U.S. patent application number 12/904311 was filed with the patent office on 2012-04-19 for golf ball with single thermoplastic cover layer of heterogeneous composition.
Invention is credited to Edmund A. Hebert, Donald A. Serino, Michael J. Sullivan.
Application Number | 20120094784 12/904311 |
Document ID | / |
Family ID | 45934624 |
Filed Date | 2012-04-19 |
United States Patent
Application |
20120094784 |
Kind Code |
A1 |
Hebert; Edmund A. ; et
al. |
April 19, 2012 |
GOLF BALL WITH SINGLE THERMOPLASTIC COVER LAYER OF HETEROGENEOUS
COMPOSITION
Abstract
The invention relates generally to golf balls, and more
specifically, to a golf ball having a single cover layer that is
comprised of a blend of two or more distinct resinous materials.
The present invention relates to a method of manufacturing a golf
ball having a single cover layer of heterogeneous composition. One
embodiment of the invention describes a method wherein a core,
comprising one or more layers, has pre-molded hemispherical cover
cups placed about the core and each cover cup has at least two
layers of distinct resinous materials, and the cover cups are
heated and compressed such that the resinous materials in the cover
cups intermingle with each other to form a single cover layer
comprised of a non-distinct blend of the materials.
Inventors: |
Hebert; Edmund A.;
(Mattapoisett, MA) ; Sullivan; Michael J.;
(Barrington, RI) ; Serino; Donald A.; (Plymouth,
MA) |
Family ID: |
45934624 |
Appl. No.: |
12/904311 |
Filed: |
October 14, 2010 |
Current U.S.
Class: |
473/374 ;
264/241; 264/402 |
Current CPC
Class: |
A63B 37/0044 20130101;
A63B 37/0024 20130101; A63B 37/0033 20130101; B29L 2031/546
20130101; A63B 45/00 20130101; A63B 37/0075 20130101; A63B 2037/087
20130101; B29C 35/0261 20130101; A63B 37/04 20130101; A63B 37/0003
20130101; B29C 2035/0822 20130101; B29C 2043/3665 20130101; A63B
37/0031 20130101; A63B 37/0036 20130101; A63B 37/12 20130101; B29C
43/027 20130101 |
Class at
Publication: |
473/374 ;
264/241; 264/402 |
International
Class: |
A63B 37/12 20060101
A63B037/12; B29C 43/02 20060101 B29C043/02; B29C 35/08 20060101
B29C035/08; A63B 37/02 20060101 A63B037/02 |
Claims
1. A golf ball comprised of a core and a cover, wherein the cover
has an inner surface and an outer surface and is formed from a
mixture of a first material and a second material and a first
percent of the first material on the outer surface is greater than
a second percent of the second material on the outer surface.
2. The golf ball of claim 1, wherein the first and second materials
are blends of two or more thermoplastic materials.
3. The golf ball of claim 1, wherein the outer surface has a first
hardness as measured on the surface thereof and the inner surface
has a second hardness as measured on the surface thereof that is
different from the first hardness.
4. The golf ball of claim 1, wherein the cover has a first
thickness, and a second thickness extending from the outer surface
to a 50/50 blend point within the cover, and the ratio of the
second thickness to the first thickness is proportional to a melt
flow of the first material.
5. The golf ball of claim 4, wherein the melt flow of the second
material is greater than the melt flow of the first material.
6. The golf ball of claim 4, wherein the melt flow of the first
material is greater than the melt flow of the second material, such
that as the melt flow of the first material increases with respect
to the second material, the blend depth of the second thickness
decreases.
7. The golf ball of claim 1, wherein the materials of the cover are
comprised of one or more polymers selected from the group
consisting of partially or fully neutralized thermoplastic
ionomers, a dynamically vulcanized thermoplastic elastomer, a
functionalized styrene-butadiene elastomer, a polyetherester, a
polyesterester, a metallocene polymer, a thermoplastic
polyetheramide, a thermoplastic polyester, a thermoplastic
polyurethane, a ethylene or propylene based polymer, a methyl
acrylate, a methyl methacrylate polymer, a polycarbonate, a
polyamide, a polyphenylene oxide, a polyether ketone, a
polysulfone, a acrylonitrile butadiene polymer, a acrylic
styrene-acrylonitrile polymer, a terphthalate polymer, a
ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a
reinforced polymer, a urea or hybrids, silicones and silicone
copolymers, styrene block copolymers and blends thereof.
8. The golf ball of claim 1, wherein the core is solid and
comprised of more than one layer.
