hardness of less than 60.
[0009] Endo, U.S. Pat. No. 6,520,872 discloses a three-piece golf
ball comprising a center, an intermediate layer formed over the
center, and a cover formed over the intermediate layer. The center
is preferably made of high-cis polybutadiene rubber; and the
intermediate and cover layers are preferably made of an ionomer
resin such as an ethylene acid copolymer.
[0010] Watanabe, U.S. Pat. No. 7,160,208 discloses a three-piece
golf ball comprising a rubber-based inner core; a rubber-based
outer core layer; and a polyurethane elastomer-based cover. The
inner core layer has a JIS-C hardness of 50 to 85; the outer core
layer has a JIS-C hardness of 70 to 90; and the cover has a Shore D
hardness of 46 to 55. Also, the inner core has a specific gravity
of more than 1.0, and the core outer layer has a specific gravity
equal to or greater than that of that of the inner core.
[0011] The core sub-structure located inside of the golf ball acts
as an engine or spring for the ball. Thus, the composition and
construction of the core is a key factor in determining the
resiliency and rebounding performance of the ball. In general, the
rebounding performance of the ball is determined by calculating its
initial velocity after being struck by the face of the 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 such conditions. Balls with a higher rebound
velocity have a higher COR value. Such golf balls rebound faster,
retain more total energy when struck with a club, and have longer
flight distance as opposed to balls with low COR values. These
properties are particularly important for long distance shots. For
example, balls having high resiliency and COR values tend to travel
a far distance when struck by a driver club from a tee.
[0012] The durability, spin rate, and feel of the ball also are
important properties. In general, the durability of the ball refers
to the impact-resistance of the ball. Balls having low durability
appear worn and damaged even when such balls are used only for
brief time periods. In some instances, the cover may be cracked or
torn. The spin rate refers to the ball's rate of rotation after it
is hit by a club. Balls having a relatively high spin rate are
advantageous for short distance shots made with irons and wedges.
Professional and highly skilled amateur golfers can place a back
spin more easily on such balls. This helps a player better control
the ball and improves shot accuracy and placement. By placing the
right amount of spin on the ball, the player can get the ball to
stop precisely on the green or place a fade on the ball during
approach shots. On the other hand, recreational players who cannot
intentionally control the spin of the ball when hitting it with a
club are less likely to use high spin balls. For such players, the
ball can spin sideways more easily and drift far-off the course,
especially if it is hooked or sliced. Meanwhile, the "feel" of the
ball generally refers to the sensation that a player experiences
when striking the ball with the club and it is a difficult property
to quantify. Most players prefer balls having a soft feel, because
the player experience a more natural and comfortable sensation when
their club face makes contact with these balls. Balls having a
softer feel are particularly desirable when making short shots
around the green, because the player senses more with such balls.
The feel of the ball primarily depends upon the hardness and
compression of the ball.
[0013] Manufacturers of golf balls are constantly looking to
different materials for improving the playing performance
properties of the ball. Different materials for constructing the
core have been considered over the years. For example, golf balls
containing cores made from foam compositions are generally known in
the industry. Puckett and Cadorniga, U.S. Pat. Nos. 4,836,552 and
4,839,116 disclose one-piece, short distance golf balls made of a
foam composition comprising a thermoplastic polymer (ethylene acid
copolymer ionomer such as Surlyn.RTM.) and filler material
(microscopic glass bubbles). The density of the composition
increases from the center to the surface of the ball. Thus, the
ball has relatively dense outer skin and a cellular inner core.
According to the '552 and '116 patents, by providing a short
distance golf ball, which will play approximately 50% of the
distance of a conventional golf ball, the land requirements for a
golf course can be reduced 67% to 50%.
[0014] Gentiluomo, U.S. Pat. No. 5,104,126 discloses a three-piece
golf ball (FIG. 2) containing a high density center (3) made of
steel, surrounded by an outer core (4) of low density resilient
syntactic foam composition, and encapsulated by an ethylene acid
copolymer ionomer (Surlyn.RTM.) cover (5). The '126 patent defines
the syntactic foam as being a low density composition consisting of
granulated cork or hollow spheres of either phenolic, epoxy,
ceramic or glass, dispersed within a resilient elastomer.
[0015] Aoyama, U.S. Pat. Nos. 5,688,192 and 5,823,889 disclose a
golf ball containing a core, wherein the core comprising an inner
and outer portion, and a cover made of a material such as balata
rubber or ethylene acid copolymer ionomer. The core is made by
foaming, injecting a compressible material, gasses, blowing agents,
or gas-containing microspheres into polybutadiene or other core
material. According to the '889 patent, polyurethane compositions
may be used. The compressible material, for example, gas-containing
compressible cells may be dispersed in a limited part of the core
so that the portion containing the compressible material has a
specific gravity of greater than 1.00. Alternatively, the
compressible material may be dispersed throughout the entire core.
In one embodiment, the core comprises an inner and outer portion.
In another embodiment, the core comprises inner and outer
layers.
[0016] Sullivan and Binette, U.S. Pat. No. 5,833,553 discloses a
golf ball having core with a coefficient of restitution of at least
0.650 and a cover with a thickness of at least 3.6 mm (0.142
inches) and a Shore D hardness of at least 60. According to the
'553 patent, the combination of a soft core with a thick, hard
cover results in a ball having better distance. The '553 patent
discloses that the core may be formed from a uniform composition or
may be a dual or multi-layer core, and it may be foamed or
unfoamed. Polybutadiene rubber, natural rubber, metallocene
catalyzed polyolefins, and polyurethanes are described as being
suitable materials for making the core.
[0017] Sullivan and Ladd, U.S. Pat. No. 6,688,991 discloses a golf
ball containing a low specific gravity core and an optional
intermediate layer. This sub-assembly is encased within a high
specific gravity cover with Shore D hardness in the range of about
40 to about 80. The core is preferably made from a highly
neutralized thermoplastic polymer such as ethylene acid copolymer
which has been foamed. The cover preferably has high specific
gravity fillers dispersed therein.
[0018] Nesbitt, U.S. Pat. No. 6,767,294 discloses a golf ball
comprising: i) a pressurized foamed inner center formed from a
thermoset material, a thermoplastic material, or combinations
thereof, a blowing agent and a cross-linking agent and, ii) an
outer core layer formed from a second thermoset material, a
thermoplastic material, or combinations thereof. Additionally, a
barrier resin or film can be applied over the outer core layer to
reduce the diffusion of the internal gas and pressure from the
nucleus (center and outer core layer). Preferred polymers for the
barrier layer have low permeability such as Saran.RTM. film (poly
(vinylidene chloride), Barex.RTM. resin (acyrlonitrile-co-methyl
acrylate), poly (vinyl alcohol), and PET film (polyethylene
terephthalate). The '294 patent does not disclose core layers
having different hardness gradients.
[0019] Sullivan, Ladd, and Hebert, U.S. Pat. No. 7,708,654
discloses a golf ball having a foamed intermediate layer. Referring
to FIG. 1 in the '654 patent, the golf ball includes a core (12),
an intermediate layer (14) made of a highly neutralized polymer
having a reduced specific gravity (less than 0.95), and a cover
(16). According to the '654 patent, the intermediate layer can be
an outer core, a mantle layer, or an inner cover. The reduction in
specific gravity of the intermediate layer is caused by foaming the
composition of the layer and this reduction can be as high as 30%.
The '654 patent discloses that other foamed compositions such as
foamed polyurethanes and polyureas may be used to form the
intermediate layer.
[0020] Tutmark, U.S. Pat. No. 8,272,971 is directed to golf balls
containing an element that reduces the distance of the ball's
flight path. In one embodiment, the ball includes a core and cover.
A cavity is formed between core and cover and this may be filled by
a foamed polyurethane "middle layer" in order to dampen the ball's
flight properties. The foam of the middle layer is relatively light
in weight; and the core is relatively heavy and dense. According to
the '971 patent, when a golfer strikes the ball with a club, the
foam in the middle layer actuates and compresses, thereby absorbing
much of the impact from the impact of the ball.
[0021] Although some foam core constructions for gold balls have
been considered over the years, there are drawbacks with using such
foam materials. For example, one disadvantage with golf balls
having a foam core is the ball tends to have low resiliency. That
is, the velocity of the ball tends to be low after being hit by a
club and the ball generally travels short distances. Golf balls
having foam inner cores are often referred to as reduced distance
balls. There is a need for new balls having a foam core with
improved resiliency that will allow players to generate higher
initial ball speed. This will allow players to make longer distance
shots. The present invention provides new foam core constructions
having improved resiliency as well as other advantageous
properties, features, and benefits. The invention also encompasses
golf balls containing the improved core constructions.
SUMMARY OF THE INVENTION
[0022] In one embodiment, the present invention is directed to a
golf ball having a diameter of 1.70 inches or greater and
comprising an inner core layer and a cover layer. The inner core
layer has a diameter of 1.60 inches or greater and is formed from a
foamed polyurethane composition. The cover layer is formed from a
composition comprising an acid copolymer of ethylene and an
.alpha.,.beta.-unsaturated carboxylic acid, optionally including a
softening monomer selected from the group consisting of alkyl
acrylates and methacrylates; an organic acid or salt thereof; a
cation source present in an amount sufficient to neutralize greater
than 80% of all acid groups present in the composition; and
optionally a non-acid polymer selected from the group consisting of
polyolefins, polyamides, polyesters, polyethers, polyurethanes,
metallocene-catalyzed polymers, single-site catalyst polymerized
polymers, ethylene propylene rubber, ethylene propylene diene
rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,
and functionalized derivatives thereof. In a particular aspect of
this embodiment, the inner core layer has an outer surface hardness
(H.sub.inner core surface) and a center hardness (H.sub.inner core
center), the H.sub.inner core surface being greater than the
H.sub.inner core center to provide a positive hardness gradient. In
another particular aspect of this embodiment, the inner core layer
has an outer surface hardness (H.sub.inner core surface) and a
center hardness (H.sub.inner core center), the H.sub.inner core
surface being the same or less than the H.sub.inner core center to
provide a zero or negative hardness gradient.
[0023] In another embodiment, the present invention is directed to
a golf ball having a diameter of greater than 1.70 inches and
comprising an inner core layer, an outer core layer, and a cover
layer. The inner core layer has a diameter of 1.30 or greater and
is formed from a foamed polyurethane composition. The outer core
layer has a thickness of 0.20 inches or greater and formed from a
thermoset composition.
[0024] In a particular aspect of this embodiment, the inner core
layer has an outer surface hardness (H.sub.inner core surface) and
a center hardness (H.sub.inner core center), the H.sub.inner core
surface being greater than the H.sub.inner core center to provide a
positive hardness gradient; and the outer core layer has an outer
surface hardness (H.sub.outer surface of OC) and an inner surface
hardness (H.sub.inner surface of OC), the H.sub.outer surface of OC
being greater than the H.sub.inner surface of OC to provide a
positive hardness gradient.
[0025] In another particular aspect of this embodiment, the inner
core layer has an outer surface hardness (H.sub.inner core surface)
and a center hardness (H.sub.inner core center), the H.sub.inner
core surface being greater than the H.sub.inner core center to
provide a positive hardness gradient; and the outer core layer has
an outer surface hardness (H.sub.outer surface of OC) and an inner
surface hardness (H.sub.inner surface of OC), the H.sub.outer
surface of OC being the same or less than the H.sub.inner surface
of OC to provide a zero or negative hardness gradient.
[0026] In another particular aspect of this embodiment, the inner
core layer has an outer surface hardness (H.sub.inner core surface)
and a center hardness (H.sub.inner core center), the H.sub.inner
core surface being the same or less than the H.sub.inner core
center to provide a zero or negative hardness gradient; and the
outer core layer has an outer surface hardness (H.sub.outer surface
of OC) and an inner surface hardness (H.sub.inner surface of OC),
the H.sub.outer surface of OC being greater than the H.sub.inner
surface of OC to provide a positive hardness gradient.
[0027] In another particular aspect of this embodiment, the inner
core layer has an outer surface hardness (H.sub.inner core surface)
and a center hardness (H.sub.inner core center), the H.sub.inner
core surface being the same or less than the H.sub.inner core
center to provide a zero or negative hardness gradient; and the
outer core layer has an outer surface hardness (H.sub.outer surface
of OC) and an inner surface hardness (H.sub.inner surface of OC),
the H.sub.outer surface of OC being the same or less than the
H.sub.inner surface of OC to provide a zero or negative hardness
gradient.
[0028] In another embodiment, the present invention is directed to
a core assembly for a golf ball comprising a foamed inner core
layer and an outer core layer. The inner core layer has a diameter
of from 0.100 inches to 1.100 inches. The outer core layer has a
thickness of from 0.100 inches to 0.750 inches. The specific
gravity of the outer core layer is greater than the specific
gravity of the inner core layer.
[0029] In a particular aspect of this embodiment, the inner core
layer has a positive hardness gradient, the outer core layer is
formed from a thermoplastic composition and has a positive hardness
gradient, and at least one of the inner core layer composition and
the outer core layer composition is a highly neutralized polymer
composition comprising an acid copolymer of ethylene and an
.alpha.,.beta.-unsaturated carboxylic acid, optionally including a
softening monomer selected from the group consisting of alkyl
acrylates and methacrylates; an organic acid or salt thereof; a
cation source present in an amount sufficient to neutralize greater
than 80% of all acid groups present in the composition; and
optionally a non-acid polymer selected from the group consisting of
polyolefins, polyamides, polyesters, polyethers, polyurethanes,
metallocene-catalyzed polymers, single-site catalyst polymerized
polymers, ethylene propylene rubber, ethylene propylene diene
rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,
and functionalized derivatives thereof.
[0030] In another particular aspect of this embodiment, the inner
core layer has a positive hardness gradient, the outer core layer
is formed from a thermoplastic composition and has a zero or
negative hardness gradient, and at least one of the inner core
layer composition and the outer core layer composition is a highly
neutralized polymer composition comprising an acid copolymer of
ethylene and an .alpha.,.beta.-unsaturated carboxylic acid,
optionally including a softening monomer selected from the group
consisting of alkyl acrylates and methacrylates; an organic acid or
salt thereof; a cation source present in an amount sufficient to
neutralize greater than 80% of all acid groups present in the
composition; and optionally a non-acid polymer selected from the
group consisting of polyolefins, polyamides, polyesters,
polyethers, polyurethanes, metallocene-catalyzed polymers,
single-site catalyst polymerized polymers, ethylene propylene
rubber, ethylene propylene diene rubber, styrenic block copolymer
rubbers, alkyl acrylate rubbers, and functionalized derivatives
thereof.
[0031] In another particular aspect of this embodiment, the inner
core layer has a zero or negative hardness gradient, the outer core
layer is formed from a thermoplastic composition and has a positive
hardness gradient, and at least one of the inner core layer
composition and the outer core layer composition is a highly
neutralized polymer composition comprising an acid copolymer of
ethylene and an .alpha.,.beta.-unsaturated carboxylic acid,
optionally including a softening monomer selected from the group
consisting of alkyl acrylates and methacrylates; an organic acid or
salt thereof; a cation source present in an amount sufficient to
neutralize greater than 80% of all acid groups present in the
composition; and optionally a non-acid polymer selected from the
group consisting of polyolefins, polyamides, polyesters,
polyethers, polyurethanes, metallocene-catalyzed polymers,
single-site catalyst polymerized polymers, ethylene propylene
rubber, ethylene propylene diene rubber, styrenic block copolymer
rubbers, alkyl acrylate rubbers, and functionalized derivatives
thereof.
[0032] In another particular aspect of this embodiment, the inner
core layer has a zero or negative hardness gradient, the outer core
layer is formed from a thermoplastic composition and has a zero or
negative hardness gradient, and at least one of the inner core
layer composition and the outer core layer composition is a highly
neutralized polymer composition comprising an acid copolymer of
ethylene and an .alpha.,.beta.-unsaturated carboxylic acid,
optionally including a softening monomer selected from the group
consisting of alkyl acrylates and methacrylates; an organic acid or
salt thereof; a cation source present in an amount sufficient to
neutralize greater than 80% of all acid groups present in the
composition; and optionally a non-acid polymer selected from the
group consisting of polyolefins, polyamides, polyesters,
polyethers, polyurethanes, metallocene-catalyzed polymers,
single-site catalyst polymerized polymers, ethylene propylene
rubber, ethylene propylene diene rubber, styrenic block copolymer
rubbers, alkyl acrylate rubbers, and functionalized derivatives
thereof.
[0033] In another particular aspect of this embodiment, the inner
core layer is formed from a foamed polyurethane composition
comprising mineral filler particulate in an amount of from 0.1 wt %
to 9.0 wt %, based on the total weight of the foamed polyurethane
composition, and the outer core layer is formed from a non-foamed
highly neutralized polymer composition comprising an acid copolymer
of ethylene and an .alpha.,.beta.-unsaturated carboxylic acid,
optionally including a softening monomer selected from the group
consisting of alkyl acrylates and methacrylates; an organic acid or
salt thereof; a cation source present in an amount sufficient to
neutralize greater than 80% of all acid groups present in the
composition; and optionally a non-acid polymer selected from the
group consisting of polyolefins, polyamides, polyesters,
polyethers, polyurethanes, metallocene-catalyzed polymers,
single-site catalyst polymerized polymers, ethylene propylene
rubber, ethylene propylene diene rubber, styrenic block copolymer
rubbers, alkyl acrylate rubbers, and functionalized derivatives
thereof.
[0034] In another particular aspect of this embodiment, the outer
core layer has a positive hardness gradient and is formed from a
thermoset composition, and the inner core layer has a positive
hardness gradient and is formed from a highly neutralized polymer
composition comprising an acid copolymer of ethylene and an
.alpha.,.beta.-unsaturated carboxylic acid, optionally including a
softening monomer selected from the group consisting of alkyl
acrylates and methacrylates; an organic acid or salt thereof; a
cation source present in an amount sufficient to neutralize greater
than 80% of all acid groups present in the composition; and
optionally a non-acid polymer selected from the group consisting of
polyolefins, polyamides, polyesters, polyethers, polyurethanes,
metallocene-catalyzed polymers, single-site catalyst polymerized
polymers, ethylene propylene rubber, ethylene propylene diene
rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,
and functionalized derivatives thereof.
[0035] In another particular aspect of this embodiment, the outer
core layer has a zero or negative hardness gradient and is formed
from a thermoset composition, and the inner core layer has a
positive hardness gradient and is formed from a highly neutralized
polymer composition comprising an acid copolymer of ethylene and an
.alpha.,.beta.-unsaturated carboxylic acid, optionally including a
softening monomer selected from the group consisting of alkyl
acrylates and methacrylates; an organic acid or salt thereof; a
cation source present in an amount sufficient to neutralize greater
than 80% of all acid groups present in the composition; and
optionally a non-acid polymer selected from the group consisting of
polyolefins, polyamides, polyesters, polyethers, polyurethanes,
metallocene-catalyzed polymers, single-site catalyst polymerized
polymers, ethylene propylene rubber, ethylene propylene diene
rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,
and functionalized derivatives thereof.
[0036] In another particular aspect of this embodiment, the outer
core layer has a positive hardness gradient and is formed from a
thermoset composition, and the inner core layer has a zero or
negative hardness gradient and is formed from a highly neutralized
polymer composition comprising an acid copolymer of ethylene and an
.alpha.,.beta.-unsaturated carboxylic acid, optionally including a
softening monomer selected from the group consisting of alkyl
acrylates and methacrylates; an organic acid or salt thereof; a
cation source present in an amount sufficient to neutralize greater
than 80% of all acid groups present in the composition; and
optionally a non-acid polymer selected from the group consisting of
polyolefins, polyamides, polyesters, polyethers, polyurethanes,
metallocene-catalyzed polymers, single-site catalyst polymerized
polymers, ethylene propylene rubber, ethylene propylene diene
rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,
and functionalized derivatives thereof.
[0037] In another particular aspect of this embodiment, the outer
core layer has a zero or negative hardness gradient and is formed
from a thermoset composition, and the inner core layer has a zero
or negative hardness gradient and is formed from a highly
neutralized polymer composition comprising an acid copolymer of
ethylene and an .alpha.,.beta.-unsaturated carboxylic acid,
optionally including a softening monomer selected from the group
consisting of alkyl acrylates and methacrylates; an organic acid or
salt thereof; a cation source present in an amount sufficient to
neutralize greater than 80% of all acid groups present in the
composition; and optionally a non-acid polymer selected from the
group consisting of polyolefins, polyamides, polyesters,
polyethers, polyurethanes, metallocene-catalyzed polymers,
single-site catalyst polymerized polymers, ethylene propylene
rubber, ethylene propylene diene rubber, styrenic block copolymer
rubbers, alkyl acrylate rubbers, and functionalized derivatives
thereof.
