U.S. patent application number 10/900488 was filed with the patent office on 2005-01-13 for molding processes and equipment for forming golf balls with deep dimples.
This patent application is currently assigned to Callaway Golf Company. Invention is credited to Shannon, Kevin J., Simonds, Vincent J., Veilleux, Thomas A..
Application Number | 20050006815 10/900488 |
Document ID | / |
Family ID | 27739112 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050006815 |
Kind Code |
A1 |
Simonds, Vincent J. ; et
al. |
January 13, 2005 |
Molding processes and equipment for forming golf balls with deep
dimples
Abstract
Molding equipment and related techniques for forming a golf ball
are disclosed. The golf ball comprises a core and a cover layer,
wherein the cover layer provides one or more deep dimples that
extend through the cover layer to and/or into a layer or component
underneath are disclosed. The molding equipment provides one or
more selectively positionable knock-out pins along the surface of
the molding chamber. These pins are specially tailored such that
after their retraction subsequent to molding, the resulting voids
are deep dimples. The molding equipment and related processes are
particularly useful when forming the various layers by reaction
injection molding.
Inventors: |
Simonds, Vincent J.;
(Brimfield, MA) ; Shannon, Kevin J.; (Springfield,
MA) ; Veilleux, Thomas A.; (Charlton, MA) |
Correspondence
Address: |
THE TOP-FLITE GOLF COMPANY, A WHOLLY OWNED
SUBSIDIARY OF CALLAWAY GOLF COMPANY
P.O. BOX 901
425 MEADOW STREET
CHICOPEE
MA
01021-0901
US
|
Assignee: |
Callaway Golf Company
Carlsbad
CA
|
Family ID: |
27739112 |
Appl. No.: |
10/900488 |
Filed: |
July 28, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10900488 |
Jul 28, 2004 |
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10305680 |
Nov 27, 2002 |
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6817853 |
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60337123 |
Dec 4, 2001 |
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60356400 |
Feb 11, 2002 |
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60422423 |
Oct 30, 2002 |
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Current U.S.
Class: |
264/278 ;
264/279; 264/279.1; 473/351 |
Current CPC
Class: |
B29C 45/372 20130101;
B29L 2031/545 20130101; A63B 37/0018 20130101; B29C 45/1676
20130101; A63B 37/0004 20130101; B29L 2031/54 20130101; B29C 67/246
20130101; A63B 37/0003 20130101; A63B 37/0019 20130101; A63B 45/00
20130101; A63B 37/002 20130101; B29C 45/14065 20130101; A63B 37/04
20130101; B29C 45/1671 20130101; B29D 99/0042 20130101 |
Class at
Publication: |
264/278 ;
264/279; 264/279.1; 473/351 |
International
Class: |
B29C 039/10; B29C
045/14; B29C 045/36; A63B 037/00 |
Claims
1-8. (CANCELED)
9. A process for forming a golf ball having a plurality of deep
dimples, said process comprising: providing a molding apparatus
having (i) an upper mold including a first molding surface that
defines at least one aperture, said upper mold further including a
selectively positionable pin in each of said apertures, and (ii) a
lower mold including a second molding surface that defines at least
one aperture, said lower mold further including a selectively
positionable pin in each of said apertures, said pins of said upper
and lower molds having a distal end that may be extended past said
respective first and second molding surface, said upper and lower
molds adapted to engage each other such that said first molding
surface and said second molding surface form a generally spherical
molding chamber; positioning a golf ball core or intermediate ball
assembly within said molding chamber; extending at least one of
said pins within said molding chamber so that said distal end of
said extended pin contacts said golf ball core or intermediate ball
assembly; introducing a molding material within said molding
chamber and around said golf ball core or intermediate ball
assembly to thereby form a layer of said material around said golf
ball core or intermediate ball assembly; at least partially
hardening said molding material; retracting said pins to thereby
form deep dimples in said resulting layered core or ball
assembly.
10. The process of claim 9, wherein said pins are extended into
said molding chamber a distance of from about 0.002 inches to about
0.140 inches as measured from said respective first and second
molding surface.
11. The process of claim 10, wherein said distance is from about
0.002 inches to about 0.050 inches.
12. The process of claim 9, further comprising: providing on at
least one of said first and second molding surfaces, a raised
protuberance that upon said steps of introducing and at least
partially hardening said molding material, forms a deep dimple in
said resulting layered core or ball assembly.
13. The process of claim 9, further comprising; removing said
resulting layered core or ball assembly from said molding
chamber.
14. The layered core or ball assembly resulting from the process of
claim 13.
15. A process for forming a golf ball having a plurality of deep
dimples, said process comprising: providing a molding apparatus
having (i) an upper mold including a first molding surface that
defines a first raised protuberance adapted to form a deep dimple
and at least one aperture, said upper mold further including a
selectively positionable pin in each of said apertures, and (ii) a
lower mold including a second molding surface that defines a second
raised protuberance adapted to form a deep dimple and at least one
aperture, said lower mold further including a selectively
positionable pin in each of said apertures, said pins of said upper
and lower molds having a distal end that may be extended past said
respective first and second molding surface, said upper and lower
molds adapted to engage each other such that said first molding
surface and said second molding surface form a generally spherical
molding chamber; positioning a golf ball core or intermediate ball
assembly within said molding chamber; extending at least one of
said pins within said molding chamber so that said distal end of
said extended pin contacts said golf ball core or intermediate ball
assembly; introducing a molding material within said molding
chamber and around said golf ball core or intermediate ball
assembly to thereby form a layer of said material around said golf
ball core or intermediate ball assembly; at least partially
hardening said molding material.
16. The process of claim 15 wherein upon positioning said golf ball
core or intermediate ball assembly within said molding chamber,
said core or ball assembly contacts said first and second raised
protuberances defined in said first and second molding
surfaces.
17. The process of claim 15, wherein said first and second raised
protuberances have a height of from about 0.002 inches to about
0.140 inches.
18. The process of claim 15, wherein said pins are extended into
said molding chamber a distance of from about 0.002 inches to about
0.140 inches as measured from said respective first and second
molding surface.
19. The process of claim 15, further comprising: removing said
resulting golf ball having deep dimples from said molding
chamber.
20. The process of claim 15, further comprising: extending said
pins to displace said resulting layered core or ball assembly from
said molding chamber.
21. The process of claim 17, further comprising: retracting said
pins to thereby form additional deep dimples in said resulting
layered core or ball assembly.
22. The process of claim 15, further comprising: retracting said
pins to thereby form additional deep dimples in said resulting
layered core or ball assembly.
23. The ball formed from the process of claim 15.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] The present application claims priority upon U.S.
Provisional Application Ser. No. 60/337,123, filed Dec. 4, 2001;
U.S. Provisional Application Ser. No. 60/356,400, filed Feb. 11,
2002; and U.S. Provisional Application Ser. No., ______, filed Oct.
30, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to processes and apparatuses
for forming golf balls, and more particularly to processes and
equipment for forming golf balls having one or more deep dimples
that extend through a cover layer to and/or into one or more layers
or components thereunder. The present invention also relates to
processes and apparatuses for forming golf balls with deep dimples
by utilizing one or more specifically tailored "knock-out" pins
that serve to support the core or ball assembly during molding,
assist in removing the molded ball from the mold, and form deep
dimples in the ball. These particularly tailored pins are
preferably used in conjunction with other features in the mold to
form deep dimples in the resulting ball. The various processes and
apparatuses described herein are particularly well suited for use
in conjunction with reaction injection molding techniques.
BACKGROUND OF THE INVENTION
[0003] A number of two-piece (a solid resilient center or core with
a molded cover) and multi-layer (liquid or solid center and
multiple mantle and/or cover layers) golf balls have been produced.
Different types of materials and/or processing parameters have been
utilized to formulate the cores, covers, etc. of these balls, which
dramatically alter the balls' overall characteristics. In addition,
multi-layer covers of different materials have also been formulated
in an attempt to produce a golf ball having the overall distance,
playability and durability characteristics desired.
[0004] For certain applications it is desirable to produce a golf
ball having a very thin cover layer. However, due to equipment
limitations, it is often very difficult to mold a thin cover.
Accordingly, it would be beneficial to provide an apparatus and
technique for producing a relatively thin outer cover layer.
[0005] Moreover, retractable pins have been utilized to hold, or
center, the core or core and mantle and/or cover layer(s) in place
while molding an outer cover layer thereon. However, these pins
have only been utilized to support the core during molding and have
not contributed to the outer appearance of the ball. In fact,
conventional pins sometimes produce centering difficulties and
cosmetic problems (i.e. pin flash, pin marks, etc.) during
retraction, which in turn require additional handling to produce a
golf ball suitable for use and sale. Accordingly, it would be
desirable to provide an apparatus and method for forming a cover
layer on a golf ball with retractable pins that overcame the
problems associated with conventional pins.
SUMMARY OF THE INVENTION
[0006] One aspect of the present invention is to provide equipment
and methods for forming a golf ball with a thin cover that has a
favorable combination of playability properties yet which may be
manufactured more cost effectively and without many of the problems
associated with prior balls.
[0007] Yet another aspect of the invention is to provide equipment
and methods for forming a golf ball having one or more deep dimples
and a resulting favorable combination of spin, resiliency and
durability characteristics.
[0008] A further aspect of the invention is to provide equipment
and methods for forming a golf ball having a dimpled cover that is
thinner than traditional cover layers with one or more deep
dimples.
[0009] Another aspect of the invention is to provide equipment and
methods for forming a golf ball having dimples in an outer cover
layer that extend to, and/or into at least the next inner layer of
the ball.
[0010] Yet another aspect of the invention is to provide equipment
and methods for forming a golf ball core or intermediate ball
assembly that in many instances may be readily removed from a
molding assembly.
[0011] Another aspect of the invention is to provide novel molding
equipment that simplifies manufacturing of golf balls and
components thereof. The equipment utilizes one or more specifically
tailored "knock-out" pins that serve to support the core or ball
during molding, assist in removing the molded ball from the mold,
and form deep dimples in the ball. These particularly tailored pins
are preferably used in conjunction with other features in the mold
to form deep dimples in the resulting ball.
[0012] In a further aspect, the present invention provides a
molding apparatus adapted for forming a golf ball having one or
more deep dimples. The apparatus comprises an upper mold having a
first hemispherical molding surface that defines a hemispherical
molding cavity, and at least one aperture defined along the first
molding surface. The upper mold further has, in each of the
apertures, a selectively positionable pin having a distal end that
may be extended into the cavity or retracted from the cavity. The
molding apparatus further comprises a lower mold having a second
hemispherical molding surface that defines a hemispherical molding
cavity and at least one aperture defined along the second molding
surface. The lower mold further has, in each of the apertures, a
selectively positionable pin having a distal end that may be
extended into the cavity or retracted therefrom. The upper mold and
the lower mold are adapted to engage each other such that the first
molding surface and the second molding surface form a generally
spherical molding chamber. The pins in each of the apertures
defined in the upper mold and lower mold extend into the molding
chamber a distance of from about 0.002 inches to about 0.140 inches
as measured from the respective first or second molding surface.
The pins remain in the extended position during a molding operation
so as to form a corresponding number of deep dimples in the
resulting golf ball.
[0013] In another aspect, the present invention provides a molding
apparatus adapted to form a golf ball with a plurality of deep
dimples along an outer surface of the ball. The apparatus comprises
a first mold including a first hemispherical molding surface
defining a first molding cavity and at least one aperture defined
along the first molding surface. The first molding surface has at
least one raised protuberance adapted to form a deep dimple. The
first mold further includes, in each of the apertures, a
selectively positionable pin having a distal end that may be
extended into the first cavity or retracted from the first cavity.
The molding apparatus further includes a second mold having a
second hemispherical molding surface that defines a second molding
cavity and at least one aperture defined along the second molding
surface. The second molding surface has at least one raised
protuberance adapted to form a deep dimple. The second mold further
includes, in each of the apertures, a selectively positionable pin
having a distal end that may be extended into the second cavity or
retracted from the second cavity. The first mold and the second
mold are adapted to engage each other such that the first molding
surface and the second molding surface form a generally spherical
molding chamber. At least a portion of the raised protuberances in
the first and second molding surfaces have a height, as measured
from their respective molding surface, of from about 0.002 inches
to about 0.140 inches.
[0014] In yet another aspect, the present invention provides a
molding apparatus adapted for forming a golf ball with a plurality
of deep dimples along an outer surface of the golf ball. The
apparatus comprises a first mold including a first hemispherical
molding surface defining a first molding cavity and at least one
aperture defined along the first molding surface. The first molding
surface has at least one raised protuberance adapted to form a deep
dimple. The first mold further includes, in each of the apertures,
a selectively positionable pin having a distal end that may be
extended into the first cavity or retracted from the first cavity.
Each of the pins associated with the first mold are positionable
such that the distal end extends into the first molding chamber a
distance of from about 0.002 inches to about 0.140 inches as
measured from the first molding surface. The molding apparatus
further comprises a second mold including a second hemispherical
molding surface defining a second molding cavity and at least one
aperture defined along the second molding surface. The second
molding surface has at least one raised protuberance adapted to
form a deep dimple. The second mold further includes, in each of
the apertures, a selectively positionable pin having a distal end
that may be extended into the second cavity or retracted therefrom.
Each of the pins associated with the second mold is positionable
such that the distal end of the pin extends into the second molding
chamber a distance of from about 0.002 inches to about 0.140 inches
as measured from the second molding surface. Each of the first and
second molds are adapted to engage each other such that the first
molding surface and the second molding surface form a generally
spherical molding chamber. At least a portion of the raised
protuberances in the first and second molding surfaces have a
height, as measured from their respective molding surface, of from
about 0.002 inches to about 0.140 inches.
[0015] In yet a further aspect, the present invention provides a
process for forming a golf ball having a plurality of deep dimples.
The process comprises a step of providing a molding apparatus
having an upper mold including a first molding surface that defines
at least one aperture. The upper mold further includes a
selectively positionable pin in each of the apertures. The molding
apparatus also includes a lower mold including a second molding
surface that defines at least one aperture and also including a
selectively positionable pin in each of the apertures. The pins of
the upper and lower molds have a distal end that may be extended
past the respective first and second molding surfaces. The upper
and lower molds are adapted to engage each other such that the
first molding surface and the second molding surface form a
generally spherical molding chamber. The process also comprises a
step of positioning a golf ball core or intermediate ball assembly
within the molding chamber. The process includes an additional step
of extending at least one the pins within the molding chamber so
that the distal end of the extended pin contacts the golf ball core
assembly or intermediate ball assembly. The process includes an
additional step of introducing a molding material within the
molding chamber and around the golf ball core or intermediate ball
assembly to thereby form a layer of material around the golf ball
core or intermediate ball assembly. The process includes another
step of at least partially hardening the molding material. And, the
process includes a step of retracting the pins to thereby form deep
dimples in the resulting layered core or ball assembly.
[0016] In yet another aspect, the present invention provides a
process for forming a golf ball having a plurality of deep dimples.
The process comprises a step of providing a molding apparatus
having an upper mold including a first molding surface that defines
a first raised protuberance adapted to form a deep dimple and at
least one aperture. The upper mold includes a selectively
positionable pin in each of the apertures. The molding apparatus
includes a lower mold having a second molding surface that defines
a second raised protuberance adapted to form a deep dimple and at
least one aperture. The lower mold further includes a selectively
positionable pin in each of the apertures. The pins of the upper
and lower molds have a distal end that may be extended past the
respective first and second molding surface. The upper and lower
molds are adapted to engage each other such that the first molding
surface and the second molding surface form a generally spherical
molding chamber. The process includes a step of positioning a golf
ball core or intermediate ball assembly within the molding chamber.
The process includes another step of extending at least one of the
pins within the molding chamber so that the distal end of the
extended pin contacts the golf ball core or intermediate ball
assembly. The process further includes a step of introducing a
molding material within the molding chamber and around a golf ball
core or intermediate ball assembly to thereby form a layer of the
molding material around a golf ball core or intermediate ball
assembly. The process includes a step of at least partially
hardening the molding material. And, the process includes a step of
retracting the pins to thereby form additional deep dimples in the
resulting layered core or ball assembly.
[0017] The invention accordingly comprises several apparatuses,
processes, compositions, components and steps and the relation of
one or more of such apparatuses, processes, compositions,
components and steps with respect to each other. Moreover, the
invention is directed to articles possessing the features,
properties, and the relation of elements exemplified in the
following detailed disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The following is a brief description of the drawings, which
are presented for the purposes of illustrating the present
invention and not for the purposes of limiting the same.
[0019] FIG. 1 is a cross-sectional view of a preferred embodiment
golf ball according to the present invention having a core and a
single cover layer having dimples, wherein one or more of the
dimples extends through the cover to and/or into the underlying
core.