9. The golf ball of claim 1, wherein the core is a wound core.
10. The golf ball of claim 1, wherein the core is a dual core.
11. A golf ball comprised of: a core: a cover comprising of a
thermoset polyurethane; and an intermediate layer between the core
and cover; wherein the intermediate layer comprises an inner
surface and an outer surface and is formed from a mixture of a
first material and a second material with a first percent of the
first material on the outer surface being greater than a second
percent of the second material on the outer surface.
12. The golf ball of claim 11, wherein the first and second
materials are blends of two or more thermoplastic materials.
13. The golf ball of claim 11, wherein the outer surface has a
first hardness as measured on the surface thereof and the inner
surface has a second hardness as measured on the surface thereof
that is different from the first hardness.
14. The golf ball of claim 11, wherein the intermediate layer has a
first thickness, and a second thickness extending from the outer
surface to a 50/50 blend point within the cover, and the ratio of
the second thickness to the first is proportional to a melt flow of
the first material.
15. The golf ball of claim 14, wherein the melt flow of the second
material is greater than the melt flow of the first material.
16. The golf ball of claim 14, wherein the melt flow of the first
material is greater than the melt flow of the second material, such
that as the melt flow of the first material increases with respect
to the second material, the blend depth of the second thickness
decreases.
17. The golf ball of claim 11, wherein the materials of the
intermediate layer are comprised of one or more polymers selected
from the group consisting of partially or fully neutralized
thermoplastic ionomers, a dynamically vulcanized thermoplastic
elastomer, a functionalized styrene-butadiene elastomer, a
polyetherester, a polyesterester, a metallocene polymer, a
thermoplastic polyetheramide, a thermoplastic polyester, a
thermoplastic polyurethane, a ethylene or propylene based polymer,
a methyl acrylate, a methyl methacrylate polymer, a polycarbonate,
a polyamide, a polyphenylene oxide, a polyether ketone, a
polysulfone, a acrylonitrile butadiene polymer, a acrylic
styrene-acrylonitrile polymer, a terphthalate polymer, a
ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a
reinforced polymer, a urea or hybrids, silicones and silicone
copolymers, styrene block copolymers and blends thereof.
18. A method of manufacturing a golf ball having a single cover
layer of heterogeneous composition, the method comprising:
providing a core; placing a mating pair of hemispherical pre-molded
cover cups about the core, each cup having at least two layers,
each layer consisting of distinct resinous materials; and heating
and compressing the cover cups such that the resinous materials in
the cover cups intermingle with each other to form a single cover
layer comprised of a non-distinct blend of the materials.
19. The method of claim 18, wherein the heating and compression is
done by a conventional one-step golf ball compression molding
process.
20. The method of claim 18, wherein the heating is at a temperature
between about 300.degree. F. to 600.degree. F.
21. The method of claim 18, wherein the intermingling of the cups
may be further promoted by the application ultrasonic energy,
electromagnetic energy, or infrared radiation.
22. The method of claim 18, wherein the pre-molded cover cups are
made by a method consisting of lamination, co-injection molding, or
rotational molding.
23. The method of claim 18, wherein the materials of the layers are
comprised of one or more polymers selected from the group
consisting of partially or fully neutralized thermoplastic
ionomers, a dynamically vulcanized thermoplastic elastomer, a
functionalized styrene-butadiene elastomer, a polyetherester, a
polyesterester, a metallocene polymer, a thermoplastic
polyetheramide, a thermoplastic polyester, a thermoplastic
polyurethane, a ethylene or propylene based polymer, a methyl
acrylate, a methyl methacrylate polymer, a polycarbonate, a
polyamide, a polyphenylene oxide, a polyether ketone, a
polysulfone, a acrylonitrile butadiene polymer, a acrylic
styrene-acrylonitrile polymer, a terphthalate polymer, a
ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a
reinforced polymer, a urea or hybrids, silicones and silicone
copolymers, styrene block copolymers and blends thereof.
Description
FIELD OF INVENTION
[0001] The invention relates generally to golf balls, and more
specifically, to a golf ball having a single cover layer that is
comprised of a blend of two or more distinct resinous
materials.
BACKGROUND OF THE INVENTION
[0002] It is well known that golf balls are typically constructed
with a cover that tightly surrounds a core. It is typical for a
golf ball core to have a solid construction or a wound construction
and the methods of forming these cores are well known in the art.
Traditionally, golf ball covers are formed from polymeric
materials. For instance, golf balls have traditionally incorporated
covers made of balata rubber, which may be a natural balata, a
synthetic balata, or a blend of natural and synthetic balata.