[0038] In the above embodiments, the highly neutralized composition
comprising an acid copolymer, a non-acid polymer, an organic acid
or salt thereof, and a cation source optionally has one or more of
the following properties: [0039] (a) the acid copolymer does not
include a softening monomer; [0040] (b) the acid of the acid
copolymer is selected from acrylic acid and methacrylic acid;
[0041] (c) the acid of the acid copolymer is present in the acid
copolymer in an amount of from 15 mol % to 30 mol %, based on the
total weight of the acid copolymer; [0042] (d) the non-acid polymer
is an alkyl acrylate rubber selected from ethylene-alkyl acrylates
and ethylene-alkyl methacrylates; [0043] (e) the non-acid polymer
is present in an amount of greater than 50 wt %, based on the
combined weight of the acid copolymer and the non-acid polymer;
[0044] (f) the non-acid polymer is present in an amount of 20 wt %
or greater, based on the total weight of the highly neutralized
composition; [0045] (g) the non-acid polymer is present in an
amount of less than 50 wt %, based on the combined weight of the
acid copolymer and the non-acid polymer; [0046] (h) the highly
neutralized polymer composition has a solid sphere compression of
40 or less and a coefficient of restitution of 0.820 or greater;
[0047] (i) the highly neutralized polymer composition has a solid
sphere compression of 100 or greater and a coefficient of
restitution of 0.860 or greater; [0048] (j) the organic acid salt
is a metal salt of oleic acid; [0049] (k) the organic salt is
magnesium oleate; [0050] (l) the organic salt is present in an
amount of 30 parts or greater, per 100 parts of acid copolymer and
non-acid copolymer combined; and [0051] (m) the cation source is
present in an amount sufficient to neutralize 110% or greater of
all acid groups present in the composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] 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:
[0053] FIG. 1 is a perspective view of a spherical inner core made
of a foamed composition in accordance with the present
invention;
[0054] FIG. 2 is a perspective view of one embodiment of upper and
lower mold cavities used to make the dual-layered cores of the
present invention;
[0055] FIG. 3 is a cross-sectional view of a three-piece golf ball
having a dual-layered core made in accordance with the present
invention;
[0056] FIG. 4 is a cross-sectional view of a four-piece golf ball
having a dual-layered core made in accordance with the present
invention;
[0057] FIG. 5 is a graph showing the hardness of a two (2)
different dual-layered core samples (each sample having a foam
center and thermoset rubber outer layer) at different points in the
respective core structures per two examples of this invention;
[0058] FIG. 6A is a graph showing the hardness of a dual-layered
core having a diameter of 0.5 inches (foam center and thermoplastic
outer layer) at different points in the core structure per an
example of this invention;
[0059] FIG. 6B is a graph showing the hardness of a dual-layered
core having a diameter of 0.5 inches (foam center and thermoplastic
outer layer) at different points in the core structure per an
example of this invention;
[0060] FIG. 6C is a graph showing the hardness of a dual-layered
core having a diameter of 0.5 inches (foam center and thermoplastic
outer layer) at different points in the core structure per an
example of this invention; and
[0061] FIG. 6D is a graph showing the hardness of a dual-layered
core having a diameter of 0.75 inches (foam center and
thermoplastic outer layer) at different points in the core
structure per an example of this invention.
DETAILED DESCRIPTION OF THE INVENTION
Golf Ball Constructions
[0062] Golf balls having various constructions may be made in
accordance with this invention. For example, one-piece golf balls,
two-piece golf balls, and golf balls having three piece,
four-piece, and five-piece constructions with single or
multi-layered cover materials may be made. Representative
illustrations of such golf ball constructions are provided and
discussed further below. 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 containing a
dual-layered core and single-layered cover is made. The dual-core
includes an inner core (center) and surrounding outer core layer.
In another version, a four-piece golf ball containing a dual-core
and dual-cover (inner cover and outer cover layers) is made. In yet
another construction, a four-piece or five-piece golf ball
containing a dual-core; casing layer(s); and cover layer(s) may be
made. As used herein, the term, "casing layer" means a layer of the
ball disposed between the multi-layered core sub-assembly and
cover. The casing layer also may be referred to as a mantle or
intermediate 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.
Inner Core Composition
[0063] In general, foam compositions are made by forming gas
bubbles in a polymer mixture using a foaming (blowing) agent. As
the bubbles form, the mixture expands and forms a foam composition
that can be molded into an end-use product having either an open or
closed cellular structure. Flexible foams generally have an open
cell structure, where the cells walls are incomplete and contain
small holes through which liquid and air can permeate. Such
flexible foams are used for automobile seats, cushioning,
mattresses, and the like. Rigid foams generally have a closed cell
structure, where the cell walls are continuous and complete, and
are used for used for automobile panels and parts, building
insulation and the like.
[0064] In the present invention, the inner core (center) comprises
a lightweight foam thermoplastic or thermoset polymer composition
that may range from relatively rigid foam to very flexible foam.
Referring to FIG. 1, a foamed inner core (4) having a geometric
center (6) and outer skin (8) may be prepared in accordance with
this invention.
[0065] A wide variety of thermoplastic and thermoset materials may
be used in forming the foam composition of this invention
including, for example, polyurethanes; polyureas; copolymers,
blends and hybrids of polyurethane and polyurea; olefin-based
copolymer ionomer resins (for example, Surlyn.RTM. ionomer resins
and DuPont HPF.RTM. 1000 and HPF.RTM. 2000, commercially available
from DuPont; Iotek.RTM. ionomers, commercially available from
ExxonMobil Chemical Company; Amplify.RTM. IO ionomers of ethylene
acrylic acid copolymers, commercially available from Dow Chemical
Company; and 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 or RiteFlex.RTM.,
commercially available from Ticona Engineering Polymers;
polyurethane-based thermoplastic elastomers, such as
Elastollan.RTM., commercially available from BASF; synthetic or
natural vulcanized rubber; and combinations thereof.
[0066] In a particular embodiment, the inner core layer is formed
from a foamed HNP composition, wherein the HNP composition is
formed by blending an acid polymer, a non-acid polymer, a cation
source, and a fatty acid or metal salt thereof. Such HNP
compositions are disclosed further below as suitable compositions
for forming the outer core layer.
[0067] Castable polyurethanes, polyureas, and hybrids of
polyurethanes-polyureas are particularly desirable for forming the
inner core layer because these materials can be used to make a golf
ball having good playing performance properties as discussed
further below. By the term, "hybrids of polyurethane and polyurea,"
it is meant to include copolymers and blends thereof.
[0068] Basically, polyurethane compositions contain urethane
linkages formed by the reaction of a multi-functional isocyanate
containing two or more NCO groups with a polyol having two or more
hydroxyl groups (OH--OH) sometimes in the presence of a catalyst
and other additives. Generally, polyurethanes can be produced in a
single-step reaction (one-shot) or in a two-step reaction via a
prepolymer or quasi-prepolymer. In the one-shot method, all of the
components are combined at once, that is, all of the raw
ingredients are added to a reaction vessel, and the reaction is
allowed to take place. In the prepolymer method, an excess of
polyisocyanate is first reacted with some amount of a polyol to
form the prepolymer which contains reactive NCO groups. This
prepolymer is then reacted again with a chain extender or curing
agent polyol to form the final polyurethane. Polyurea compositions,
which are distinct from the above-described polyurethanes, also can
be formed. In general, polyurea compositions contain urea linkages
formed by reacting an isocyanate group (--N.dbd.C.dbd.O) with an
amine group (NH or NH.sub.2). Polyureas can be produced in similar
fashion to polyurethanes by either a one shot or prepolymer method.
In forming a polyurea polymer, the polyol would be substituted with
a suitable polyamine. Hybrid compositions containing urethane and
urea linkages also may be produced. For example, when polyurethane
prepolymer is reacted with amine-terminated curing agents during
the chain-extending step, any excess isocyanate groups in the
prepolymer will react with the amine groups in the curing agent.
The resulting polyurethane-urea composition contains urethane and
urea linkages and may be referred to as a hybrid. In another
example, a hybrid composition may be produced when a polyurea
prepolymer is reacted with a hydroxyl-terminated curing agent. A
wide variety of isocyanates, polyols, polyamines, and curing agents
can be used to form the polyurethane and polyurea compositions as
discussed further below.
[0069] To prepare the foamed polyurethane, polyurea, or other
polymer composition, a foaming agent is introduced into the polymer
formulation. In general, there are two types of foaming agents:
physical foaming agents and chemical foaming agents.
[0070] Physical Foaming Agents.
[0071] These foaming agents typically are gasses that are
introduced under high pressure directly into the polymer
composition. Chlorofluorocarbons (CFCs) and partially halogenated
chlorofluorocarbons are effective, but these compounds are banned
in many countries because of their environmental side effects.
Alternatively, aliphatic and cyclic hydrocarbon gasses such as
isobutene and pentane may be used. Inert gasses, such as carbon
dioxide and nitrogen, also are suitable.
[0072] Chemical Foaming Agents.
[0073] These foaming agents typically are in the form of powder,
pellets, or liquids and they are added to the composition, where
they decompose or react during heating and generate gaseous
by-products (for example, nitrogen or carbon dioxide). The gas is
dispersed and trapped throughout the composition and foams it.
[0074] Preferably, a chemical foaming agent is used to prepare the
foam compositions of this invention. Chemical blowing agents may be
inorganic, such as ammonium carbonate and carbonates of alkalai
metals, or may be organic, such as azo and diazo compounds, such as
nitrogen-based azo compounds. Suitable azo compounds include, but
are not limited to, 2,2'-azobis(2-cyanobutane),
2,2'-azobis(methylbutyronitrile), azodicarbonamide,
p,p'-oxybis(benzene sulfonyl hydrazide), p-toluene sulfonyl
semicarbazide, p-toluene sulfonyl hydrazide. Other foaming agents
include any of the Celogens.RTM. sold by Crompton Chemical
Corporation, and nitroso compounds, sulfonylhydrazides, azides of
organic acids and their analogs, triazines, tri- and tetrazole
derivatives, sulfonyl semicarbazides, urea derivatives, guanidine
derivatives, and esters such as alkoxyboroxines. Also, foaming
agents that liberate gasses as a result of chemical interaction
between components such as mixtures of acids and metals, mixtures
of organic acids and inorganic carbonates, mixtures of nitriles and
ammonium salts, and the hydrolytic decomposition of urea may be
used. Water is a preferred foaming agent. When added to the
polyurethane formulation, water will react with the isocyanate
groups and form carbamic acid intermediates. The carbamic acids
readily decarboxylate to form an amine and carbon dioxide. The
newly formed amine can then further react with other isocyanate
groups to form urea linkages and the carbon dioxide forms the
bubbles to produce the foam.
[0075] During the decomposition reaction of certain chemical
foaming agents, more heat and energy is released than is needed for
the reaction. Once the decomposition has started, it continues for
a relatively long time period. If these foaming agents are used,
longer cooling periods are generally required. Hydrazide and
azo-based compounds often are used as exothermic foaming agents. On
the other hand, endothermic foaming agents need energy for
decomposition. Thus, the release of the gasses quickly stops after
the supply of heat to the composition has been terminated. If the
composition is produced using these foaming agents, shorter cooling
periods are needed. Bicarbonate and citric acid-based foaming
agents can be used as exothermic foaming agents.
[0076] Other suitable foaming agents include expandable
gas-containing microspheres. Exemplary microspheres consist of an
acrylonitrile polymer shell encapsulating a volatile gas, such as
isopentane gas. This gas is contained within the sphere as a
blowing agent. In their unexpanded state, the diameter of these
hollow spheres range from 10 to 17 .mu.m and have a true density of
1000 to 1300 kg/m.sup.3. When heated, the gas inside the shell
increases its pressure and the thermoplastic shell softens,
resulting in a dramatic increase of the volume of the microspheres.
Fully expanded, the volume of the microspheres will increase more
than 40 times (typical diameter values would be an increase from 10
to 40 .mu.m), resulting in a true density below 30 kg/m.sup.3 (0.25
lbs/gallon). Typical expansion temperatures range from
80-190.degree. C. (176-374.degree. F.). Such expandable
microspheres are commercially available as Expancel.RTM. from
Expancel of Sweden or Akzo Nobel.
[0077] As an alternative to chemical and physical foaming agents or
in addition to such foaming agents, as described above, other types
of fillers that lower the specific gravity of the composition can
be used in accordance with this invention. For example, polymeric,
ceramic, and glass unfilled microspheres having a density of 0.1 to
1.0 g/cc and an average particle size of 10 to 250 microns can be
used to help lower specific gravity of the composition and achieve
the desired density and physical properties.
[0078] Additionally, BASF polyurethane materials sold under the
trade name Cellasto.RTM. and Elastocell.RTM., microcellular
polyurethanes, Elastopor.RTM. H that is a closed-cell polyurethane
rigid foam, Elastoflex.RTM. W flexible foam systems,
Elastoflex.RTM. E semiflexible foam systems, Elastofoam.RTM.
flexible integrally-skinning systems, Elastolit.RTM. D/K/R integral
rigid foams, Elastopan.RTM. S, Elastollan.RTM. thermoplastic
polyurethane elastomers (TPUs), and the like may be used in
accordance with the present invention. Bayer also produces a
variety of materials sold as Texin.RTM. TPUs, Baytec.RTM. and
Vulkollan.RTM. elastomers, Baymer.RTM. rigid foams, Baydur.RTM.
integral skinning foams, Bayfit.RTM. flexible foams available as
castable, RIM grades, sprayable, and the like that may be used.
Additional foam materials that may be used herein include
polyisocyanurate foams and a variety of "thermoplastic" foams,
which may be cross-linked to varying extents using free-radical
(for example, peroxide) or radiation cross-linking (for example,
UV, IR, Gamma, EB irradiation). Also, foams may be prepared from
polybutadiene, polystyrene, polyolefin (including metallocene and
other single site catalyzed polymers), ethylene vinyl acetate
(EVA), acrylate copolymers, such as EMA, EBA, Nucrel.RTM.-type acid
co and terpolymers, ethylene propylene rubber (such as EPR, EPDM,
and any ethylene copolymers), styrene-butadiene, and SEBS (any
Kraton-type), PVC, PVDC, CPE (chlorinated polyethylene). Epoxy
foams, urea-formaldehyde foams, latex foams and sponge, silicone
foams, fluoropolymer foams and syntactic foams (hollow sphere
filled) also may be used.
[0079] In addition to the polymer and foaming agent, the foam
composition also may include other ingredients such as, for
example, cross-linking agents, chain extenders, surfactants, dyes
and pigments, coloring agents, fluorescent agents, adsorbents,
stabilizers, softening agents, impact modifiers, antioxidants,
antiozonants, and the like. The formulations used to prepare the
polyurethane foam compositions of this invention preferably contain
a polyol, polyisocyanate, water, an amine or hydroxyl curing agent,
surfactant, and a catalyst as described further below.
[0080] In one preferred version, the foam composition includes
nanoclay particles, more preferably quaternary ammonium nanoclay
particulate. While not wishing to be bound by any theory, it is
believed that adding the nanoclay to the foam composition helps
improve the foam cell structure and morphology. As the nanoclay is
dispersed in the foam composition, it helps create a greater number
of smaller sized foam cells. Thus, the foam cells are packed
together more tightly and cell density is increased. The dimensions
and geometry of the foam cells across the matrix tends to be more
uniform. The cell structure is maintained as the nanoclay help
prevent air from diffusing through the cell walls. The resulting
foam material has greater compression strength and modulus.
Preferably, the foam composition contains about 0.25 to about 2%
and more preferably about 0.25 to about 0.75% of nanoclay particles
based on total weight of the composition. Since the addition of the
nanoclay may have a catalytic effect on the reaction rate of the
reactants used to make the polyurethane foam, it is preferred that
the nanoclay be added during the curing step.
Properties of Polyurethane Foams
[0081] The polyurethane foam compositions of this invention have
numerous chemical and physical properties making them suitable for
core assemblies in golf balls. For example, there are properties
relating to the reaction of the isocyanate and polyol components
and blowing agent, particularly "cream time," "gel time," "rise
time," "tack-free time," and "free-rise density." In general, cream
time refers to the time period from the point of mixing the raw
ingredients together to the point where the mixture turns cloudy in
appearance or changes color and begins to rise from its initial
stable state. Normally, the cream time of the foam compositions of
this invention is within the range of about 20 to about 240
seconds. In general, gel time refers to the time period from the
point of mixing the raw ingredients together to the point where the
expanded foam starts polymerizing/gelling. Rise time generally
refers to the time period from the point of mixing the raw
ingredients together to the point where the reacted foam has
reached its largest volume or maximum height. The rise time of the
foam compositions of this invention typically is in the range of
about 60 to about 360 seconds. Tack-free time generally refers to
the time it takes for the reacted foam to lose its tackiness, and
the foam compositions of this invention normally have a tack-free
time of about 60 to about 3600 seconds. Free-rise density refers to
the density of the resulting foam when it is allowed to rise
unrestricted without a cover or top being placed on the mold.
[0082] The density of the foam is an important property and is
defines as the weight per unit volume (typically, g/cm.sup.3) and
can be measured per ASTM D-1622. The hardness, stiffness, and
load-bearing capacity of the foam are independent of the foam's
density, although foams having a high density typically have high
hardness and stiffness. Normally, foams having higher densities
have higher compression strength. Surprisingly, the foam
compositions used to produce the inner core of the golf balls per
this invention have a relatively low density; however, the foams
are not necessarily soft and flexible, rather, they may be
relatively firm, rigid, or semi-rigid depending upon the desired
golf ball properties. Tensile strength, tear-resistance, and
elongation generally refer to the foam's ability to resist breaking
or tearing, and these properties can be measured per ASTM D-1623.
The durability of foams is important, because introducing fillers
and other additives into the foam composition can increase the
tendency of the foam to break or tear apart. In general, the
tensile strength of the foam compositions of this invention is in
the range of about 20 to about 1000 psi (parallel to the foam rise)
and about 50 to about 1000 psi (perpendicular to the foam rise) as
measured per ASTM D-1623 at 23.degree. C. and 50% relative humidity
(RH). Meanwhile, the flex modulus of the foams of this invention is
generally in the range of about 5 to about 45 kPa as measured per
ASTM D-790, and the foams generally have a compressive modulus of
200 to 50,000 psi.
[0083] In another test, compression strength is measured on an
Instron machine according to ASTM D-1621. The foam is cut into
blocks and the compression strength is measured as the force
required to compress the block by 10%. In general, the compressive
strength of the foam compositions of this invention is in the range
of about 100 to about 1800 psi (parallel and perpendicular to the
foam rise) as measured per ASTM D-1621 at 23.degree. C. and 50%
relative humidity (RH). The test is conducted perpendicular to the
rise of the foam or parallel to the rise of the foam. The
Percentage (%) of Compression Set also can be used. This is a
measure of the permanent deformation of a foam sample after it has
been compressed between two metal plates under controlled time and
temperature condition (standard--22 hours at 70.degree. C.
(158.degree. F.)). The foam is compressed to a thickness given as a
percentage of its original thickness that remained "set."
Preferably, the Compression Set of the foam is less than ten
percent (10%), that is, the foam recovers to a point of 90% or
greater of its original thickness.
Methods of Preparing the Foam Composition
[0084] The foam compositions of this invention may be prepared
using different methods. In one preferred embodiment, the method
involves preparing a castable composition comprising a reactive
mixture of a polyisocyanate, polyol, water, curing agent,
surfactant, and catalyst. A motorized mixer can be used to mix the
starting ingredients together and form a reactive liquid mixture.
Alternatively, the ingredients can be manually mixed together. An
exothermic reaction occurs when the ingredients are mixed together
and this continues as the reactive mixture is dispensed into the
mold cavities (otherwise referred to as half-molds or mold cups).
The mold cavities may be referred to as first and second, or upper
and lower, mold cavities. The mold cavities preferably are made of
metal such as, for example, brass or silicon bronze.
[0085] Referring to FIG. 2, the mold cavities are generally
indicated at (9) and (10). The lower and upper mold cavities (9,
10) are placed in lower and upper mold frame plates (11, 12). The
frame plates (11, 12) contain guide pins and complementary
alignment holes (not shown in drawing). The guide pins are inserted
into the alignment holes to secure the lower plate (11) to the
upper plate (12). The lower and upper mold cavities (9, 10) are
mated together as the frame plates (11, 12) are fastened. When the
lower and upper mold cavities (9, 10) are joined together, they
define an interior spherical cavity that houses the spherical core.
The upper mold contains a vent or hole (14) to allow for the
expanding foam to fill the cavities uniformly. A secondary overflow
chamber (16), which is located above the vent (14), can be used to
adjust the amount of foam overflow and thus adjust the density of
the core structure being molded in the cavities. As the lower and
upper mold cavities (9, 10) are mated together and sufficient heat
and pressure is applied, the foamed composition cures and
solidifies to form a relatively rigid and lightweight spherical
core. The resulting cores are cooled and then removed from the
mold.
Hardness of the Inner Core
[0086] As shown in FIG. 1, a foamed inner core (4) having a
geometric center (6) and outer skin (8) may be prepared per the
molding method discussed above. The outer skin (8) is generally a
non-foamed region that forms the outer surface of the core
structure. The resulting inner core preferably has a diameter
within a range of about 0.100 to about 1.100 inches, or,
alternatively a diameter of 1.30 inches or greater, or 1.40 inches
or greater, or 1.50 inches or greater, or 1.60 inches or greater,
or 1.70 inches or greater, or 1.80 inches or greater, or 1.90
inches or greater, or 2.00 inches or greater, or 2.10 or greater,
or 2.20 or greater. For example, the inner core may have a diameter
within a range of about 0.250 to about 1.000 inches, or a diameter
within a range of about 0.100 to about 0.500 inches, or a diameter
within a range of about 0.300 to about 0.800 inches, or a diameter
within a range of about 0.400 to about 0.800 inches. More
particularly, the inner core preferably has a diameter size with a
lower limit of about 0.10 or 0.12 or 0.15 or 0.25 or 0.30 or 0.35
or 0.40 or 0.45 or 0.50 or 0.55 inches and an upper limit of about
0.50 or 0.55 or 0.60 or 0.65 or 0.70 or 0.80 or 0.90 or 1.00 or
1.10 or 1.30 or 1.40 or 1.50 or 1.60 or 1.70 or 1.80 or 1.90 or
2.00 or 2.10 or 2.20 inches. The outer skin (8) of the inner core
is relatively thin preferably having a thickness of less than about
0.020 inches and more preferably less than 0.010 inches. In one
preferred embodiment, the foamed core has a "positive" hardness
gradient (that is, the outer skin of the inner core is harder than
its geometric center.)