[0020] FIG. 2 is a diametrical cross-sectional view of the
preferred embodiment golf ball illustrated in FIG. 1.
[0021] FIG. 3 is a cross-sectional view of another preferred
embodiment golf ball according to the present invention having a
core component and a cover component, wherein the cover component
includes an inner cover layer and an outer cover layer having
dimples formed therein, and wherein one or more of the dimples of
the outer cover layer extends to and/or into the underlying inner
cover layer.
[0022] FIG. 4 is a diametrical cross-sectional view of the
preferred embodiment golf ball illustrated in FIG. 3.
[0023] FIG. 5 is a cross-sectional detail view of a portion of a
preferred embodiment golf ball according to the present invention
having a core and a cover illustrating a dual radius dimple that
extends through the cover into the underlying core.
[0024] FIG. 6 is a cross-sectional detail view of a portion of a
preferred embodiment golf ball according to the present invention
having a core and a cover illustrating a dual radius dimple that
extends through the outer cover layer to the outer surface of the
core.
[0025] FIG. 7 is a cross-sectional detail view of a portion of a
preferred embodiment golf ball according to the present invention
having a core, an inner cover layer, and an outer cover layer,
wherein the outer cover layer has a dual radius dimple that extends
into the inner cover layer.
[0026] FIG. 8 is a cross-sectional detail view of a portion of a
preferred embodiment golf ball according to the present invention
having a core, an inner cover layer, and an outer cover layer
illustrating a dual radius dimple that extends through the outer
cover layer to the inner cover layer of the ball.
[0027] FIG. 9 is a top view of a preferred embodiment golf ball
according to the present invention having a first population of
typical dimples along with three deeper dimples configured in a
triangular pattern about the pole of the ball.
[0028] FIG. 10 is a top view of a preferred embodiment golf ball
according to the present invention having a first population of
typical dimples along with four deeper dimples arranged in a
diamond pattern about the pole of the ball.
[0029] FIG. 11 is a cross-sectional detail view of a portion of a
preferred embodiment golf ball according to the present invention
having a core, an inner cover or mantle layer, and an outer cover
layer illustrating a dimple that extends through the outer cover
layer to the mantle layer.
[0030] FIG. 12 is a top view of a portion of a preferred embodiment
golf ball according to the present invention having a cover with
dimples formed in two layers of the cover and illustrating an inner
dimple portion formed in the inner cover layer and an outer dimple
portion formed in the outer cover layer.
[0031] FIG. 13 is a graph illustrating the relationship between the
location on a golf ball of certain dimples according to the
invention and the resulting forces in a self-supporting cavity
during molding.
[0032] FIG. 14 is a perspective view of a golf ball illustrating a
region defined along the outer surface of the ball.
[0033] FIG. 15 is a schematic view of a preferred embodiment
molding assembly and a golf ball core according to the present
invention.
[0034] FIG. 16 is a process flow diagram that schematically depicts
a reaction injection molding process according to the
invention.
[0035] FIG. 17 schematically shows a mold for reaction injection
molding a golf ball cover according to the invention.
[0036] FIG. 18 is a perspective view of a preferred embodiment
molding apparatus according to an aspect of the present
invention.
[0037] FIG. 19 is another view of an intermediate ball molded in
accordance with an aspect of the present invention.
[0038] FIG. 20 is a view of a lower portion of the molding assembly
illustrated in FIG. 18 containing an intermediate ball shown in
FIG. 19.
[0039] FIG. 21 is a perspective view of another preferred
embodiment molding apparatus according to the present
invention.
[0040] FIG. 22 is a schematic cross-sectional view of the molding
apparatus depicted in FIG. 21 in a closed position.
[0041] FIG. 23 is a schematic cross-sectional view of the molding
apparatus depicted in FIG. 21 containing a golf ball core around
which a layer is molded.
[0042] FIG. 24 is a detailed view of a portion of the
cross-sectional view illustrated in FIG. 23.
[0043] FIG. 25 is a schematic top view of a preferred embodiment
molding apparatus according to the present invention.
[0044] FIG. 26 is a schematic side view of the preferred embodiment
molding apparatus shown in FIG. 25.
[0045] FIG. 27 is a detailed view of the region identified by a
circular dashed line in FIG. 26.
[0046] FIG. 28 is a schematic top view of another preferred
embodiment molding apparatus according to the present
invention.
[0047] FIG. 29 is a schematic side view of the preferred embodiment
molding apparatus shown in FIG. 28.
[0048] FIG. 30 is a detailed view of the region identified by a
circular dashed line in FIG. 29.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] The present invention relates to equipment and methods for
producing improved golf balls, particularly a golf ball comprising
a cover disposed about a core in which the cover has one or more,
preferably a plurality of, deep dimples or apertures that extend
through the outer cover to and/or into one or more layers
underneath. The golf balls of the present invention, which can be
of a standard or enlarged size, have a unique combination of cover
thickness and dimple configuration.
[0050] The present invention is also directed to processes and
apparatuses for forming golf balls with deep dimples by utilizing
one or more specifically tailored "knock-out" pins that serve to
support the core or ball assembly during molding. The pins also
assist in removing the ball from the mold and in forming deep
dimples in the mold ball. The pins are also preferably used in
combination with other features in the mold to form deep dimples in
the resulting ball.
[0051] As explained in greater detail herein, the present invention
also relates to equipment and methods for forming one or more "deep
dimples." These deep dimples have depths greater than other dimples
on a ball. Preferably, such deep dimples extend through at least
one cover layer to, and/or into, or essentially to, the underlying
surface or component or layer.
[0052] With regard to dimple configuration or cross-sectional
geometry, the present invention is based upon the identification of
various particularly preferred characteristics as follows.
Typically, for circular dimples, dimple diameter is used in
characterizing dimple size rather than dimple circumference. The
diameter of typical dimples may range from about 0.050 inches to
about 0.250 inches. A preferred diameter of a typical dimple is
about 0.150 inches. The deep dimples may have these same dimensions
or may have dimensions as described in greater detail herein. As
will be appreciated, circumference of a dimple can be calculated by
multiplying the diameter times .pi..
[0053] The depth of typical dimples previously utilized in the
trade may range from about 0.002 inches to about 0.020 inches, or
as much as 0.050 inches. Preferably, a depth of about 0.010 inches
is preferred for typical or conventional dimples. It is preferred
that the depth of a deep dimple as described herein is greater than
the depth of a typical dimple. Most preferably, the deep dimples
have a depth that is deeper than the depth of the typical dimples
by at least 0.002 inches.
[0054] Specifically, depth of a dimple may be defined in at least
two fashions. A first approach is to extend a chord from one side
of a dimple to another side and then measure the maximum distance
from that chord to the bottom of the dimple. This is referred to
herein as a chordal depth. Alternatively, another approach is to
extend an imaginary line corresponding to the curvature of the
outer surface of the ball over the dimple whose depth is to be
measured. Then, the distance from that imaginary line to a bottom
most point in the dimple is measured. This is referred to herein as
a "periphery depth." The latter format of dimple depth
determination is used herein unless noted otherwise.
[0055] As described herein, the deep dimples included in the
present invention are particularly useful when molding certain
layers or components about cores or intermediate ball assemblies.
The deep dimples result from providing one or more protrusions or
projections on the surfaces of the molding chamber, that also
serves to support and properly position a golf ball core or
intermediate ball assembly during molding. The depth of a deep
dimple as described herein may range from about 0.002 inches to
about 0.140 inches, more preferably from about 0.002 inches to
about 0.050 inches, and more preferably from about 0.005 inches to
about 0.040 inches. Preferably, a total depth of about 0.025 inches
is desired. Greater or lesser depths for the deep dimples may be
utilized. It is most preferred that the depth of a deep dimple as
described herein is greater than the depth of a typical dimple, and
extend to at least the outermost region of the mantle or core.
Alternatively, the deep dimples preferably extend to the bottom of
a matched set of dimples on the mantle or the core. The diameter of
the deep dimples may be dissimilar, but preferably is the same as
other dimples on a ball, and may range from about 0.025 inches to
about 0.250 inches, and more preferably from about 0.050 inches to
about 0.200 inches. A preferred diameter is about 0.150 inches.
Generally, periphery depth is measured from the outer surface of a
finished ball, unless stated otherwise.
[0056] In one embodiment, the present invention relates to an
apparatus and technique for forming a golf ball comprising a core
and a cover layer, wherein the cover layer provides dimples
including one or more deep dimples that extend into the next inner
layer or component. The cover may be a single layer or comprise
multiple layers, such as two, three, four, five or more layers and
the like. If the cover is a multi-layer cover, the dimples extend
into at least the first inner cover layer, and may extend into a
further inner cover layer, a mantle or intermediate layer, and/or
the core. If the cover is a single layer, the deep dimples may
extend into a mantle layer and/or the core. The cover layer(s) may
be formed from any material suitable for use as a cover, including,
but not limited to, ionomers, non-ionomers and blends of ionomers
and non-ionomers.
[0057] In another embodiment, the present invention relates to an
apparatus and technique for forming a golf ball comprising a core
and a cover layer, wherein the cover layer provides dimples that
extend to the core. The golf ball may optionally comprise a thin
barrier coating between the core and the cover that limits the
transition of moisture to the core. The barrier coating is
preferably at least about 0.0001 inches thick. Preferably, the
barrier layer is at least 0.003 inches thick. In a two-piece golf
ball, a barrier coating is preferably provided between the core and
the cover.
[0058] In a further embodiment, the present invention relates to
equipment and processes for forming a golf ball having a plurality
of dimples along its outer surface. In accordance with the present
invention, one or more of these dimples are deep dimples that
extend entirely through the cover layer of the ball, and into one
or more underlying components or layers of the ball. For instance,
for a golf ball comprising a core and a cover layer disposed about
the core, the deep dimples preferably extend through the cover
layer and into the core. The core or mantle layer may be "dimpled"
such that the dimples on the core or mantle match up with and
accept the deep dimples from the mold. If one or more layers such
as an intermediate mantle layer are provided between the core and
the cover layer, the deep dimples preferably extend through the
cover layer and into one or more of those layers. The deep dimples
may additionally extend into the core.
[0059] Specifically, in yet another aspect, the present invention
provides a process for forming a cover layer for a golf ball
comprising the steps of providing an intermediate ball comprising
at least a core. The process also includes a step of providing a
molding apparatus having a generally spherical molding chamber with
a molding surface defined by (i) a first collection of raised
regions for forming a collection of dimples on the cover layer, and
(ii) a second collection of raised regions, each extending beyond
the first collection of raised regions for concentrically
positioning an object within the molding chamber. The molding
apparatus also includes an assembly for administering a flowable
material into the molding chamber. The process additionally
includes a step of providing a flowable material suitable for use
as the cover layer for the golf ball. The process also includes a
step of positioning the intermediate ball within the molding
chamber such that the second collection of raised regions of the
molding surface contact and retain the intermediate ball within the
molding chamber. This process also includes a step of administering
the flowable material into the molding chamber and generally
between the intermediate ball and the molding surface.
[0060] In yet another aspect, the present invention provides a
process for forming a layer on a golf ball core. The method
comprises the steps of providing a golf ball core and providing a
flowable material adapted for forming the layer on the golf ball
core. The process also includes a step of providing a mold
including (i) a generally spherical molding chamber having an outer
surface including a collection of raised protrusions that form a
plurality of dimples in the layer, and (ii) provisions for
introducing the flowable material into the molding chamber. The
process also includes a step of concentrically positioning the golf
ball core in the molding chamber such that the collection of raised
protrusions contact the golf ball core. The process also includes a
step of introducing the flowable material into the molding chamber
such that the flowable material flows between the golf ball core
and the outer surface of the molding chamber to thereby form the
layer.
[0061] In still a further aspect, the present invention provides a
process for forming a golf ball having at least one dimple that
extends through an outer layer of the golf ball. The process
comprises providing an intermediate golf ball assembly and
providing a molding apparatus. The molding apparatus includes a
generally spherical molding chamber having a first population of
raised regions for forming a plurality of dimples on an outer layer
of the golf ball. The molding chamber also includes at least one
other raised region having a height that is greater than or equal
to the thickness of the outer layer of the golf ball. The process
additionally includes a step of positioning the intermediate golf
ball assembly in the molding chamber. The process further includes
a step of administering to the molding apparatus a flowable
material adapted to form the outer layer of the golf ball.
[0062] FIGS. 1 and 2 illustrate a preferred embodiment golf ball in
accordance with the present invention. Specifically, FIGS. 1 and 2
illustrate a golf ball 10 comprising a core 20 having a cover layer
30 formed about the core. The cover layer 30 defines a plurality of
dimples 40 along its outer surface 35. One or more of the dimples,
and preferably two or more of the dimples, extend into the core 20
disposed underneath the cover layer 30. These dimples are herein
referred to as deep dimples and shown in the figures as dimples
42.
[0063] FIGS. 3 and 4 illustrate another preferred embodiment golf
ball 110 in accordance with the present invention. The golf ball
110 comprises a core 120 having an inner cover layer 150 disposed
thereon and an outer cover layer 160 formed about the inner cover
layer 150. The cover layers 160 and 150 define a plurality of
dimples 140 along the outer surface of the outer cover layer 160.
One or more of the dimples, and preferably two or more of the
dimples, and more preferably three or more of the dimples per
hemisphere, extend entirely through the outer cover layer 160 and
at least partially into the inner cover layer 150. These dimples,
which extend through the outer cover layer, are again referred to
herein as deep dimples and shown in the figures as dimples 142.
[0064] FIG. 11 illustrates a partial cross section of a golf ball
810 defining a deep dimple 850 formed in an outer cover layer 820
disposed on a mantle layer 830 that in turn is disposed on a core
840. The deep dimple 850 has a common curvature. Alternatively, the
deep dimples may be defined by regions of different curvature or
shape. That is, a deep dimple according to the present invention
may include one or more dimples defined within its interior. This
is described in greater detail below.
[0065] The deep dimples, when viewed in a planar view, can be
circular, non-circular, a combination of circular and non-circular,
or any other shape desired. They may be of the same or differing
shape, such as a circular larger dimple having an oval smaller
dimple within the circular dimple, or an oval larger dimple having
a circular or other shape within the larger dimple. The dimples do
not have to be symmetrical. Generally, the deep dimples of the
present invention may be spherical or non-spherical. Additionally,
the portion of the deep dimple that extends to, or into the next
inner layer or component may be the same or different size and/or
shape as the outer portion of the dimple.
[0066] Providing deep dimples formed in multiple layers allows the
dimple depth to be distributed over two or more layers. FIG. 12
illustrates dimples 940 formed in both the inner cover layer and
the outer cover layer. The inner portion of the dimple 946 is
formed in the inner cover layer, and the outer portion of the
dimple 948 is formed in the outer cover layer. For a two-piece
ball, dimples may be formed in the core and the single cover layer
in the same way as previously described. Additionally, dimples may
be formed in more than two cover and/or core layers if desired.
[0067] In another preferred embodiment, a multi-layer golf ball is
produced that has one or more deep dimples that extend into the
ball through at least one layer, such as an outer cover layer. In a
further preferred embodiment, the deep dimple extends through at
least two layers. The dimples of the at least two layers are
configured with the same geometric coordinates (that is, the
approximate center of the both dimples would be in the same
location, and so the dimples are concentric with respect to each
other), producing a golf ball having a dimpled layer over a dimpled
layer. This allows for much thinner layers with traditional
dimples. The dimples of one or more inner layers may be of varying
depths, diameters and radii, yet still aligned with the dimples of
the outer layer. This also allows for a dimple within a dimple,
where there is a smaller dimple in at least one inner or mantle
layer that is within a larger diameter dimple in the outer layer,
such as the dimples shown in FIGS. 5 to 8.
[0068] FIGS. 5 to 8 illustrate a deep dimple that is a dual radius
dimple, or a dimple within a dimple. One advantage of a dual radius
dimple is that the deeper part of the dual radius may be filled in
with a coating or other material. This provides an effective method
for forming dimple depths to a desired value as compared to other
methods of dimple formation. The dimple shape may be any shape
desired, and each dimple may be the same or different shape. The
shape of a dimple or region thereof is given when viewed in a
direction extending along a diameter of the golf ball. The
respective regions of the dual region dimples may be in a variety
of different (or the same) shapes such as circular, elliptical,
oval, square, triangular, and polygonal. Preferably, the depth of
the second or deepest portion of the dual radius dimple may be
expressed as a percentage of the total depth of the dimple.