[0003] Other golf balls have incorporated covers which are formed
from synthetic polymeric materials such as polyolefins and in
particular, polyethylene, poly-urethanes, and ionic copolymers of
olefins. The latter mentioned ionic copolymers of olefins were
commercially introduced in the mid 1960's by E. I. Du Pont de
Nemours & Co., Inc., Wilmington, Del. (DuPont) and sold under
the trademark "SURLYN." Golf balls incorporating SURLYN covers are
generally described in U.S. Pat. No. 3,454,280. Cover compositions
that are based on SURLYN resins are advantageous in that the
resulting covers are cut and abrasion resistant compared to the
balata covers. While golf balls incorporating SURLYN resin covers
are commonly known by players to be more cut resistant than balata
covered balls, they traditionally tend to reduce the spin imparted
to a golf ball and produce a less desirable "feel" as compared to a
balata covered ball.
[0004] SURLYN resins sold by DuPont typically contain zinc,
lithium, magnesium or sodium ions. A number of SURLYN resins, of
varying physical properties, are sold by DuPont. The physical
properties of these resins are described in technical bulletins
that are readily available from DuPont. Mixtures of various SURLYN
resins as cover stock materials are likewise highly advantageous.
Suitable mixtures for use as cover materials are described in U.S.
Pat. No. 3,819,768.
[0005] For purposes of control, golfers strike a golf ball in such
a manner that the ball has substantial backspin. It is desirable
that a golfer be able to impart backspin to a golf ball for
purposes of controlling its flight and controlling the action of
the ball upon landing on the ground. For example, substantial
backspin will make the ball stop once it strikes the landing
surface instead of bounding forward. The ability to impart back
spin onto a golf ball is related to the deformation of the golf
ball cover when struck with a golf club. Generally, the more
deformable the cover is, the easier it is to impart spin to the
balls. This is particularly true for short or wedge shots.
[0006] Thus, it is desirable to combine the properties of SURLYN
covered golf balls with the properties of Balata covered golf
balls. For example it is desirable to have less spin on a drive,
such that the ball will have a "low spin trajectory". The result is
that the ball does not climb like a typical high spin rate ball
would, and the ball has substantial roll after it lands on the
ground to provide maximum distance. On the other hand, for approach
shots, i.e., short shots into the green, spin is critical to
control the ball when it lands. With a high spin rate, the ball
will stop or "sit" when it hits the green. Thus, with a high spin
rate, the ball can be hit directly at the target. With a low spin
rate, the ball often bounces off the green or "runs" off the green.
Thus, it is desirable to have a high spin rate for approach shots
into the green.
[0007] Further, it is desirable to combine the durability of SURLYN
covered balls with the characteristics of balata covered balls.
[0008] Typically, the golf ball cover layer is formed by one of two
processes. The first process includes the compression molding of
hemispheres. First, two hemispherical covers, called half-shells,
are injection molded. The hemispheres are then placed around a core
and compression molded so that they fuse around the core and
wherein dimples are imparted into the cover. The cover is then
finished to remove any visible molding lines or residue. The second
process, called the retractable pin injection molding process,
involves injection molding of the cover directly around a core
positioned on pins, removing the pins once the cover material
surrounds the core, removing the covered core, and finishing it to
form a completed golf ball. In both cover forming processes, the
injection molding of the covers involves techniques known in the
art. These techniques generally involve forcing melted material to
substantially fill and take on the shape of a mold, thereby forming
a cover or hemisphere. When the material is cool enough to
substantially maintain the shape of the mold, it is ejected from
the mold.
[0009] There are also many patents that are directed to golf balls
having multiple cover layers. For example, U.S. Pat. No. 4,431,193
relates to a golf ball having a multilayer cover wherein the inner
layer is a hard, high flexural modulus ionomer resin and the outer
layer is a soft, low flexural modulus ionomer resin, and wherein
either or both layers may comprise a foamed ionomer resin.
[0010] U.S. Pat. No. 5,314,187 also relates to golf balls having
multiple layer covers, wherein the outer layer is molded over the
inner layer and comprises a blend of balata and an elastomer where
the inner layer is an ionomer resin.
[0011] U.S. Pat. No. 4,919,434 is directed towards a golf ball
having a cover which comprises an inner layer and an outer layer
each of which is a thermoplastic resin. Preferably the layers
comprise thermoplastic resin materials that are capable of fusion
bonding with each other.
[0012] U.S. Pat. No. 5,783,293 discloses a golf ball with a
multi-layered cover formed by a co-injection molding process,
wherein the golf ball cover comprises an inner and outer layer of a
first material and an intermediate layer therebetween of a second
material.
SUMMARY OF THE INVENTION
[0013] A golf ball comprised of a core and a cover, wherein the
cover has an inner surface and an outer surface and is formed from
a mixture of a first material and a second material that are a
blend of two or more thermoplastic materials and a first percent of
the first material on the outer surface is greater than a second
percent of the second material on the outer surface.