[0087] For example, the geometric center hardness of the inner core
(H.sub.inner core center), as measured in Shore C units, is about
10 Shore C or greater and preferably has a lower limit of about 10
or 16 or 20 or 25 or 30 or 32 or 34 or 36 or 40 Shore C and an
upper limit of about 42 or 44 or 46 or 48 or 50 or 52 or 56 or 60
or 62 or 65 or 68 or 70 or 74 or 78 or 80 Shore C. In one preferred
version, the geometric center hardness of the inner core
(H.sub.inner core center) is about 60 Shore C. When a flexible,
relatively soft foam is used, the foam may have a Shore A hardness
of about 10 or greater, and preferably has a lower limit of 15, 20,
25, 30, or 35 Shore A and an upper limit of about 60, 65, 70, 80,
85, or 90 Shore A. In one preferred embodiment, the geometric
center hardness of the inner core is about 55 Shore A. The
H.sub.inner core center, as measured in Shore D units, is about 15
Shore D or greater and more preferably within a range having a
lower limit of about 15 or 18 or 20 or 22 or 25 or 28 or 30 or 32
or 36 or 40 or 44 Shore D and an upper limit of about 45 or 48 or
50 or 52 or 55 or 58 or 60 or 62 or 64 or 66 or 70 or 72 or 74 or
78 or 80 or 82 or 84 or 88 or 90 Shore D. Meanwhile, the outer
surface hardness of the inner core (H.sub.inner core surface), as
measured in Shore C, is about 20 Shore C or greater and preferably
has a lower limit of about 13 or 17 or 20 or 22 or 24 or 28 or 30
or 32 or 35 or 36 or 40 or 42 or 44 or 46 or 48 or 50 Shore C and
an upper limit of about 52 or 55 or 58 or 60 or 62 or 64 or 66 or
70 or 74 or 78 or 80 or 86 or 88 or 90 or 92 or 95 Shore C. The
outer surface hardness of the inner core (H.sub.inner core
surface), as measured in Shore D units, preferably has a lower
limit of about 25 or 28 or 30 or 32 or 36 or 40 or 44 Shore D and
an upper limit of about 45 or 48 or 50 or 52 or 55 or 58 or 60 or
62 or 64 or 66 or 70 or 74 or 78 or 80 or 82 or 84 or 88 or 90 or
94 or 96 Shore D. In a particular embodiment, the H.sub.inner core
center is in the range of about 10 Shore C to about 50 Shore C, and
the H.sub.inner core surface is in the range of about 13 Shore C to
about 60 Shore C.
Density of the Inner Core
[0088] The foamed inner core preferably has a specific gravity of
about 0.25 to about 1.25 g/cc. That is, the density of the inner
core (as measured at any point of the inner core structure) is
preferably within the range of about 0.25 to about 1.25 g/cc. By
the term, "specific gravity of the inner core"
("SG.sub.inner.sup."), it is generally meant the specific gravity
of the inner core as measured at any point of the inner core
structure. It should be understood, however, that the specific
gravity values, as taken at different points of the inner core
structure, may vary. For example, the foamed inner core may have a
"positive" density gradient (that is, the outer surface (skin) of
the inner core may have a density greater than the geometric center
of the inner core.) In one preferred version, the specific gravity
of the geometric center of the inner core (SG.sub.center of inner
core) is less than 1.00 g/cc and more preferably 0.90 g/cc or less.
More particularly, in one version, the (SG.sub.center of inner
core) is in the range of about 0.10 to about 0.90 g/cc. For
example, the (SG.sub.center of inner core) may be within a range
having a lower limit of about 0.10 or 0.15 of 0.20 or 0.24 or 0.25
or 0.30 or 0.35 or 0.37 or 0.40 or 0.42 or 0.45 or 0.47 or 0.50 and
an upper limit of about 0.60 or 0.65 or 0.70 or 0.74 or 0.78 or
0.80, or 0.82 or 0.84 or 0.85 or 0.88 or 0.90 or 0.95 g/cc.
Meanwhile, the specific gravity of the outer surface (skin) of the
inner core (SG.sub.skin of inner core), in one preferred version,
is greater than about 0.90 g/cc and more preferably greater than
1.00 g/cc. For example, the (SG.sub.skin of inner core) may fall
within the range of about 0.90 to about 2.00. More particularly, in
one version, the (SG.sub.skin of inner core) may have a specific
gravity with a lower limit of about 0.90 or 0.92 or 0.95 or 0.98 or
1.00 or 1.02 or 1.06 or 1.10 or 1.12 or 1.15 or 1.18 and an upper
limit of about 1.20 or 1.24 or 1.30 or 1.32 or 1.35 or 1.38 or 1.40
or 1.44 or 1.50 or 1.60 or 1.65 or 1.70 or 1.76 or 1.80 or 1.90 or
1.92 or 2.00. In other instances, the outer skin may have a
specific gravity of less than 0.90 g/cc. For example, the specific
gravity of the outer skin (SG.sub.skin of inner core) may be about
0.75 or 0.80 or 0.82 or 0.85 or 0.88 g/cc. In such instances,
wherein both the (SG.sub.center of inner core) and (SG.sub.skin of
inner core) are less than 0.90 g/cc, it is still preferred that the
(SG.sub.center of inner core) is less than the (SG.sub.skin of
inner core).
Polyisocyanates and Polyols for Making the Polyurethane Foams
[0089] As discussed above, in one preferred embodiment, a foamed
polyurethane composition is used to form the inner core. In
general, the polyurethane compositions contain urethane linkages
formed by reacting an isocyanate group (--N.dbd.C.dbd.O) with a
hydroxyl group (OH). The polyurethanes are produced by the reaction
of multi-functional isocyanates containing two or more isocyanate
groups with a polyol having two or more hydroxyl groups. The
formulation may also contain a catalyst, surfactant, and other
additives.
[0090] In particular, the foam inner core of this invention may be
prepared from a composition comprising an aromatic polyurethane,
which is preferably formed by reacting an aromatic diisocyanate
with a polyol. Suitable aromatic diisocyanates that may be used in
accordance with this invention include, for example, toluene
2,4-diisocyanate (TDI), toluene 2,6-diisocyanate (TDI),
4,4'-methylene diphenyl diisocyanate (MDI), 2,4'-methylene diphenyl
diisocyanate (MDI), polymeric methylene diphenyl diisocyanate
(PMDI), p-phenylene diisocyanate (PPDI), m-phenylene diisocyanate
(PDI), naphthalene 1,5-diisocyanate (NDI), naphthalene
2,4-diisocyanate (NDI), p-xylene diisocyanate (XDI), and
homopolymers and copolymers and blends thereof. The aromatic
isocyanates are able to react with the hydroxyl or amine compounds
and form a durable and tough polymer having a high melting point.
The resulting polyurethane generally has good mechanical strength
and tear-resistance.
[0091] Alternatively, the foamed composition of the inner core may
be prepared from a composition comprising aliphatic polyurethane,
which is preferably formed by reacting an aliphatic diisocyanate
with a polyol. Suitable aliphatic diisocyanates that may be used in
accordance with this invention include, for example, isophorone
diisocyanate (IPDI), 1,6-hexamethylene diisocyanate (HDI),
4,4'-dicyclohexylmethane diisocyanate ("H.sub.12 MDI"),
meta-tetramethylxylyene diisocyanate (TMXDI), trans-cyclohexane
diisocyanate (CHDI), 1,3-bis(isocyanatomethyl)cyclohexane;
1,4-bis(isocyanatomethyl)cyclohexane; and homopolymers and
copolymers and blends thereof. The resulting polyurethane generally
has good light and thermal stability. Preferred polyfunctional
isocyanates include 4,4'-methylene diphenyl diisocyanate (MDI),
2,4'-methylene diphenyl diisocyanate (MDI), and polymeric MDI
having a functionality in the range of 2.0 to 3.5 and more
preferably 2.2 to 2.5.
[0092] Any suitable polyol may be used to react with the
polyisocyanate in accordance with this invention. Exemplary polyols
include, but are not limited to, polyether polyols,
hydroxy-terminated polybutadiene (including partially/fully
hydrogenated derivatives), polyester polyols, polycaprolactone
polyols, and polycarbonate polyols. In one preferred embodiment,
the polyol includes polyether polyol. Examples include, but are not
limited to, polytetramethylene ether glycol (PTMEG), polyethylene
propylene glycol, polyoxypropylene glycol, and mixtures thereof.
The hydrocarbon chain can have saturated or unsaturated bonds and
substituted or unsubstituted aromatic and cyclic groups.
Preferably, the polyol of the present invention includes PTMEG.
[0093] As discussed further below, chain extenders (curing agents)
are added to the mixture to build-up the molecular weight of the
polyurethane polymer. In general, hydroxyl-terminated curing
agents, amine-terminated curing agents, and mixtures thereof are
used.
[0094] A catalyst may be employed to promote the reaction between
the isocyanate and polyol compounds. Suitable catalysts include,
but are not limited to, bismuth catalyst; zinc octoate; tin
catalysts such as bis-butyltin dilaurate, bis-butyltin diacetate,
stannous octoate; tin (II) chloride, tin (IV) chloride,
bis-butyltin dimethoxide, dimethyl-bis[1-oxonedecyl)oxy]stannane,
di-n-octyltin bis-isooctyl mercaptoacetate; amine catalysts such as
triethylenediamine, triethylamine, tributylamine,
1,4-diaza(2,2,2)bicyclooctane, tetramethylbutane diamine,
bis[2-dimethylaminoethyl]ether, N,N-dimethylaminopropylamine,
N,N-dimethylcyclohexylamine,
N,N,N',N',N''-pentamethyldiethylenetriamine, diethanolamine,
dimethtlethanolamine,
N-[2-(dimethylamino)ethyl]-N-methylethanolamine, N-ethylmorpholine,
3-dimethylamino-N,N-dimethylpropionamide, and
N,N',N''-dimethylaminopropylhexahydrotriazine; organic acids such
as oleic acid and acetic acid; delayed catalysts; and mixtures
thereof. Zirconium-based catalysts such as, for example,
bis(2-dimethyl aminoethyl) ether; mixtures of zinc complexes and
amine compounds such as KKAT.TM. XK 614, available from King
Industries; and amine catalysts such as Niax.TM. A-2 and A-33,
available from Momentive Specialty Chemicals, Inc. are particularly
preferred. The catalyst is preferably added in an amount sufficient
to catalyze the reaction of the components in the reactive mixture.
In one embodiment, the catalyst is present in an amount from about
0.001 percent to about 1 percent, and preferably 0.1 to 0.5
percent, by weight of the composition.
[0095] In one preferred embodiment, as described above, water is
used as the foaming agent--the water reacts with the polyisocyanate
compound(s) and forms carbon dioxide gas which induces foaming of
the mixture. The reaction rate of the water and polyisocyanate
compounds affects how quickly the foam is formed as measured per
reaction profile properties such as cream time, gel time, and rise
time of the foam.
[0096] The hydroxyl chain-extending (curing) agents are preferably
selected from the group consisting of ethylene glycol; diethylene
glycol; polyethylene glycol; propylene glycol;
2-methyl-1,3-propanediol; 2-methyl-1,4-butanediol;
monoethanolamine; diethanolamine; triethanolamine;
monoisopropanolamine; diisopropanolamine; dipropylene glycol;
polypropylene glycol; 1,2-butanediol; 1,3-butanediol;
1,4-butanediol; 2,3-butanediol; 2,3-dimethyl-2,3-butanediol;
trimethylolpropane; cyclohexyldimethylol; triisopropanolamine;
N,N,N',N'-tetra-(2-hydroxypropyl)-ethylene diamine; diethylene
glycol bis-(aminopropyl) ether; 1,5-pentanediol; 1,6-hexanediol;
1,3-bis-(2-hydroxyethoxy) cyclohexane; 1,4-cyclohexyldimethylol;
1,3-bis-[2-(2-hydroxyethoxy) ethoxy]cyclohexane;
1,3-bis-{2-[2-(2-hydroxyethoxy) ethoxy]ethoxy}cyclohexane;
trimethylolpropane; polytetramethylene ether glycol (PTMEG),
preferably having a molecular weight from about 250 to about 3900;
and mixtures thereof. Di, tri, and tetra-functional
polycaprolactone diols such as, 2-oxepanone polymer initiated with
1,4-butanediol, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, or
2,2-bis(hydroxymethyl)-1,3-propanediolsuch, may be used.
[0097] Suitable amine chain-extending (curing) agents that can be
used in chain-extending the polyurethane prepolymer include, but
are not limited to, unsaturated diamines such as
4,4'-diamino-diphenylmethane (i.e., 4,4'-methylene-dianiline or
"MDA"), m-phenylenediamine, p-phenylenediamine, 1,2- or
1,4-bis(sec-butylamino)benzene, 3,5-diethyl-(2,4- or 2,6-)
toluenediamine or "DETDA", 3,5-dimethylthio-(2,4- or
2,6-)toluenediamine, 3,5-diethylthio-(2,4- or 2,6-)toluenediamine,
3,3'-dimethyl-4,4'-diamino-diphenylmethane,
3,3'-diethyl-5,5'-dimethyl4,4'-diamino-diphenylmethane (i.e.,
4,4'-methylene-bis(2-ethyl-6-methyl-benezeneamine)),
3,3'-dichloro-4,4'-diamino-diphenylmethane (i.e.,
4,4'-methylene-bis(2-chloroaniline) or "MOCA"),
3,3',5,5'-tetraethyl-4,4'-diamino-diphenylmethane (i.e.,
4,4'-methylene-bis(2,6-diethylaniline),
2,2'-dichloro-3,3',5,5'-tetraethyl-4,4'-diamino-diphenylmethane
(i.e., 4,4'-methylene-bis(3-chloro-2,6-diethyleneaniline) or
"MCDEA"), 3,3'-diethyl-5,5'-dichloro-4,4'-diamino-diphenylmethane,
or "MDEA"),
3,3'-dichloro-2,2',6,6'-tetraethyl-4,4'-diamino-diphenylmethane,
3,3'-dichloro-4,4'-diamino-diphenylmethane,
4,4'-methylene-bis(2,3-dichloroaniline) (i.e.,
2,2',3,3'-tetrachloro-4,4'-diamino-diphenylmethane or "MDCA"),
4,4'-bis(sec-butylamino)-diphenylmethane,
N,N'-dialkylamino-diphenylmethane,
trimethyleneglycol-di(p-aminobenzoate),
polyethyleneglycol-di(p-aminobenzoate),
polytetramethyleneglycol-di(p-aminobenzoate); saturated diamines
such as ethylene diamine, 1,3-propylene diamine,
2-methyl-pentamethylene diamine, hexamethylene diamine, 2,2,4- and
2,4,4-trimethyl-1,6-hexane diamine, imino-bis(propylamine),
imido-bis(propylamine), methylimino-bis(propylamine) (i.e.,
N-(3-aminopropyl)-N-methyl-1,3-propanediamine),
1,4-bis(3-aminopropoxy)butane (i.e.,
3,3'-[1,4-butanediylbis-(oxy)bis]-1-propanamine),
diethyleneglycol-bis(propylamine) (i.e.,
diethyleneglycol-di(aminopropyl)ether),
4,7,10-trioxatridecane-1,13-diamine,
1-methyl-2,6-diamino-cyclohexane, 1,4-diamino-cyclohexane,
poly(oxyethylene-oxypropylene) diamines, 1,3- or
1,4-bis(methylamino)-cyclohexane, isophorone diamine, 1,2- or
1,4-bis(sec-butylamino)-cyclohexane, N,N'-diisopropyl-isophorone
diamine, 4,4'-diamino-dicyclohexylmethane,
3,3'-dimethyl-4,4'-diamino-dicyclohexylmethane,
3,3'-dichloro-4,4'-diamino-dicyclohexylmethane,
N,N'-dialkylamino-dicyclohexylmethane, polyoxyethylene diamines,
3,3'-diethyl-5,5'-dimethyl-4,4'-diamino-dicyclohexylmethane,
polyoxypropylene diamines,
3,3'-diethyl-5,5'-dichloro-4,4'-diamino-dicyclohexylmethane,
polytetramethylene ether diamines, 3,3',5,5
`-tetraethyl-4,4`-diamino-dicyclohexylmethane (i.e.,
4,4'-methylene-bis(2,6-diethylaminocyclohexane)),
3,3'-dichloro-4,4'-diamino-dicyclohexylmethane,
2,2'-dichloro-3,3',5,5'-tetraethyl-4,4'-diamino-dicyclohexylmethane,
(ethylene oxide)-capped polyoxypropylene ether diamines,
2,2',3,3'-tetrachloro-4,4'-diamino-dicyclohexylmethane,
4,4'-bis(sec-butylamino)-dicyclohexylmethane; triamines such as
diethylene triamine, dipropylene triamine, (propylene oxide)-based
triamines (i.e., polyoxypropylene triamines),
N-(2-aminoethyl)-1,3-propylenediamine (i.e., N.sub.3-amine),
glycerin-based triamines, (all saturated); tetramines such as
N,N'-bis(3-aminopropyl)ethylene diamine (i.e., N.sub.4-amine) (both
saturated), triethylene tetramine; and other polyamines such as
tetraethylene pentamine (also saturated). One suitable
amine-terminated chain-extending agent is Ethacure 300.TM.
(dimethylthiotoluenediamine or a mixture of
2,6-diamino-3,5-dimethylthiotoluene and
2,4-diamino-3,5-dimethylthiotoluene.) The amine curing agents used
as chain extenders normally have a cyclic structure and a low
molecular weight (250 or less).
[0098] When a hydroxyl-terminated curing agent is used, the
resulting polyurethane composition contains urethane linkages. On
the other hand, when an amine-terminated curing agent is used, any
excess isocyanate groups will react with the amine groups in the
curing agent. The resulting polyurethane composition contains
urethane and urea linkages and may be referred to as a
polyurethane/urea hybrid.
Outer Core Layer Composition
[0099] As discussed above, the inner core is made preferably from a
foamed composition. In one embodiment, the optional outer core
layer is formed from a foamed or non-foamed thermoset composition
and more preferably from a foamed or non-foamed thermoset rubber
composition. In another embodiment, the optional outer core layer
is formed from a foamed or non-foamed thermoplastic
composition.
[0100] Suitable thermoset rubber materials for forming the outer
core layer include, but are not limited to, polybutadiene,
polyisoprene, ethylene propylene rubber ("EPR"),
ethylene-propylene-diene ("EPDM") rubber, 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, polystyrene
elastomers, polyethylene elastomers, polyurethane elastomers,
polyurea elastomers, metallocene-catalyzed elastomers and
plastomers, copolymers of isobutylene and p-alkylstyrene,
halogenated copolymers of isobutylene and p-alkylstyrene,
copolymers of butadiene with acrylonitrile, polychloroprene, alkyl
acrylate rubber, chlorinated isoprene rubber, acrylonitrile
chlorinated isoprene rubber, and blends of two or more thereof.
Preferably, the outer core layer is formed from a polybutadiene
rubber composition.
[0101] The thermoset rubber composition may be cured using
conventional curing processes. Suitable curing processes include,
for example, peroxide-curing, sulfur-curing, high-energy radiation,
and combinations thereof. Preferably, the rubber composition
contains a free-radical initiator selected from organic peroxides,
high energy radiation sources capable of generating free-radicals,
and combinations thereof. In one preferred version, the rubber
composition is peroxide-cured. Suitable organic peroxides include,
but are not limited to, dicumyl peroxide;
n-butyl-4,4-di(t-butylperoxy) valerate;
1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;
2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;
di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;
2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;
di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoyl
peroxide; t-butyl hydroperoxide; and combinations thereof. In a
particular embodiment, the free radical initiator is dicumyl
peroxide, including, but not limited to Perkadox.RTM. BC,
commercially available from Akzo Nobel. Peroxide free-radical
initiators are generally present in the rubber composition in an
amount of at least 0.05 parts by weight per 100 parts of the total
rubber, or an amount within the range having a lower limit of 0.05
parts or 0.1 parts or 1 part or 1.25 parts or 1.5 parts or 2.5
parts or 5 parts by weight per 100 parts of the total rubbers, and
an upper limit of 2.5 parts or 3 parts or 5 parts or 6 parts or 10
parts or 15 parts by weight per 100 parts of the total rubber.
Concentrations are in parts per hundred (phr) unless otherwise
indicated. As used herein, the term, "parts per hundred," also
known as "phr" or "pph" is defined as the number of parts by weight
of a particular component present in a mixture, relative to 100
parts by weight of the polymer component. Mathematically, this can
be expressed as the weight of an ingredient divided by the total
weight of the polymer, multiplied by a factor of 100.
[0102] The rubber compositions may further include a reactive
cross-linking co-agent. Suitable co-agents include, but are not
limited to, metal salts of unsaturated carboxylic acids having from
3 to 8 carbon atoms; unsaturated vinyl compounds and polyfunctional
monomers (e.g., trimethylolpropane trimethacrylate); phenylene
bismaleimide; and combinations thereof. Particular examples of
suitable metal salts include, but are not limited to, one or more
metal salts of acrylates, diacrylates, methacrylates, and
dimethacrylates, wherein the metal is selected from magnesium,
calcium, zinc, aluminum, lithium, and nickel. In a particular
embodiment, the co-agent is selected from zinc salts of acrylates,
diacrylates, methacrylates, and dimethacrylates. In another
particular embodiment, the agent is zinc diacrylate (ZDA). When the
co-agent is zinc diacrylate and/or zinc dimethacrylate, the
co-agent is typically included in the rubber composition in an
amount within the range having a lower limit of 1 or 5 or 10 or 15
or 19 or 20 parts by weight per 100 parts of the total rubber, and
an upper limit of 24 or 25 or 30 or 35 or 40 or 45 or 50 or 60
parts by weight per 100 parts of the base rubber.
[0103] Radical scavengers such as a halogenated organosulfur,
organic disulfide, or inorganic disulfide compounds may be added to
the rubber composition. These compounds also may function as "soft
and fast agents." As used herein, "soft and fast agent" means any
compound or a blend thereof that is capable of making a core: 1)
softer (having a lower compression) at a constant "coefficient of
restitution" (COR); and/or 2) faster (having a higher COR at equal
compression), when compared to a core equivalently prepared without
a soft and fast agent. Preferred halogenated organosulfur compounds
include, but are not limited to, pentachlorothiophenol (PCTP) and
salts of PCTP such as zinc pentachlorothiophenol (ZnPCTP). Using
PCTP and ZnPCTP in golf ball inner cores helps produce softer and
faster inner cores. The PCTP and ZnPCTP compounds help increase the
resiliency and the coefficient of restitution of the core. In a
particular embodiment, the soft and fast agent is selected from
ZnPCTP, PCTP, ditolyl disulfide, diphenyl disulfide, dixylyl
disulfide, 2-nitroresorcinol, and combinations thereof.