Specifically, the region or portion of the dimple that extends to
the outermost surface of the ball may be referred to herein as the
"major" dimple. And, likewise, the portion of the dimple that
extends to the deepest portion or depth of the dimple can be
referred to herein as the "minor" dimple. Accordingly, the
preferred depth of the major dimple is approximately from about 40%
to about 80% of the overall dimple depth. Accordingly, the
preferred depth of the minor dimple is approximately 20% to about
60% of the overall dimple depth. The overall dimple depth is
measured from a point along an outermost region of a phantom sphere
extending within the region, or slightly above the region of, the
outermost portion of the dimple to the bottom most portion of the
dimple. With regard to diameters, the preferred diameter of the
minor dimple is from about 10% to about 70% of the diameter of the
major dimple.
[0069] FIG. 5 is a cross-sectional detail illustrating a portion of
a preferred embodiment golf ball produced in accordance with the
present invention. This preferred embodiment golf ball 210
comprises a core 220 having a cover layer 230 formed thereon. The
cover layer defines at least one deep dimple 240 along its outer
surface 235. As described in conjunction with FIGS. 1 and 2, it is
preferred that one or more (preferably two or more, more preferably
three or more per hemisphere) of the dimples extends entirely
through the cover layer and into the core disposed underneath the
cover layer. FIG. 5 illustrates a deep dimple defined by two
different curvatures. Referring to FIG. 5, a first radius R.sub.1
defines the portion of the dimple from the outer surface 235 of the
golf ball 210 to a point at which the deep dimple extends into a
layer underneath the cover layer. At this point, the curvature of
the dimple changes and is defined by radius R.sub.2. Preferably,
R.sub.1, is from about 0.130 inches to about 0.190 inches, and most
preferably, R.sub.1, is from about 0.140 to about 0.180 inches. For
some embodiments, R.sub.1 ranges from about 0.100 inches to about
1.000 inch, and most preferably from about 0.200 inches to about
0.800 inches. Preferably, R.sub.2 is from about 0.025 inches to
about 0.075 inches, and most preferably, R.sub.2 is about 0.050
inches to about 0.065 inches. For some embodiments, R.sub.2 ranges
from about 0.002 inches to about 0.50 inches, and most preferably
from about 0.010 inches to about 0.200 inches. The overall diameter
or span, generally referred to as the "chordal diameter," of the
dimple 240 is designated herein as D.sub.1. The diameter or span of
the portion of the dimple that extends into the layer underneath
the outer cover layer is designated herein as D.sub.2. Preferably,
D.sub.1 is from about 0.030 inches to about 0.250 inches, more
preferably from about 0.100 inches to about 0.186 inches, and most
preferably, D.sub.1 is about 0.146 inches to about 0.168 inches.
For some embodiments, D.sub.1 ranges from about 0.100 inches to
about 0.250 inches, and most preferably D.sub.1 is about 0.140
inches to about 0.180 inches. Preferably D.sub.2 is from about
0.020 inches to about 0.160 inches, more preferably from about
0.030 inches to about 0.080 inches and most preferably, D.sub.2 is
about 0.056 inches. For some embodiments, D.sub.2 is from about
0.040 inches to about 0.060 inches. Accordingly, the overall depth
of the deep dimple portion that is defined by R.sub.1 is designated
herein as HI and the depth or portion of the dimple that is defined
by R.sub.2 is designated herein as H.sub.2. Preferably, H.sub.1 is
from about 0.005 inches to about 0.135 inches, more preferably from
about 0.005 inches to about 0.025 inches, more preferably from
about 0.010 inches to about 0.015 inches, and most preferably,
H.sub.1 is about 0.015 inches. For some embodiments, H.sub.1 is
from about 0.005 inches to about 0.015 inches. H.sub.2 may range
from about 0.005 inches to about 0.135 inches, and more preferably
from about 0.005 to about 0.050 inches. Preferably, H.sub.2 ranges
from about 0.005 inches to about 0.030 inches and is about 0.010
inches. For some embodiments H.sub.2 is from about 0.005 inches to
about 0.015 inches.
[0070] Referring to. FIG. 6, another preferred embodiment golf ball
310 is illustrated. In this version of the present invention, a
golf ball 310 comprises a core 320 and a cover layer 330 formed
thereon. The cover layer 330 defines at least one deep dimple 340
along the outer surface 335 of the golf ball 310. As can be seen,
the dimple 340 is defined by two different curvatures, each of
which is defined by radii R.sub.2 and R.sub.1 as previously
described with respect to FIG. 5. The other parameters D.sub.1,
D.sub.2, H.sub.1, and H.sub.2 are as described with respect to FIG.
5. FIG. 6 illustrates an embodiment in which the dimple 340 extends
to the core 320 and not significantly into the core. In contrast,
the version illustrated in FIG. 5 is directed to a dimple
configuration in which a dimple extends significantly into the
underlying core.
[0071] FIG. 7 illustrates a preferred embodiment golf ball 410
comprising a core 420, a mantle or inner cover layer 450, and an
outer cover layer 460. The outer cover layer 460 defines at least
one deep dimple 440 along the outer surface 435 of the ball 410.
The dimple 440 is defined by two different regions or two
curvatures, each of which is in turn defined by radii R.sub.2 and
R.sub.1. The other parameters D.sub.1, D.sub.2, H.sub.1, and
H.sub.2 are as described with respect to FIG. 5. As can be seen in
FIG. 7, the dimple 440 extends entirely through the outer cover
layer 460 and into the inner cover layer or mantle layer 450.
[0072] FIG. 8 illustrates another preferred embodiment golf ball
510 in accordance with the present invention. The golf ball 510
comprises a core 520 having disposed thereon an inner cover layer
or mantle layer 550 and an outer cover layer 560. Defined along the
perimeter or outer periphery of the ball 510 is at least one deep
dimple 540. The dimple 540 is defined along the outer surface 535
of the ball 510. The dimple 540 has two different regions or
curvatures each defined by radii R.sub.2 and R.sub.1 The other
parameters D.sub.1, D.sub.2, H.sub.1, and H.sub.2 are as described
with respect to FIG. 5. The version illustrated in FIG. 8 reveals a
dimple 540 that does not significantly extend into the mantle layer
or inner cover layer 550. Instead, the dimple 540 only extends to
the outermost region of the mantle layer or inner cover layer
550.
[0073] In the various dual-radius dimples, dual region dimples, or
dimples-within-dimples described herein, the present invention
includes filling either or both of the regions with various
materials. The filler materials are preferably different than cover
materials, but may include such. Preferably, the filler materials
incorporate one or more coloring agents.
[0074] An important characteristic of dimple configuration is the
volume ratio. The volume ratio is the sum of the volume of all
dimples taken below a chord extending across the top of a dimple,
divided by the total volume of the ball. The volume ratio is a
critical parameter for ball flight. A high volume ratio generally
results in a low flying ball. And a low volume ratio often results
in a high-flying ball. A preferred volume ratio is about 1%. The
balls of the present invention however may be configured with
greater or lesser volume ratios.
[0075] The number and/or layout of dimples will not necessarily
change the coverage, i.e. surface area. A typical coverage for a
ball of the present invention is about 60% to about 90% and
preferably about 83.8%. In other embodiments this preferred
coverage is about 84% to about 85%. These percentages are the
percent of surface area of the ball occupied by dimples. It will be
appreciated that the present invention golf balls may exhibit
coverages greater or less than that amount.
[0076] For configurations utilizing dimples having two or more
regions of different curvature, i.e. dimple within a dimple, there
is less impact on the volume ratio than the use of deep dimples. If
there are enough of either dimples within dimples or deep dimples,
the aerodynamics of the ball will eventually be impacted.
[0077] The optimum or preferred number of deep dimples utilized per
ball varies. It is the amount necessary to secure or center the
core or intermediate ball during molding without adversely
affecting the aerodynamics of the finished ball. However, the
present invention includes the use of a relatively large number of
deep dimples. That is, although most of the focus of the present
invention is directed to the use of only a few deep dimples per
golf ball, i.e. from 1 to 10, preferably 1 to 8, more preferably 1
to 6, the invention includes the use of a significantly greater
number such as from about 50 to about 250. It is also contemplated
that for some applications, it may be desirable to form all, or
nearly all, dimples on a golf ball as deep dimples, such as for
example, from about 50 to about 500.
[0078] In general, as dimples are made deeper, the ball will fly
lower as compared to the use of dimples that are shallower. As the
number of deep dimples increases, the ball will exhibit a lower
flight trajectory. Accordingly, the preferred approach is to
utilize a small number of deep dimples. However, for other
applications, the present invention includes a ball with many deep
dimples.
[0079] During molding, deep dimples can extend into the core or
mantle. Generally, the deep dimples (or rather, the protrusions
that extend from the molding surface that form the deep dimples and
which are described in greater detail herein) will extend into, to,
or substantially to the core from the molding cavity and contact or
extend to or near the core. But, the core will rebound back to its
original shape to some extent so that the volume of the dimple at
the point of contact is less than would otherwise be expected. This
is explained in greater detail below.
[0080] The overall shape of the dimples, including deep dimples,
may be nearly any shape. For example, shapes such as hexagon,
pentagon, triangle, ellipse, circle, etc. are all suitable. There
is no limit to the number of shapes, although some shapes are
preferred over others. At present, circular dimples are preferred.
As for the cross-sectional configuration, the dimples may utilize
any geometry. For instance, dimples may be defined by a constant
curvature or a multiple curvature or dual radius configuration or
an elliptical or teardrop shaped region.
[0081] Cover Layer(s)
[0082] The cover comprises at least one layer. For a multi-layer
cover, the cover comprises at least two layers, and it may comprise
any number of layers desired, such as two, three, four, five, six
and the like. A two-piece cover comprises a first or inner layer or
ply (also referred to as a mantle layer) and a second or outer
layer or ply. The inner layer can be ionomer, ionomer blends,
non-ionomer, non-ionomer blends, or blends of ionomer and
non-ionomer. The outer layer can be ionomer, ionomer blends,
non-ionomer, non-ionomer blends, or blends of ionomer and
non-ionomer, and may be of the same or different material as the
inner cover layer. For multi-layer covers having three or more
layers, each layer can be ionomer, non-ionomer, or blends thereof,
and the layers may be of the same or different materials.
[0083] In one preferred embodiment of a golf ball, the inner layer
or single cover layer is comprised of a high acid (i.e. greater
than 16 weight percent acid) ionomer resin or high acid ionomer
blend. More preferably, the inner layer is comprised of a blend of
two or more high acid (i.e. greater than 16 weight percent acid)
ionomer resins neutralized to various extents by different metal
cations. The inner cover layer may or may not include a metal
stearate (e.g., zinc stearate) or other metal fatty acid salt. The
purpose of the metal stearate or other metal fatty acid salt is to
lower the cost of production without affecting the overall
performance of the finished golf ball.
[0084] In a further embodiment, the inner layer or single cover
layer is comprised of a low acid (i.e. 16 weight percent acid or
less) ionomer resin or low acid ionomer blend. Preferably, the
inner layer or single layer is comprised of a blend of two or more
low acid (i.e. 16 weight percent acid or less) ionomer resins
neutralized to various extents by different metal cations. As with
the high acid inner cover layer embodied, the inner cover layer may
or may not include a metal stearate (e.g., zinc stearate) or other
metal fatty acid salt.
[0085] In golf balls having a multi-layer cover, it has been found
that a hard inner layer(s) provides for a substantial increase in
resilience (i.e., enhanced distance) over known multi-layer covered
balls. A softer outer layer (or layers) provides for desirable
"feel" and high spin rate while maintaining respectable resiliency.
The soft outer layer allows the cover to deform more during impact
and increases the area of contact between the club face and the
cover, thereby imparting more spin on the ball. As a result, the
soft cover provides the ball with a balata-like feel and
playability characteristics with improved distance and durability.
Consequently, the overall combination of the inner and outer cover
layers results in a golf ball having enhanced resilience (improved
travel distance) and durability (i.e. cut resistance, etc.)
characteristics while maintaining and in many instances, improving,
the playability properties of the ball.
[0086] The combination of a hard inner cover layer with a soft
outer cover layer provides for excellent overall coefficient of
restitution (for example, excellent resilience) because of the
improved resiliency produced by the inner cover layer. While some
improvement in resiliency is also produced by the outer cover
layer, the outer cover layer generally provides for a more
desirable feel and high spin, particularly at lower swing speeds
with highly lofted clubs such as half wedge shots.
[0087] In one preferred embodiment, the inner cover layer may be
harder than the outer cover layer and generally has a thickness in
the range of 0.0005 to 0.15 inches, preferably 0.001 to 0.10 inches
for a 1.68 inch ball, and sometimes slightly thicker for a 1.72
inch (or more) ball. The core and inner cover layer (if applicable)
together preferably form an inner ball having a coefficient of
restitution of 0.780 or more and more preferably 0.790 or more, and
a diameter in the range of 1.48 to 1.66 inches for a 1.68 inch ball
and 1.50 to 1.70 inches for a 1.72 inch (or more) ball.
[0088] The inner cover layer preferably has a Shore D hardness of
60 or more (or at least 90 Shore C). It is particularly
advantageous if the golf balls of the invention have an inner layer
with a Shore D hardness of 65 or more (or at least 100Shore C).
These measurements are made in general accordance to ASTM 2240
except that they are made on the ball itself and not on a plaque.
If the inner layer is too soft or thin, it is sometimes difficult
to measure the Shore D of the inner layer as the layer may puncture
during measurement. In such circumstances, an alternative Shore C
measurement should be utilized. Additionally, if the core (or inner
layer) is harder than the layer being measured, this will sometimes
influence the reading.
[0089] Moreover, if the Shore C or Shore D is measured on a plaque
of material, different values than those measured on the ball will
result. Consequently, when a Shore hardness measurement is
referenced to herein, it is based on a measurement made on the
ball, except if specific reference is made to plaque
measurements.
[0090] The above-described characteristics of the inner cover layer
provide an inner ball having a PGA compression of 100 or less. It
is found that when the inner ball has a PGA compression of 90 or
less, excellent playability results.
[0091] The inner layer compositions of the embodiments described
herein may include the high acid ionomers such as those developed
by E.I. DuPont de Nemours & Company under the trademark
Surlyn.RTM. and by Exxon Corporation under the trademarks
Escor.RTM. or lotek.RTM., or blends thereof. Examples of
compositions which may be used as the inner layer herein are set
forth in detail in U.S. Pat. No. 5,688,869, which is incorporated
herein by reference. Of course, the inner layer high acid ionomer
compositions are not limited in any way to those compositions set
forth in said patent. Those compositions are incorporated herein by
way of examples only.
[0092] The high acid ionomers which may be suitable for use in
formulating the inner layer compositions are ionic copolymers which
are the metal (such as sodium, zinc, magnesium, etc.) salts of the
reaction product of an olefin having from about 2 to 8 carbon atoms
and an unsaturated monocarboxylic acid having from about 3 to 8
carbon atoms. Preferably, the ionomeric resins are copolymers of
ethylene and either acrylic or methacrylic acid. In some
circumstances, an additional comonomer such as an acrylate ester
(for example, iso- or n-butylacrylate, etc.) can also be included
to produce a softer terpolymer. The carboxylic acid groups of the
copolymer are partially neutralized (for example, approximately
10-100%, preferably 30-70%) by the metal ions. Each of the high
acid ionomer resins which may be included in the inner layer cover
compositions of the invention contains greater than 16% by weight
of a carboxylic acid, preferably from about 17% to about 25% by
weight of a carboxylic acid, more preferably from about 18.5% to
about 21.5% by weight of a carboxylic acid.
[0093] The high acid ionomeric resins available from Exxon under
the designation Escor.RTM. or lotek.RTM., are somewhat similar to
the high acid ionomeric resins available under the Surlyn.RTM.
trademark. However, since the Escor.RTM./lotek.RTM. ionomeric
resins are sodium, zinc, etc. salts of poly(ethylene-acrylic acid)
and the Surlyn.RTM. resins are zinc, sodium, magnesium, etc. salts
of poly(ethylene-methacrylic acid), distinct differences in
properties exist. It is also contemplated to utilize commercially
available resins that have been modified with ethylene/acrylic acid
resins for example.
[0094] Examples of the high acid methacrylic acid based ionomers
found suitable for use in accordance with this invention include,
but are not limited to, Surlyn.RTM. 8220 and 8240 (both formerly
known as forms of Surlyn.RTM. AD-8422), Surlyn.RTM. 9220 (zinc
cation), Surlyn.RTM. SEP-503-1 (zinc cation), and Surlyn.RTM.
SEP-503-2 (magnesium cation). Another high acid ionomer that may be
suitable is Surlyn.RTM. Another high acid ionomer that may be
suitable is Surlyn.RTM. S6120. According to DuPont, all of these
ionomers contain from about 18.5 to about 21.5% by weight
methacrylic acid.