[0014] An embodiment of the invention provides that the outer
surface of the cover has a first hardness as measured on the
surface thereof and the inner surface has a second hardness as
measured on the surface thereof that is different from the first
hardness and the cover has a first thickness near the outer surface
and a second thickness measured from the outer surface to a 50/50
blend point within the cover; the ratio of the second thickness to
the first is proportional to a melt flow of the first material. The
properties of the cover may be varied by varying the melt flows of
the first and second materials.
[0015] The materials selected for the cover of the golf ball golf
ball are comprised of one or more polymers selected from the group
consisting of partially or fully neutralized thermoplastic
ionomers, a dynamically vulcanized thermoplastic elastomer, a
functionalized styrene-butadiene elastomer, a polyetherester, a
polyesterester, a metallocene polymer, a thermoplastic
polyetheramide, a thermoplastic polyester, a thermoplastic
polyurethane, a ethylene or propylene based polymer, a methyl
acrylate, a methyl methacrylate polymer, a polycarbonate, a
polyamide, a polyphenylene oxide, a polyether ketone, a
polysulfone, a acrylonitrile butadiene polymer, a acrylic
styrene-acrylonitrile polymer, a terphthalate polymer, a
ethylene-vinyl alcohol polymer, a tetrafluoroethylene polymer, a
reinforced polymer, a urea or hybrids, silicones and silicone
copolymers, styrene block copolymers and blends thereof.
[0016] One embodiment of the invention presents an intermediate
layer between the core and cover and which may comprise an inner
surface and an outer surface and is formed from a mixture of a
first material and a second material and a first percent of the
first material on the outer surface is greater than a second
percent of the second material on the outer surface.
[0017] An embodiment of the golf ball provides for a method of
manufacturing the golf ball having a single cover layer of
heterogeneous composition. One embodiment of the invention
describes a method wherein a core, comprising one or more layers,
has pre-molded hemispherical cover cups placed about the core and
each cover cup has at least two layers of distinct resinous
materials, and the cover cups are heated and compressed such that
the resinous materials in the cover cups intermingle with each
other to form a single cover layer comprised of a non-distinct
blend of the materials.
[0018] In another embodiment the heating and compression is done by
a conventional one-step golf ball compression molding process that
heats at a temperature between about 300.degree. F. to 600.degree.
F. The intermingling of the cups may be further promoted by the
application ultrasonic energy, electromagnetic energy, or infrared
radiation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a golf ball of the present invention wherein a
core is covered by two layers, each layer having distinct
properties from the other layer.
[0020] FIG. 2 is a cross-section of a resultant golf ball cover
layer formed from two layers having relatively the same melt flow
rates.
[0021] FIG. 3 is a cross-section of a resultant golf ball cover
layer formed from two or more layers having different melt flow
rates.
[0022] FIG. 4 is a golf ball according to FIG. 1, wherein the outer
cover consists of three thin layers formed by a co-injection
process.
[0023] FIG. 5 is a resultant cross-sectional view of an outer cover
comprising two materials of varying flow rates which have been
allowed to mix into a single cover of varying densities and
hardness.
[0024] FIG. 6 is a golf ball according to an embodiment of the
present invention disclosing a dual cover, with the inner cover
consisting of three thin layers of two different materials formed
by a co-injection molding process.
[0025] FIG. 7 is a golf ball wherein both the inner cover and outer
covers consist of three thin layers of two different materials and
are formed by a co-injection process.
DETAILED DESCRIPTION OF THE INVENTION
[0026] In a conventional golf ball construction one or more
distinct layers of material (either homogeneously blended or pure)
are molded or cast about a golf ball core to create a golf ball
component layer. Multiple molding steps are employed to mold a new
layer or layers of a differing material to create a multilayered
construction. These layers have distinct dimensional boundaries
between them, and are intended to act as homogeneous entities and
not to mesh or blend with each other. However, in the present
invention, golf ball subcomponents are manufactured consisting of
two or more thermoplastic material layers that are receptive to
blending with each other at temperature. This subassembly part
(known in the golf manufacturing art as a "cup") can then be
incorporated into a conventional golf ball compression molding
operation, just as cups of homogeneous construction are used in the
art today.
[0027] Referring to FIG. 1, a golf ball 10 is shown having a core
11 and a pair of inner cups 12 and a pair of outer cups 13 which
may be provided by well known means in the industry. The two layers
will have distinct physical properties but will have similar melt
flow numbers which will allow the materials to intermingle when
heat and compression is applied. The resulting cover is a single
thermoplastic cover layer comprised of a dimensionally non-distinct
blend of the selected materials, which have flowed together as a
result of their melt properties and depicted by FIG. 2, which shows
the resultant homogeneous cover 14 as substantially consisting of a
homogeneous mixture 15.