[0104] The rubber composition also may include filler(s) such as
materials 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. Metal fillers such as, for
example, particulate; powders; flakes; and fibers of copper, steel,
brass, tungsten, titanium, aluminum, magnesium, molybdenum, cobalt,
nickel, iron, lead, tin, zinc, barium, bismuth, bronze, silver,
gold, and platinum, and alloys and combinations thereof also may be
added to the rubber composition to adjust the specific gravity of
the composition as needed.
[0105] In addition, the rubber compositions may include
antioxidants to prevent the breakdown of the elastomers. Also,
processing aids such as high molecular weight organic acids and
salts thereof may be added to the composition. Suitable organic
acids are aliphatic organic acids, aromatic organic acids,
saturated mono-functional organic acids, unsaturated monofunctional
organic acids, multi-unsaturated mono-functional organic acids, and
dimerized derivatives thereof. 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. The organic acids are aliphatic,
mono-functional (saturated, unsaturated, or multi-unsaturated)
organic acids. Salts of these organic acids may also be employed.
The salts of organic acids include the salts of barium, lithium,
sodium, zinc, bismuth, chromium, cobalt, copper, potassium,
strontium, titanium, tungsten, magnesium, cesium, iron, nickel,
silver, aluminum, tin, or calcium, salts of fatty acids,
particularly stearic, behenic, erucic, oleic, linoelic or dimerized
derivatives thereof. It is preferred that the organic acids and
salts of the present invention 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.) Other ingredients such as accelerators (for
example, tetra methylthiuram), processing aids, dyes and pigments,
wetting agents, surfactants, plasticizers, coloring agents,
fluorescent agents, chemical blowing and foaming agents, defoaming
agents, stabilizers, softening agents, impact modifiers,
antiozonants, as well as other additives known in the art may be
added to the rubber composition.
[0106] Examples of commercially-available polybutadiene rubbers
that can be used in accordance with this invention, include, but
are not limited to, BR 01 and BR 1220, available from BST
Elastomers of Bangkok, Thailand; SE BR 1220LA and SE BR1203,
available from DOW Chemical Co of Midland, Mich.; BUDENE 1207,
1207s, 1208, and 1280 available from Goodyear, Inc of Akron, Ohio;
BR 01, 51 and 730, available from Japan Synthetic Rubber (JSR) of
Tokyo, Japan; BUNA CB 21, CB 22, CB 23, CB 24, CB 25, CB 29 MES, CB
60, CB Nd 60, CB 55 NF, CB 70 B, CB KA 8967, and CB 1221, available
from Lanxess Corp. of Pittsburgh. Pa.; BR1208, available from LG
Chemical of Seoul, South Korea; UBEPOL BR130B, BR150, BR150B,
BR150L, BR230, BR360L, BR710, and VCR617, available from UBE
Industries, Ltd. of Tokyo, Japan; EUROPRENE NEOCIS BR 60, INTENE 60
AF and P30AF, and EUROPRENE BR HV80, available from Polimeri Europa
of Rome, Italy; AFDENE 50 and NEODENE BR40, BR45, BR50 and BR60,
available from Karbochem (PTY) Ltd. of Bruma, South Africa; KBR 01,
NdBr 40, NdBR-45, NdBr 60, KBR 710S, KBR 710H, and KBR 750,
available from Kumho Petrochemical Co., Ltd. Of Seoul, South Korea;
DIENE 55NF, 70AC, and 320 AC, available from Firestone Polymers of
Akron, Ohio; and PBR-Nd Group II and Group III, available from
Nizhnekamskneftekhim, Inc. of Nizhnekamsk, Tartarstan Republic.
[0107] The polybutadiene rubber is used in an amount of at least
about 5% by weight based on total weight of composition and is
generally present in an amount of about 5% to about 100%, or an
amount within a range having a lower limit of 5% or 10% or 20% or
30% or 40% or 50% and an upper limit of 55% or 60% or 70% or 80% or
90% or 95% or 100%. Preferably, the concentration of polybutadiene
rubber is about 40 to about 95 weight percent. If desirable, lesser
amounts of other thermoset materials may be incorporated into the
base rubber. Such materials include the rubbers discussed above,
for example, cis-polyisoprene, trans-polyisoprene, balata,
polychloroprene, polynorbornene, polyoctenamer, polypentenamer,
butyl rubber, EPR, EPDM, styrene-butadiene, and the like.
[0108] Suitable thermoplastic materials for forming the outer core
layer include, but are not limited to, ionomer compositions
containing acid groups that are at least partially-neutralized.
Suitable ionomer compositions include partially-neutralized
ionomers and highly-neutralized ionomers (HNPs), including ionomers
formed from blends of two or more partially-neutralized ionomers,
blends of two or more highly-neutralized ionomers, and blends of
one or more partially-neutralized ionomers with one or more
highly-neutralized ionomers. For purposes of the present
disclosure, "HNP" refers to an acid copolymer after at least 70% of
all acid groups present in the composition are neutralized.
Preferred ionomers are salts of O/X- and O/X/Y-type acid
copolymers, wherein O is an .alpha.-olefin, X is a C.sub.3-C.sub.8
.alpha.,.beta.-ethylenically unsaturated carboxylic acid, and Y is
a softening monomer. O is preferably selected from ethylene and
propylene. X is preferably selected from methacrylic acid, acrylic
acid, ethacrylic acid, crotonic acid, and itaconic acid.
Methacrylic acid and acrylic acid are particularly preferred. Y is
preferably selected from (meth) acrylate and alkyl (meth) acrylates
wherein the alkyl groups have from 1 to 8 carbon atoms, including,
but not limited to, n-butyl (meth) acrylate, isobutyl (meth)
acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate.
[0109] Preferred O/X and O/X/Y-type copolymers 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
.alpha., .beta.-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.
[0110] Suitable acid polymers for forming the ionomer composition
also include acid polymers that are already partially neutralized.
Examples of 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.;
and Iotek.RTM. ionomers, commercially available from ExxonMobil
Chemical Company. Also suitable are DuPont.RTM. HPF 1000 and
DuPont.RTM. HPF 2000, ionomeric materials commercially available
from E. I. du Pont de Nemours and Company. In some embodiments,
very low modulus ionomer- ("VLMI-") type ethylene-acid polymers are
particularly suitable for forming the ionomer composition, such as
Surlyn.RTM. 6320, Surlyn.RTM. 8120, Surlyn.RTM. 8320, and
Surlyn.RTM. 9320, commercially available from E. I. du Pont de
Nemours and Company.
[0111] The .alpha.-olefin is typically present in the O/X or
O/X/Y-type copolymer in an amount of 15 wt. % or greater, or 25 wt.
% or greater, or 40 wt. % or greater, or 60 wt. % or greater, based
on the total weight of the acid copolymer. The acid is typically
present in the acid copolymer in an amount of 6 wt. % or greater,
or 9 wt. % or greater, or 10 wt. % or greater, or 11 wt. % or
greater, or 15 wt. % or greater, or 16 wt. % or greater, or in an
amount within a range having a lower limit of 1 or 4 or 5 or 6 or 8
or 10 or 11 or 12 or 15 or 16 or 20 wt. % and an upper limit of 15
or 16 or 17 or 19 or 20 or 20.5 or 21 or 25 or 26 or 30 or 35 or 40
wt. %, based on the total weight of the acid copolymer. The
optional softening monomer is typically present in the acid
copolymer in an amount within a range having a lower limit of 0 or
1 or 3 or 5 or 11 or 15 or 20 wt. % and an upper limit of 23 or 25
or 30 or 35 or 50 wt. %, based on the total weight of the acid
copolymer.
[0112] Additional suitable acid polymers are more fully described,
for example, in U.S. Pat. Nos. 5,691,418, 6,562,906, 6,653,382,
6,777,472, 6,762,246, 6,815,480, and 6,953,820 and U.S. Patent
Application Publication Nos. 2005/0148725, 2005/0049367,
2005/0020741, 2004/0220343, and 2003/0130434, the entire
disclosures of which are hereby incorporated herein by
reference.
[0113] The O/X or O/X/Y-type copolymer is at least partially
neutralized with a cation source, optionally in the presence of a
high molecular weight organic acid, such as those disclosed in U.S.
Pat. No. 6,756,436, the entire disclosure of which is hereby
incorporated herein by reference, such that at least 70%,
preferably at least 80%, more preferably at least 90%, more
preferably at least 95%, and even more preferably 100%, of all acid
groups present are neutralized. In a particular embodiment, the
cation source is present in an amount sufficient to neutralize,
theoretically, greater than 100%, or 105% or greater, or 110% or
greater, or 115% or greater, or 120% or greater, or 125% or
greater, or 200% or greater, or 250% or greater of all acid groups
present in the composition. The acid copolymer can be reacted with
the optional high molecular weight organic acid and the cation
source simultaneously, or prior to the addition of the cation
source.
[0114] Suitable cation sources include, but are not limited to,
metal ion sources, such as compounds of alkali metals, alkaline
earth metals, transition metals, and rare earth elements; ammonium
salts and monoamine salts; and combinations thereof. Preferred
cation sources are compounds of magnesium, sodium, potassium,
cesium, calcium, barium, manganese, copper, zinc, lead, tin,
aluminum, nickel, chromium, lithium, and rare earth metals. Methods
of preparing ionomers, and the acid polymers on which ionomers are
based, are disclosed, for example, in U.S. Pat. Nos. 3,264,272, and
4,351,931, and U.S. Patent Application Publication No.
2002/0013413.
[0115] Suitable high molecular weight organic acids are aliphatic
organic acids, aromatic organic acids, saturated monofunctional
organic acids, unsaturated monofunctional organic acids,
multi-unsaturated monofunctional organic acids, and dimerized
derivatives thereof. 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, dimerized derivatives
thereof, and combinations thereof. Salts of high molecular weight
organic acids comprise the salts, particularly the barium, lithium,
sodium, zinc, bismuth, chromium, cobalt, copper, potassium,
stontium, titanium, tungsten, magnesium, and calcium salts, of
aliphatic organic acids, aromatic organic acids, saturated
monofunctional organic acids, unsaturated monofunctional organic
acids, multi-unsaturated monofunctional organic acids, dimerized
derivatives thereof, and combinations thereof. Suitable organic
acids and salts thereof 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. In a particular embodiment, the
HNP composition comprises an organic acid salt in an amount of 20
phr or greater, or 25 phr or greater, or 30 phr or greater, or 35
phr or greater, or 40 phr or greater.
[0116] The ionomer composition optionally comprises at least one
additional polymer component selected from partially neutralized
ionomers as disclosed, for example, in U.S. Patent Application
Publication No. 2006/0128904, the entire disclosure of which is
hereby incorporated herein by reference; bimodal ionomers, such as
those disclosed in U.S. Patent Application Publication No.
2004/0220343 and U.S. Pat. Nos. 6,562,906, 6,762,246, 7,273,903,
8,193,283, 8,410,219, and 8,410,220, the entire disclosures of
which are hereby incorporated herein by reference, and particularly
Surlyn.RTM. AD 1043, 1092, and 1022 ionomer resins, commercially
available from E. I. du Pont de Nemours and Company; ionomers
modified with rosins, such as those disclosed in U.S. Patent
Application Publication No. 2005/0020741, the entire disclosure of
which is hereby incorporated by reference; soft and resilient
ethylene copolymers, such as those disclosed U.S. Patent
Application Publication No. 2003/0114565, the entire disclosure of
which is hereby incorporated herein by reference; polyolefins, such
as 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; polyamides; polyesters; polyethers;
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 copolymers, and conventional HNPs, such as those
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; polyurethanes; grafted and non-grafted
metallocene-catalyzed polymers, such as single-site catalyst
polymerized polymers, high crystalline acid polymers, cationic
ionomers, and combinations thereof; natural and synthetic rubbers,
including, but not limited to, ethylene propylene rubber ("EPR"),
ethylene propylene diene rubber ("EPDM"), 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 (such as
ethylene-alkyl acrylates and ethylene-alkyl methacrylates, and,
more specifically, ethylene-ethyl acrylate, ethylene-methyl
acrylate, and ethylene-butyl acrylate), chlorinated isoprene
rubber, acrylonitrile chlorinated isoprene rubber, and
polybutadiene rubber (cis and trans). Additional suitable blend
polymers include those described in U.S. Pat. No. 5,981,658, for
example at column 14, lines 30 to 56, the entire disclosure of
which is hereby incorporated herein by reference. The blend 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. In a particular embodiment, the ionomer
composition comprises an acid copolymer and an additional polymer
component, wherein the additional polymer component is a non-acid
polymer present in an amount of greater than 50 wt %, or an amount
within a range having a lower limit of 50 or 55 or 60 or 65 or 70
and an upper limit of 80 or 85 or 90, based on the combined weight
of the acid copolymer and the non-acid polymer. In another
particular embodiment, the ionomer composition comprises an acid
copolymer and an additional polymer component, wherein the
additional polymer component is a non-acid polymer present in an
amount of less than 50 wt %, or an amount within a range having a
lower limit of 10 or 15 or 20 or 25 or 30 and an upper limit of 40
or 45 or 50, based on the combined weight of the acid copolymer and
the non-acid polymer.
[0117] Suitable HNP compositions are further disclosed, for
example, in U.S. Pat. Nos. 6,653,382, 6,756,436, 6,777,472,
6,815,480, 6,894,098, 6,919,393, 6,953,820, 6,994,638, 7,375,151,
the entire disclosures of which are hereby incorporated herein by
reference.
[0118] Non-limiting examples of suitable commercially available
ionomers and other thermoplastic materials that can be used in
accordance with this invention are Surlyn.RTM. ionomers and
DuPont.RTM. HPF 1000 and HPF 2000 highly neutralized polymers,
commercially available from E. I. du Pont de Nemours and Company;
Clarix.RTM. ionomers, commercially available from A. Schulman,
Inc.; Iotek.RTM. ionomers, commercially available from ExxonMobil
Chemical Company; and Amplify.RTM. IO ionomers, commercially
available from The Dow Chemical Company; Amplify.RTM. GR functional
polymers and Amplify.RTM. TY functional polymers, commercially
available from The Dow Chemical Company; Fusabond.RTM.
functionalized polymers, commercially available from E. I. du Pont
de Nemours and Company; Exxelor.RTM. maleic anhydride grafted
polymers, commercially available from ExxonMobil Chemical Company;
ExxonMobil.RTM. PP series polypropylene impact copolymers,
commercially available from ExxonMobil Chemical Company;
Vistamaxx.RTM. propylene-based elastomers, commercially available
from ExxonMobil Chemical Company; Exact.RTM. plastomers,
commercially available from ExxonMobil Chemical Company;
Santoprene.RTM. thermoplastic vulcanized elastomers, commercially
available from ExxonMobil Chemical Company; Kraton.RTM. styrenic
block copolymers, commercially available from Kraton Performance
Polymers Inc.; Septon.RTM. styrenic block copolymers, commercially
available from Kuraray Co., Ltd.; Lotader.RTM. ethylene acrylate
based polymers, commercially available from Arkema Corporation;
Polybond.RTM. grafted polyethylenes and polypropylenes,
commercially available from Chemtura Corporation; Pebax.RTM.
polyether and polyester amides, commercially available from Arkema
Inc.; polyester-based thermoplastic elastomers, such as Hytrel.RTM.
polyester elastomers, commercially available from E. I. du Pont de
Nemours and Company, and Riteflex.RTM. polyester elastomers,
commercially available from Ticona; Estane.RTM. thermoplastic
polyurethanes, commercially available from The Lubrizol
Corporation; Grivory.RTM. polyamides and Grilamid.RTM. polyamides,
commercially available from EMS Grivory; Zytel.RTM. polyamide
resins and Elvamide.RTM. nylon multipolymer resins, commercially
available from E. I. du Pont de Nemours and Company; Elvaloy.RTM.
acrylate copolymer resins, commercially available from E. I. du
Pont de Nemours and Company; Elastollan.RTM. polyurethane-based
thermoplastic elastomers, commercially available from BASF;
Xylex.RTM. polycarbonate/polyester blends, commercially available
from SABIC Innovative Plastics; and combinations of two or more
thereof.
[0119] As discussed above, the acid is typically present in the O/X
or O/X/Y-type copolymer in an amount of 6 wt. % or greater. "Low
acid" and "high acid" ionomeric copolymers, 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. The acidic
groups in the acid copolymers 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. Suitable cation sources include, for example,
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.
[0120] For example, olefin acid copolymer ionomer resins having
acid groups that are neutralized from about 10 percent or greater
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 or
partial-neutralization. On the other hand, the ionomer composition
may contain acid groups that are highly or fully-neutralized. In
these HNPs, 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.
[0121] When the .alpha.-olefin monomer is ethylene, such copolymers
are referred to herein as E/X-type copolymers and 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.
[0122] The amount of ethylene in the E/X and E/X/Y-type copolymers
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 ethylene 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 monomer in the ethylene 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. As discussed above, "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.
[0123] As discussed above, the acidic groups in the E/X and
E/X/Y-type copolymer 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.
[0124] For example, ethylene acid copolymers having acid groups
that are neutralized from about 10 percent or greater may be used.
In one ethylene acid copolymer 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 ethylene acid copolymer compositions,
containing acid groups neutralized to 70% or less, may be referred
to ionomers having relatively low neutralization levels or
partial-neutralization. On the other hand, the ethylene acid
copolymer composition may contain acid groups that are highly or
fully-neutralized. In these HNPs, 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.
[0125] "Ionic plasticizers" such as organic acids or salts of
organic acids, particularly fatty acids, may be added to any of the
ionomer resins if needed. 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 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).
[0126] As noted above, the final ionomer compositions 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.
[0127] The ionomer compositions may contain a wide variety of
fillers and some of these fillers may be used to adjust the
specific gravity of the composition as needed. High surface-area
fillers that have an affinity for the acid groups in ionomer may be
used. In particular, fillers such as particulate, fibers, or flakes
having cationic nature such that they may also contribute to the
neutralization of the ionomer are suitable. For example, aluminum
oxide, zinc oxide, tin oxide, barium sulfate, zinc sulfate, calcium
oxide, calcium carbonate, zinc carbonate, barium carbonate,
tungsten, tungsten carbide, and lead silicate fillers may be used.
Also, silica, fumed silica, and precipitated silica, such as those
sold under the tradename, HISIL.TM., from PPG Industries, carbon
black, carbon fibers, and nano-scale materials such as nanotubes,
nanoflakes, nanofillers, and nanoclays may be used. Relatively
heavy-weight fillers also may be added to the ionomer compositions
including, but not limited to, particulate, powders, fibers and
flakes of heavy metals such as copper, nickel, tungsten, brass,
steel, magnesium, molybdenum, cobalt, lead, tin, silver, gold, and
platinum, and alloys thereof. Steel materials also can be added. In
other instances, it may be desirable to add relatively light-weight
metals such as titanium and aluminum alloys thereof. 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, titanium dioxide, acid copolymer wax,
surfactants, rubber regrind (recycled core material), clay, mica,
talc, glass flakes, 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 25 wt. % or less, or 20 wt. % or less, or
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 total weight of the ionomeric
composition.
[0128] The acid copolymer ionomer is used in an amount of at least
about 5% by weight based on total weight of composition and is
generally present in an amount of about 5% to about 100%, or an
amount within a range having a lower limit of 5% or 10% or 20% or
30% or 40% or 50% and an upper limit of 55% or 60% or 70% or 80% or
90% or 95% or 100%. Preferably, the concentration of acid copolymer
is about 40 to about 95 weight percent.
[0129] In a particular embodiment, the thermoplastic outer core
layer is formed from an HNP composition, wherein the HNP
composition is formed by blending an acid polymer, a non-acid
polymer, a cation source, and a fatty acid or metal salt thereof.
For purposes of the present invention, maleic anhydride modified
polymers are defined herein as a non-acid polymer despite having
anhydride groups that can ring-open to the acid form during
processing of the polymer to form the HNP compositions herein. The
maleic anhydride groups are grafted onto a polymer, are present at
relatively very low levels, and are not part of the polymer
backbone, as is the case with the acid polymers, which are
exclusively E/X and E/X/Y copolymers of ethylene and an acid,
particularly methacrylic acid and acrylic acid.
[0130] In a particular aspect of this embodiment, the acid polymer
is selected from ethylene-acrylic acid and ethylene-methacrylic
acid copolymers, optionally containing a softening monomer selected
from n-butyl acrylate and iso-butyl acrylate. The acid polymer
preferably has an acid content with a range having a lower limit of
2 or 10 or 15 or 16 mol % and an upper limit of 20 or 25 or 26 or
30 mol %. Examples of particularly suitable commercially available
acid polymers include, but are not limited to, those given in Table
1A below.
TABLE-US-00001 TABLE 1A Acid Softening Monomer Melt Index Acid
Polymer (wt %) (wt %) (2.16 kg, 190.degree. C., g/10 min) Nucrel
.RTM. 9-1 methacrylic acid n-butyl acrylate 25 (9.0) (23.5) Nucrel
.RTM. 599 methacrylic acid none 450 (10.0) Nucrel .RTM. 960
methyacrylic acid none 60 (15.0) Nucrel .RTM. 0407 methacrylic acid
none 7.5 (4.0) Nucrel .RTM. 0609 methacrylic acid none 9 (6.0)
Nucrel .RTM. 1214 methacrylic acid none 13.5 (12.0) Nucrel .RTM.
2906 methacrylic acid none 60 (19.0) Nucrel .RTM. 2940 methacrylic
acid none 395 (19.0) Nucrel .RTM. 30707 acrylic acid none 7 (7.0)
Nucrel .RTM. 31001 acrylic acid none 1.3 (9.5) Nucrel .RTM. AE
methacrylic acid isobutyl acrylate 11 (2.0) (6.0) Nucrel .RTM. 2806
acrylic acid none 60 (18.0) Nucrel .RTM. 0403 methacrylic acid none
3 (4.0) Nucrel .RTM. 925 methacrylic acid none 25 (15.0) Escor
.RTM. AT-310 acrylic acid methyl acrylate 6 (6.5) (6.5) Escor .RTM.
AT-325 acrylic acid methyl acrylate 20 (6.0) (20.0) Escor .RTM.
