U.S. patent application number 09/800292 was filed with the patent office on 2001-10-04 for mantle surface topography for optimum energy transfer in multi-layer golf ball.
This patent application is currently assigned to SPALDING SPORTS WORLDWIDE, INC.. Invention is credited to Bellinger, Michelle A., Tavares, Gary.
Application Number | 20010027140 09/800292 |
Document ID | / |
Family ID | 27535850 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010027140 |
Kind Code |
A1 |
Bellinger, Michelle A. ; et
al. |
October 4, 2001 |
Mantle surface topography for optimum energy transfer in
multi-layer golf ball
Abstract
A multi-layer golf ball is disclosed having a mantle assembly,
comprising a core and one or more mantle layers disposed about the
core, and a cover disposed about the mantle assembly. At least one
of the one or more mantle layers of the mantle assembly has a
unique surface configuration. The unique surface configuration is
preferably a protuberant surface. Protuberant surface
configurations are preferably provided by a plurality of
geometrical shaped projections, which extend outwardly from the
surface. A protuberant surface provides a protuberant interface
between the layer having the protuberant surface and a layer
disposed immediately thereon. A protuberant interface is more
efficient in terms of energy transfer compared to traditional
smooth spherical golf ball layers. Additionally, a golf ball having
desired performance characteristics may be formed by the
incorporation of a unique protuberant interface.
Inventors: |
Bellinger, Michelle A.;
(West Hartford, CT) ; Tavares, Gary; (Banks,
OR) |
Correspondence
Address: |
MICHELLE BUGBEE, ASSOCIATE PATENT COUNSEL
SPALDING SPORTS WORLDWIDE INC
425 MEADOW STREET
PO BOX 901
CHICOPEE
MA
01021-0901
US
|
Assignee: |
SPALDING SPORTS WORLDWIDE,
INC.
|
Family ID: |
27535850 |
Appl. No.: |
09/800292 |
Filed: |
March 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09800292 |
Mar 5, 2001 |
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08998243 |
Dec 24, 1997 |
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08998243 |
Dec 24, 1997 |
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08920070 |
Aug 26, 1997 |
|
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|
6224498 |
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08920070 |
Aug 26, 1997 |
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08542793 |
Oct 13, 1995 |
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08542793 |
Oct 13, 1995 |
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08070510 |
Jun 1, 1993 |
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60227190 |
Aug 17, 2000 |
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Current U.S.
Class: |
473/356 |
Current CPC
Class: |
C08L 2666/04 20130101;
C08L 2666/02 20130101; C08L 2666/18 20130101; A63B 37/0003
20130101; C08L 23/08 20130101; A63B 37/008 20130101; C08L 75/04
20130101; C08L 53/00 20130101; C08L 23/08 20130101; C08L 23/08
20130101; A63B 37/0076 20130101; C08L 69/00 20130101; A63B 37/02
20130101; C08L 23/08 20130101; A63B 37/0037 20130101; C08L 23/0876
20130101; A63B 37/0097 20130101 |
Class at
Publication: |
473/356 |
International
Class: |
A63B 037/02; A63B
037/12 |
Claims
What is claimed:
1. A golf ball mantle assembly comprising: a core, and one or more
mantle layers disposed about the core, wherein the one or more
mantle layers comprise a material having a flexural modulus of from
1,000 psi to 400,000 psi, and at least one of the one or more
mantle layers has a protuberant surface defined by a plurality of
projections extending outward from the at least one mantle layer,
each projection having a height of at least 0.020 inches and a
width, as measured proximate the mantle layer from which the
projection extends, of from about 0.05 inches to about 0.20
inches.
2. The mantle assembly of claim 1, wherein the plurality of
projections each utilize the same geometrical shape.
3. The mantle assembly of claim 2, wherein the geometrical shape is
selected from the group consisting of hemispherical, elliptical,
conical, pyramidal, rectangular, hexagonal, pentagonal,
trapezoidal, and cylindrical.
4. The mantle assembly of claim 3, wherein the geometrical shape is
hemispherical.
5. The mantle assembly of claim 3, wherein the geometrical shape is
selected from the group consisting of hemispherical, cylindrical,
and conical, and the projections have a base diameter of from about
0.05 inches to about 0.200 inches.
6. The mantle assembly according to claim 5, wherein the
projections have a base diameter of from about 0.07 inches to about
0.190 inches.