[0028] A novel aspect of the invention is shown in FIG. 3 wherein
the outer cover 16 formed therein is resultant from employing inner
and outer cup layers which have varying melt flows. In this
embodiment the cover 16 results in an outer surface 17 having a
first hardness as measured on the surface thereof and an inner
surface 18 having a second hardness as measured on the surface
thereof that is different from the first hardness and the resultant
cover 16 has a first thickness t1 nearer the outer surface and a
second thickness t2 measured from the outer surface to a 50/50
blend point within the cover 16; the ratio of the second thickness
t2 to the first thickness t1 is proportional to a melt flow of the
first material. The properties of the cover 16 can be altered by
varying the melt flows of the first and second materials. Since the
cover 16 has an inner surface and an outer surface and is formed
from a mixture of a first material and a second material that are a
blend of two or more thermoplastic materials and a first percent of
the first material on the outer surface is greater than a second
percent of the second material on the outer surface, the density
near the outer surface 17 is different than that nearer the inner
surface 18, which is also shown in FIG. 3. Normally, in most golf
ball applications the outer surface 17 would preferably be softer
than the inner surface 18.
[0029] There are numerous combinations of layers that may be
applied within the concept and scope of the present invention. For
instance, the cover layer described above could be an intermediate
layer and a cover layer then placed about it. Many other
combinations and methods of forming the inventive layer are
described below.
[0030] Referring to FIG. 4, a golf ball 20 is shown having a core
21, an outer cover 23 and an inner cover 22, which could be also a
dual core. The outer cover 23 consists of three thin layers, an
inner 27, an intermediate 28 and an outer 29 formed by a
co-injection molding machine and process, as described in U.S. Pat.
No. 5,783,293, which employs a sandwich injection molding machine
and produces a distinct two-material.
[0031] The golf ball hemisphere 30 of the outer cover 23 is shown
in FIG. 5. Multi-layer covers could also be prepared by
incorporating other methods such as film laminates, rotational
molding, blow molding, or similar. The layers 27, 28 and 29 may be
as thin as 0.005 inches. In this embodiment layers 27 and 29 will
be formed from one material while layer 28 is formed of a different
material having different properties from the other and the amount
of interaction between layers is a function of flow rates of the
two materials. An inventive concept of the present invention is
that the resulting golf ball 20 will have a cover hemisphere 23
that is then exposed to a conventional one-step golf ball
compression molding process, wherein the layers 27, 28 and 29 are
allowed to flow and intermesh with each other as temperature and
pressure is applied in the compression molding process. This
creates a single thermoplastic cover layer comprised of a
dimensionally non-distinct blend of the selected materials, which
have flowed together somewhat as a result of their melt properties.
A greater concentration of a desired material might exist at the
surface or towards the inner part of the ball, and the intermediate
boundary between the two is comprised of a heterogeneous gradation
of the two blended materials. While this embodiment shows a golf
ball having an inner and outer layers 27, 29 of one material
sandwiched about an intermediate layer 28, it is to be appreciated
that the three layers could each be of a distinct material having
three distinct physical properties.
[0032] FIG. 6 illustrates a ball 30 wherein the cover features seen
in FIG. 4 are utilized not in the outer cover layer 23 but in the
inner layer 22 which also consists of an inner layer 24, an
intermediate layer 25 and an outer layer 26.
[0033] As previously stated, the invention manufactures a cup with
several distinct layers of material, but it is intended that the
materials flow together once exposed to subsequent molding
processes, creating a single layer with a heterogeneous gradation
of materials that work well with each other. For example, a softer
material might be applied at the outer surface of a ball to enhance
short game spin rate performance, but this layer almost immediately
begins transitioning into a harder material that aids in driver
spin reduction. There is no visual distinction between the layers,
and dimensionally, the "soft layer" or "hard layer" doesn't really
exist--it's entirely a variable heterogeneous blend between the
materials throughout the entire cover.
[0034] The transition point, and degree of intermixing of the
materials, is dependant on the melt flow index and chemical
composition of the materials selected, and the blending of the
distinct materials may be controlled in this manner. But the intent
is that the materials blend together fluidly and readily, in a
dimensionally non-distinct way. This blending is accomplished by
compression molding of a preformed cup or laminate comprising
multiple layers at an elevated temperature that promotes
intermingling of the materials comprising the layers of the cup or
laminate. The cup or laminate comprises at least two and preferably
at least three layers. In addition to the application of heat and
pressure to promote at least partial mixing and/or intermingling of
polymer chains (to form the previously described heterogeneous
composition), ultrasonic energy, electromagnetic energy, IR or any
means of molecular excitation may be used to further promote mixing
and/or intermingling.