AT-320 acrylic acid methyl acrylate 5 (6.0) (18.0) Escor .RTM. 5070
acrylic acid none 30 (9.0) Escor .RTM. 5100 acrylic acid none 8.5
(11.0) Escor .RTM. 5200 acrylic acid none 38 (15.0) A-C .RTM. 5120
acrylic acid none not reported (15) A-C .RTM. 540 acrylic acid none
not reported (5) A-C .RTM. 580 acrylic acid none not reported (10)
Primacor .RTM. 3150 acrylic acid none 5.8 (6.5) Primacor .RTM. 3330
acrylic acid none 11 (3.0) Primacor .RTM. 5985 acrylic acid none
240 (20.5) Primacor .RTM. 5986 acrylic acid none 300 (20.5)
Primacor .RTM. 5980I acrylic acid none 300 (20.5) Primacor .RTM.
5990I acrylic acid none 1300 (20.0) XUS 60751.17 acrylic acid none
600 (19.8) XUS 60753.02L acrylic acid none 60 (17.0) Nucrel .RTM.
acid polymers are commercially available from E. I. du Pont de
Nemours and Company. Escor .RTM. acid polymers are commercially
available from ExxonMobil Chemical Company. A-C .RTM. acid polymers
are commercially available from Honeywell International Inc.
Primacor .RTM. acid polymers and XUS acid polymers are commercially
available from The Dow Chemical Company.
[0131] In another particular aspect of this embodiment, the
non-acid polymer is an elastomeric polymer. Suitable elastomeric
polymers include, but are not limited to: [0132] (a) ethylene-alkyl
acrylate polymers, particularly polyethylene-butyl acrylate,
polyethylene-methyl acrylate, and polyethylene-ethyl acrylate;
[0133] (b) metallocene-catalyzed polymers; [0134] (c)
ethylene-butyl acrylate-carbon monoxide polymers and ethylene-vinyl
acetate-carbon monoxide polymers; [0135] (d) polyethylene-vinyl
acetates; [0136] (e) ethylene-alkyl acrylate polymers containing a
cure site monomer; [0137] (f) ethylene-propylene rubbers and
ethylene-propylene-diene monomer rubbers; [0138] (g) olefinic
ethylene elastomers, particularly ethylene-octene polymers,
ethylene-butene polymers, ethylene-propylene polymers, and
ethylene-hexene polymers; [0139] (h) styrenic block copolymers;
[0140] (i) polyester elastomers; [0141] (j) polyamide elastomers;
[0142] (k) polyolefin rubbers, particularly polybutadiene,
polyisoprene, and styrene-butadiene rubber; and [0143] (l)
thermoplastic polyurethanes.
[0144] Examples of particularly suitable commercially available
non-acid polymers include, but are not limited to, Lotader.RTM.
ethylene-alkyl acrylate polymers and Lotryl.RTM. ethylene-alkyl
acrylate polymers, and particularly Lotader.RTM. 4210, 4603, 4700,
4720, 6200, 8200, and AX8900 commercially available from Arkema
Corporation; Elvaloy.RTM. AC ethylene-alkyl acrylate polymers, and
particularly AC 1224, AC 1335, AC 2116, AC3117, AC3427, and
AC34035, commercially available from E. I. du Pont de Nemours and
Company; Fusabond.RTM. elastomeric polymers, such as ethylene vinyl
acetates, polyethylenes, metallocene-catalyzed polyethylenes,
ethylene propylene rubbers, and polypropylenes, and particularly
Fusabond.RTM. N525, C190, C250, A560, N416, N493, N614, P614, M603,
E100, E158, E226, E265, E528, and E589, commercially available from
E. I. du Pont de Nemours and Company; Honeywell A-C polyethylenes
and ethylene maleic anhydride copolymers, and particularly A-C
5180, A-C 575, A-C 573, A-C 655, and A-C 395, commercially
available from Honeywell; Nordel.RTM. IP rubber, Elite.RTM.
polyethylenes, Engage.RTM. elastomers, and Amplify.RTM. functional
polymers, and particularly Amplify.RTM. GR 207, GR 208, GR 209, GR
213, GR 216, GR 320, GR 380, and EA 100, commercially available
from The Dow Chemical Company; Enable.RTM. metallocene
polyethylenes, Exact.RTM. plastomers, Vistamaxx.RTM.
propylene-based elastomers, and Vistalon.RTM. EPDM rubber,
commercially available from ExxonMobil Chemical Company;
Starflex.RTM. metallocene linear low density polyethylene,
commercially available from LyondellBasell; Elvaloy.RTM. HP4051,
HP441, HP661 and HP662 ethylene-butyl acrylate-carbon monoxide
polymers and Elvaloy.RTM. 741, 742 and 4924 ethylene-vinyl
acetate-carbon monoxide polymers, commercially available from E. I.
du Pont de Nemours and Company; Evatane.RTM. ethylene-vinyl acetate
polymers having a vinyl acetate content of from 18 to 42%,
commercially available from Arkema Corporation; Elvax.RTM.
ethylene-vinyl acetate polymers having a vinyl acetate content of
from 7.5 to 40%, commercially available from E. I. du Pont de
Nemours and Company; Vamac.RTM. G terpolymer of ethylene,
methylacrylate and a cure site monomer, commercially available from
E. I. du Pont de Nemours and Company; Vistalon.RTM. EPDM rubbers,
commercially available from ExxonMobil Chemical Company;
Kraton.RTM. styrenic block copolymers, and particularly Kraton.RTM.
FG1901GT, FG1924GT, and RP6670GT, commercially available from
Kraton Performance Polymers Inc.; Septon.RTM. styrenic block
copolymers, commercially available from Kuraray Co., Ltd.;
Hytrel.RTM. polyester elastomers, and particularly Hytrel.RTM.
3078, 4069, and 556, commercially available from E. I. du Pont de
Nemours and Company; Riteflex.RTM. polyester elastomers,
commercially available from Celanese Corporation; Pebax.RTM.
thermoplastic polyether block amides, and particularly Pebax.RTM.
2533, 3533, 4033, and 5533, commercially available from Arkema
Inc.; Affinity.RTM. and Affinity.RTM. GA elastomers, Versify.RTM.
ethylene-propylene copolymer elastomers, and Infuse.RTM. olefin
block copolymers, commercially available from The Dow Chemical
Company; Exxelor.RTM. polymer resins, and particularly Exxelor.RTM.
PE 1040, PO 1015, PO 1020, VA 1202, VA 1801, VA 1803, and VA 1840,
commercially available from ExxonMobil Chemical Company; and
Royaltuf.RTM. EPDM, and particularly Royaltuf.RTM. 498 maleic
anhydride modified polyolefin based on an amorphous EPDM and
Royaltuf.RTM.485 maleic anhydride modified polyolefin based on an
semi-crystalline EPDM, commercially available from Chemtura
Corporation.
[0145] Additional examples of particularly suitable commercially
available elastomeric polymers include, but are not limited to,
those given in Table 1B below.
TABLE-US-00002 TABLE 1B Melt Index % Maleic (2.16 kg, % Ester
Anhydride 190.degree. C., g/10 min) Polyethylene Butyl Acrylates
Lotader .RTM. 3210 6 3.1 5 Lotader .RTM. 4210 6.5 3.6 9 Lotader
.RTM. 3410 17 3.1 5 Lotryl .RTM. 17BA04 16-19 0 3.5-4.5 Lotryl
.RTM. 35BA320 33-37 0 260-350 Elvaloy .RTM. AC 3117 17 0 1.5
Elvaloy .RTM. AC 3427 27 0 4 Elvaloy .RTM. AC 34035 35 0 40
Polyethylene Methyl Acrylates Lotader .RTM. 4503 19 0.3 8 Lotader
.RTM. 4603 26 0.3 8 Lotader .RTM. AX 8900 26 8% GMA 6 Lotryl .RTM.
24MA02 23-26 0 1-3 Elvaloy .RTM. AC 12024S 24 0 20 Elvaloy .RTM. AC
1330 30 0 3 Elvaloy .RTM. AC 1335 35 0 3 Elvaloy .RTM. AC 1224 24 0
2 Polyethylene Ethyl Acrylates Lotader .RTM. 6200 6.5 2.8 40
Lotader .RTM. 8200 6.5 2.8 200 Lotader .RTM. LX 4110 5 3.0 5
Lotader .RTM. HX 8290 17 2.8 70 Lotader .RTM. 5500 20 2.8 20
Lotader .RTM. 4700 29 1.3 7 Lotader .RTM. 4720 29 0.3 7 Elvaloy
.RTM. AC 2116 16 0 1
[0146] The acid polymer and non-acid polymer are combined and
reacted with a cation source, such that at least 80% of all acid
groups present are neutralized. The present invention is not meant
to be limited by a particular order for combining and reacting the
acid polymer, non-acid polymer and cation source. In a particular
embodiment, the fatty acid or metal salt thereof is used in an
amount such that the fatty acid or metal salt thereof is present in
the HNP composition in an amount of from 10 wt % to 60 wt %, or
within a range having a lower limit of 10 or 20 or 30 or 40 wt %
and an upper limit of 40 or 50 or 60 wt %, based on the total
weight of the HNP composition. Suitable cation sources and fatty
acids and metal salts thereof are further disclosed above.
[0147] In another particular aspect of this embodiment, the acid
polymer is an ethylene-acrylic acid polymer having an acid content
of 19 wt % or greater, the non-acid polymer is a
metallocene-catalyzed ethylene-butene copolymer, optionally
modified with maleic anhydride, the cation source is magnesium, and
the fatty acid or metal salt thereof is magnesium oleate present in
the composition in an amount of 20 to 50 wt %, based on the total
weight of the composition.
[0148] Other suitable thermoplastic polymers that may be used to
form the outer core layer include, but are not limited to, the
following polymers, including homopolymers, copolymers, and
derivatives thereof:
[0149] (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;
[0150] (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;
[0151] (c) polyurethanes, polyureas, polyurethane-polyurea hybrids,
and blends of two or more thereof;
[0152] (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;
[0153] (e) polystyrenes, such as poly(styrene-co-maleic anhydride),
acrylonitrile-butadiene-styrene, poly(styrene sulfonate),
polyethylene styrene, and blends of two or more thereof;
[0154] (f) polyvinyl chlorides and grafted polyvinyl chlorides, and
blends of two or more thereof;
[0155] (g) polycarbonates, blends of
polycarbonate/acrylonitrile-butadiene-styrene, blends of
polycarbonate/polyurethane, blends of polycarbonate/polyester, and
blends of two or more thereof;
[0156] (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;
[0157] (i) polyimides, polyetherketones, polyamideimides, and
blends of two or more thereof; and
[0158] (j) polycarbonate/polyester copolymers and blends.
[0159] These thermoplastic polymers may be used by and in
themselves to form the outer core layer, or blends of thermoplastic
polymers including the above-described polymers and ethylene acid
copolymer ionomers may be used. It also is recognized that 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.
[0160] It also is recognized that thermoplastic materials can be
"converted" into thermoset materials by cross-linking the polymer
chains so they form a network structure, and such cross-linked
thermoplastic materials may be used to form the core layers in
accordance with this invention. For example, thermoplastic
polyolefins such as linear low density polyethylene (LLDPE), low
density polyethylene (LDPE), and high density polyethylene (HDPE)
may be cross-linked to form bonds between the polymer chains. The
cross-linked thermoplastic material typically has improved physical
properties and strength over non-cross-linked thermoplastics,
particularly at temperatures above the crystalline melting point.
Preferably a partially or fully-neutralized ionomer, as described
above, is covalently cross-linked to render it into a thermoset
composition (that is, it contains at least some level of covalent,
irreversable cross-links). Thermoplastic polyurethanes and
polyureas also may be converted into thermoset materials in
accordance with the present invention.
[0161] The cross-linked thermoplastic material may be created by
exposing the thermoplastic to: 1) a high-energy radiation
treatment, such as electron beam or gamma radiation, such as
disclosed in U.S. Pat. No. 5,891,973, which is incorporated by
reference herein, 2) lower energy radiation, such as ultra-violet
(UV) or infra-red (IR) radiation; 3) a solution treatment, such as
an isocyanate or a silane; 4) incorporation of additional free
radical initiator groups in the thermoplastic prior to molding;
and/or 5) chemical modification, such as esterification or
saponification, to name a few.
[0162] Modifications in thermoplastic polymeric structure of
thermoplastic can be induced by a number of methods, including
exposing the thermoplastic material to high-energy radiation or
through a chemical process using peroxide. Radiation sources
include, but are not limited to, gamma-rays, electrons, neutrons,
protons, x-rays, helium nuclei, or the like. Gamma radiation,
typically using radioactive cobalt atoms and allows for
considerable depth of treatment, if necessary. For core layers
requiring lower depth of penetration, electron-beam accelerators or
UV and IR light sources can be used. Useful UV and IR irradiation
methods are disclosed in U.S. Pat. Nos. 6,855,070 and 7,198,576,
which are incorporated herein by reference. The thermoplastic core
layers may be irradiated at dosages greater than 0.05 Mrd,
preferably ranging from 1 Mrd to 20 Mrd, more preferably from 2 Mrd
to 15 Mrd, and most preferably from 4 Mrd to 10 Mrd. In one
preferred embodiment, the cores are irradiated at a dosage from 5
Mrd to 8 Mrd and in another preferred embodiment, the cores are
irradiated with a dosage from 0.05 Mrd to 3 Mrd, more preferably
0.05 Mrd to 1.5 Mrd.
[0163] For example, a core assembly having a thermoplastic layer
may be converted to a thermoset layer by placing the core assembly
on a slowly move along a channel. Radiation from a radiation
source, such as gamma rays, is allowed to contact the surface of
the cores. The source is positioned to provide a generally uniform
dose of radiation to the cores as they roll along the channel. The
speed of the cores as they pass through the radiation source is
easily controlled to ensure the cores receive sufficient dosage to
create the desired hardness gradient. The cores are irradiated with
a dosage of 1 or more Mrd, more preferably 2 Mrd to 15 Mrd. The
intensity of the dosage is typically in the range of 1 MeV to 20
MeV. For thermoplastic resins having a reactive group (e.g.,
ionomers, thermoplastic urethanes, and the like), treating the
thermoplastic core layer in a chemical solution of an isocyanate or
an amine affects cross-linking and provides a harder surface and
subsequent hardness gradient. Incorporation of peroxide or other
free-radical initiator in the thermoplastic polymer, prior to
molding or forming, also allows for heat curing on the molded core
layer to create the desired hardness gradient. By proper selection
of time/temperature, an annealing process can be used to create a
gradient. Suitable annealing and/or peroxide (free radical) methods
are such as disclosed in U.S. Pat. Nos. 5,274,041 and 5,356,941,
respectively, which are incorporated by reference herein.
Additionally, silane or amino-silane crosslinking may also be
employed as disclosed in U.S. Pat. No. 7,279,529, the disclosure of
which incorporated herein by reference. The core layer may be
chemically treated in a solution, such as a solution containing one
or more isocyanates, to form the desired "positive hardness
gradient." The cores are typically exposed to the solution
containing the isocyanate by immersing them in a bath at a
particular temperature for a given time. Exposure time should be
greater than 1 minute, preferably from 1 minute to 120 minutes,
more preferably 5 minutes to 90 minutes, and most preferably 10
minutes to 60 minutes. In one preferred embodiment, the cores are
immersed in the treating solution from 15 minutes to 45 minutes,
more preferably from 20 minutes to 40 minutes, and most preferably
from 25 minutes to 30 minutes.
[0164] The core layers may be chemically treated in a solution,
such as a solution containing one or more isocyanates, to form the
desired "positive hardness gradient." The cores are typically
exposed to the solution containing the isocyanate by immersing them
in a bath at a particular temperature for a given time. Exposure
time should be greater than 1 minute, preferably from 1 minute to
120 minutes, more preferably 5 minutes to 90 minutes, and most
preferably 10 minutes to 60 minutes. In one preferred embodiment,
the cores are immersed in the treating solution from 15 minutes to
45 minutes, more preferably from 20 minutes to 40 minutes, and most
preferably from 25 minutes to 30 minutes. Both irradiative and
chemical methods promote molecular bonding, or cross-links, within
the TP polymer. Radiative methods permit cross-linking and grafting
in situ on finished products and cross-linking occurs at lower
temperatures with radiation than with chemical processing. Chemical
methods depend on the particular polymer, the presence of modifying
agents, and variables in processing, such as the level of
irradiation. Significant property benefits in the thermoplastic
materials can be attained and include, but are not limited to,
improved thermomechanical properties; lower permeability and
improved chemical resistance; reduced stress cracking; and overall
improvement in physical toughness.
[0165] Additional embodiments involve the use of plasticizers to
treat the core layers, thereby creating a softer outer portion of
the core for a "negative" hardness gradient. The plasticizer may be
reactive (such as higher alkyl acrylates) or non-reactive (that is,
phthalates, dioctylphthalate, or stearamides, etc). Other suitable
plasticizers include, but are not limited to, oxa acids, fatty
amines, fatty amides, fatty acid esters, phthalates, adipates, and
sebacates. Oxa acids are preferred plasticizers, more preferably
those having at least one or two acid functional groups and a
variety of different chain lengths. Preferred oxa acids include
3,6-dioxaheptanoic acid, 3,6,9-trioxadecanoic acid, diglycolic
acid, 3,6,9-trioxaundecanoic acid, polyglycol diacid, and
3,6-dioxaoctanedioic acid, such as those commercially available
from Archimica of Wilmington, Del. Any means of chemical
degradation will also result in a "negative" hardness gradient.
Chemical modifications such as esterification or saponification are
also suitable for modification of the thermoplastic core layer
surface and can result in the desired "positive hardness
gradient.
Core Structure
[0166] As discussed above, in one embodiment, the core of the golf
ball of this invention has a dual-layered structure comprising an
inner core and outer core layer. Referring to FIG. 3, one version
of a golf ball that can be made in accordance with this invention
is generally indicated at (20). The ball (20) contains a
dual-layered core (22) having an inner core (center) (22a) and
outer core layer (22b) surrounded by a single-layered cover (24).
The inner core (22a) is relatively small in volume and generally
has a diameter within a range of about 0.10 to about 1.10 inches.
More particularly, the inner core (22a) preferably has a diameter
size with a lower limit of about 0.15 or 0.25 or 0.35 or 0.45 or
0.55 inches and an upper limit of about 0.60 or 0.70 or 0.80 or
0.90 inches. In one preferred version, the diameter of the inner
core (22a) is in the range of about 0.025 to about 0.080 inches,
more preferably about 0.030 to about 0.075 inches. Meanwhile, the
outer core layer (22b) generally has a thickness within a range of
about 0.010 to about 0.250 inches and preferably has a lower limit
of 0.010 or 0.020 or 0.025 or 0.030 inches and an upper limit of
0.070 or 0.080 or 0.100 or 0.200 inches. In one preferred version,
the outer core layer has a thickness in the range of about 0.040 to
about 0.170 inches, more preferably about 0.060 to about 0.150
inches.
[0167] Referring to FIG. 4, in another version, the golf ball (25)
contains a dual-core (26) having an inner core (center) (26a) and
outer core layer (26b). The dual-core (26) is surrounded by a
multi-layered cover (28) having an inner cover layer (28a) and
outer cover layer (28b).
[0168] The hardness of the core sub-assembly (inner core and outer
core layer) is an important property. In general, cores with
relatively high hardness values have higher compression and tend to
have good durability and resiliency. However, some high compression
balls are stiff and this may have a detrimental effect on shot
control and placement. Thus, the optimum balance of hardness in the
core sub-assembly needs to be attained.
[0169] 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 such cases where both the inner core and
outer core layer each has a "positive" hardness gradient, the outer
surface hardness of the outer core layer is preferably greater than
the hardness of the geometric center of the inner core. In one
preferred version, the positive hardness gradient of the inner core
is in the range of about 2 to about 40 Shore C units and even more
preferably about 10 to about 25 Shore C units; while the positive
hardness gradient of the outer core is in the range of about 2 to
about 20 Shore C and even more preferably about 3 to about 10 Shore
C.
[0170] In an alternative version, the inner core may have a
positive hardness gradient; and 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) or 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.) For
example, in one version, the inner core has a positive hardness
gradient; and the outer core layer has a negative hardness gradient
in the range of about 2 to about 25 Shore C. In a second
alternative version, the inner core may have a zero or negative
hardness gradient; and the outer core layer may have a positive
hardness gradient. Still yet, in another embodiment, both the inner
core and outer core layers have zero or negative hardness
gradients.
[0171] In general, hardness gradients are further described in
Bulpett et al., U.S. Pat. Nos. 7,537,529 and 7,410,429, the
disclosures of which are hereby incorporated by reference. Methods
for measuring the hardness of the inner core and outer core layers
along with other layers in the golf ball and determining the
hardness gradients of the various layers are described in further
detail below. The core layers have positive, negative, or zero
hardness gradients defined by hardness measurements made at the
outer surface of the inner core (or outer surface of the outer core
layer) and radially inward towards the center of the inner core (or
inner surface of the outer core layer). These measurements are made
typically at 2-mm increments as described in the test methods
below. In general, the hardness gradient is determined by
subtracting the hardness value at the innermost portion of the
component being measured (for example, the center of the inner core
or inner surface of the outer core layer) from the hardness value
at the outer surface of the component being measured (for example,
the outer surface of the inner core or outer surface of the outer
core layer).
[0172] Positive Hardness Gradient.
[0173] For example, if the hardness value of the outer surface of
the inner core is greater than the hardness value of the inner
core's geometric center (that is, the inner core has a surface
harder than its geometric center), the hardness gradient will be
deemed "positive" (a larger number minus a smaller number equals a
positive number.) For example, if the outer surface of the inner
core has a hardness of 67 Shore C and the geometric center of the
inner core has a hardness of 60 Shore C, then the inner core has a
positive hardness gradient of 7. Likewise, if the outer surface of
the outer core layer has a greater hardness value than the inner
surface of the outer core layer, the given outer core layer will be
considered to have a positive hardness gradient.
[0174] Negative Hardness Gradient.