[0095] Examples of the high acid acrylic acid based ionomers
suitable for use in the present invention also include, but are not
limited to, the Escor.RTM. or lotek.RTM. high acid ethylene acrylic
acid ionomers produced by Exxon such as Ex 1001, 1002, 959, 960,
989, 990, 1003, 1004, 993, and 994. In this regard, Escor.RTM. or
lotek.RTM. 959 is a sodium ion neutralized ethylene-acrylic
neutralized ethylene-acrylic acid copolymer. According to Exxon,
loteks.RTM. 959 and 960 contain from about 19.0 to about 21.0% by
weight acrylic acid with approximately 30 to about 70 percent of
the acid groups neutralized with sodium and zinc ions,
respectively.
[0096] Furthermore, as a result of the previous development by the
assignee of this application of a number of high acid ionomers
neutralized to various extents by several different types of metal
cations, such as by manganese, lithium, potassium, calcium and
nickel cations, several high acid ionomers and/or high acid ionomer
blends besides sodium, zinc and magnesium high acid ionomers or
ionomer blends are also available for golf ball cover production.
It has been found that these additional cation neutralized high
acid ionomer blends produce inner cover layer compositions
exhibiting enhanced hardness and resilience due to synergies that
occur during processing. Consequently, these metal cation
neutralized high acid ionomer resins can be blended to produce
substantially higher C.O.R.'s than those produced by the low acid
ionomer inner cover compositions presently commercially
available.
[0097] More particularly, several metal cation neutralized high
acid ionomer resins have been produced by the assignee of this
invention by neutralizing, to various extents, high acid copolymers
of an alpha-olefin and an alpha, beta-unsaturated carboxylic acid
with a wide variety of different metal cation salts. This discovery
is the subject matter of U.S. Pat. No. 5,688,869, incorporated
herein by reference. It has been found that numerous metal cation
neutralized high acid ionomer resins can be obtained by reacting a
high acid copolymer (i.e. a copolymer containing greater than 16%
by weight acid, preferably from about 17 to about 25 weight percent
acid, and more preferably about 20 weight percent acid), with a
metal cation salt capable of ionizing or neutralizing the copolymer
to the extent desired (for example, from about 10% to 90%).
[0098] The base copolymer is made up of greater than 16% by weight
of an alpha, beta-unsaturated carboxylic acid and an alpha-olefin.
Optionally, a softening comonomer can be included in the copolymer.
Generally, the alpha-olefin has from 2 to 10 carbon atoms and is
preferably ethylene, and the unsaturated carboxylic acid is a
carboxylic acid having from about 3 to 8 carbons. Examples of such
acids include acrylic acid, methacrylic acid, ethacrylic acid,
chloroacrylic acid, crotonic acid, maleic acid, fumaric acid, and
itaconic acid, with acrylic acid being preferred.
[0099] The softening comonomer that can be optionally included in
the inner cover layer of the golf ball of the invention may be
selected from the group consisting of vinyl esters of aliphatic
carboxylic acids wherein the acids have 2 to 10 carbon atoms, vinyl
ethers wherein the alkyl groups contain 1 to 10 carbon atoms, and
alkyl acrylates or methacrylates wherein the alkyl group contains 1
to 10 carbon atoms. Suitable softening comonomers include vinyl
acetate, methyl acrylate, methyl methacrylate, ethyl acrylate,
ethyl methacrylate, butyl acrylate, butyl methacrylate, or the
like.
[0100] Consequently, examples of a number of copolymers suitable
for use to produce the high acid ionomers included in the present
invention include, but are not limited to, high acid embodiments of
an ethylene/acrylic acid copolymer, an ethylene/methacrylic acid
copolymer, an ethylene/itaconic acid copolymer, an ethylene/maleic
acid copolymer, an ethylene/methacrylic acid/vinyl acetate
copolymer, an ethylene/acrylic acid/vinyl alcohol copolymer, etc.
The base copolymer broadly contains greater than 16% by weight
unsaturated carboxylic acid, from about 39 to about 83% by weight
ethylene and from 0 to about 40% by weight of a softening
comonomer. Preferably, the copolymer contains about 20% by weight
unsaturated carboxylic acid and about 80% by weight ethylene. Most
preferably, the copolymer contains about 20% acrylic acid with the
remainder being ethylene.
[0101] Along these lines, examples of the preferred high acid base
copolymers which fulfill the criteria set forth above are a series
of ethylene-acrylic copolymers which are commercially available
from The Dow Chemical Company, Midland, Mich., under the
Primacor.RTM. designation.
[0102] The metal cation salts utilized in the invention are those
salts which provide the metal cations capable of neutralizing, to
various extents, the carboxylic acid groups of the high acid
copolymer. These include acetate, oxide or hydroxide salts of
lithium, calcium, zinc, sodium, potassium, nickel, magnesium, and
manganese.
[0103] Examples of such lithium ion sources are lithium hydroxide
monohydrate, lithium hydroxide, lithium oxide and lithium acetate.
Sources for the calcium ion include calcium hydroxide, calcium
acetate and calcium oxide. Suitable zinc ion sources are zinc
acetate dihydrate and zinc acetate, a blend of zinc oxide and
acetic acid. Examples of sodium ion sources are sodium hydroxide
and sodium acetate. Sources for the potassium ion include potassium
hydroxide and potassium acetate. Suitable nickel ion sources are
nickel acetate, nickel oxide and nickel hydroxide. Sources of
magnesium include magnesium oxide, magnesium hydroxide, and
magnesium acetate. Sources of manganese include manganese acetate
and manganese oxide.
[0104] The metal cation neutralized high acid ionomer resins are
produced by reacting the high acid base copolymer with various
amounts of the metal cation salts above the crystalline melting
point of the copolymer, such as at a temperature from about
200.degree. F. to about 500.degree. F., preferably from about
250.degree. F. to about 350.degree. F. under high shear conditions
at a pressure of from about 10 psi to 10,000 psi. Other well known
blending techniques may also be used. The amount of metal cation
salt utilized to produce the new metal cation neutralized high acid
based ionomer resins is the quantity which provides a sufficient
amount of the metal cations to neutralize the desired percentage of
the carboxylic acid groups in the high acid copolymer. The extent
of neutralization is generally from about 10% to about 90%.
[0105] A number of different types of metal cation neutralized high
acid ionomers can be obtained from the above indicated process.
These include high acid ionomer resins neutralized to various
extents with manganese, lithium, potassium, calcium and nickel
cations. In addition, when a high acid ethylene/acrylic acid
copolymer is utilized as the base copolymer component of the
invention and this component is subsequently neutralized to various
extents with the metal cation salts producing acrylic acid based
high acid ionomer resins neutralized with cations such as sodium,
potassium, lithium, zinc, magnesium, manganese, calcium and nickel,
several cation neutralized acrylic acid based high acid ionomer
resins are produced.
[0106] When compared to low acid versions of similar cation
neutralized ionomer resins, the metal cation neutralized high acid
ionomer resins exhibit enhanced hardness, modulus and resilience
characteristics. These are properties that are particularly
desirable in a number of thermoplastic fields, including the field
of golf ball manufacturing.
[0107] The low acid ionomers which may be suitable for use in
formulating the inner layer compositions of the subject invention
are ionic copolymers which are the metal (sodium, zinc, magnesium,
etc.) salts of the reaction product of an olefin having from about
2 to 8 carbon atoms and an unsaturated monocarboxylic acid having
from about 3 to 8 carbon atoms. Preferably, the ionomeric resins
are copolymers of ethylene and either acrylic or methacrylic acid.
In some circumstances, an additional comonomer such as an acrylate
ester (for example, iso- or n-butylacrylate, etc.) can also be
included to produce a softer terpolymer. The carboxylic acid groups
of the copolymer are partially neutralized (for example,
approximately 10 to 100%, preferably 30 to 70%) by the metal ions.
Each of the low acid ionomer resins which may be included in the
inner layer cover compositions of the invention contains 16% by
weight or less of a carboxylic acid.
[0108] The inner layer compositions may include the low acid
ionomers such as those developed and sold by E.I. DuPont de Nemours
& Company under the trademark Surlyn.RTM. and by Exxon
Corporation under the trademarks Escor.RTM. or lotek.RTM., ionomers
made in-situ, or blends thereof.
[0109] In one embodiment of the inner cover layer, a blend of high
and low acid ionomer resins is used. These can be the ionomer
resins described above, combined in a weight ratio which preferably
is within the range of 10 to 90 to 90 to 10 percent high and low
acid ionomer resins.
[0110] Another embodiment of the inner cover layer is a cover
comprising a non-ionomeric thermoplastic material or thermoset
material. Suitable non-ionomeric materials include, but are not
limited to, metallocene catalyzed polyolefins or polyamides,
polyamide/ionomer blends, polyphenylene ether/ionomer blends, etc.,
which have a Shore D hardness of at least 60 (or a Shore C hardness
of at least about 90) and a flex modulus of greater than about
30,000 psi, preferably greater than about 50,000 psi, or other
hardness and flex modulus values which are comparable to the
properties of the ionomers described above. Other suitable
materials include but are not limited to, thermoplastic or
thermosetting polyurethanes, thermoplastic block polyesters, for
example, a polyester elastomer such as that marketed by DuPont
under the trademark Hytrel.RTM., or thermoplastic block polyamides,
for example, a polyether amide such as that marketed by Elf Atochem
S.A. under the trademark Pebax.RTM., a blend of two or more
non-ionomeric thermoplastic elastomers, or a blend of one or more
ionomers and one or more non-ionomeric thermoplastic elastomers.
These materials can be blended with the ionomers described above in
order to reduce cost relative to the use of higher quantities of
ionomer. Although Hytrel.RTM. and Pebax.RTM. are sometimes more
expensive than certain ionomers, these materials typically have
higher densities than ionomers and have different resiliency
characteristics at low impacts, and so, may be desirable.
[0111] Additional materials suitable for use in the inner cover
layer or single cover layer of the present invention include
polyurethanes. These are described in more detail below.
[0112] Any number of inner layers may be used. Each layer may be
the same or different material as any other layer, and each may be
of the same or different thickness. One or more of the inner
layers, if applicable, may also be the same as the outer cover
layer.
[0113] A core with a hard inner cover layer formed thereon
generally provides the multi-layer golf ball with resilience and
distance. In one preferred embodiment, the outer cover layer is
comparatively softer than the inner cover layer. For a golf ball
having a single cover layer and a core, the cover layer may be a
soft cover layer, as described herein. The softness provides for
the feel and playability characteristics typically associated with
balata or balata-blend balls.
[0114] The soft outer cover layer or ply is comprised of a
relatively soft, low flex modulus (about 500 psi to about 50,000
psi, preferably about 1,000 psi to about 20,000 psi, and more
preferably about 5,000 psi to about 20,000 psi), preferably about
1,000 psi to about 20,000 psi, more preferably about 2,500 psi to
about 20,000) material or blend of materials. The outer cover layer
(or single cover layer, if applicable) comprises ionomers,
non-ionomers, blends of ionomers, blends of non-ionomers and blends
of ionomers and non-ionomers. Preferably, the outer cover layer
comprises a polyurethane, a polyurea, a blend of two or more
polyurethanes/polyureas, or a blend of one or more ionomers or one
or more non-ionomeric thermoplastic materials with a
polyurethane/polyurea, preferably a thermoplastic polyurethane or
reaction injection molded polyurethane/polyurea (described in more
detail below). The outer layer is 0.0005 to about 0.15 inches in
thickness, preferably about 0.001 to about 0.10 inches in
thickness, and sometimes slightly thicker for a 1.72 inch (or more)
ball, but thick enough to achieve desired playability
characteristics while minimizing expense. Thickness is defined as
the average thickness of the non-dimpled areas of the outer cover
layer. The outer cover layer preferably has a Shore D hardness of
60 or less (or less than 90 Shore C), and more preferably 55 or
less (or about 80 Shore C or less).
[0115] In another preferred embodiment, the outer cover layer is
comparatively harder than the inner cover layer. The outer layer is
comprised of a relatively hard, higher flex modulus (about 40,000
psi or greater) material or blend of materials. The inner cover
layer(s) may be a softer material such as a polyurethane or other
non-ionomer, or a blend of materials, and the outer layer may be a
harder material such as a harder ionomer, non-ionomer, or blend of
materials.
[0116] Moreover, in alternative embodiments, either the inner
and/or the outer cover layer (or single cover layer, if applicable)
may also additionally comprise up to 100 wt % of a soft, low
modulus, non-ionomeric thermoplastic or thermoset material.
Non-ionomeric materials are suitable so long as they produce the
playability and durability characteristics desired without
adversely affecting the properties of the cover layer(s). These
include, but are not limited to, styrene-butadiene-styrene block
copolymers, including functionalized styrene-butadiene-styrene
block copolymers, styrene-ethylene-butadiene-st- yrene (SEBS) block
copolymers such as Kraton.RTM. materials from Shell Chem. Co., and
functionalized SEBS block copolymers; metallocene catalyzed
polyolefins; ionomer/rubber blends such as those in Spalding U.S.
Pat. Nos. 4,986,545; 5,098,105 and 5,187,013; and, Hytrel.RTM.
polyester elastomers from DuPont and Pebax.RTM. polyetheramides
from Elf Atochem S.A.
[0117] The outer cover layer of the invention is formed over a core
(and inner cover layer or layers if a multi-layer cover) to result
in a golf ball having a coefficient of restitution of at least
0.770, more preferably at least 0.780, and most preferably at least
0.790. The coefficient of restitution of the ball will depend upon
the properties of both the core and the cover. The PGA compression
of the golf ball is 100 or less, and preferably is 90 or less.
[0118] In one preferred embodiment, the outer cover layer comprises
a polyurethane, a polyurea or a blend of polyurethanes/polyureas.
Polyurethanes are polymers that are used to form a broad range of
products. They are generally formed by mixing two primary
ingredients during processing. For the most commonly used
polyurethanes, the two primary ingredients are a polyisocyanate
(for example, diphenylmethane diisocyanate monomer ("MDI") and
toluene diisocyanate ("TDI") and their derivatives) and a polyol
(for example, a polyester polyol or a polyether polyol).
[0119] A wide range of combinations of polyisocyanates and polyols,
as well as other ingredients, are available. Furthermore, the
end-use properties of polyurethanes can be controlled by the type
of polyurethane utilized, such as whether the material is thermoset
(cross linked molecular structure not flowable with heat) or
thermoplastic (linear molecular structure flowable with heat).
[0120] Cross linking occurs between the isocyanate groups (--NCO)
and the polyol's hydroxyl end-groups (--OH). Additionally, the
end-use characteristics of polyurethanes can also be controlled by
different types of reactive chemicals and processing parameters.
For example, catalysts are utilized to control polymerization
rates. Depending upon the processing method, reaction rates can be
very quick (as in the case for some reaction injection molding
systems ("RIM")) or may be on the order of several hours or longer
(as in several coating systems such as a cast system).
Consequently, a great variety of polyurethanes are suitable for
different end-uses.
[0121] Polyurethanes are typically classified as thermosetting or
thermoplastic. A polyurethane becomes irreversibly "set" when a
polyurethane prepolymer is cross linked with a polyfunctional
curing agent, such as a polyamine or a polyol. The prepolymer
typically is made from polyether or polyester. A prepolymer is
typically an isocyanate terminated polymer that is produced by
reacting an isocyanate with a moiety that has active hydrogen
groups, such as a polyester and/or polyether polyol. The reactive
moiety is a hydroxyl group. Diisocyanate polyethers are preferred
because of their water resistance.
[0122] The physical properties of thermoset polyurethanes are
controlled substantially by the degree of cross linking and by the
hard and soft segment content. Tightly cross linked polyurethanes
are fairly rigid and strong. A lower amount of cross linking
results in materials that are flexible and resilient. Thermoplastic
polyurethanes have some cross linking, but primarily by physical
means such as hydrogen bonding. The crosslinking bonds can be
reversibly broken by increasing temperature, such as during molding
or extrusion. In this regard, thermoplastic polyurethanes can be
injection molded, and extruded as sheet and blow film. They can be
used up to about 400.degree. F. and are available in a wide range
of hardnesses.
[0123] Polyurethane materials suitable for the present invention
may be formed by the reaction of a polyisocyanate, a polyol, and
optionally one or more chain extenders. The polyol component
includes any suitable polyether- or polyester polyol. Additionally,
in an alternative embodiment, the polyol component is polybutadiene
diol. The chain extenders include, but are not limited, to diols,
triols and amine extenders. Any suitable polyisocyanate may be used
to form a polyurethane according to the present invention. The
polyisocyanate is preferably selected from the group of
diisocyanates including, but not limited, to 4,4'-diphenylmethane
diisocyanate ("MDI"); 2,4-toluene diisocyanate ("TDI"); m-xylylene
diisocyanate ("XDI"); 4,4'-methylenebis (cyclohexyl isocyanate)
(H.sub.12MDI); hexamethylene diisocyanate;
naphthalene-1,5,-diisocyanate ("NDI"); 3,3'-dimethyl-4,4'-biphenyl
diisocyanate; 1,4-diisocyanate benzene;
phenylene-1,4-diisocyanate("PPDI"- ); and 2,2,4- or 2,4,4-trimethyl
hexamethylene diisocyanate ("TMDI").