7. The mantle assembly according to claim 6, wherein the
projections have a base diameter of from about 0.09 inches to about
0.180 inches.
8. The mantle assembly according to claim 3, wherein the
projections utilize a geometrical shape selected from the group
consisting of pyramidal, rectangular, hexagonal, pentagonal,
trapezoidal, and combinations thereof, and the base of the
projections have a length and width, independent of each other, of
from about 0.05 inches to about 0.20 inches.
9. The mantle assembly according to claim 8, wherein the base of
the projections have a length and width of from about 0.07 inches
to about 0.190 inches.
10. The mantle assembly according to claim 9, wherein the base of
the projections have a length and width of about 0.09 inches to
about 0.180 inches.
11. The mantle assembly according to claim 1, wherein the height of
the projections is from about 0.020 inches to about 0.06
inches.
12. The mantle assembly according to claim 1, wherein the plurality
of projections are angled projections.
13. The mantle assembly according to claim 12, wherein the angled
projections define a conical angle.
14. The mantle assembly according to claim 13, wherein the conical
angle is from about 75.degree. to about 110.degree..
15. The mantle assembly according to claim 12, wherein the angled
projections have a base diameter of from about 0.05 inches to about
0.200 inches.
16. The mantle assembly according to claim 12, wherein the angled
projections have a height of from about 0.02 inches to about 0.06
inches.
17. The mantle assembly according to claim 1, wherein the
projections are stepped projections.
18. The mantle assembly according to claim 17, wherein the stepped
projections comprise a plurality of steps.
19. The mantle assembly according to claim 18, wherein the
plurality of steps utilize the same geometrical shape.
20. The mantle assembly according to claim 19, wherein the
geometric shape of the plurality of projections is selected from
the group consisting of cylinders, rectangles, squares, rhombuses,
pentagons, hexagons, octagons, and triangles.
21. The mantle assembly according to claim 20, wherein the
geometric shape is a cylinder.
22. The mantle assembly according to claim 21, wherein the
cylindrical steps have a diameter of from about 0.05 inches to
about 0.130 inches.
23. The mantle assembly according to claim 22, wherein the
cylindrical steps have diameters that differ in an amount of from
about 0.005 inches to about 0.02 inches.
24. The mantle assembly according to claim 18, wherein the steps
each have a height of from about 0.005 inches to about 0.03
inches.
25. The mantle assembly according to claim 24, wherein the steps
have the same height.
26. The mantle assembly according to claim 1, further comprising an
innermost mantle layer and an outermost mantle layer, wherein the
outermost mantle layer has a protuberant surface defined by a
plurality of projections.
27. The mantle assembly according to claim 2, wherein the distance
between the bases of adjacent projections is from about 0.010
inches to about 0.250 inches.
28. The mantle assembly according to claim 1 wherein the one or
more mantle layers comprise a material having a flexural modulus of
from 10,000 psi to about 200,000 psi.
29. The mantle assembly according to claim 28 wherein the one or
more mantle layers comprise a material having a flexural modulus of
from about 40,000 psi to about 100,000 psi.
30. A golf ball comprising a cover layer disposed about the mantle
assembly according to claim 1.
31. A golf ball comprising a cover layer disposed about the mantle
assembly according to claim 26.
32. A mantle assembly comprising: a core; a first mantle layer
disposed about the core, the first mantle layer having a
protuberant surface defined by a plurality of projections; and a
second mantle layer disposed about the first mantle layer, the
second mantle layer having a protuberant surface defined by a
plurality of projections.
33. The mantle assembly according to claim 32, wherein the second
mantle layer defines an inner surface comprising a plurality of
depressions corresponding to the plurality of projections defining
the protuberant surface of the first mantle layer.
34. The mantle assembly according to claim 33, wherein the
projections of the first mantle layer are in adhesive contact with
the depressions and inner surface of the second mantle layer.
35. The mantle assembly according to claim 32, wherein the
projections of at least the first mantle layer and the second
mantle layer utilize a geometrical shape selected from the group
consisting of hemispherical, elliptical, conical, pyramidal,
rectangular, hexagonal, pentagonal, trapezoidal, cylindrical, and
combinations thereof.
36. The mantle assembly according to claim 35, wherein the
projections of the first mantle layer and the second mantle layer
utilize the same geometrical shape.
37. The mantle assembly according to claim 36, wherein the
projections of the first mantle layer exhibit the same arrangement
as the projections of the second mantle layer.