[0175] On the other hand, if the hardness value of the outer
surface of the inner core is less than the hardness value of the
inner core's geometric center (that is, the inner core has a
surface softer than its geometric center), the hardness gradient
will be deemed "negative." For example, if the outer surface of the
inner core has a hardness of 68 Shore C and the geometric center of
the inner core has a hardness of 70 Shore C, then the inner core
has a negative hardness gradient of 2. Likewise, if the outer
surface of the outer core layer has a lesser hardness value than
the inner surface of the outer core layer, the given outer core
layer will be considered to have a negative hardness gradient.
[0176] Zero Hardness Gradient.
[0177] In another example, if the hardness value of the outer
surface of the inner core is substantially the same as the hardness
value of the inner core's geometric center (that is, the surface of
the inner core has about the same hardness as the geometric
center), the hardness gradient will be deemed "zero." For example,
if the outer surface of the inner core and the geometric center of
the inner core each has a hardness of 65 Shore C, then the inner
core has a zero hardness gradient. Likewise, if the outer surface
of the outer core layer has a hardness value approximately the same
as the inner surface of the outer core layer, the outer core layer
will be considered to have a zero hardness gradient.
[0178] More particularly, the term, "positive hardness gradient" as
used herein means a hardness gradient of positive 3 Shore C or
greater, preferably 7 Shore C or greater, more preferably 10 Shore
C, and even more preferably 20 Shore C or greater. The term, "zero
hardness gradient" as used herein means a hardness gradient of less
than 3 Shore C, preferably less than 1 Shore C and may have a value
of zero or negative 1 to negative 10 Shore C. The term, "negative
hardness gradient" as used herein means a hardness value of less
than zero, for example, negative 3, negative 5, negative 7,
negative 10, negative 15, or negative 20 or negative 25. The terms,
"zero hardness gradient" and "negative hardness gradient" may be
used herein interchangeably to refer to hardness gradients of
negative 1 to negative 10.
[0179] The inner core preferably has a geometric center hardness
(H.sub.inner core center) of about 5 Shore D or greater. For
example, the (H.sub.inner core center) may be in the range of about
5 to about 88 Shore D and more particularly within a range having a
lower limit of about 5 or 10 or 14 or 18 or 20 or 26 or 30 or 34 or
36 or 38 or 42 or 48 or 50 or 52 Shore D and an upper limit of
about 54 or 56 or 58 or 60 or 62 or 64 or 68 or 70 or 74 or 76 or
80 or 82 or 84 or 88 Shore D. In another example, the center
hardness of the inner core (H.sub.inner core center), as measured
in Shore C units, is preferably about 10 Shore C or greater; for
example, the H.sub.inner core center may have a lower limit of
about 10 or 12 or 14 or 16 or 20 or 22 or 23 or 24 or 28 or 31 or
34 or 37 or 40 or 44 or 52 or 58 Shore C and an upper limit of
about 46 or 48 or 50 or 51 or 53 or 55 or 58 or 61 or 62 or 65 or
68 or 71 or 74 or 76 or 78 or 79 or 80 or 84 or 90 Shore C.
Concerning the outer surface hardness of the inner core
(H.sub.inner core surface), this hardness is preferably about 12
Shore D or greater or about 15 Shore D or greater; for example, the
H.sub.inner core surface may fall within a range having a lower
limit of about 12 or 15 or 18 or 20 or 22 or 23 or 26 or 30 or 34
or 36 or 38 or 42 or 48 or 50 or 52 Shore D and an upper limit of
about 54 or 56 or 58 or 60 or 62 or 70 or 72 or 75 or 78 or 80 or
82 or 84 or 86 or 90 Shore D. In one version, the outer surface
hardness of the inner core (H.sub.inner core surface), as measured
in Shore C units, has a lower limit of about 13 or 15 or 18 or 20
or 22 or 24 or 27 or 28 or 30 or 32 or 34 or 38 or 44 or 47 or 48
or 58 or 60 or 70 or 74 Shore C and an upper limit of about 50 or
54 or 56 or 61 or 65 or 66 or 68 or 70 or 73 or 76 or 78 or 80 or
84 or 86 or 88 or 90 or 92 Shore C. In another version, the
geometric center hardness (H.sub.inner core center) is in the range
of about 10 Shore C to about 50 Shore C; and the outer surface
hardness of the inner core (H.sub.inner core surface) is in the
range of about 5 Shore C to about 50 Shore C or in the range of
about 5 Shore C to about 48 Shore C.
[0180] On the other hand, the outer core layer preferably has an
outer surface hardness (H.sub.outer surface of OC) of about 40
Shore D or greater, and more preferably within a range having a
lower limit of about 40 or 42 or 44 or 46 or 48 or 50 or 52 and an
upper limit of about 54 or 56 or 58 or 60 or 62 or 64 or 70 or 74
or 78 or 80 or 82 or 85 or 87 or 88 or 90 Shore D. The outer
surface hardness of the outer core layer (H.sub.outer surface of
OC), as measured in Shore C units, preferably has a lower limit of
about 40 or 42 or 43 or 45 or 48 or 50 or 54 or 58 or 60 or 63 or
65 or 67 or 70 or 72 or 73 or 76 Shore C, and an upper limit of
about 78 or 80 or 84 or 85 or 87 or 88 or 89 or 90 or 92 or 95
Shore C. And, the inner surface of the outer core layer
(H.sub.inner surface of OC) preferably has a hardness of about 40
Shore D or greater, and more preferably within a range having a
lower limit of about 40 or 42 or 44 or 46 or 48 or 50 or 52 and an
upper limit of about 54 or 56 or 58 or 60 or 62 or 64 or 70 or 74
or 78 or 80 or 82 or 85 or 87 or 88 or 90 Shore D. The inner
surface hardness of the outer core layer (H.sub.inner surface of
OC), as measured in Shore C units, preferably has a lower limit of
about 40 or 42 or 44 or 45 or 47 or 50 or 52 or 54 or 55 or 58 or
60 or 63 or 65 or 67 or 70 or 73 or 76 Shore C, and an upper limit
of about 78 or 80 or 85 or 87 or 88 or 89 or 90 or 92 or 95 Shore
C.
[0181] In one embodiment, the outer surface hardness of the outer
core layer (H.sub.outer surface of OC), is less than the outer
surface hardness (H.sub.inner core surface) of the inner core by at
least 3 Shore C units and more preferably by at least 5 Shore
C.
[0182] In another embodiment, the outer surface hardness of the
outer core layer (H.sub.outer surface of OC), is greater than the
outer surface hardness (H.sub.inner core surface) of the inner core
by at least 3 Shore C units and more preferably by at least 5 Shore
C.
[0183] The core structure also has a hardness gradient across the
entire core assembly. In one embodiment, the (H.sub.inner core
center) is in the range of about 10 Shore C to about 60 Shore C,
preferably about 20 Shore C to about 50 Shore C; and the
(H.sub.outer surface of OC) is in the range of about 40 Shore C to
about 90 Shore C, preferably about 43 Shore C to about 87 Shore C,
to provide a positive hardness gradient across the core assembly.
In another embodiment, the (H.sub.inner core center) is in the
range of about 10 Shore C to about 60 Shore C, preferably about 13
Shore C to about 55 Shore C; and the (H.sub.outer surface of OC) is
in the range of about 65 to about 96 Shore C, preferably about 68
Shore C to about 94 Shore C or about 75 Shore C to about 93 Shore
C, to provide a positive hardness gradient across the core
assembly. The gradient across the core assembly will vary based on
several factors including, but not limited to, the dimensions of
the inner core, intermediate core, and outer core layers.
[0184] As discussed above, the inner core is preferably formed from
a foamed thermoplastic or thermoset composition and more preferably
foamed polyurethanes. And, the outer core layer is formed
preferably from a foamed or non-foamed thermoset composition or a
foamed or non-foamed thermoplastic composition.
[0185] The inner core preferably has a diameter in the range of
about 0.100 to about 1.100 inches, or a diameter of 1.30 inches or
greater, or 1.40 inches or greater, or 1.50 inches or greater, or
1.60 inches or greater, or 1.70 inches or greater, or 1.80 inches
or greater, or 1.90 inches or greater, or 2.00 inches or greater,
or 2.10 or greater, or 2.20 or greater. For example, the inner core
may have a diameter within a range of about 0.100 to about 0.500
inches. In another example, the inner core may have a diameter
within a range of about 0.300 to about 0.800 inches. More
particularly, the inner core may have a diameter size with a lower
limit of about 0.10 or 0.12 or 0.15 or 0.25 or 0.30 or 0.35 or 0.45
or 0.55 inches and an upper limit of about 0.60 or 0.65 or 0.70 or
0.80 or 0.90 or 1.00 or 1.10 inches, or the inner core may have a
diameter of 1.30 inches or greater, or 1.40 inches or greater, or
1.50 inches or greater, or 1.60 inches or greater, or 1.70 inches
or greater, or 1.80 inches or greater, or 1.90 inches or greater,
or 2.00 inches or greater, or 2.10 or greater, or 2.20 or greater.
As far as the optional outer core layer is concerned, it preferably
has a thickness in the range of about 0.100 to about 0.750 inches.
For example, the lower limit of thickness may be about 0.050 or
0.100 or 0.150 or 0.200 or 0.250 or 0.300 or 0.340 or 0.400 and the
upper limit may be about 0.500 or 0.550 or 0.600 or 0.650 or 0.700
or 0.750 inches.
[0186] Dual-layered core structures containing layers with various
thickness and volume levels may be made in accordance with this
invention. For example, in one version, the total diameter of the
core structure is 0.20 inches and the total volume of the core
structure is 0.23 cc. More particularly, in this example, the
diameter of the inner core is 0.10 inches and the volume of the
inner core is 0.10 cc; while the thickness of the outer core is
0.100 inches and the volume of the outer core is 0.13 cc. In
another version, the total core diameter is about 1.55 inches and
the total core volume is 31.96 cc. In this version, the outer core
layer has a thickness of 0.400 inches and volume of 28.34 cc.
Meanwhile, the inner core has a diameter of 0.75 inches and volume
of 3.62 cm. In one embodiment, the volume of the outer core layer
is greater than the volume of the inner core. In another
embodiment, the volume of the outer core layer and inner core are
equivalent. In still another embodiment, the volume of the outer
core layer is less than the volume of the inner core. Other
examples of core structures containing layers of varying
thicknesses and volumes are described below in Table 1C.
TABLE-US-00003 TABLE 1C Sample Core Dimensions Foamed Volume Total
Total Outer Outer Inner of Core Core Core Core Core Inner Example
Diameter Volume Thickness Volume Diameter Core A 0.30'' 0.23 cc
0.100'' 0.13 cc 0.10'' 0.10 cc B 1.60'' 33.15 cc 0.750'' 33.05 cc
0.10'' 0.10 cc C 1.55'' 31.96 cc 0.225'' 11.42 cc 1.10'' 11.42 cc D
1.55'' 31.96 cc 0.400'' 28.34 cc 0.75'' 3.62 cc E 1.55'' 31.96 cc
0.525'' 28.34 cc 0.50'' 3.62 cc
[0187] In one preferred embodiment, the inner core has a specific
gravity in the range of about 0.25 to about 1.25 g/cc. Also, as
discussed above, the specific gravity of the inner core may vary at
different points of the inner core structure. That is, there may be
a specific gravity gradient in the inner core. For example, in one
preferred version, the geometric center of the inner core has a
density in the range of about 0.25 to about 0.75 g/cc; while the
outer skin of the inner core has a density in the range of about
0.75 to about 1.50 g/cc.
[0188] Meanwhile, the outer core layer preferably has a relatively
high specific gravity. Thus, the specific gravity of the inner core
layer (SG.sub.inner) is preferably less than the specific gravity
of the outer core layer (SG.sub.outer). By the term, "specific
gravity of the outer core layer" ("SG.sub.outer"), it is generally
meant the specific gravity of the outer core layer as measured at
any point of the outer core layer. The specific gravity values at
different points in the outer core layer may vary. That is, there
may be specific gravity gradients in the outer core layer similar
to the inner core. For example, the outer core layer may have a
specific gravity within a range having a lower limit of about 0.50
or 0.60 or 0.70 or 0.75 or 0.85 or 0.90 or 0.95 or 1.00 or 1.10 or
1.25 or 1.30 or 1.36 or 1.40 or 1.42 or 1.48 or 1.50 or 1.60 or
1.66 or 1.75 or 2.00 and an upper limit of 2.50 or 2.60 or 2.80 or
2.90 or 3.00 or 3.10 or 3.25 or 3.50 or 3.60 or 3.80 or 4.00, 4.25
or 5.00 or 5.10 or 5.20 or 5.30 or 5.40 or 6.00 or 6.20 or 6.25 or
6.30 or 6.40 or 6.50 or 7.00 or 7.10 or 7.25 or 7.50 or 7.60 or
7.65 or 7.80 or 8.00 or 8.20 or 8.50 or 9.00 or 9.75 or 10.00
g/cc.
[0189] In general, the specific gravities of the respective pieces
of an object affect the Moment of Inertia (MOI) of the object. The
Moment of Inertia of a ball (or other object) about a given axis
generally refers to how difficult it is to change the ball's
angular motion about that axis. If the ball's mass is concentrated
towards the center (the center piece (for example, inner core) has
a higher specific gravity than the outer piece (for example, outer
core layers), less force is required to change its rotational rate,
and the ball has a relatively low Moment of Inertia. In such balls,
most of the mass is located close to the ball's axis of rotation
and less force is needed to generate spin. Thus, the ball has a
generally high spin rate as the ball leaves the club's face after
making impact. Conversely, if the ball's mass is concentrated
towards the outer surface (the outer piece (for example, outer core
layers) has a higher specific gravity than the center piece (for
example, inner core), more force is required to change its
rotational rate, and the ball has a relatively high Moment of
Inertia. That is, in such balls, most of the mass is located away
from the ball's axis of rotation and more force is needed to
generate spin. Such balls have a generally low spin rate as the
ball leaves the club's face after making impact.
[0190] More particularly, as described in Sullivan, U.S. Pat. No.
6,494,795 and Ladd et al., U.S. Pat. No. 7,651,415, the formula for
the Moment of Inertia for a sphere through any diameter is given in
the CRC Standard Mathematical Tables, 24th Edition, 1976 at 20
(hereinafter CRC reference). The term, "specific gravity" as used
herein, has its ordinary and customary meaning, that is, the ratio
of the density of a substance to the density of water at 4.degree.
C., and the density of water at this temperature is 1
g/cm.sup.3.
[0191] In one embodiment, the golf balls of this invention are
relatively low spin and long distance. That is, the foam core
construction, as described above, wherein the inner core is made of
a foamed composition helps provide a relatively low spin ball
having good resiliency. The inner foam cores of this invention
preferably have a Coefficient of Restitution (COR) of about 0.300
or greater; more preferably about 0.400 or greater, and even more
preferably about 0.450 or greater. The resulting balls containing
the dual-layered core constructions of this invention and cover of
at least one layer preferably have a COR of about 0.700 or greater,
more preferably about 0.730 or greater; and even more preferably
about 0.750 to 0.810 or greater. The inner foam cores preferably
have a Soft Center Deflection Index ("SCDI") compression, as
described in the Test Methods below, in the range of about 50 to
about 190, and more preferably in the range of about 60 to about
170.
[0192] The USGA has established a maximum weight of 45.93 g (1.62
ounces) for golf balls. For play outside of USGA rules, the golf
balls can be heavier. In one preferred embodiment, the weight of
the multi-layered core is in the range of about 28 to about 38
grams. Also, golf balls made in accordance with this invention can
be of any size, although the USGA requires that golf balls used in
competition have a diameter of at least 1.68 inches. For play
outside of United States Golf Association (USGA) rules, the golf
balls can be of a smaller size. Normally, golf balls are
manufactured in accordance with USGA requirements and have a
diameter in the range of about 1.68 to about 1.80 inches. In a
particular embodiment, the present invention provides large
diameter golf balls having an overall diameter of 1.70 inches or
greater, or greater than 1.70 inches, or 1.80 inches or greater, or
1.90 inches or greater, or 2.00 inches or greater, or 2.10 inches
or greater, or 2.20 inches or greater. As discussed further below,
the golf ball contains a cover which may be multi-layered and in
addition may contain intermediate (casing) layers, and the
thickness levels of these layers also must be considered. Thus, in
general, the dual-layer core structure normally has an overall
diameter within a range having a lower limit of about 1.00 or 1.20
or 1.30 or 1.40 inches and an upper limit of about 1.58 or 1.60 or
1.62 or 1.66 inches, and more preferably in the range of about 1.3
to 1.65 inches. In one embodiment, the diameter of the core
sub-assembly is in the range of about 1.45 to about 1.62
inches.
Cover Structure
[0193] The golf ball sub-assemblies of this invention may be
enclosed with one or more cover layers. The golf ball sub-assembly
may comprise the multi-layered core structure as discussed above.
In other versions, the golf ball sub-assembly includes the core
structure and one or more casing (mantle) layers disposed about the
core. In one particularly preferred version, the golf ball includes
a multi-layered 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. 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). Fusabond 525D.RTM. 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 an 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.
[0194] The inner cover layer also may be 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,
the composition has a material hardness of from 80 to 85 Shore C.
In yet another version, 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. The inner cover layer also
may be 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. A composition comprising a 50/50
blend of Surlyn.RTM. 8940 and Surlyn.RTM. 7940 also may be used.
Surlyn.RTM. 8940 is an E/MAA 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 E/MAA copolymer in
which the MAA acid groups have been partially neutralized with zinc
ions. Nucrel.RTM. 960 is an E/MAA copolymer resin nominally made
with 15 wt % methacrylic acid.
[0195] 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;
olefin-based copolymer ionomer resins (for example, Surlyn.RTM.
ionomer resins and DuPont HPF.RTM. 1000 and HPF.RTM. 2000,
commercially available from DuPont; Iotek.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
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 or RiteFlex.RTM.,
commercially available from Ticona Engineering Polymers;
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
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.
[0196] 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.
[0197] The compositions used to make the casing (mantle) and cover
layers may contain a wide variety of fillers and additives to
impart specific properties to the ball. For example, relatively
heavy-weight and light-weight metal fillers such as, particulate;
powders; flakes; and fibers of copper, steel, brass, tungsten,
titanium, aluminum, magnesium, molybdenum, cobalt, nickel, iron,
lead, tin, zinc, barium, bismuth, bronze, silver, gold, and
platinum, and alloys and combinations thereof may be used to adjust
the specific gravity of the ball. Other additives and fillers
include, but are not limited to, optical brighteners, coloring
agents, fluorescent agents, whitening agents, UV absorbers, light
stabilizers, surfactants, processing aids, antioxidants,
stabilizers, softening agents, fragrance components, plasticizers,
impact modifiers, titanium dioxide, clay, mica, talc, glass flakes,
milled glass, and mixtures thereof.
[0198] The inner cover layer preferably has a material hardness
within a range having a lower limit of 70 or 75 or 80 or 82 Shore C
and an upper limit of 85 or 86 or 90 or 92 Shore C. The thickness
of the intermediate 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. Methods for
measuring hardness of the layers in the golf ball are described in
further detail below.
[0199] A single cover or, preferably, an inner cover layer is
formed around the outer core layer. When an inner cover layer is
present, an outer cover layer is formed over the inner cover layer.
Most preferably, the inner cover is formed from an ionomeric
material and the outer cover layer is formed from a polyurethane
material, and the outer cover layer has a hardness that is less
than that of the inner cover layer. Preferably, the inner cover has
a hardness of greater than about 60 Shore D and the outer cover
layer has a hardness of less than about 60 Shore D. In an
alternative embodiment, the inner cover layer is comprised of a
partially or fully neutralized ionomer, a thermoplastic polyester
elastomer such as Hytrel.TM., commercially available form DuPont, a
thermoplastic polyether block amide, such as Pebax.TM.,
commercially available from Arkema, Inc., or a thermoplastic or
thermosetting polyurethane or polyurea, and the outer cover layer
is comprised of an ionomeric material. In this alternative
embodiment, the inner cover layer has a hardness of less than about
60 Shore D and the outer cover layer has a hardness of greater than
about 55 Shore D and the inner cover layer hardness is less than
the outer cover layer hardness.
[0200] As discussed above, the core structure of this invention may
be enclosed with one or more cover layers. In one 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. For this harder outer
cover/softer inner cover embodiment, the ionomer resins described
above would preferably be used as outer cover material.
Manufacturing of Golf Balls
[0201] As described above, the inner core preferably is formed by a
casting method. The outer core layer, which surrounds the inner
core, is formed by molding compositions over the inner core.
Compression or injection molding techniques may be used to form the
other layers of the core sub-assembly. Then, the casing and/or
cover layers are applied over the core sub-assembly. Prior to this
step, the core structure may be surface-treated to increase the
adhesion between its outer surface and the next layer that will be
applied over the core. Such surface-treatment may include
mechanically or chemically-abrading the outer surface of the core.
For example, the core may be subjected to corona-discharge,
plasma-treatment, silane-dipping, or other treatment methods known
to those in the art.
[0202] The cover layers are formed over the core or ball
sub-assembly (the core structure and any casing layers disposed
about the core) using a suitable technique such as, for example,
compression-molding, flip-molding, injection-molding, retractable
pin injection-molding, reaction injection-molding (RIM), liquid
injection-molding, casting, spraying, powder-coating,
vacuum-forming, flow-coating, dipping, spin-coating, and the like.
Preferably, each cover layer is separately formed over the ball
subassembly. For example, an ethylene acid copolymer ionomer
composition may be injection-molded to produce half-shells.
Alternatively, the ionomer composition can be placed into a
compression mold and molded under sufficient pressure, temperature,
and time to produce the hemispherical shells. The smooth-surfaced
hemispherical shells are then placed around the core sub-assembly
in a compression mold. Under sufficient heating and pressure, the
shells fuse together to form an inner cover layer that surrounds
the sub-assembly. In another method, the ionomer composition is
injection-molded directly onto the core sub-assembly using
retractable pin injection molding. An outer cover layer comprising
a polyurethane or polyurea composition over the ball sub-assembly
may be formed by using a casting process.