[0124] Other less preferred diisocyanates include, but are not
limited to, isophorone diisocyanate ("IPDI"); 1,4-cyclohexyl
diisocyanate ("CHDI"); diphenylether-4,4'-diisocyanate;
p,p'-diphenyl diisocyanate; lysine diisocyanate ("LDI"); 1,3-bis
(isocyanato methyl) cyclohexane; and polymethylene polyphenyl
isocyanate ("PMDI").
[0125] One additional polyurethane component that can be used in
the present invention incorporates TMXDI ("META") aliphatic
isocyanate (Cytec Industries, West Paterson, N.J.). Polyurethanes
based on meta-tetramethylxylylene diisocyanate (TMXDI) can provide
improved gloss retention UV light stability, thermal stability, and
hydrolytic stability. Additionally, TMXDI ("META") aliphatic
isocyanate has demonstrated favorable toxicological properties.
Furthermore, because it has a low viscosity, it is usable with a
wider range of diols (to polyurethane) and diamines (to polyureas).
If TMXDI is used, it typically, but not necessarily, is added as a
direct replacement for some or all of the other aliphatic
isocyanates in accordance with the suggestions of the supplier.
Because of slow reactivity of TMXDI, it may be useful or necessary
to use catalysts to have practical demolding times. Hardness,
tensile strength and elongation can be adjusted by adding further
materials in accordance with the supplier's instructions.
[0126] The polyurethane which is selected for use as a golf ball
cover preferably has a Shore D hardness (plaque) of from about 10
to about 55 (Shore C of about 15 to about 75), more preferably from
about 25 to about 55 (Shore C of about 40 to about 75), and most
preferably from about 30 to about 55 (Shore C of about 45 to about
75) for a soft cover layer and from about 20 to about 90,
preferably about 30 to about 80, and more preferably about 40 to
about 70 for a hard cover layer.
[0127] The polyurethane which is to be used for a cover layer
preferably has a flex modulus from about 1 to about 310 Kpsi, more
preferably from about 3 to about 100 Kpsi, and most preferably from
about 3 to about 40 Kpsi for a soft cover layer and 40 to 90 Kpsi
for a hard cover layer. Accordingly, covers comprising these
materials exhibit similar properties. The polyurethane preferably
has good light fastness.
[0128] Non-limiting examples of a polyurethane suitable for use in
the outer cover layer (or inner cover layer) include a
thermoplastic polyester polyurethane such as Bayer Corporation's
Texin.RTM. polyester polyurethane (such as Texin.RTM. DP7-1097 and
Texin.RTM. 285 grades) and a polyester polyurethane such as B.F.
Goodrich Company's Estane.RTM. polyester polyurethane (such as
Estane.RTM. X-4517 grade). The thermoplastic polyurethane material
may be blended with a soft ionomer or other non-ionomer. For
example, polyamides blend well with soft ionomer.
[0129] Other soft, relatively low modulus non-ionomeric
thermoplastic or thermoset polyurethanes may also be utilized to
produce the outer cover layers, or any of the inner cover layers,
as long as the non-ionomeric materials produce the playability and
durability characteristics desired without adversely affecting the
enhanced travel distance characteristic produced by the high acid
ionomer resin composition. These include, but are not limited to
thermoplastic polyurethanes such as the Pellethane.RTM.
thermoplastic polyurethanes from Dow Chemical Co.; and
non-ionomeric thermoset polyurethanes including but not limited to
those disclosed in U.S. Pat. No. 5,334,673, incorporated herein by
reference.
[0130] Typically, there are two classes of thermoplastic
polyurethane materials: aliphatic polyurethanes and aromatic
polyurethanes. The aliphatic materials are produced from a polyol
or polyols and aliphatic isocyanates, such as H.sub.12MDI or HDI,
and the aromatic materials are produced from a polyol or polyols
and aromatic isocyanates, such as MDI or TDI. The thermoplastic
polyurethanes may also be produced from a blend of both aliphatic
and aromatic materials, such as a blend of HDI and TDI with a
polyol or polyols.
[0131] Generally, the aliphatic thermoplastic polyurethanes are
lightfast, meaning that they do not yellow appreciably upon
exposure to ultraviolet light. Conversely, aromatic thermoplastic
polyurethanes tend to yellow upon exposure to ultraviolet light.
One method of stopping the yellowing of the aromatic materials is
to paint the outer surface of the finished ball with a coating
containing a pigment, such as titanium dioxide, so that the
ultraviolet light is prevented from reaching the surface of the
ball. Another method is to add UV absorbers, optical brighteners
and stabilizers to the clear coating(s) on the outer cover, as well
as to the thermoplastic polyurethane material itself. By adding UV
absorbers and stabilizers to the thermoplastic polyurethane and the
coating(s), aromatic polyurethanes can be effectively used in the
outer cover layer of golf balls. This is advantageous because
aromatic polyurethanes typically have better scuff resistance
characteristics than aliphatic polyurethanes, and the aromatic
polyurethanes typically cost less than the aliphatic
polyurethanes.
[0132] Other suitable polyurethane materials for use in the present
invention golf balls include reaction injection molded ("RIM")
polyurethanes. RIM is a process by which highly reactive liquids
are injected into a closed mold, mixed usually by impingement
and/or mechanical mixing in an in-line device such as a "peanut
mixer," where they polymerize primarily in the mold to form a
coherent, one-piece molded article. The RIM process usually
involves a rapid reaction between one or more reactive components
such as a polyether polyol or polyester polyol, polyamine, or other
material with an active hydrogen, and one or more
isocyanate-containing constituents, often in the presence of a
catalyst.
[0133] The constituents are stored in separate tanks prior to
molding and may be first mixed in a mix head upstream of a mold and
then injected into the mold. The liquid streams are metered in the
desired weight to weight ratio and fed into an impingement mix
head, with mixing occurring under high pressure, for example, 1,500
to 3,000 psi. The liquid streams impinge upon each other in the
mixing chamber of the mix head and the mixture is injected into the
mold. One of the liquid streams typically contains a catalyst for
the reaction. The constituents react rapidly after mixing to gel
and form polyurethane polymers. Polyureas, epoxies, and various
unsaturated polyesters also can be molded by RIM.
[0134] Non-limiting examples of suitable RIM systems for use in the
present invention are Bayflex.RTM. elastomeric polyurethane RIM
systems, Baydur.RTM. GS solid polyurethane RIM systems, Prism.RTM.
solid polyurethane RIM systems, all from Bayer Corp. (Pittsburgh,
Pa.), Spectrim.RTM. reaction moldable polyurethane and polyurea
systems from Dow Chemical USA (Midland, Mich.), including
Spectrim.RTM. MM 373-A (isocyanate) and 373-B (polyol), and
Elastolit.RTM. SR systems from BASF (Parsippany, N.J.). Preferred
RIM systems include Bayflexe MP-10000, Bayflexe MP-7500, MP-5000
and Bayflex.RTM. 110-50, filled and unfilled. Further preferred
examples are polyols, polyamines and isocyanates formed by
processes for recycling polyurethanes and polyureas. Additionally,
these various systems may be modified by incorporating a butadiene
component in the diol agent.
[0135] Another preferred embodiment is a golf ball in which at
least one of the inner cover layer and/or the outer cover layer
comprises a fast-chemical-reaction-produced component. This
component comprises at least one material selected from the group
consisting of polyurethane, polyurea, polyurethane ionomer, epoxy,
and unsaturated polyesters, and preferably comprises polyurethane,
polyurea or a blend comprising polyurethanes and/or polymers. A
particularly preferred form of the invention is a golf ball with a
cover comprising polyurethane or a polyurethane blend.
[0136] The polyol component typically contains additives, such as
stabilizers, flow modifiers, catalysts, combustion modifiers,
blowing agents, fillers, pigments, optical brighteners, and release
agents to modify physical characteristics of the cover.
Polyurethane/polyurea constituent molecules that were derived from
recycled polyurethane can be added in the polyol component.
[0137] A golf ball inner cover layer or single cover layer
according to the present invention formed from a polyurethane
material typically contains from about 0 to about 60 weight percent
of filler material, more preferably from about 1 to about 30 weight
percent, and most preferably from about 1 to about 20 weight
percent.
[0138] A golf ball outer cover layer according to the present
invention formed from a polyurethane material typically contains
from about 0 to about 20 weight percent of filler material, more
preferably from about 1 to about 10 weight percent, and most
preferably from about 1 to about 5 weight percent.
[0139] Additional materials may also be added to the inner and
outer cover layer of the present invention as long as they do not
substantially reduce the playability properties of the ball. Such
materials include dyes and/or optical brighteners (for example,
Ultramarine Blue.TM. sold by Whittaker, Clark, and Daniels of South
Plainsfield, N.J.) (see U.S. Pat. No. 4,679,795); pigments such as
titanium dioxide, zinc oxide, barium sulfate and zinc sulfate; UV
absorbers; antioxidants; antistatic agents; and stabilizers.
Moreover, the cover compositions of the present invention may also
contain softening agents such as those disclosed in U.S. Pat. Nos.
5,312,857 and 5,306,760, including plasticizers, metal stearates,
processing acids, and the like, and reinforcing materials such as
glass fibers and inorganic fillers, as long as the desired
properties produced by the golf ball covers of the invention are
not impaired.
[0140] Core Layer(s)
[0141] The core of the golf ball can be formed of a solid, a
liquid, or any other substance that will result in a core or an
inner ball (core and at least one inner cover layer, if the ball is
a multi-layer ball), having the desired COR, compression and
hardness and other physical properties.
[0142] The cores of the inventive golf balls typically have a
coefficient of restitution of about 0.750 or more, more preferably
0.770 or more and a PGA compression of about 90 or less, and more
preferably 70 or less. Furthermore, in some applications it may be
desirable to provide a core with a coefficient of restitution of
about 0.780 to 0.790 or more. The core used in the golf ball of the
invention preferably is a solid, but any core type known in the art
may be used, such as wound, liquid, hollow, metal, and the like.
The term "solid cores" as used herein refers not only to one piece
cores but also to those cores having a separate solid layer beneath
the covers and over the central core. The cores generally have a
weight of about 25 to about 40 grams and preferably about 30 to
about 40 grams. Larger and heavier cores, or lighter and smaller
cores, may also be used when there is no desire to meet U.S.G.A. or
R. & A. standards.
[0143] When the golf ball of the invention has a solid core, this
core can be compression molded from a slug of uncured or lightly
cured elastomer composition comprising a high cis content
polybutadiene and a metal salt of an .alpha., .beta., ethylenically
unsaturated carboxylic acid such as zinc mono- or diacrylate or
methacrylate. To achieve higher coefficients of restitution and/or
to increase hardness in the core, the manufacturer may include a
small amount of a metal oxide such as zinc oxide. In addition,
larger amounts of metal oxide than are needed to achieve the
desired coefficient may be included in order to increase the core
weight so that the finished ball more closely approaches the
U.S.G.A. upper weight limit of 1.620 ounces.
[0144] Non-limiting examples of other materials that may be used in
the core composition include, but are not limited to, compatible
rubbers or ionomers, and low molecular weight fatty acids such as
stearic acid. Free radical initiator catalysts such as peroxides
may be admixed with the core composition so that on the application
of heat and pressure, a curing or cross-linking reaction takes
place. The core may also be formed from any other process for
molding golf ball cores known in the art.
[0145] A thread wound core may comprise a liquid, solid, gel or
multi-piece center. The thread wound core is typically obtained by
winding a thread of natural or synthetic rubber, or thermoplastic
or thermosetting elastomer such as polyurethane, polyester,
polyamide, etc. on a solid, liquid, gel or gas filled center to
form a thread rubber layer that is then covered with one or more
mantle or cover layers. Additionally, prior to applying the cover
layer(s), the thread wound core may be further treated or coated
with an adhesive layer, protective layer, or any substance that may
improve the integrity of the wound core during application of the
cover layers and ultimately in usage as a golf ball.
[0146] Since the core material is not an integral part of the
present invention, a detailed discussion concerning the specific
types of core materials which may be utilized with the cover
compositions of the invention are not specifically set forth
herein.
[0147] Manufacturing Golf Balls
[0148] In accordance with a preferred technique of the invention,
one or more deep dimples are formed that extend to or into various
internal layers or components of a golf ball. Specifically, each
layer of the preferred embodiment golf balls has dimples formed
therein by a dimpled cavity having a pattern having the same
geometric coordinates as other corresponding dimpled cavities. The
core or core and inner layer(s) need to be aligned such that the
dimples are formed over one another in the subsequent layers. For
example, for a dimple in a preferred embodiment ball of the present
invention, the outer layer may account for a portion of the total
depth, and the inner layer(s) will account for the remainder. In a
traditional prior art ball, the dimple depth, which is generally
about 0.010 inches, is generally less than the thickness of the
cover so that the dimple does not touch or extend to the next layer
or even come close to the next layer. Therefore, there is a minimum
cover thickness that can be used in order to have dimples of the
desired depth. The present invention eliminates the need to have a
cover thickness greater than the desired dimple depth because two
or more layers can make up the dimple, and thus, each layer may be
very thin (less than 0.010 inches).
[0149] Furthermore, the golf balls of the present invention may
incorporate both deep dimples and dual dimples (dimple within a
dimple) or dimples formed in multiple layers, as previously
described.
[0150] In preparing golf balls in accordance with a preferred
embodiment process of the present invention, a single cover layer
or an inner cover layer (or mantle layer) is molded about a core
(preferably a solid core). The cover layer(s) may be molded using
any molding processing known in the art. Examples of molding
processes include, but are not limited to, injection molding,
transfer molding, reaction injection molding, liquid injection
molding, casting, compression molding, and the like.
[0151] For a multi-layer ball, as shown in FIGS. 3 and 4, an outer
layer 160 is molded over the inner layer 150. The core (or core and
inner layer(s)) is supported by one or more, preferably two or
more, support pins or protrusions which form the deep-dimples that
contact the core or intermediate ball assembly. That is, the
exterior surface of the support pins or protrusions form the inner
surface of the deep dimples.
[0152] The core (or core and inner layer(s)) is held in place by a
holding force created by designing the dimples, or rather the
raised projections on a molding surface that form such dimples,
deep enough to grip the ball by slightly pre-loading the core or
intermediate ball assembly. Ignoring friction, the only force
generated is in the radial direction, and radial pre-load force is
proportional to radial interference between the deep dimples and
the core or core and inner layer(s).
[0153] The number of deep dimples on a golf ball of the present
invention may vary as desired. Any number and pattern of deep
dimples may be used, although a limited number of deep dimples in a
specific geometric pattern is preferred. The geometric pattern is
preferably approximately centered about the pole of the ball. Given
the limited number of coordinates or points, it is generally not
possible to exactly center certain geometric patterns with some
shapes, such as a triangle. Additionally, it may be desirable to
shift the pattern slightly to accommodate different forces (due to
the molding of the layer(s)) on different sides of the ball.
[0154] FIGS. 9 and 10 are top views (one hemisphere of the ball) of
a golf ball having certain preferred arrangements of deep dimples.
FIG. 9 illustrates a golf ball 610 having a triangular arrangement
of three deep dimples 42 located approximately symmetrically around
a pole 44. FIG. 10 illustrates a golf ball 710 having a diamond
shaped arrangement of four deep dimples 42 located approximately
symmetrically around a pole 44. The figures are for illustrative
purposes since any desired number of deep dimples may be used, such
as one, two, three, four, five, six and the like. The deep dimples
do not have to be symmetrically located, although symmetry enhances
their aerodynamic effect. This results in a finished ball where the
deep dimples extend from the outer layer into the next inner
layer(s) and/or the core. Multiple cover layers, of the same or
different materials and thicknesses, may be added to the ball using
this procedure. The deep dimples may extend into multiple layers if
there are multiple layers on the ball, if desired.
[0155] The deep dimple locations may be anywhere on the ball, such
as at about 30 degrees latitude on each hemisphere, about 40 to 45
degrees latitude, about 50 to 60 degrees latitude, and the like.