[0035] The compression method for forming the ball in FIG. 4, is
accomplished by creating a "heterogeneous layer" by co-injecting
mold half shells or cups having 3 or more distinct layers, with the
innermost and outermost layers being the same material and
sandwiching an intermediate layer or a second material. A core is
then positioned inside an upper and a lower 3-layered cup and
placed into a hot mold (about 300.degree. F. to 600.degree. F.)
consisting of two female spherical half shells (with or without
projections that will ultimately form the dimples of the ball) and
the mold is closed. The time, temperatures, etc. and the degree of
mixing or intermingling desired. A longer time and/or higher
temperature will generally promote greater intermingling.
[0036] The intermingling of the materials may be done in a single
step or multiple steps at increasing times and temperatures to
create the golf ball properties desired. The goal is to create a
single layer having a compositional gradient and therefore a
hardness and modulus gradient. When using ionomeric materials it is
proposed that choice of cation, melt flow, degree of
neutralization, and type and level of ionic plasticizer (when used)
are critical factors. For example, the use of smaller cations such
as lithium are believed to promote greater mobility or
"ion-hopping" from one polymer to another, thereby promoting
greater intermingling. Further, the use of a more mobile cations
such as amines, in addition to or as a replacement for a metal
cation, may also promote greater mixing. Fatty acids, fatty acid
salts and other plasticizers are more apt to "move" from one
polymer to another, particularly it used in excess of the available
cations present.
[0037] Referring to FIG. 7, another embodiment of the invention is
shown, wherein the completed golf ball 20 is presented. This
embodiment employs the core 21 as being surrounded by two sets of
cups, the inner sets 22 that comprises the three layer hemispheres
placed over the core 21 on both sides of the ball equator 60, and
outer sets 23 which comprise having three layer hemispheres placed
over the inner sets. The inner sets 22 each consist of an inner
layer 24 and outer layer 26 that are comprised of a first material
and these layers sandwich an intermediate layer 25 which is
comprised of a second material that is distinct in physical
properties from the first material. The outer set of cups 23 each
have three layer hemispheres consisting of an inner layer 27 and
outer layer 29 that are comprised of a third material and these
layers sandwiching an intermediate layer 28 comprised of a fourth
material that is distinct in physical properties from the first
material. The first and the third materials may be the same or
different from each other. Also the second and the fourth materials
may be the same or different from each other.
[0038] The inner hemispheres are compression molding onto a core
that generally involves applying pressure and heat to the
hemispheres and is known in the art. It is contemplated that the
core 21 is a solid, polybutadiene type core, or a solid core having
multiple layers or a wound core. It is suggested that first
material and second material each comprise one or more polymers.
Useful polymers include a thermoplastic ionomer, a dynamically
vulcanized thermoplastic elastomer, a functionalized
styrene-butadiene elastomer, a polyetherester, a polyesterester, a
metallocene polymer, a thermoplastic polyetheramide, a
thermoplastic polyester, a thermoplastic polyurethane, an ethylene
or propylene based polymer, a methyl acrylate, a methyl
methacrylate polymer, a polycarbonate, a polyamide, a polyphenylene
oxide, a polyether ketone, a polysulfone, an acrylonitrile
butadiene polymer, an acrylic styrene-acrylonitrile polymer, a
terphthalate polymer, an ethylenevinyl alcohol polymer, a
tetrafluoroethylene polymer, a reinforced polymer, or blends
thereof. As noted above, the first and second layers should be
different polymers or be polymers that have different
properties.
[0039] Most preferably the first material and second material are
comprised of thermoplastic ionomers or of a balata rubber and a
thermoplastic ionomer, respectively. Suitable thermoplastic ionomer
resins include any number of olefinic based ionomers including
SURLYN.RTM. and IOTEK.RTM. which are commercially available from
DuPont and Exxon, respectively.