[0203] After the golf balls have been removed from the mold, they
may be subjected to finishing steps such as flash-trimming,
surface-treatment, marking, coating, and the like using techniques
known in the art. For example, in traditional white-colored golf
balls, the white-pigmented cover may be surface-treated using a
suitable method such as, for example, corona, plasma, or
ultraviolet (UV) light-treatment. Then, indicia such as trademarks,
symbols, logos, letters, and the like may be printed on the ball's
cover using pad-printing, ink-jet printing, dye-sublimation, or
other suitable printing methods. Clear surface coatings (for
example, primer and top-coats), which may contain a fluorescent
whitening agent, are applied to the cover. The resulting golf ball
has a glossy and durable surface finish.
[0204] In another finishing process, the golf balls are painted
with one or more paint coatings. For example, white primer paint
may be applied first to the surface of the ball and then a white
top-coat of paint may be applied over the primer. Of course, the
golf ball may be painted with other colors, for example, red, blue,
orange, and yellow. As noted above, markings such as trademarks and
logos may be applied to the painted cover of the golf ball.
Finally, a clear surface coating may be applied to the cover to
provide a shiny appearance and protect any logos and other markings
printed on the ball.
[0205] Different ball constructions can be made using the core
construction of this invention as shown in FIGS. 1-5 and 6A-6D.
Such golf ball constructions include, for example, five-piece, and
six-piece constructions. It should be understood that the golf
balls shown in FIGS. 1-5 and 6A-6D are for illustrative purposes
only, and they are not meant to be restrictive. Other golf ball
constructions can be made in accordance with this invention.
[0206] For example, other constructions include a core sub-assembly
having a foam or non-foam inner core (center); and a foam or
non-foam outer core layer. Dual-core sub-assemblies (inner core and
outer core layer), wherein the inner core and/or the outer core
layer is foamed also may be made. Furthermore, the inner cover
layer, which surrounds the core sub-assembly, may be foamed or
non-foamed. As discussed above, thermoplastic and thermoset foam
compositions may be used to form the different layers. Where more
than one foam layer is used in a single golf ball, the foamed
composition may be the same or different, and the composition may
have the same or different hardness or specific gravity values. For
example, a golf ball may contain a dual-core having a foamed center
with a specific gravity of about 0.40 g/cc and a geometric center
hardness of about 50 Shore C and a center surface hardness of about
75 Shore C that is formed from a polyurethane composition and an
outer core layer that is formed from a foamed highly neutralized
ionomer composition, wherein the outer core layer has a specific
gravity of about 0.80 g/cc and a surface hardness of about 80 Shore
C.
[0207] Golf balls of the present invention typically have a dimple
coverage of 50% or greater, or 60% or greater, or 65% or greater,
or 70% or greater, or 75% or greater, or 80% or greater, or 85% or
greater, or 90% or greater, or 95% or greater.
[0208] The dimples are not limited to a particular plan view shape,
and, in one embodiment, have a plan view shape selected from
circular, polygonal, oval, flower-like lobed shape, multi-armed
shape, amorphous shape, and annular shape.
[0209] The dimples are not limited to a particular cross-sectional
profile shape, and, in one embodiment, have a profile shape
selected from spherical, truncated, catenary, multi-radius, saucer,
dimple-in-dimple, conical, and bramble.
[0210] The dimples are not limited to a particular dimple
arrangement, and, in one embodiment, are arranged in an overall
pattern selected from polyhedron-based patterns (e.g., icosahedron,
octahedron, dodecahedron, icosidodecahedron, cuboctahedron, and
triangular dipyramid), phyllotaxis-based patterns, spherical tiling
patterns, and random arrangements.
[0211] In a particular embodiment, the dimples have a diameter of
from 6% to 12% of the ball diameter and a surface depth, as
measured from the phantom ball surface over the dimple to the
bottom of the dimple, of from 0.3% to 1.0% of the ball diameter. In
a particular aspect of this embodiment, the dimples have an edge
angle of from 13.degree. to 20.degree.. In another particular
aspect of this embodiment, the total dimple volume, defined herein
as the space enclosed between the phantom ball surface and the
actual ball surface, is from 1.0% to 2.0% of the phantom ball
volume. In another particular aspect of this embodiment, the dimple
count is from 300 to 500. In another particular aspect of this
embodiment, the ball has a diameter of from 1.68 inches to 2.00
inches.
[0212] In another particular embodiment, the dimples have a
diameter of from 3% to 14% of the ball diameter, or from 3% to 9%
of the ball diameter, and a surface depth, as measured from the
phantom ball surface over the dimple to the bottom of the dimple,
of from 0.2% to 1.5% of the ball diameter. In a particular aspect
of this embodiment, the dimples have an edge angle of from
10.degree. to 25.degree.. In another particular aspect of this
embodiment, the total dimple volume, defined herein as the space
enclosed between the phantom ball surface and the actual ball
surface, is from 0.5% to 3.0% of the phantom ball volume. In
another particular aspect of this embodiment, the dimple count is
from 300 to 700, or from 500 to 700. In another particular aspect
of this embodiment, the ball has a diameter of from 2.00 inches or
greater.
[0213] Generally, it may be difficult to define and measure the
edge angle and diameter of a dimple due to the indistinct nature of
the boundary dividing the undimpled land surface of the ball from
the dimple depression. For example, the effects of paint and/or the
dimple design itself can cause the junction between the land
surface and the dimple sidewall to be indistinct, making the
measurement of dimple edge angle and dimple diameter seem somewhat
ambiguous. Thus, the following method can be used to define and
measure edge angle and dimple diameter. A continuation of the land
surface is constructed above the dimple to define the phantom
surface of the ball. A first tangent line, T1, is then constructed
at a point on the dimple sidewall that is spaced 0.003 inches
radially inward from the phantom surface. T1 intersects the phantom
surface at point P1, which defines a nominal dimple edge position.
A second tangent line, T2, tangent to the phantom surface at P1, is
then constructed. The edge angle is defined as the angle between T1
and T2. The dimple diameter is defined as the distance between P1
and the equivalent point diametrically opposite along the dimple
perimeter. Alternatively, the dimple diameter is defined as twice
the distance between P1 and the centerline, measured in a direction
perpendicular to the centerline. Methods for defining and measuring
dimple parameters are further disclosed, for example, in U.S. Pat.
No. 6,916,255 to Aoyama et al. and U.S. Pat. No. 8,333,669 to
Sullivan et al., the entire disclosures of which are hereby
incorporated herein by reference.
Test Methods
[0214] Hardness.
[0215] 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.
[0216] 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 sub-assembly 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.
[0217] 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.
[0218] 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.
[0219] 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.
[0220] Compression.
[0221] 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 Soft
Center Deflection Index ("SCDI"). The SCDI is a program change for
the Dynamic Compression Machine ("DCM") that allows determination
of the pounds required to deflect a core 10% of its diameter. The
DCM is an apparatus that applies a load to a core or ball and
measures the number of inches the core or ball is deflected at
measured loads. A crude load/deflection curve is generated that is
fit to the Atti compression scale that results in a number being
generated that represents an Atti compression. The DCM does this
via a load cell attached to the bottom of a hydraulic cylinder that
is triggered pneumatically at a fixed rate (typically about 1.0
ft/s) towards a stationary core. Attached to the cylinder is an
LVDT that measures the distance the cylinder travels during the
testing timeframe. A software-based logarithmic algorithm ensures
that measurements are not taken until at least five successive
increases in load are detected during the initial phase of the
test. The SCDI is a slight variation of this set up. The hardware
is the same, but the software and output has changed. With the
SCDI, the interest is in the pounds of force required to deflect a
core x amount of inches. That amount of deflection is 10% percent
of the core diameter. The DCM is triggered, the cylinder deflects
the core by 10% of its diameter, and the DCM reports back the
pounds of force required (as measured from the attached load cell)
to deflect the core by that amount. The value displayed is a single
number in units of pounds.
[0222] Drop Rebound.
[0223] By "drop rebound," it is meant the number of inches a sphere
will rebound when dropped from a height of 72 inches in this case,
measuring from the bottom of the sphere. A scale, in inches is
mounted directly behind the path of the dropped sphere and the
sphere is dropped onto a heavy, hard base such as a slab of marble
or granite (typically about 1 ft wide by 1 ft high by 1 ft deep).
The test is carried out at about 72-75.degree. F. and about 50%
RH.
[0224] Coefficient of Restitution ("COR").
[0225] The COR is determined according to a known procedure,
wherein a golf ball or golf ball sub-assembly (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.
[0226] 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).
[0227] Density.
[0228] The density refers to the weight per unit volume (typically,
g/cm.sup.3) of the material and can be measured per ASTM
D-1622.
[0229] The present invention is illustrated further by the
following Examples, but these Examples should not be construed as
limiting the scope of the invention.
EXAMPLES
[0230] The examples below are for illustrative purposes only. In no
manner is the present invention limited to the specific disclosures
therein.
[0231] In the following Examples, different foam formulations were
used to prepare core samples using the above-described molding
methods. The different formulations are described in Tables 2 and 3
below.
TABLE-US-00004 TABLE 2 (Sample A) Ingredient Weight Percent 4,4
Methylene Diphenyl Diisocyanate (MDI) 14.65% Polyetratmethylene
ether glycol (PTMEG 34.92% 2000) *Mondur .TM. 582 (2.5 fn) 29.11%
Trifunctional caprolactone polyol (CAPA 20.22% 3031) (3.0 fn) Water
0.67% **Niax .TM. L-1500 surfactant 0.04% *** KKAT .TM. XK 614
catalyst 0.40% Dibutyl tin dilaurate (T-12) 0.03% *Mondur .TM. 582
(2.5 fn) - polymeric methylene diphenyl diisocyanate (p-MDI) with
2.5 functionality, available from Bayer Material Science. **Niax
.TM. L-1500 silicone-based surfactant, available from Momentive
Specialty Chemicals, Inc. ***KKAT .TM. XK 614 zinc-based catalyst,
available from King Industries.
[0232] The resulting spherical core Sample A (0.75 inch diameter)
had a density of 0.45 g/cm.sup.3, a compression (SCDI) of 75, and
drop rebound of 46% based on average measurements using the test
methods as described above.
TABLE-US-00005 TABLE 3 (Sample B) Ingredient Weight Percent Mondur
.TM. 582 (2.5 fn) 30.35% *Desmodur .TM. 3900 aliphatic 30.35%
**Polymeg .TM. 650 19.43% ***Ethacure .TM. 300 19.43% Water 0.31%
Niax .TM. L-1500 surfactant 0.04% Dibutyl tin dilaurate (T-12)
0.09% *Desmodur .TM. 3900 - polyfunctional aliphatic polyisocyanate
resin based on hexamethylene diisocyanate (HDI), available from
Bayer Material Science. **Polymeg .TM. 650 - polyetratmethylene
ether glycol, available from Lyondell Chemical Company. ***Ethacure
.TM. 300 - aromatic diamine curing agent, available from Albemarle
Corp.
[0233] The resulting spherical core Sample B (0.75 inch diameter)
had a density of 0.61 g/cm.sup.3, a compression (SCDI) of 160, and
drop rebound of 56% based on average measurements using the test
methods as described above.
[0234] In the following Examples, different foam formulations were
used to prepare single core samples using the above-described
molding methods. The different formulations are described in Tables
4-8 below. The resulting spherical cores were measured for density
and tested for compression and Coefficient of Restitution (COR)
using the test methods as described above and the results are
reported in Tables 4-8.
[0235] Concentrations are in parts per hundred (phr) unless
otherwise indicated. As used herein, the term "parts per hundred,"
also known as "phr," is defined as the number of parts by weight of
a particular component present in a mixture, relative to 100 parts
by weight of the base rubber component. Mathematically, this can be
expressed as the weight of an ingredient divided by the total
weight of the polymer, multiplied by a factor of 100.
TABLE-US-00006 TABLE 4 Spherical Foam Core Samples Example No. 1 2
3 4 5 6 6.5% MDI 41 43.72 45.01 33.58 49.48 31.83 Frepolymer Mondur
MR 7.33 13.64 Monclur CD 19.75 Mondur ML 17 13.06 8.06 Poly THF 650
13.06 29.01 CAPA 3031 13.77 13.77 4 CAPA 3091 27.86 CAPA 4101 CAPA
4801 D.I. Water 0.5 0.50 0.45 0.50 0.45 0.50 Niax 1500 0.75 0.75
0.75 0.75 0.75 Varox MPBC Irganox 1135 Dabco 33LV 0.2 0.2 0.2 0.2
0.2 Garamite 1958 0.375 0.375 0.375 0.375 0.375 Total Pans 76.345
76.315 76.315 76.325 75.05 76.305 Density 0.54 0.7 0.6 0.53 0.6
Compression 35 106 -217 -242 -217 CoR @ 125 ft/s 0.434 0.503 0.52
0.278 0.41 6.5% MDI Prepolymer is made from 4,4'-MDI and
polytetramethylene glycol ether Mondur .TM. MR - polymeric MDI,
available from Bayer. Mondur .TM. CD - modified 4,4'-MDI, available
from Bayer. Mondur .TM. ML - isomer mixture of 2,4 and 4,4'- MDI,
available from Bayer. Poly THF .TM. 650 - 650 molecular weight
polyetratmethylene ether glycol (PTMEG), available from BASF. CAPA
.TM. 3031 - low molecular weight trifunctional polycaprolactone
polyol, available from Perstorp CAPA .TM. 3091 - polyester triol
terminated by primary hydroxyl groups, available from Perstorp.
CAPA .TM. 4101 - tetra-functional polyol terminated with primary
hydroxyl groups, available from Perstorp. CAPA .TM. 4801 -
tetra-functional polyol terminated with primary hydroxyl groups,
available from Perstorp. Niax .TM. L-1500 - silicone surfactant
from Momentive Specialty Chemicals, Inc. Vanox .TM. MBPC -
antioxidant, available from R.T. Vanderbuilt. Irganox .TM. 1135 -
antioxidant, available BASF. Dabco .TM. 33LV - tertiary amine
catalyst, available from Air Products. Garamite .TM. 1958 -
rheological additive, available from Southern Clay.
TABLE-US-00007 TABLE 5 Spherical Foam Core Samples Example No. 7 8
9 10 11 12 6.5% MDI 21.67 45.81 49.22 45.01 45.01 55.8 Prepolymer
Mondur MR 18.46 7.46 8.01 7.33 7.33 9.08 Mondur CD Mondur ML Poly
THF 650 34.33 20.57 13 22.2 22.2 CAPA 3031 0.7 4 9.66 CAPA 3091
CAPA 4101 CAPA 4801 D.I. Water 0.53 0.45 0.45 0.45 0.45 0.45 Niax
1500 0.75 0.75 0.75 0.75 0.75 0.75 Varox MPBC 0.375 Irganox 1135
0.38 Dabco 33LV 0.2 0.2 0.2 0.2 0.2 0.2 Garamite 1958 0.375 0.375
0.375 0.375 0.375 0.375 Total Parts 76.315 76.315 76.005 76.69
76.695 76.315 Density 0.46 0.4 Compression -245 -109 CoR @ 0.388
0.515 125 ft/s
TABLE-US-00008 TABLE 6 Spherical Foam Core Samples Example No. 13
14 15 16 17 18 6.5% MDI 68.81 44.28 33.1 42.39 49.48 40.75
Prepolymer Mondur MR 12.49 17.05 11.96 8.06 11.5 Mondur CD Mondur
ML Poly THF 650 CAPA 3031 5.79 5.047 2.86 2.37 2 CAPA 3091 CAPA
4101 12.67 21.48 17.79 15 22.27 CAPA 4801 D.I. Water 0.39 0.45 0.67
0.48 0.45 0.48 Niax 1500 0.75 0.75 0.75 0.75 0.75 0.75 Varox MPBC
Irganox 1135 Dabco 33LV 0.2 0.2 0.2 0.2 0.2 0.2 Garamite 1958 0.375
0.375 0.38 0.38 0.38 0.38 Total Parts 76.315 76.262 76.49 76.32
76.32 76.33 Density 0.52 0.35 0.64 0.39 0.46 0.39 Compression -200
-144 45 -135 -165 -120 CoR @ 125 ft/s 0.54 0.534 0.571 0.553 0.537
0.543
TABLE-US-00009 TABLE 7 Spherical Foam Core Samples Example No. 19
20 21 22 6.5% MDI Prepolymer 47.83 56.05 29.18 19.58 Mondur MR 7.78
9.12 12.51 16.68 Mondur CD Mondur ML Poly THF 650 CAPA 3031 CAPA
3091 CAPA 4101 18.92 18.11 17.37 20.23 CAPA 4801 16.1 15.44 17.98
D.I. Water 0.45 0.61 0.5 0.52 Niax 1500 0.75 0.75 0.75 0.75 Varox
MPBC Irganox 1135 Dabco 33LV 0.2 0.2 0.2 0.2 Garamite 1958 0.38
0.38 0.38 0.38 Total Parts 76.31 101.32 76.33 76.32 Density 0.42
0.66 0.51 Compression -165 -169 -100 CoR @125 ft/s 0.609 0.492
0.425
TABLE-US-00010 TABLE 8 Spherical Foam Core Samples Example No. 23
24 25 26 6.5% MDI Prepolymer 43.87 50.63 37.21 43.57 Mondur MR 9.63
5.63 13.07 9.56 Mondur CD Mondur ML Poly THF 650 CAPA 3031 CAPA
3091 CAPA 4101 18.36 15.98 21.18 16.15 CAPA 4801 D.I. Water 0.47
0.45 0.49 0.47 Niax 1500 0.75 0.75 0.75 0.75 Varox MPBC Irganox
1135 Dabco 33LV 0.2 0.2 0.2 0.2 Garamite 1958 0.38 0.38 0.38 0.38
Total Parts 76.31 76.33 76.34 76.33 Density 0.46 0.57 0.43 0.48
Compression -164 -169 -137 -147 CoR @125 ft/s 0.578 0.600 0.541
0.571
[0236] In the following Examples, different formulations were used
to prepare dual-core samples having a foam center and surrounding
thermoset outer core layer using the above-described molding
methods. The sample cores were tested for compression (DCM),
Coefficient of Restitution (COR), and hardness using the
above-described test methods and the results are reported below in
Table 13.
[0237] Concentrations are in parts per hundred (phr) unless
otherwise indicated. As used herein, the term "parts per hundred,"
also known as "phr," is defined as the number of parts by weight of
a particular component present in a mixture, relative to 100 parts
by weight of the base rubber component. Mathematically, this can be
expressed as the weight of an ingredient divided by the total
weight of the polymer, multiplied by a factor of 100.
Sample C (0.5'' Foamed Center)
[0238] In this Sample, the foam formulation in below Table 9 was
used to prepare an inner core having a diameter of 0.5 inches.
TABLE-US-00011 TABLE 9 (Foam Center of Sample C) Ingredient Parts
6.5% MDI Prepolymer 45.010 Mondur .TM. 582 (2.5 fn) 7.330 Poly THF
.TM. 650 22.200 Deionized Water 0.450 Niax .TM. L-1500 surfactant
0.750 Dabco .TM. 33LV 0.200 Garamite .TM. 1958 0.375
[0239] The following rubber formulation (Table 10) was molded about
the foamed inner core and cured to form a thermoset rubber outer
core layer.
TABLE-US-00012 TABLE 10 (Rubber Outer Core Layer of Sample C)
Ingredient Parts *Buna .TM. CB23 100.0 Zinc Diacrylate (ZDA) 35.0
**Perkadox BC 0.5 Zinc Pentachlorothiophenol (ZnPCTP) 0.5 Zinc
Oxide 14.9 *Buna .TM. CB23 - polybutadiene rubber, available from
Lanxess Corp. **Perkadox .TM. BC, peroxide free-radical initiator,
available from Akzo Nobel.
[0240] The dual-layered core of Sample C (foam center and thermoset
rubber outer core layer with a center diameter of 0.5) inches was
tested for hardness and the core was found to have a hardness
gradient (across the entire core as measured at points in
millimeters (mm) from the geometric center) in the range of about
21 Shore C to about 89 Shore C. The hardness of the core measured
at the geometric center was about 21 Shore C and the hardness of
the core measured at about 20 mm from the geometric center (that
is, the surface of the outer core layer) was about 89 Shore C. The
hardness values measured at various points along this core
structure are described in Table 17 below and the hardness plot is
shown in FIG. 5.
Sample D (0.5'' Foamed Center)
[0241] In this Sample D, the foam formulation in below Table 11 was
used to prepare an inner core having a diameter of 0.5 inches.
TABLE-US-00013 TABLE 11 (Foam Center of Sample D) Ingredient Parts
6.5% MDI Prepolymer 55.800 Mondur .TM. 582 (2.5 fn) 9.080 CAPA .TM.
3031 9.660 Deionized Water 0.450 Niax .TM. L-1500 surfactant 0.750
Dabco .TM. 33LV 0.200 Garamite .TM. 1958 0.375
[0242] The same rubber formulation as described above in Sample C
(Table 10) was molded about the foam center of Sample D and cured
to form a thermoset rubber outer core layer.
Sample E (0.5'' Foamed Center)
[0243] In this Sample E, the foam formulation in below Table 12 was
used to prepare an inner core having a diameter of 0.5 inches.
TABLE-US-00014 TABLE 12 (Foam Center of Sample E) Ingredient Parts
6.5% MDI Prepolymer 44.280 Mondur .TM. 582 (2.5 fn) 12.490 CAPA
.TM. 3031 5.047 Deionized Water 0.450 Niax .TM. L-1500 surfactant
0.750 Dabco .TM. 33LV 0.200 Garamite .TM. 1958 0.375
[0244] The same rubber formulation as described above in Sample C
(Table 10) was molded about the foam center of Sample E and cured
to form a thermoset rubber outer core layer.
TABLE-US-00015 TABLE 13 Properties of Core Samples (C-E)
Compression COR@ Surface Center Hardness Sample (DCM) 125 ft/sec
Hardness Hardness Gradient C 85 0.816 88.9 22.1 66.8 D 81 0.797
86.1 46.0 40.2 E 81 0.806 87.0 43.7 43.3
Sample F (0.75'' Foamed Center)
[0245] In this Sample, the foam formulation in below Table 14 was
used to prepare an inner core having a diameter of 0.75 inches.