That is, the deep dimples may be within a region along the outer
surface of a ball from about 30 degrees latitude to about 60
degrees latitude in either or both hemispheres. Preferably, the
deep dimples are located at about 40 to 45 degrees latitude or more
on each hemisphere. As used herein, latitude refers to the location
of the dimple on the ball, with the equator defined as 0 degrees
latitude, and each pole of the ball defined as 90 degrees
latitude
[0156] FIG. 13 is a graph illustrating the relationship between the
location of these deep dimples on a ball and the resulting force
applied to the core. Table 1, set forth below lists the data that
is illustrated graphically in FIG. 13.
1TABLE 1 Angle Lateral Vertical deg % Radial % Radial 0 100% 0% 5
100% 9% 10 98% 17% 15 97% 26% 20 94% 34% 25 91% 42% 30 87% 50% 35
82% 57% 40 77% 64% 45 71% 71% 50 64% 77% 55 57% 82% 60 50% 87% 65
42% 91% 70 34% 94% 75 26% 97% 80 17% 98% 85 9% 100% 90 0% 100%
Notes 1. Cavity with no retractable core pins 2. Core is supported
by 3 or more deep dimples that contact the core 3. Force is created
by designing the deepest dimple to pre-load core slightly 4. The
only force generated is in the radial direction (all force vectors
pass through ball center) 5. Radial pre-load force is proportional
to radial interference between deepest dimples & core 6. If
core is undersized, there is no pre-load force 7. Friction is
ignored.
[0157] In another preferred embodiment, the core or intermediate
ball (core plus one or more mantle or inner cover layer(s)) is
supported by one or more deep dimples (or rather the protrusions
extending from the molding surface that form the deep dimples) that
nearly contact or extend to the core. The deep dimple locations may
be anywhere on the ball, such as at about 30 degrees latitude on
each hemisphere, about 40 to 45 degrees latitude, about 50 to 60
degrees latitude, and the like. Preferably, the deep dimples are
located at about 40 to 45 degrees latitude or more on each
hemisphere. The number of deep dimples may vary as desired. Any
number and pattern may be used, although a limited number in a
specific geometric pattern is preferred. The geometric pattern
should preferably be approximately centered about the pole of the
ball. It is not possible to exactly center the geometric pattern
with some shapes, such as a triangle. Additionally, it may be
desirable to shift the pattern slightly to accommodate different
forces (due to the molding of the layer(s)) on different sides of
the ball. This results in a finished ball where the deep dimples
extend from the outer layer to the next inner layer or the core. As
described above, multiple cover layers, of the same or different
materials and thicknesses, may be added to the ball using this
procedure.
[0158] FIG. 14 is a perspective view of a preferred embodiment golf
ball according to the present invention. This illustration reveals
a circumferential region defined along the outer surface of the
ball. This region corresponds to the preferred location within
which are defined one or more deep dimples as described herein.
Specifically, the preferred location for the deep dimples is the
region along the outer surface of the ball extending between about
300 latitude and about 600 latitude. The pole of the ball is an
axis extending through the ball shown in FIG. 14 as line P-P. The
equator is illustrated in FIG. 14 as a circumferential line E
extending about the ball at a latitude of 0.degree..
[0159] Any number of cover and/or mantle layers may be used, and
the deep dimples may extend into as many layers as desired. For
example, a golf ball having a core and three cover layers (a first
inner cover layer, a second inner cover layer, and an outer cover
layer) may be produced according to the present invention. The deep
dimples may extend to or through the first inner cover layer,
through both the first inner layer and the second inner cover
layer, or, the deep dimple may extend through all the cover layers
to or into the core.
[0160] Additionally, if desired, the mantle layer could be colored
or contain other visible or cosmetic features that could be seen
through the cover layer. The cover layer may also be transparent,
translucent or opaque if desired to enhance or highlight the mantle
layer.
[0161] Other methods of molding golf balls without the use of core
pins include the use of tabs on the equator of the core such that
the dimpled cavity can receive the tabs to hold the core in place
during molding of one or more layers about the core. Alternatively,
the golf ball may be molded with a mantle having one or more
keyways or openings. The cover mold would then be equipped with
side pulls that engage the keys and hold the core in place. These
techniques are explained in greater detail herein.
[0162] The core, preferably a solid core, for the ball is
preferably about 1.2 to about 1.6 inches in diameter, although it
may be possible to use cores in the range of about 1.0 to 2.0
inches. If the ball has a single cover layer, the core size may be
up to about 1.660 inches.
[0163] The present invention includes one or more auxiliary layers
disposed on the core, and preferably immediately adjacent to the
outer core surface. For example, for some applications, it may be
preferred to deposit a barrier coating that limits transmission of
moisture to the core. As previously noted, such barrier coatings or
layers are relatively thin. Generally, such coatings are at least
0.0001 inches, and preferably, at least 0.003 inches in thickness.
Furthermore, an adhesion promoting layer may be used between the
cover layers and/or the core, or the cover and core having a
barrier coating disposed thereon. Such adhesion promoting layers
are known in the art and may be used in combination with the
inventive features described herein. See for example U.S. Pat. No.
5,820,488 herein incorporated by reference.
[0164] The inner cover layer that is molded over the core is
preferably about 0.0005 inches to about 0.15 inches in thickness.
The inner ball that includes the core and inner cover layer(s), or
core for a two piece ball, preferably has a diameter in the range
of 1.25 to 1.60 inches. The outer cover layer is about 0.0005
inches to about 0.15 inches thick. Together, the core, the inner
cover layer(s) and the outer cover layer (or core and single cover
layer) combine to form a ball having a diameter of 1.680 inches or
more, the minimum diameter permitted by the rules of the U.S.G.A
and weighing no more than 1.62 ounces. If desired, golf balls of
different weights and diameters may also be formed if the rules of
the U.S.G.A. are not an issue.
[0165] In a particularly preferred embodiment of the invention, the
golf ball has a dimple pattern that provides dimple coverage of 65%
or more, preferably 75% or more, and more preferably about 80 to
85% or more. In a preferred embodiment of the invention, there are
from 300 to less than 500 dimples, preferably from about 340 to
about 440 dimples.
[0166] Specifically, the arrangement and total number of dimples
are not critical and may be properly selected within ranges that
are well known. For example, the dimple arrangement may be an
octahedral, dodecahedral or icosahedral arrangement. The total
number of dimples is generally from about 250 to about 600, and
especially from about 300 to about 500.
[0167] In a preferred embodiment, the golf ball typically is coated
with a durable, abrasion-resistant, relatively non-yellowing finish
coat or coats if necessary. The finish coat or coats may have some
optical brightener and/or pigment added to improve the brightness
of the finished golf ball. In a preferred embodiment, from 0.001 to
about 10% optical brightener may be added to one or more of the
finish coatings. If desired, optical brightener may also be added
to the cover materials. One type of preferred finish coatings are
solvent based urethane coatings known in the art. It is also
contemplated to provide a transparent outer coating or layer on the
final finished golf ball.
[0168] Golf balls also typically include logos and other markings
printed onto the dimpled spherical surface of the ball. Paint,
typically clear paint, is applied for the purposes of protecting
the cover and improving the outer appearance before the ball is
completed as a commercial product. FIG. 11 is a fragmental enlarged
view showing the radial cross-sectional shape of a dimple formed in
the surface of a golf ball prior to paint coating. Most often, the
dimple is circular in plane shape. In general, dimples such as the
deep dimple shown in FIG. 11, are formed in a golf ball surface as
a recess or indentation. The cross-sectional shape of a dimple is
defined by a portion of a curved surface such as a circle, ellipse,
or hyper ellipse. For example, the cross-sectional shape of the
dimple in FIG. 11 is a portion of a circle. The dimple is
circumscribed by an upper edge, which is continuously connected to
a land area of the outer surface of the golf ball where no dimples
are formed. The edge is generally beveled from the land area as a
steep slope to form the dimple. The edge is generally initially
angular prior to paint coating and somewhat rounded after paint
coating.
[0169] The various cover composition layers of the present
invention may be produced according to conventional melt blending
procedures or any other method known in the art. For example, the
cover materials may be blended in a Banbury.RTM. type mixer,
two-roll mill, or extruder prior to neutralization. After blending,
neutralization then occurs in the melt or molten state in the
Banbury.RTM. mixer. The blended composition is then formed into
slabs, pellets, etc., and maintained in such a state until molding
is desired. Alternatively, a simple dry blend of the pelletized or
granulated materials (which have previously been neutralized to a
desired extent, if applicable) and colored master batch may be
prepared and fed directly into the injection molding machine where
homogenization occurs in the mixing section of the barrel prior to
injection into the mold. If necessary, further additives such as an
inorganic filler, etc., may be added and uniformly mixed before
initiation of the molding process.
[0170] The golf balls of the present invention can be produced by
molding processes, which include, but are not limited to, those
which are currently well known in the golf ball art. As mentioned
above, the golf balls can be produced, for example, by injection
molding, reaction injection molding (RIM), liquid injection
molding, compression molding, and the like, the novel cover
compositions around a wound, solid, or other type of core to
produce an inner ball which typically has a diameter of about 1.50
to 1.67 inches.
[0171] Alternatively, the cover layer(s) may be cast around the
core or core and inner layer(s), such as in a cast polyurethane
system. The outer layer is subsequently molded over the inner layer
to produce a golf ball having a diameter of 1.620 inches or more,
preferably about 1.680 inches or more. Although any type of core,
such as either solid cores or wound cores can be used in the
present invention, as a result of their lower cost and superior
performance, solid molded cores are preferred over wound cores. The
standards for both the minimum diameter and maximum weight of the
balls are established by the United States Golf Association
(U.S.G.A.), but not all golf balls are designed to meet these
standards.
[0172] In compression molding, smooth surfaced hemispherical shells
(previously molded) are positioned around the core in a mold having
the desired inner cover thickness. The core and shells are then
subjected to compression molding at about 200.degree. F. to
300.degree. F. for about 2 to 10 minutes, followed by cooling at
50.degree. F. to 70.degree. F. for about 2 to 7 minutes to fuse the
shells together to form a unitary intermediate ball. In addition,
the intermediate balls may be produced by injection molding wherein
the inner cover layer is injected directly around the core placed
at the center of an intermediate ball mold for a period of time in
a mold temperature of from 50.degree. F. to about 100.degree. F.
Subsequently, the outer cover layer is molded about the core and
the inner layer by similar molding techniques to form a dimpled
golf ball of a diameter of 1.680 inches or more. To improve the
adhesion between the inner cover layer and the outer cover layer,
or any of the cover layers and/or the core, an adhesion promoter
may be used. Some adhesion promoters, such as abrasion of the
surface, corona treatment, and the like, are known in the art. A
preferred adhesion promoter is a chemical adhesion promoter, such
as a silane or other silicon compound, preferably
N-(2-aminoethyl-3)-aminopropyltrimethoxysilane. The intermediate
golf ball (core and inner cover layer) may be dipped or sprayed
with the chemical, and then the outer cover layer is formed over
the treated inner cover layer. For multiple cover layers, the ball
may be treated more than once if necessary or desired.
[0173] A typical process for casting covers around a core or core
and inner layer(s) comprises two part (for example, bookcase type)
molds that are heated to approximately 80 to 180.degree. F. The
cover material, such as a polyurethane, is heated to approximately
80 to 180.degree. F. The material gel time is approximately 20 to
90 seconds, and mold closure time (heat step) is approximately 2 to
8 minutes, and the cooling step is approximately 2 to 8 minutes.
After the material forms a cover, the molds are opened, and the
balls are removed from the molds. The cavities may optionally be
cleaned and/or coated with a mold release before the process is
repeated.
[0174] FIG. 15 illustrates a preferred embodiment molding apparatus
1000 in accordance with the present invention. Molding apparatus
1000 comprises two mold halves 1020 and 1040 that each define a
hemispherical portion of a molding chamber 1024 and 1044. Defined
along the outer surface of the hemispherical portion of the molding
chamber 1024, are a plurality of raised regions or protrusions
1032. These raised regions form conventional dimples in a cover
layer in a golf ball formed using molding apparatus 1000. Also
provided along the outer surface of the hemispherical molding
chamber 1024 are a plurality of outwardly extending raised regions,
protrusions, or support pins 1026, 1028, and 1030. These raised
regions are of a height greater than the height of the raised
regions 1032. Specifically, the raised regions 1026, 1028, and 1030
form deep dimples as described herein. These raised regions are
used to retain and support a golf ball core or intermediate ball
assembly placed in the mold. After molding a cover layer on the
core or ball assembly, a final golf ball 1010 is produced. A ball
1010 illustrated in FIG. 15 is depicted with a plurality of dimples
or dimple portions formed along its outer surface. The ball also
includes a plurality of deep dimples along its outer surface
resulting from the raised regions 1026, 1028, and 1030. These deep
dimples may correspond to a dimple such as item 240 in FIG. 5. A
passage 1022 is provided in the mold half 1020. The passage 1022
provides communication and a path for a flowable moldable material
to be introduced into the molding chamber. The molding apparatus
1000 also includes a second molding portion or plate 1040. The
plate 1040 defines a hemispherical molding chamber 1044 also having
a plurality of raised regions, protrusions, or support pins along
its outer surface. Specifically, raised regions 1046 and 1048 are
provided similar to the previously described raised regions 1026,
1028, and 1030. The molding plate 1040 also defines a channel 1042
extending from the molding chamber 1044 to the exterior of the
plate. Most preferably, the molding channel 1042 is aligned with
channel 1022 in the other plate 1020 when the mold is closed to
provide a unitary passage providing communication between the
molding chamber and the exterior of the mold. A golf ball core or
intermediate ball assembly placed in the molding chamber 1020,1040
is supported by the various raised regions 1026, 1028, 1030, 1046,
and 1048 as previously described. A golf ball 1010 or ball
component is produced.
[0175] It will be appreciated that the present invention includes a
molding process, molding equipment, and the resulting molded golf
balls and components thereof from utilizing a molding chamber in
which most or all of the dimples that are formed in the ball are
deep dimples and thus, extend into or through an underlying layer.
For instance, in this embodiment, the raised regions or protrusions
1032 defined in the molding chamber 1024 in FIG. 15, would all form
deep dimples. And, the set of raised protrusions or support pins
1026, 1028, and 1030 would have a height greater than the height of
the protrusions 1032. And so, the deep dimples formed from support
pins 1026, 1028 and 1030 would have a depth greater than the other
population of deep dimples, i.e. those formed from the protrusions
1032. A similar configuration would be utilized for the molding
chamber 1044.
[0176] Additionally, golf balls of the present invention that
comprise polyurethane/polyurea (or other suitable materials) in any
of the inner and outer cover layer may be produced by a reaction
injection molding process (RIM), as previously described.
[0177] Golf balls and, more specifically, cover layers formed by
RIM are preferably formed by the process described in application
Ser. No. 09/040,798, filed Mar. 18, 1998, incorporated herein by
reference, or by a similar RIM process.
[0178] RIM differs from non-reaction injection molding in a number
of ways. The main distinction is that in RIM a chemical reaction
takes place in the mold to transform a monomer or adducts to
polymers and the components are in liquid form. Thus, a RIM mold
need not be made to withstand the pressures that occur in
conventional injection molding.
[0179] In contrast, injection molding is conducted at high molding
pressures in the mold cavity by melting a solid resin and conveying
it into a mold, with the molten resin often being at about 150 to
about 350.degree. C. At this elevated temperature, the viscosity of
the molten resin usually is in the range of about 50,000 to about
1,000,000 centipoise, and is typically around 200,000 centipoise.
In an injection molding process, the solidification of the resins
occurs after about 10 to about 90 seconds, depending upon the size
of the molded product, the temperature and heat transfer
conditions, and the hardness of the injection molded material.
Subsequently, the molded product is removed from the mold. There is
no significant chemical reaction taking place in an injection
molding process when the thermoplastic resin is introduced into the
mold.
[0180] In contrast, in a RIM process, the chemical reaction causes
the material to set in less than about 5 minutes, often in less
than 2 minutes, preferably in less than one minute, more preferably
in less than 30 seconds, and in many cases in about 10 seconds or
less.
[0181] Catalysts can be added to the RIM polyurethane system
starting materials as long as the catalysts generally do not react
with the constituent with which they are combined. Suitable
catalysts include those which are known to be useful with
polyurethanes and polyureas.
[0182] The polyol component typically contains additives, such as
stabilizers, flow modifiers, catalysts, combustion modifiers,
blowing agents, fillers, pigments, optical brighteners, and release
agents to modify physical characteristics of the cover. Recycled
polyurethane/polyurea also can be added to the core.
Polyurethane/polyurea constituent molecules that were derived from
recycled polyurethane can be added in the polyol component.
[0183] In accordance with one aspect of the present invention, the
mold cavity preferably contains nonretractable support pins and is
generally constructed in the same manner as a mold cavity used to
injection mold a thermoplastic, for example, ionomeric golf ball
cover. However, two differences when RIM is used are that tighter
pin tolerances generally are required, and a lower injection
pressure is used. Also, the molds can be produced from lower
strength material such as aluminum. As described herein, in another
aspect of the invention, the mold cavity may contain one or more
selectively positionable, i.e. retractable, pins disposed about the
molding cavity.