[0040] Among the preferred materials for first material and/or
second material are ionomer resins obtained by providing a cross
metallic bond to polymers of mono-olefin with at least one member
selected from the group consisting of unsaturated mono- or
di-carboxylic acids having 3 to 12 carbon atoms and esters thereof
(the polymer contains 1 to 50% by weight of the unsaturated mono-
or di-carboxylic acid and/or ester thereof). More particularly,
such acid-containing ethylene copolymer ionomer component of the
subject invention includes E/X/Y copolymers where E is ethylene, X
is a softening comonomer such as an acrylate, e.g., methyl
acrylate, iso-butyl acrylate or n-butyl acrylate, present in 1-60
(preferably 10-40, most preferably 10-25), weight percent of the
polymer, and Y is ethylenically unsaturated organic acid, such as
acrylic or methacrylic acid, present in 5-35 (preferably 10-35,
most preferably 10-21) weight percent of the polymer, wherein the
acid moiety is neutralized 1-90% (preferably at least 40%, most
preferably at least about 60%) to form an ionomer by a cation such
as lithium, sodium, potassium, magnesium, calcium, barium, lead,
tin, zinc or aluminum, or a combination of such cations. Lithium,
sodium, magnesium and/or zinc are preferred. Specific
acid-containing ethylene copolymers include ethylene/acrylic acid,
ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate,
ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylic
acid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,
ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylic
acid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,
ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylic
acid/methyl methacrylate, and ethylene/acrylic acid/n-butyl
methacrylate. Preferred acid-containing ethylene copolymers include
ethylene/methacrylic acid, ethylene/acrylic acid,
ethylene/methacrylic acid/n-butyl acrylate, ethylene/acrylic
acid/n-butyl acrylate, ethylene/methacrylic acid/methyl acrylate
and ethylene/acrylic acid/methyl acrylate copolymers. The most
preferred acid-containing ethylene copolymers are
ethylene/methacrylic acid, ethylene/acrylic acid,
ethylene/(meth)acrylic acid/n-butyl acrylate,
ethylene/(meth)acrylic acid/ethyl acrylate, and
ethylene/(meth)acrylic acid/methyl acrylate copolymers.
[0041] The manner in which the ionomers are made is well known in
the art as described, e.g., in U.S. Pat. No. 3,262,272. Such
ionomer resins are commercially available from DuPont Co. under the
trade name SURLYN.RTM..
[0042] Additionally, foamed polymeric materials, in particular,
metallocene-based foam resins are suitable for use in the cover
layers of the present invention.
[0043] Still further, the first or second materials can be
comprised of balata rubber or of a synthetic balata.
[0044] In the present invention, first material has a melting point
or heat of reaction (cure) temperature that is similar to that of
second material.
[0045] The golf balls discussed in this present invention were
constructed using a compression molding method. However, it will be
apparent to those skilled in the art that the golf balls can also
be constructed by the retractable pin injection molding process,
which involves injection molding of the cover directly around a
core positioned on pins. The pins are removed once the cover
material surrounds the core and has solidified to the extent the
core will not move. In this process, the compression molding seam
60 can be eliminated. After the cover materials have hardened, the
covered core is removed and finished to form a completed golf ball.
Based on the teachings herein, the necessary modifications to the
standard retractable pin injection molding processes will be
readily apparent to those skilled in the art.
[0046] Optionally, one or more of the inner layers may have
materials that would work as moisture barrier layers that will
protect against reduced COR values, due to moisture take-up by the
core 21. Preferably one of the intermediate layers may serve as a
moisture barrier layer, more preferably the intermediate layer will
serve as the moisture barrier. The use of moisture barriers is
described in U.S. Pat. No. 6,632,147, which is incorporated by
reference herein in its entirety.
[0047] A moisture barrier should have a moisture vapor transmission
rate that is less than that of the outer cover layer, and more
preferably, less than the moisture vapor transmission rate of an
ionomer resin such as Surlyn.RTM., which has a rate in the range of
about 0.45 to about 0.95 grams per mm/m.sup.2 per day. The moisture
vapor transmission rate is defined as: the mass of moisture vapor
that diffuses into a material of a given thickness per unit area
per unit time. The preferred standards of measuring the moisture
vapor transmission rate include: ASTM F1249-90 entitled "Standard
Test Method for Water Vapor Transmission Rate Through Plastic Film
and Sheeting Using a Modulated Infrared Sensor," and ASTM F372-99
entitled "Standard Test Method for Water Vapor Transmission Rate of
Flexible Barrier Materials Using an Infrared Detection Technique,"
among others.
[0048] The manipulation of moment of inertia via the filling (or
foaming or otherwise reducing specific gravity) of the core and
cover layers provide the opportunity to further improve upon
distance and spin. The low specific gravity core or layers can be
made from a number of suitable materials, so long as the low
specific gravity contributes to the soft compression and resilience
of the golf ball. The material can be from a thermosetting
syntactic foam with hollow sphere fillers or microspheres in a
polymeric matrix of epoxy, urethane, polyester or any suitable
thermosetting binder, where the cured composition has a specific
gravity less than 1.1 g/cc and preferably less than 1.0 g/cc.
Additionally, any number of foamed or otherwise specific gravity
reduced thermoplastic or thermosetting polymer compositions or
foaming agents may also be used such as metallocene-catalyzed
polymers and blends thereof described in U.S. Pat. Nos. 5,824,746
and 6,025,442 which are incorporated by reference herein in their
entirety. Further, a thermoset polyurethane composition having a
specific gravity or less than 1.3 g/cc such as a nucleated reaction
injection molded or cast polyurethane may be used. Such a
composition may result in a gas-filled or cellular solid layer.