TABLE-US-00016 TABLE 14 (Foam Center of Sample F) Ingredient Parts
6.5% MDI Prepolymer 47.830 Mondur .TM. 582 (2.5 fn) 7.780 CAPA .TM.
4101 18.920 Deionized Water 0.450 Niax .TM. L-1500 surfactant 0.750
Dabco .TM. 33LV 0.200 Garamite .TM.1958 0.380
[0246] In this Sample F, the following rubber formulation (Table
15) was molded about the foamed inner core and cured to form a
thermoset rubber outer core layer. Different core samples having
different densities (F1-F5) were prepared and are further described
in Table 17 below.
TABLE-US-00017 TABLE 15 (Rubber Outer Core Layer of Sample F)
Ingredient Parts Buna .TM. CB23 100.0 Zinc Diacrylate (ZDA) 36.0
Perkadox BC 0.5 Zinc Pentachlorothiophenol (ZnPCTP) 0.5 Zinc Oxide
21.3
[0247] The Sample F1-F5 cores were tested for compression (DCM),
Coefficient of Restitution (COR), and hardness using the
above-described test methods and the results are reported below in
Table 16.
TABLE-US-00018 TABLE 16 Properties of Core Samples (F1-F5) Density
of Foamed Com- Surface Center Hardness Center pression COR @
Hardness Hardness Gradient Sample (g/cm.sup.3) (DCM) 125 ft/sec
(Shore C) (Shore C) (Shore C) F-1 0.40 80 0.779 86.6 33.5 53.0 F-2
0.46 78 0.775 86.4 31.8 54.3 F-3 0.59 77 0.770 86.4 34. 52.3 F-4
0.75 78 0.769 87.3 43.0 44.3 F-5 0.83 75 0.766 87.4 37.4 50.0
[0248] The dual-layered core of Sample F-2 (foam center and
thermoset rubber outer core layer having a center diameter of 0.75
inches) was tested for hardness and the core was found to have a
hardness gradient (across the entire core as measured at points in
millimeters (mm) from the geometric center) in the range of about
32 Shore C to about 86 Shore C. The hardness of the core measured
at the geometric center was about 32 Shore C and the hardness of
the core measured at about 20 mm from the geometric center (that
is, the surface of the outer core layer) was about 86 Shore C. The
hardness values measured at various points along the core structure
are described in Table 17 below and the hardness plot is shown in
FIG. 5.
TABLE-US-00019 TABLE 17 Hardness Properties of Core Samples (C and
F-2) Distance from Geometric Center of Core Sample Hardness
Gradient of Hardness Gradient of (mm) Sample C (Shore C) Sample F-2
(Shore C) 0 (Center) 21 31.8 2 20.8 32.6 4 25 35.7 6 28.1 35.1 8 72
37.8 10 72.8 70.9 12 73.1 70.2 14 72.7 70.2 16 76.5 76.9 18 82.6
81.8 20 (Surface) 88.9 86.4
[0249] Set forth below are particularly suitable highly neutralized
polymer compositions for forming thermoplastic core layers. The
following commercially available materials were used in the below
examples: [0250] A-C.RTM. 5120 ethylene acrylic acid copolymer with
an acrylic acid content of 15%, A-C.RTM. 5180 ethylene acrylic acid
copolymer with an acrylic acid content of 20%, A-C.RTM. 395 high
density oxidized polyethylene homopolymer, and A-C.RTM. 575
ethylene maleic anhydride copolymer, commercially available from
Honeywell; CB23 high-cis neodymium-catalyzed polybutadiene rubber,
commercially available from Lanxess Corporation; CA1700 Soya fatty
acid, CA1726 linoleic acid, and CA1725 conjugated linoleic acid,
commercially available from Chemical Associates; Century.RTM. 1107
highly purified isostearic acid mixture of branched and
straight-chain C18 fatty acid, commercially available from Arizona
Chemical; Clarix.RTM. 011370-01 ethylene acrylic acid copolymer
with an acrylic acid content of 13% and Clarix.RTM. 011536-01
ethylene acrylic acid copolymer with an acrylic acid content of
15%, commercially available from A. Schulman Inc.; Elvaloy.RTM. AC
1224 ethylene-methyl acrylate copolymer with a methyl acrylate
content of 24 wt %, Elvaloy.RTM. AC 1335 ethylene-methyl acrylate
copolymer with a methyl acrylate content of 35 wt %, Elvaloy.RTM.
AC 2116 ethylene-ethyl acrylate copolymer with an ethyl acrylate
content of 16 wt %, Elvaloy.RTM. AC 3427 ethylene-butyl acrylate
copolymer having a butyl acrylate content of 27 wt %, and
Elvaloy.RTM. AC 34035 ethylene-butyl acrylate copolymer having a
butyl acrylate content of 35 wt %, commercially available from E.
I. du Pont de Nemours and Company; Escor.RTM. AT-320 ethylene acid
terpolymer, commercially available from ExxonMobil Chemical
Company; Exxelor.RTM. VA 1803 amorphous ethylene copolymer
functionalized with maleic anhydride, commercially available from
ExxonMobil Chemical Company; Fusabond.RTM. N525
metallocene-catalyzed polyethylene, Fusabond.RTM. N416 chemically
modified ethylene elastomer, Fusabond.RTM. C190 anhydride modified
ethylene vinyl acetate copolymer, and Fusabond.RTM. P614
functionalized polypropylene, commercially available from E. I. du
Pont de Nemours and Company; Hytrel.RTM. 3078 very low modulus
thermoplastic polyester elastomer, commercially available from E.
I. du Pont de Nemours and Company; Kraton.RTM. FG 1901 GT linear
triblock copolymer based on styrene and ethylene/butylene with a
polystyrene content of 30% and Kraton.RTM. FG1924GT linear triblock
copolymer based on styrene and ethylene/butylene with a polystyrene
content of 13%, commercially available from Kraton Performance
Polymers Inc.; Lotader.RTM. 4603, 4700 and 4720, random copolymers
of ethylene, acrylic ester and maleic anhydride, commercially
available from Arkema Corporation; Nordel.RTM. IP 4770 high
molecular weight semi-crystalline EPDM rubber, commercially
available from The Dow Chemical Company; Nucrel.RTM. 9-1,
Nucrel.RTM. 599, Nucrel.RTM. 960, Nucrel.RTM. 0407, Nucrel.RTM.
0609, Nucrel.RTM. 1214, Nucrel.RTM. 2906, Nucrel.RTM. 2940,
Nucrel.RTM. 30707, Nucrel.RTM. 31001, and Nucrel.RTM. AE acid
copolymers, commercially available from E. I. du Pont de Nemours
and Company; Primacor.RTM. 3150, 3330, 59801, and 59901 acid
copolymers, commercially available from The Dow Chemical Company;
Royaltuf.RTM. 498 maleic anhydride modified polyolefin based on an
amorphous EPDM, commercially available from Chemtura Corporation;
Sylfat.RTM. FA2 tall oil fatty acid, commercially available from
Arizona Chemical; Vamac.RTM. G terpolymer of ethylene,
methylacrylate and a cure site monomer, commercially available from
E. I. du Pont de Nemours and Company; and XUS 60758.08L ethylene
acrylic acid copolymer with an acrylic acid content of 13.5%,
commercially available from The Dow Chemical Company.
[0251] Various compositions were melt blended using components as
given in Table 18 below. The compositions were neutralized by
adding a cation source in an amount sufficient to neutralize,
theoretically, 110% of the acid groups present in components 1 and
3, except for example 72, in which the cation source was added in
an amount sufficient to neutralize 75% of the acid groups.
Magnesium hydroxide was used as the cation source, except for
example 68, in which magnesium hydroxide and sodium hydroxide were
used in an equivalent ratio of 4:1. In addition to components 1-3
and the cation source, example 71 contains ethyl oleate
plasticizer.
[0252] The relative amounts of component 1 and component 2 used are
indicated in Table 18 below, and are reported in wt %, based on the
combined weight of components 1 and 2. The relative amounts of
component 3 used are indicated in Table 18 below, and are reported
in wt %, based on the total weight of the composition.
TABLE-US-00020 TABLE 18 Example Component 1 wt % Component 2 wt %
Component 3 wt % 1 Primacor 5980I 78 Lotader 4603 22 magnesium
oleate 41.6 2 Primacor 5980I 84 Elvaloy AC 1335 16 magnesium oleate
41.6 3 Primacor 5980I 78 Elvaloy AC 3427 22 magnesium oleate 41.6 4
Primacor 5980I 78 Elvaloy AC 1335 22 magnesium oleate 41.6 5
Primacor 5980I 78 Elvaloy AC 1224 22 magnesium oleate 41.6 6
Primacor 5980I 78 Lotader 4720 22 magnesium oleate 41.6 7 Primacor
5980I 85 Vamac G 15 magnesium oleate 41.6 8 Primacor 5980I 90 Vamac
G 10 magnesium oleate 41.6 8.1 Primacor 5990I 90 Fusabond 614 10
magnesium oleate 41.6 9 Primacor 5980I 78 Vamac G 22 magnesium
oleate 41.6 10 Primacor 5980I 75 Lotader 4720 25 magnesium oleate
41.6 11 Primacor 5980I 55 Elvaloy AC 3427 45 magnesium oleate 41.6
12 Primacor 5980I 55 Elvaloy AC 1335 45 magnesium oleate 41.6 12.1
Primacor 5980I 55 Elvaloy AC 34035 45 magnesium oleate 41.6 13
Primacor 5980I 55 Elvaloy AC 2116 45 magnesium oleate 41.6 14
Primacor 5980I 78 Elvaloy AC 34035 22 magnesium oleate 41.6 14.1
Primacor 5990I 80 Elvaloy AC 34035 20 magnesium oleate 41.6 15
Primacor 5980I 34 Elvaloy AC 34035 66 magnesium oleate 41.6 16
Primacor 5980I 58 Vamac G 42 magnesium oleate 41.6 17 Primacor
5990I 80 Fusabond 416 20 magnesium oleate 41.6 18 Primacor 5980I
100 -- -- magnesium oleate 41.6 19 Primacor 5980I 78 Fusabond 416
22 magnesium oleate 41.6 20 Primacor 5990I 100 -- -- magnesium
oleate 41.6 21 Primacor 5990I 20 Fusabond 416 80 magnesium oleate
41.6 21.1 Primacor 5990I 20 Fusabond 416 80 magnesium oleate 31.2
21.2 Primacor 5990I 20 Fusabond 416 80 magnesium oleate 20.8 22
Clarix 011370 30.7 Fusabond 416 69.3 magnesium oleate 41.6 23
Primacor 5990I 20 Royaltuf 498 80 magnesium oleate 41.6 24 Primacor
5990I 80 Royaltuf 498 20 magnesium oleate 41.6 25 Primacor 5990I 80
Kraton FG1924GT 20 magnesium oleate 41.6 26 Primacor 5990I 20
Kraton FG1924GT 80 magnesium oleate 41.6 27 Nucrel 30707 57
Fusabond 416 43 magnesium oleate 41.6 28 Primacor 5990I 80 Hytrel
3078 20 magnesium oleate 41.6 29 Primacor 5990I 20 Hytrel 3078 80
magnesium oleate 41.6 30 Primacor 5980I 26.8 Elvaloy AC 34035 73.2
magnesium oleate 41.6 31 Primacor 5980I 26.8 Lotader 4603 73.2
magnesium oleate 41.6 32 Primacor 5980I 26.8 Elvaloy AC 2116 73.2
magnesium oleate 41.6 33 Escor AT-320 30 Elvaloy AC 34035 52
magnesium oleate 41.6 Primacor 5980I 18 34 Nucrel 30707 78.5
Elvaloy AC 34035 21.5 magnesium oleate 41.6 35 Nucrel 30707 78.5
Fusabond 416 21.5 magnesium oleate 41.6 36 Primacor 5980I 26.8
Fusabond 416 73.2 magnesium oleate 41.6 37 Primacor 5980I 19.5
Fusabond N525 80.5 magnesium oleate 41.6 38 Clarix 011536-01 26.5
Fusabond N525 73.5 magnesium oleate 41.6 39 Clarix 011370-01 31
Fusabond N525 69 magnesium oleate 41.6 39.1 XUS 60758.08L 29.5
Fusabond N525 70.5 magnesium oleate 41.6 40 Nucrel 31001 42.5
Fusabond N525 57.5 magnesium oleate 41.6 41 Nucrel 30707 57.5
Fusabond N525 42.5 magnesium oleate 41.6 42 Escor AT-320 66.5
Fusabond N525 33.5 magnesium oleate 41.6 43 Nucrel 2906/2940 21
Fusabond N525 79 magnesium oleate 41.6 44 Nucrel 960 26.5 Fusabond
N525 73.5 magnesium oleate 41.6 45 Nucrel 1214 33 Fusabond N525 67
magnesium oleate 41.6 46 Nucrel 599 40 Fusabond N525 60 magnesium
oleate 41.6 47 Nucrel 9-1 44.5 Fusabond N525 55.5 magnesium oleate
41.6 48 Nucrel 0609 67 Fusabond N525 33 magnesium oleate 41.6 49
Nucrel 0407 100 -- -- magnesium oleate 41.6 50 Primacor 5980I 90
Fusabond N525 10 magnesium oleate 41.6 51 Primacor 5980I 80
Fusabond N525 20 magnesium oleate 41.6 52 Primacor 5980I 70
Fusabond N525 30 magnesium oleate 41.6 53 Primacor 5980I 60
Fusabond N525 40 magnesium oleate 41.6 54 Primacor 5980I 50
Fusabond N525 50 magnesium oleate 41.6 55 Primacor 5980I 40
Fusabond N525 60 magnesium oleate 41.6 56 Primacor 5980I 30
Fusabond N525 70 magnesium oleate 41.6 57 Primacor 5980I 20
Fusabond N525 80 magnesium oleate 41.6 58 Primacor 5980I 10
Fusabond N525 90 magnesium oleate 41.6 59 -- -- Fusabond N525 100
magnesium oleate 41.6 60 Nucrel 0609 40 Fusabond N525 20 magnesium
oleate 41.6 Nucrel 0407 40 61 Nucrel AE 100 -- -- magnesium oleate
41.6 62 Primacor 5980I 30 Fusabond N525 70 CA1700 soya fatty acid
41.6 magnesium salt 63 Primacor 5980I 30 Fusabond N525 70 CA1726
linoleic acid 41.6 magnesium salt 64 Primacor 5980I 30 Fusabond
N525 70 CA1725 41.6 conjugated linoleic acid magnesium salt 65
Primacor 5980I 30 Fusabond N525 70 Century 1107 41.6 isostearic
acid magnesium salt 66 A-C 5120 73.3 Lotader 4700 26.7 oleic acid
41.6 magnesium salt 67 A-C 5120 73.3 Elvaloy 34035 26.7 oleic acid
41.6 magnesium salt 68 Primacor 5980I 78.3 Lotader 4700 21.7 oleic
acid 41.6 magnesium salt and sodium salt 69 Primacor 5980I 47
Elvaloy AC34035 13 -- -- A-C 5180 40 70 Primacor 5980I 30 Fusabond
N525 70 Sylfat FA2 41.6 magnesium salt 71 Primacor 5980I 30
Fusabond N525 70 oleic acid 31.2 magnesium salt 10 ethyl oleate 72
Primacor 5980I 80 Fusabond N525 20 sebacic acid 41.6 magnesium salt
73 Primacor 5980I 60 -- -- -- -- A-C 5180 40 74 Primacor 5980I 78.3
-- -- oleic acid 41.6 A-C 575 21.7 magnesium salt 75 Primacor 5980I
78.3 Exxelor VA 1803 21.7 oleic acid 41.6 magnesium salt 76
Primacor 5980I 78.3 A-C 395 21.7 oleic acid 41.6 magnesium salt 77
Primacor 5980I 78.3 Fusabond C190 21.7 oleic acid 41.6 magnesium
salt 78 Primacor 5980I 30 Kraton FG 1901 70 oleic acid 41.6
magnesium salt 79 Primacor 5980I 30 Royaltuf 498 70 oleic acid 41.6
magnesium salt 80 A-C 5120 40 Fusabond N525 60 oleic acid 41.6
magnesium salt 81 Primacor 5980I 30 Fusabond N525 70 erucic acid
41.6 magnesium salt 82 Primacor 5980I 30 CB23 70 oleic acid
magnesium salt 41.6 83 Primacor 5980I 30 Nordel IP 4770 70 oleic
acid 41.6 magnesium salt 84 Primacor 5980I 48 Fusabond N525 20
oleic acid 41.6 A-C 5180 32 magnesium salt 85 Nucrel 2806 22.2
Fusabond N525 77.8 oleic acid 41.6 magnesium salt 86 Primacor 3330
61.5 Fusabond N525 38.5 oleic acid 41.6 magnesium salt 87 Primacor
3330 45.5 Fusabond N525 20 oleic acid 41.6 Primacor 3150 34.5
magnesium salt 88 Primacor 3330 28.5 -- -- oleic acid 41.6 Primacor
3150 71.5 magnesium salt 89 Primacor 3150 67 Fusabond N525 33 oleic
acid 41.6 magnesium salt 90 Primacor 5980I 55 Elvaloy AC 34035 45
oleic acid 31.2 magnesium salt 10 ethyl oleate
[0253] Solid spheres of each composition were injection molded, and
the solid sphere COR, compression, Shore D hardness, and Shore C
hardness of the resulting spheres were measured after two weeks.
The results are reported in Table 19 below. The surface hardness of
a sphere 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 sphere or on surface
defects, such as holes or protrusions. Hardness measurements are
made pursuant to ASTM D-2240 "Indentation Hardness of Rubber and
Plastic by Means of a Durometer." Because of the curved surface,
care must be taken to insure that the sphere is centered under the
durometer indentor before a surface hardness reading is obtained. A
calibrated, digital durometer, capable of reading to 0.1 hardness
units is used for all hardness measurements and is set to record
the maximum hardness reading obtained for each measurement. The
digital durometer must be attached to, and its foot made parallel
to, the base of an automatic stand. The weight on the durometer and
attack rate conform to ASTM D-2240.
TABLE-US-00021 TABLE 19 Solid Sphere Solid Sphere Solid Sphere
Solid Sphere Ex. COR Compression Shore D Shore C 1 0.845 120 59.6
89.2 2 * * * * 3 0.871 117 57.7 88.6 4 0.867 122 63.7 90.6 5 0.866
119 62.8 89.9 6 * * * * 7 * * * * 8 * * * * 8.1 0.869 127 65.3 92.9
9 * * * * 10 * * * * 11 * * * * 12 0.856 101 55.7 82.4 12.1 0.857
105 53.2 81.3 13 * * * * 14 0.873 122 64.0 91.1 14.1 * * * * 15 * *
* * 16 * * * * 17 0.878 117 60.1 89.4 18 0.853 135 67.6 94.9 19 * *
* * 20 0.857 131 66.2 94.4 21 0.752 26 34.8 57.1 21.1 0.729 9 34.3
56.3 21.2 0.720 2 33.8 55.2 22 * * * * 23 * * * * 24 * * * * 25 * *
* * 26 * * * * 27 * * * * 28 * * * * 29 * * * * 30 ** 66 42.7 65.5
31 0.730 67 45.6 68.8 32 ** 100 52.4 78.2 33 0.760 64 43.6 64.5 34
0.814 91 52.8 80.4 35 * * * * 36 * * * * 37 * * * * 38 * * * * 39 *
* * * 39.1 * * * * 40 * * * * 41 * * * * 42 * * * * 43 * * * * 44 *
* * * 45 * * * * 46 * * * * 47 * * * * 48 * * * * 49 * * * * 50 * *
* * 51 0.873 121 61.5 90.2 52 0.870 116 60.4 88.2 53 0.865 107 57.7
84.4 54 0.853 97 53.9 80.2 55 0.837 82 50.1 75.5 56 0.818 66 45.6
70.7 57 0.787 45 41.3 64.7 58 0.768 26 35.9 57.3 59 * * * * 60 * *
* * 61 * * * * 62 * * * * 63 * * * * 64 * * * * 65 * * * * 66 * * *
* 67 * * * * 68 * * * * 69 * * * * 70 * * * * 71 * * * * 72 * * * *
73 * * * * 74 * * * * 75 * * * * 76 * * * * 77 * * * * 78 * * * *
79 * * * * 80 * * * * 81 * * * * 82 * * * * 83 * * * * 84 * * * *
85 * * * * 86 * * * * 87 * * * * 88 * * * * 89 * * * * 90 * * * * *
not measured ** sphere broke during measurement
PROPHETIC EXAMPLES
[0254] The following prophetic examples describe two-layered core
structures that may be made in accordance with this invention. The
foam center of the core may be made using a polyurethane foam
formulation as described above in Tables 2 and 3 or any other
suitable foam material as describe above. The outer core layer may
be made of an ethylene acid copolymer ionomer or any other suitable
thermoplastic material as described above.
Example 1
[0255] Two-layered core (foam center and thermoplastic outer layer)
having a center diameter of 0.5 inches and a hardness gradient
across the core (as measured at points in millimeters (mm) from the
geometric center) in the range of about 41 Shore C to about 81
Shore C. The hardness plot of this core structure is shown in FIG.
6A.
Example 2
[0256] Two-layered core (foam center and thermoplastic outer layer)
having a center diameter of 0.5 inches and a hardness gradient
across the core (as measured at mm points from the geometric
center) in the range of about 26 Shore C to about 74 Shore C. The
hardness plot of this core structure is shown in FIG. 6B.
Example 3
[0257] Two-layered core (foam center and thermoplastic outer layer)
having a center diameter of 0.5 inches and a hardness gradient
across the core (as measured at mm points from the geometric
center) in the range of about 51 Shore C to about 73 Shore C. The
hardness plot of this core structure is shown in FIG. 6C.
Example 4
[0258] Two-layered core (foam center and thermoplastic outer layer)
having a center diameter of 0.75 inches and a hardness gradient
across the core (as measured at mm points from the geometric
center) in the range of about 24 Shore C to about 82 Shore C. The
hardness plot of this core structure is shown in FIG. 6D.
[0259] When numerical lower limits and numerical upper limits are
set forth herein, it is contemplated that any combination of these
values may be used.
[0260] 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.
[0261] 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.
* * * * *