[0184] RIM may provide for improved cover layers. If plastic
products are produced by combining components that are preformed to
some extent, subsequent failure can occur at a location on the
cover which is along the seam or parting line of the mold, as well
as at core pin locations, because these regions are intrinsically
different from the remainder of the cover layer and can be weaker
or more stressed. Cover layers produced via RIM are believed to
provide for improved durability of a golf ball cover layer by
providing a uniform or "seamless" cover in which the properties of
the cover material in the region along the parting line are
generally the same as the properties of the cover material at other
locations on the cover, including at the poles. The improvement in
durability is believed to be a result of the fact that the reaction
mixture is distributed uniformly into a closed mold. This uniform
distribution of the injected materials reduced or eliminates
knit-lines and other molding deficiencies which can be caused by
temperature differences and/or reaction differences in the injected
materials. RIM typically results in generally uniform molecular
structure, density and stress distribution as compared to
conventional injection-molding processes.
[0185] The golf balls, and particularly the cover layer(s), of the
present invention may also be formed by liquid injection molding
(LIM) techniques, or any other method known in the art.
[0186] The golf balls formed according to the present invention can
be coated using a conventional two-component spray coating or can
be coated during the RIM process, for example, using an in-mold
coating process.
[0187] Referring next to FIG. 16, a process flow diagram for
forming a RIM cover of polyurethane is shown. Isocyanate from bulk
storage is fed through line 1180 to an isocyanate tank 1200. The
isocyanate is heated to the desired temperature, e.g., 90.degree.
F. to about 170.degree. F., by circulating it through heat
exchanger 1182 via lines 1184 and 1186. Polyol, polyamine, or
another compound with an active hydrogen atom is conveyed from bulk
storage to a polyol tank 1208 via line 1188. The polyol is heated
to the desired temperature, e.g., 90.degree. F. to about
170.degree. F., by circulating it through heat exchanger 1190 via
lines 1192 and 1194. Dry nitrogen gas is fed from nitrogen tank
1196 to isocyanate tank 1200 via line 1197 and to polyol tank 1208
via line 1198. Isocyanate is fed from isocyanate tank 1200 via line
1202 through a metering cylinder or metering pump 1204 into
recirculation mix head inlet line 1206. Polyol is fed from polyol
tank 1208 via line 1210 through a metering cylinder or metering
pump 1212 into a recirculation mix head inlet line 1214. The
recirculation mix head 1216 receives isocyanate and polyol, mixes
them, and provides for them to be fed through nozzle 1218 into
injection mold 1220. The injection mold 1220 has a top mold 1222
and a bottom mold 1224. Coolant flows through cooling lines 1226 in
the top mold 1222 and lines 1240 in the bottom mold 1224. The
materials are kept under controlled temperature conditions to
insure that the desired reaction profile is maintained.
[0188] The polyol component typically contains additives, such as
stabilizers, flow modifiers, catalysts, combustion modifiers,
blowing agents, fillers, pigments, optical brighteners, and release
agents to modify physical characteristics of the cover. Recycled
polyurethane/polyurea also can be added to the core.
Polyurethane/polyurea constituent molecules that were derived from
recycled polyurethane can be added in the polyol component.
[0189] Inside the mix head 1216, injector nozzles impinge the
isocyanate and polyol at ultra-high velocity to provide excellent
mixing. Additional mixing preferably is conducted using an
aftermixer 1230, which typically is constructed inside the mold
between the mix head and the mold cavity.
[0190] As is shown in FIG. 17, a mold includes a golf ball cavity
chamber 1232 in which a spherical golf ball mold 1234 with a
dimpled, spherical mold cavity 1236 defined. The mold cavity 1236
is preferably provided with a plurality of raised regions that form
deep dimples as described herein, and which may also be utilized as
one or more nonretractable support pins, as shown and described
with regard to FIG. 15. The aftermixer 1230 can be a peanut
aftermixer, as in shown in FIG. 17, or in some cases another
suitable type, such as a heart, harp or dipper. An overflow channel
1238 receives overflow material from the golf ball mold 1234
through a shallow vent 1242. Heating/cooling passages 1226 and
1240, which preferably are in a parallel flow arrangement, carry
heat transfer fluids such as water, oil, etc. through the top mold
1222 and the bottom mold 1224. It will be appreciated that the
molding apparatus illustrated in FIG. 15 may be used in conjunction
with a RIM process by providing a mixer, i.e. aftermixer 1230 of
FIG. 17, in the molds 1020 and 1040.
[0191] The present invention also provides a technique and molding
configuration particularly well suited for automated production and
high efficiency manufacturing. In a preferred embodiment, a molding
apparatus is provided that includes a mold having one or more
outwardly extending projections that form recessed regions along
the perimeter of the molded component. Most preferably, the
resulting recesses are located along the equator of the resulting
golf ball or component thereof. This configuration enables the
molded part to be easily removed from a mold, and to be accurately
positioned in another mold. That is, mechanical positioning members
may readily grasp the intermediate molded ball by engagement in the
recessed regions and remove the molded ball or intermediate ball
from the mold. The molded component may also be accurately and
consistently positioned in a subsequent molding chamber. This
configuration also results in any flash or witness lines from
molding a layer on the intermediate component having the recesses,
to extend only along the parting line. Accordingly, since the flash
is along the equator, known finishing processes may be used to
remove the flash or markings. This molding configuration and
technique is readily applicable to RIM techniques, and also to
techniques for forming deep dimples as described herein. Most
preferably, this technique is preferred when forming a mantle layer
or other intermediate layer of a golf ball.
[0192] FIGS. 18 to 20 illustrate an aspect of the present invention
which facilitates manufacture of a golf ball in accordance with the
present invention. Specifically, FIG. 18 illustrates a preferred
embodiment molding chamber in accordance with this aspect of the
present invention. The preferred embodiment molding chamber 1300
comprises a lower mold 1320 and an upper mold 1302. The upper mold
1302 defines a semi-circular concave molding surface 1304. Defined
along the molding surface 1304 are a plurality of outwardly
extending edge projections such as 1306 and 1308 shown in FIG. 18.
Similarly, the lower mold 1320 defines a hemispherical molding
surface 1324 having one or more outwardly extending edge
projections 1326 and 1328. The molding surfaces 1304 and 1324 may
further define a plurality of raised regions that form deep dimples
as described herein, and which may further serve as nonretractable
support pins as described herein. The outwardly extending edge
projections 1306 and 1308 are located along an edge that extends
between the hemispherical molding surface 1304 and the relatively
flat mating surface of the upper mold 1302 that contacts the mating
surface of the lower mold 1320 when the molds are closed or placed
in a molding configuration. This interface between the two molds is
often referred to in the industry as a "parting line." Similarly,
the outwardly extending projections 1326 and 1328 are located along
an edge that extends between the hemispherical molding surface 1324
and the relatively flat mating surface of the lower mold.
Preferably, when the upper mold 1302 and the lower mold 1320 are
closed, the edge projection 1308 is aligned with the edge
projection 1328. And, the edge projection 1306 is aligned with the
edge projection 1326.
[0193] FIG. 19 illustrates an assembly 1400 of an intermediate
molded ball 1402 and a plurality of mechanical engagement members
adapted to engage and position the ball 1402 as desired. The
engagement members 1410 and 1420 each have distal ends 1412 and
1422, respectively, that are sized and shaped to fit within and
engage recessed regions such as 1404 defined along the outer
surface of the ball 1402. As will be understood, the recessed
regions 1404 result from the outward edge projections such as 1328
and 1308 of the molding assembly 1300 shown in FIG. 18.
Furthermore, it will be appreciated that, in the preferred
embodiment, the resulting recessed regions such as 1404 lie along
an equator 1406 of the ball 1402.
[0194] FIG. 20 is a detailed view of a lower mold 1520 that is
adapted to form an outer layer, preferably an outer cover layer on
the intermediate ball 1402. Accordingly, the diameter of the
molding surface defined in the mold 1520 is slightly larger than
the outermost diameter of the ball 1402. The ball is preferably
positioned within the lower mold 1520 by use of the mechanical
members 1410 and 1420 that position the ball such that the equator
1406 extends preferably closely along the outer molding edge 1530
of the lower mold 1520. It will be appreciated that a corresponding
upper mold (not shown) is used in conjunction with the lower mold
1520. Further, it will be understood that the molding surface
defined in the lower mold is preferably provided with a plurality
of raised regions that form deep dimples, or which serve as
nonretractable support pins as previously described herein.
[0195] The present invention also provides equipment and techniques
for forming golf ball cover layer(s) independently of golf ball
cores or intermediate ball assemblies. That is, cover layers may be
formed which are not initially retained or formed on an underlying
core or intermediate ball assembly. The cover layer is preferably
formed in two hemispherical shell portions that together form a
cover layer. This strategy provides increased flexibility in
production and manufacturing in addition to other benefits
described herein. The equipment and techniques described herein are
particularly well suited for use with RIM processes. Related to
this, the invention also provides equipment and techniques for
eliminating any seams otherwise resulting when cover layer portions
or shells are molded onto or about a core or intermediate ball
assembly.
[0196] FIG. 21 is a perspective view of another preferred
embodiment molding apparatus according to the present invention.
FIG. 21 illustrates a preferred embodiment molding apparatus 1600
comprising an upper mold 1602 and a lower mold 1620. The upper mold
1602 defines a hemispherical molding surface 1604. One or more
conduits or passageways 1606 and 1608 are provided in the upper
mold 1602 so as to enable the introduction of flowable material or
molding material into the molding chamber defined partially by the
molding surface 1604. The lower mold 1620 also defines a
hemispherical molding surface 1624 having entryways or passages
1626 and 1628 as shown. The upper and lower molds 1602 and 1620 are
sized and shaped such that when closed and placed in abutting
relationship to one another, the two hemispherical molding surfaces
1604 and 1624 together define a spherical molding chamber suitable
for molding golf balls or components thereof.
[0197] Additionally, it will be understood that in accordance with
the present invention, the molding surfaces 1604 and 1624 are
provided with a plurality of raised regions that form deep dimples
in the resulting molded ball. Furthermore, a set of raised regions
may be provided along the molding surfaces that serve as
nonretractable support pins. Moreover, in accordance with another
aspect of the present invention, the passages 1606, 1608, 1626, and
1628 may be provided in the form of a mixer such as after mixer
1230 shown in FIG. 17 if a RIM process is used.
[0198] The molding assembly 1600 also comprises a mandrel 1640
having a medially disposed spherical portion and laterally
extending projections 1642 and 1644. The mandrel 1640 also provides
a circumferential belt or lip 1650 extending about the periphery
and preferably the equator of the spherical portion of the mandrel
1640. The mandrel, and particularly the spherical portion of the
mandrel 1640 is sized such that it may be received within the two
hemispherical molding surfaces as shown in FIG. 22.
[0199] Specifically, FIG. 22 illustrates the mandrel 1640 situated
or positioned within the molding chamber defined by the upper mold
1602 and the lower mold 1620. It is preferred that the
circumferential belt or lip 1650 of the mandrel is oriented to
generally extend within the same plane or orientation as the
circular interface between the upper and lower molds 1602 and 1620,
when such molds are "closed" or placed in a molding configuration.
It will be noted that a space or void is defined between the outer
surface of the spherical portion of the mandrel 1640 and the upper
molding surface 1604 and the lower molding surface. 1624. As
explained in greater detail herein, that space or void receives
molding material which subsequently forms the component or layer as
desired for the golf ball.
[0200] In the molding configuration illustrated in FIG. 22, a
flowable molding material is introduced into the void defined
between the outer spherical surface of the mandrel 1640 and the
upper and lower molding surfaces 1604 and 1624, respectively. Upon
hardening and/or curing of this material a cover layer is formed.
As explained below, in order to form a golf ball, the mandrel is
removed from the assembly and an appropriately sized core or
intermediate ball assembly is positioned between the molds.
[0201] FIG. 23 illustrates the molding assembly 1600 after the
mandrel 1640 has been removed and a golf ball core or intermediate
ball 1660 has been placed within the spherical molding chamber. At
this juncture, a flowable molding material has been introduced into
the mold to form shell-like or layered regions 1670 and 1680 along
the upper and lower molding surfaces 1604 and 1624, respectively.
The core is placed between these two cover layer shells 1670 and
1680. As will be appreciated, since the mandrel, having the equator
lip region 1650, as best shown in FIG. 21, has been removed after
molding the layered 1670 and 1680 components, a void or space 1675
is left. This is illustrated in greater detail in FIG. 24. A second
molding operation is then performed in which flowable molding
material is introduced through passageway 1615 defined within the
molding apparatus. The second molding operation in which the void
1675 is filled further bonds the two cover layer shells 1670 and
1680 together. This second molding operation may be performed by a
RIM operation, and has surprisingly been found to eliminate or
significantly reduce the appearance of any seams along the outer
surface of the ball.
[0202] It is also contemplated that instead of using a mandrel when
forming the cover layer or portions thereof, a golf ball core or
intermediate ball assembly could be used and retained in place with
a cup or lid assembly. Specifically, in this variation of the
invention, one-half of a cover assembly is molded onto a core or
ball assembly by using only one mold, such as either the upper mold
1602 or the lower mold 1620. The core is placed in the
hemispherical molding region of the mold and a cup or "jig" is used
that fits over the core and molding region, i.e. one-half of the
spherical molding chamber that would otherwise exist if both upper
and lower molds were used. The cup or jig creates a closed molding
chamber and assists in properly centering and positioning the core
within the resulting chamber. The cup or jig may use a suction
gripping system to secure the cup or jig to the mold and/or the
core. After molding the one-half cover shell on the core, the cup
is removed and the ball assembly may be removed from the mold, or
more preferably, the other corresponding mold is positioned with
the ball assembly and the remaining cover portion may be formed
thereon.
[0203] As previously noted, the present invention includes
embodiments in which a molding apparatus provides one or more
selectively positionable, i.e. retractable and extendible,
"knock-out" pins along the surface of the molding chamber. These
pins are specially tailored such that after their retraction after
a molding operation, the resulting voids are deep dimples. The pins
extend into the molding chamber within specific ranges of
dimensions. The pins are also sized such that the resulting voids
have the desired diameters, spans, and shapes. The one or more
"knock-out" pins may preferably be used in conjunction with the
previously described raised protuberances that also form deep
dimples. These aspects are as follows.
[0204] FIG. 25 is a schematic top view of another preferred
embodiment molding apparatus 2000 according to the present
invention. FIG. 26 is a schematic side view of the preferred
embodiment molding apparatus 2000 shown in FIG. 25. The molding
apparatus 2000 comprises an upper mold half 2010 and a lower mold
half 2020. Each molding portion defines a hemispherical molding
cavity defined by molding surfaces 2050 and 2060. The upper molding
component 2010 includes a plurality and preferably four, apertures
or passages within which are movably retained, four knock-out pins
2030, 2032, 2034, and 2036. Similarly, the lower molding component
2020 defines a plurality and preferably four, apertures or passages
within which are movably retained a corresponding number of
knock-out pins 2040, 2042, 2044, and 2046 (not shown). It will be
appreciated that any number of pins may be used in each mold, such
as 1-10, 1-6,2-5, 2-4, or 3. These knock-out pins are movable
within each of their respective apertures or guide channels. Upon
molding, a golf ball core 2005 or other intermediate ball assembly
is placed within the spherical molding chamber created by
hemispherical molding surfaces 2050 and 2060 defined in the upper
and lower molding components 2010 and 2020 as shown in FIG. 26. The
core and/or ball assembly is sized such that its diameter is
slightly less than the internal diameter of the hemispherical
molding cavity. The plurality of upper and lower knock-out pins
then are moved inward toward the molding cavity such that the core
2005 or intermediate ball assembly is thus engaged and retained by
the plurality of knock-out pins, within the molding cavity. The
core or ball assembly is held in the desired position within the
molding cavity while one or more molding materials are administered
into the cavity and around the core or ball assembly.
[0205] FIG. 27 is a detailed view of the region identified by a
circular-line in FIG. 26. FIG. 27 illustrates in greater detail the
orientation of the core 2005 or intermediate ball assembly within
the molding chamber and the engagement of that core or ball
assembly by a knock-out pin. Specifically, FIG. 27 illustrates a
core. 2005 disposed within the molding cavity and positioned very
closely near the surface 2060 of the bottom or lower molding
component 2020. The outer surface 2006 of the core 2005 is adjacent
the inner molding surface 2060. The core 2005 is retained in this
particular orientation by engagement of the knock-out pin 2040, and
specifically, contact by a distal end 2041 of the knock-out pin
2040. While held in this position, one or more cover layers are
molded about the core 2005 and specifically, within the region or
void between the outer surface 2006 of the core and the inner
molding surface 2060. After molding, the knock-out pins are moved
to disengage the core or ball assembly, along with one or more
layers molded thereon, from the molding cavity.