[0049] As discussed in U.S. Pat. No. 5,971,870, which is
incorporated by reference herein in its entirety, fillers may be or
are typically in a finely divided form. For example, in a size
generally less than about 20 mesh, preferably less than about 100
mesh U.S. standard size, except for fibers and flock, which are
generally elongated, flock and fiber sizes should be small enough
to facilitate processing. Filler particle size will depend upon
desired effect, cost, ease of addition, and dusting considerations.
The filler preferably is selected from the group consisting of
precipitated hydrated silica, clay, talc, asbestos, glass fibers,
aramid fibers, mica, calcium metasilicate, barium sulfate, zinc
sulfide, lithopone, silicates, silicon carbide, diatomaceous earth,
polyvinyl chloride, carbonates, metals, metal alloys, tungsten
carbide, metal oxides, metal stearates, particulate carbonaceous
materials, micro balloons, and combinations thereof. Non-limiting
examples of suitable fillers, their densities, and their preferred
uses are as follows:
[0050] Filler Type Sp. Gr. Comments Precipitated hydrated silica
2.0 1, 2 Clay 2.62 1, 2 Talc 2.85 1, 2 Asbestos 2.5 1, 2 Glass
fibers 2.55 1, 2 Aramid fibers (KEVLAR.RTM.) 1.44 1, 2 Mica 2.8 1,
2 Calcium metasilicate 2.9 1, 2 Barium sulfate 4.6 1, 2 Zinc
sulfide 4.1 1, 2 Lithopone 4.2-4.3 1, 2 Silicates 2.1 1, 2 Silicon
carbide patelets 3.18 1, 2 Silicon carbide whiskers 3.2 1, 2
Tungsten carbide 15.6 1 Tungsten oxide 5.8 1 Diatomaceous earth 2.3
1, 2 Polyvinyl chloride 1.41 1, 2 Carbonates Calcium carbonate 2.71
1, 2 Magnesium carbonate 2.20 1, 2 Metals and Alloys (powders)
Titanium 4.51 1 Tungsten 19.35 1 Aluminum 2.70 1 Bismuth 9.78 1
Nickel 8.90 1 Molybdenum 10.2 1 Iron 7.86 1 Steel 7.8-7.9 1 Lead
11.4 1, 2 Copper 8.94 1 Brass 8.2-8.4 1 Boron 2.34 1 Boron carbide
whiskers 2.52 1, 2 Bronze 8.70-8.74 1 Cobalt 8.92 1 Beryllium 1.84
1 Zinc 7.14 1 Tin 7.31 1 Metal Oxides Zinc oxide 5.57 1, 2 Iron
oxide 5.1 1, 2 Aluminum oxide 4.0 Titanium oxide 3.9-4.1 1, 2
Magnesium oxide 3.3-3.5 1, 2 Zirconium oxide 5.73 1, 2 Metal
Stearates Zinc stearate 1.09 3, 4 Calcium stearate 1.03 3, 4 Barium
stearate 1.23 3, 4 Lithium stearate 1.01 3, 4 Magnesium stearate
1.03 3, 4 Particulate carbonaceous materials Graphite 1.5-1.8 1, 2
Carbon black 1.8 1, 2 Natural bitumen 1.2-1.4 1, 2 Cotton flock
1.3-1.4 1, 2 Cellulose flock 1.15-1.5 1, 2 Leather fiber 1.2-1.4 1,
2 Micro balloons Glass 0.15-1.1 1, 2 Ceramic 0.2-0.7 1, 2 Fly ash
0.6-0.8 1, 2 Coupling Agents Adhesion Promoters Titanates 0.95-1.11
Zirconates 0.92-1.11 Silane 0.95-1.2 1 Particularly useful for
adjusting density of the inner cover layer. 2 Particularly useful
for adjusting flex modulus of the inner cover layer.
[0051] The present invention allows for a dual cover that may
comprise four or six cover layers. The six cover layers may include
as many as four different material compositions. Utilizing a
diversity of base materials as well as the inclusion of the above
density altering materials, a wide range of density and hardness
gradients is achievable across an extremely wide spectrum.
[0052] While it is apparent that the illustrative embodiments of
the invention herein disclosed fulfills the objectives stated
above, it will be appreciated that numerous modifications and other
embodiments may be devised by those skilled in the art. Therefore,
it will be understood that the appended claims are intended to
cover all such modifications and embodiments which come within the
spirit and scope of the present invention.
* * * * *