[0206] The molding apparatus illustrated in FIGS. 25-27 may be
utilized in a manner so that one or more, or all of, the knock-out
pins, i.e. pins 2030, 2032, 2034, 2036, 2040, 2042, 2044, and 2046
are selectively positioned relative to a core or ball assembly
within the molding chamber so as to form one or more deep dimples
in the resulting golf ball. For example, one or more of these
knock-out pins are positioned such that their distal ends are
extended into the molding chamber and contact a core or ball
assembly retained within the chamber. A suitable molding material
is then administered into the chamber, and specifically within the
void between the outer surface of the core or ball and the interior
surface of the molding chamber. The knock-out pins used to form one
or more deep dimples are not retracted until the molding material
has sufficiently cured or hardened so that upon removal or
retraction of the pin, the resulting space or recessed region
remains and is not filled in from molding material flowing
therein.
[0207] FIG. 28 is a schematic top view of another preferred
embodiment molding apparatus 2100 according to the present
invention. FIG. 29 is a schematic side view of the preferred
embodiment molding apparatus 2100 shown in FIG. 28. The preferred
embodiment molding apparatus 2100 comprises an upper molding
component 2110 and a lower molding component 2120. The upper
molding component 2110 defines a hemispherical molding surface
2150. The lower molding component 2120 defines a hemispherical
molding surface 2160. Each of the upper and lower molding
components define a plurality of apertures or guide channels that
retain one or more movable knock-out pins as follows. The upper
molding component 2110 preferably includes a plurality of knock-out
pins 2130, 2132, 2134, and 2136. The lower molding component 2120
includes a plurality of knock-out pins 2140, 2142, and others (not
shown). The preferred embodiment molding apparatus 2100 further
includes one or more dimples defined in either or both of the upper
and lower molding surfaces 2150 and 2160. Specifically, the upper
molding surface 2150 preferably includes a plurality of deep
dimples such as 2172, 2174, 2176, and 2178. Actually, as will be
understood, the dimples provided on a molding surface are actually
in the form of a raised projection or protuberance. The bottom or
lower molding component 2120 preferably also provides a plurality
of deep dimples defined along the lower molding surface 2160. A
core 2105 or intermediate ball assembly is placed within the
spherical molding cavity created by the upper and lower
hemispherical molding surfaces 2150 and 2160.
[0208] FIG. 30 is a detailed view of the region identified by a
circular-line in FIG. 29. FIG. 30 further illustrates in greater
detail the orientation of the golf ball core 2150 when positioned
within the molding cavity and adjacent the lower molding surface
2160. It can be seen that a raised or outwardly extending
protuberance 2188 that forms a deep dimple, is defined along the
molding surface 2160. And, a knock-out pin 2140 is shown in a
retracted position in which the distal end 2142 of the knock-out
pin 2140 is not in contact with the core 2105 or ball assembly.
This configuration utilizing a combination of movable knock-out
pins and protuberances (that form deep dimples) along the interior
molding surfaces may be desirable for certain molding operations.
For instance, in the event that one or more layers are to be molded
or otherwise formed about a core or ball assembly, the positionable
knock-out pins may be used to retain the ball within the molding
cavity and in conjunction with the raised protuberances to further
secure the ball in a desired position. After molding, the knock-out
pins are moved to disengage the core or ball assembly, along with
one or more layers molded thereon, from the molding cavity.
Additionally, as described in conjunction with FIGS. 25-28, one or
more of the knock-out pins can be used to also form deep
dimples.
[0209] The previously described knock-out pins when fully extended
into, the molding chamber, preferably extend a distance of from
about 0.02 inches to about 0.140 inches as measured from the
corresponding and adjacent molding surface. The pins preferably
extend a distance corresponding to the desired depth of the deep
dimples to be formed in the resulting ball.
[0210] The knock-out pins described herein are selectively
positionable throughout a molding cycle. Accordingly, the pins may
be extended or retracted to any extent or degree before, during, or
after a molding operation. For certain applications, it may be
desirable to position the pins such that they are partially
extended into the molding chamber during a molding operation so as
to form deep dimples in a golf ball. After molding, instead of
retracting the pins, the pins may be extended to displace the
molded ball from the molding chamber. Preferably, the pins are
ultimately retracted or otherwise removed from the resulting molded
ball.
[0211] The preferred embodiment knock-out pins may also serve to
vent the molding chamber. Accordingly, the preferred embodiment
knock-out pins may serve one or more of the following functions:
(i) supporting a core or intermediate ball assembly during molding,
(ii) venting the mold, and (iii) displacing or extracting the
molded ball from the molding chamber.
[0212] The support function of the preferred embodiment knock-out
pins is performed by the pins retaining the core in the center of
the molding chamber until the pressure from the injected molding
material supports the core in a balanced manner so that the core is
maintained in the center of the chamber. The knock-out pins may
then be retracted so that they are flush with the molding surface.
The tip or distal end of each pin is preferably shaped like a deep
dimple. The knock-out pins must hold the core tightly so that the
core does not move during molding. The preferred locations for the
knock-out pins are as previously described with regard to the
raised protuberances.
[0213] Generally, since molding material typically enters the
molding chamber through an array of parting line gates arranged on
the ball's equators, and moves toward the top and bottom poles of
the ball, air or other gases may be trapped between the material
flow front and the poles. As noted, an additional function of the
knock-out pins is to provide venting of the gases otherwise trapped
in the molding chamber. Venting is accomplished by small gaps
between the pins and apertures in the mold, within which the pins
reside. Typical gaps or dimensions, i.e. the difference between the
pin diameter and the aperture diameter, range from about 0.003
inches to about 0.001 inches.
[0214] As noted, another function of the knock-out pins is to
displace or otherwise move the molded ball out of the molding
chamber. This is accomplished by extending the pins into their
respective mold after the molding material has sufficiently
solidified.
[0215] After molding, the golf balls produced may undergo various
further processing steps such as buffing, trimming, milling,
tumbling, painting and marking as disclosed in U.S. Pat. No.
4,911,451, herein incorporated by reference.
[0216] The resulting golf ball is produced more efficiently and
less expensively than balls of the prior art. Additionally, the
golf balls of the present invention may have multiple cover layers,
some of them very thin (less than 0.03 inches, more preferably less
than 0.02 inches, even more preferably less than 0.01 inches) if
desired, to produce golf balls having specific performance
characteristics. For example, golf balls having softer outer cover
layer(s) and harder inner cover layer(s) may be produced.
Alternatively, golf balls having harder outer cover layer(s) and
softer inner cover layer(s) may be produced. Moreover, golf balls
having inner and outer cover layers with similar hardnesses are
also anticipated by the present invention.
[0217] For golf balls having three or more layers, the hardness of
the layers may be varied alternately, such as hard-soft-hard, or
soft-hard-soft, and the like, or golf balls with a cover having a
hardness gradient may be produced. The hardness gradient may start
with hard inner layers closest to the core and get softer at the
outer layer, or vice versa. This allows a lot of flexibility and
control of finished golf ball properties. As previously described,
the layers may be of the same or different materials, and of the
same or different thicknesses.
[0218] In regards to forming a variety of golf balls, the present
invention also provides processes for forming a golf ball having at
least one deep dimple that is formed in one or more cover layers
that are formed by a RIM technique. Preferably, these processes are
carried out in conjunction with other features and aspects of the
present invention. For example, this process is as follows. An
intermediate golf ball assembly such as including a core or a core
and/or one or more intermediate layers disposed thereon, is
provided. A molding apparatus is also provided for molding an outer
cover layer about the intermediate golf ball assembly. The molding
apparatus includes a generally spherical molding chamber having a
first population or collection of raised regions defined along a
molding surface for forming a plurality of dimples on the outer
layer of the golf ball. The molding chamber also includes at least
one other raised region or collection of raised regions all of
which have a height that is greater than the thickness of the outer
layer to be formed on the golf ball. The process also includes a
step of positioning the intermediate golf ball assembly in the
molding chamber and administering a flowable material such as a
flowable cover layer material to the molding apparatus. Most
preferably, this material is introduced via multiple components
which react during the molding operation to form the desired cover
material. The material, or rather its components, is introduced
such that it flows around the intermediate golf ball assembly
disposed in the molding chamber. Preferably, the process includes a
step of also hardening the flowable material to thereby form the
outer layer. A key feature of this technique is that upon
positioning the intermediate golf ball assembly in the molding
chamber, the other raised region(s) of the molding chamber contacts
and preferably supports the intermediate golf ball assembly while
positioned within the molding chamber.
[0219] Specifically, the golf ball of the present invention is not
particularly limited with respect to its structure and
construction. By using well known ball materials and conventional
manufacturing processes, the balls may be manufactured as solid
golf balls including one-piece golf balls, two-piece golf balls,
and multi-piece golf balls with three or more layers and wound golf
balls.
[0220] The present invention is further illustrated by the
following examples in which the parts of the specific ingredients
are by weight. It is to be understood that the present invention is
not limited to the examples, and various changes and modifications
may be made in the invention without departing from the spirit and
scope thereof.
EXAMPLES
[0221] Golf balls according to the present invention were produced.
The golf balls had a core, a mantle or inner cover layer, and an
outer cover layer. The mantle was an ionomer, and the outer cover
was a polyurethane cover formed by a RIM process (Ball Type A). The
mold used had 6 support pins, 3 in each mold half, which formed
deep dimples in each hemisphere, located in a triangular
arrangement similar to that shown in FIG. 9. The balls were tested
against other balls, as described below. The results are shown in
Tables 3 to 5 below.
[0222] Ball Type B was a ball having a dual core, an ionomer mantle
and an injection molded polyurethane cover. Ball Type C was a ball
having a single core, an ionomer mantle and an ionomer cover. Ball
Type D was a commercial grade Strata.RTM. Tour Professional.TM.
ball, Ball Type E was a commercial grade Top-Flite.RTM.
Z-Balata.TM. 90 golf ball, Ball Type F was a commercial grade
Nike.RTM. Tour Accuracy TW.TM. ball, and Ball Type G was a
commercial grade Titleist.RTM. Pro V1.TM. ball.
[0223] Coefficient of restitution (C.O.R.) was measured by firing
the resulting golf ball in an air cannon at a velocity of 125 feet
per second against a steel plate positioned 12 feet from the muzzle
of the cannon. The rebound velocity was then measured. The rebound
velocity was divided by the forward velocity to give the
coefficient of restitution. Shore hardness was determined in
general accordance with ASTM Test 2240, but was measured on a
non-dimpled area of the surface of the golf ball as previously
described.
[0224] The scuff resistance test was conducted in the manner
described below. The balls that were tested were primed and top
coated. A sharp grooved sand wedge (56 degrees loft) was mounted in
a mechanical swing machine. The club swing speed used was 60 mph.
After each hit, the club face was brushed clean using a nylon
bristled brush. A minimum of three samples of each ball was tested.
Each ball was hit three times at three different locations so as
not to overlap with other strikes. The details of the club face are
critical, and are as follows:
[0225] Groove width--0.025 inches (cut with a mill cutter, leaving
a sharp edge to the groove; no sandblasting or post finishing
should be done after milling);
[0226] Groove depth--0.016 inches;
[0227] Groove spacing (one groove edge to the nearest adjacent
edge)--0.105 inches.
[0228] For each strike, a point value should be assigned for the
worst two defects according to the following Table 2:
2TABLE 2 Point Value Shear Defect 0 No visible defects 0.5 Lines 1
Lifts 2 Bad Lifts 2 Tiny (or Paint) Hairs 3 Bad Hairs 3 Shears (if
land area is removed on "hard" covers (65 Shore D+), rank as the
only defect 6 Bad Shears (dimples are completely removed, (max
value) rank as the only defect)
[0229] Example--a strike having a shear, tiny hairs, bad lifts and
a line would be ranked as a 5 (3 points for a shear and 2 points
for tiny hairs)
[0230] Note: The maximum value per strike is 6.
[0231] After completing all strikes, the average point value was
determined. This average point value, or rank, can be correlated to
the chart below.
3 Rank Average Point Value Excellent 0.0-1.0 Very Good 1.1-2.0 Good
2.1-3.0 Fair 3.1-4.0 Borderline 4.1-5.0 Poor (unacceptable)
5.1-6.0
[0232] Cut resistance was measured by utilizing a guillotine
cutting device.
[0233] The cut resistance of the balls tested herein was evaluated
on a scale of 1 to 5. The number 1 represents a cut that extends
completely through the cover to the core. A 2 represents a cut that
does not extend completely through the cover but that does break
the surface. A 3 does not break the surface of the cover but does
leave a permanent dent. A 4 leaves only a slight crease which is
permanent but not as severe as 3. A 5 represents virtually no
visible indentation or damage of any sort.
[0234] Cut and scuff testing was conducted on the golf balls of the
invention (Ball Type A), two experimental golf balls (Ball Types B
and C), and two commercial grade golf balls (Ball Types F and
G).
[0235] Initial velocity is the velocity of a ball when struck at a
hammer speed of 143.8 feet per second in accordance with a test as
prescribed by the U.S.G.A.
[0236] As used herein, "Shore D hardness" or "Shore C hardness" of
a core or cover component is measured generally in accordance with
ASTM D-2240, except the measurements are made on the curved surface
of the molded component, rather than on a plaque. Furthermore, the
Shore C and D hardness of the cover is measured while the cover
remains over the core. When a hardness measurement is made on a
dimpled cover, Shore C or Shore D hardness is measured at a land
area of the dimpled cover.
[0237] Spin rate testing was conducted with the finished
multi-layer golf balls (Ball Type A) of the invention, as well as
two other experimental multi-layer cover golf balls (Ball Types B
and C) using a driver, a 5 iron, a 9 iron, and a pitching
wedge.
[0238] For comparative purposes, two commercial grade golf balls
(Ball Types D and E) were also tested. The golf ball testing
machine was set up to emulate the launch conditions of an average
touring professional golfer for each particular club.
4TABLE 3 Ball Constructions and Test Results Nez Ball Size Weight
Riehle Comp. Fac- Cut Type (inches) (grams) Comp. (PGA) COR tor
Rank Scuff A 1.683 45.5 80 80 0.801 881 3 4* B 1.684 45.5 81 79
0.808 889 3 6 C 1.685 45.4 79 81 0.808 887 3 5.8 D 1.684 45.4 80 80
0.800 880 -- -- E -- -- -- -- -- -- 5 6 F -- -- -- -- -- -- 2 2.7*
*Defects were due to peeling of paint layers, not cover
materials
[0239] Note that Ball Type A had cut and scuff results as good as,
if not better than, most of the other ball types.
[0240] Below are the results of the spin rate and distance
testing:
5TABLE 4 Spin Rate Data (average for 12 hits per ball type) Launch
Total Spin Rate Ball Velocity Club Ball Type Angle (rpm) (ft./sec.)
Hogan A 10.3 2442 235.0 Prototype B 10.1 2776 236.0 Driver C 10.1
2776 236.5 D (Strata .RTM. Tour 10.0 2660 235.4 Professional) E
(Z-Balata 90) 10.0 2928 230.8
[0241]
6TABLE 5 Distance Data (average for 12 hits per ball type) Peak
Flight Total Ball Trajec- Time Time Carry Roll Distance Club Type
tory (sec) (sec) (yards) (yards) (yards) Hogan A 29.9 1.91 6.61
254.1 6.4 260.2 Prototype B 30.4 1.99 6.84 258.8 5.3 264.0 Driver C
31.3 2.04 6.91 257.2 3.4 260.3 D 29.4 1.85 6.49 252.1 5.8 257.9 Top
Flite A 46.6 1.93 6.47 176.1 3.1 179.2 Tour .TM. B 47.1 2.04 6.45
173.5 2.3 175.7 5 Iron C 47.4 2.08 6.51 173.5 1.6 175.1 D 45.6 1.96
6.49 177.1 2.4 179.5
[0242] Note that Ball Type A had results comparable to the other
ball types.
[0243] The foregoing description is, at present, considered to be
the preferred embodiments of the present invention. However, it is
contemplated that various changes and modifications apparent to
those skilled in the art may be made without departing from the
present invention. Furthermore, it will be understood that any of
the details, features, aspects or characteristics of a preferred
embodiment, may be combined with any other detail, feature, aspect,
or characteristic of another embodiment. Therefore, the foregoing
description is intended to cover all such changes and modifications
encompassed within the spirit and scope of the present invention,
including all equivalent aspects.
* * * * *