38. The mantle assembly according to claim 37, wherein the
projections of the first mantle layer exhibit an arrangement that
differs from the arrangement of the projections of the second
mantle layer.
39. The mantle assembly according to claim 35, wherein the size of
the projections of the first mantle layer is equal to the size of
the projections of the second mantle layer.
40. The mantle assembly according to claim 35, wherein the size of
the projections of the first mantle layer differs from the size of
the projections of the second mantle layer.
41. The mantle assembly according to claim 32 wherein the plurality
of projections of the first and second mantle layers have a height
of from 0.020 inches to 0.060 inches, and at least one of the first
mantle layer and the second mantle layer include a material having
a flexural modulus of from 1,000 psi to 400,000 psi.
42. The mantle assembly according to claim 32 wherein at least one
of the first mantle layer and the second mantle layer include a
material having a flexural modulus of from 10,000 psi to 200,000
psi.
43. The mantle assembly according to claim 42 wherein the material
has a flexural modulus of from 40,000 psi to about 100,000 psi.
44. A golf ball comprising: a mantle assembly comprising a core and
a mantle layer disposed about the core, the mantle layer having a
protuberant surface defined by a plurality of projections, and a
cover layer disposed about the mantle assembly and immediately
adjacent to the protuberant surface, wherein the projections
exhibit a geometrical shape selected from the group consisting of
hemispherical, conical, cylindrical, and angled, having a height of
from about 0.02 inches to about 0.06 inches and a base diameter of
from about 0.05 inches to about 0.200 inches.
45. The golf ball according to claim 44, wherein the cover layer
defines an inner surface having a plurality of depressions
corresponding to the projections that define the protuberant
surface of the mantle layer.
46. The golf ball according to claim 45, wherein the projections of
the mantle layer are in adhesive contact with the depressions of
the cover layer inner surface.
47. The golf ball according to claim 44, wherein the cover layer
exhibits a flexural modulus of from about 1,000 psi to about
100,000 psi and the mantle layer exhibits a flexural modulus of
from about 1,000 psi to about 400,000 psi.
48. The golf ball according to claim 47, wherein the cover layer
exhibits a flexural modulus of from about 1,000 psi to about 50,000
psi and the mantle layer exhibits a flexural modulus of from about
10,000 psi to about 200,000 psi.
49. The golf ball according to claim 48, wherein the cover layer
exhibits a flexural modulus of from about 1,000 psi to about 10,000
psi, and the mantle layer exhibits a flexural modulus of from about
40,000 psi to about 100,000 psi.
50. The golf ball according to claim 47, wherein the cover layer
and the mantle layer comprise a material selected from the group
consisting of low acid ionomers, high acid ionomers,
polyamide-ionomer compositions, polyurethanes, and combinations
thereof.
51. The golf ball according to claim 50, wherein the cover layer
comprises a low acid ionomer and the mantle layer comprises a high
acid ionomer.
52. A golf ball comprising: a core; a first mantle layer disposed
about the core, the first mantle layer having a protuberant surface
defined by a plurality of outwardly extending projections; a second
mantle layer disposed about the first mantle layer, the second
mantle layer defining an inner surface layer and an outer surface
layer, the inner surface layer defining a plurality of depressions,
the outer surface layer having a protuberant surface defined by a
plurality of projections; and a cover layer disposed about the
second mantle layer, the cover layer defining an inner surface
layer and a dimpled surface layer, the inner surface layer
comprising a plurality of depressions, wherein the depressions on
the inner surface layer of the second mantle layer correspond to
the projections of the first mantle layer, and the depressions on
the inner surface layer of the cover layer correspond to the
projections of the second mantle layer.
53. The golf ball according to claim 52, wherein the projections of
the first mantle layer are in adhesive contact with the
corresponding depressions on the inner surface of the second mantle
layer, and the projections of the second mantle layer are in
adhesive contact with the corresponding depressions on the inner
surface layer of the cover layer.
54. The golf ball according to claim 52, wherein a first
protuberant interface is defined between the outer surface of the
first mantle layer and the inner surface of the second mantle
layer, and a second protuberant interface is defined between the
outer surface of the second mantle layer and the inner surface of
the cover layer.
55. A golf ball comprising: a core; a mantle layer disposed about
the core defining a protuberant outer surface configuration
provided by a plurality of stepped projections; and a cover layer
disposed about the mantle layer.
56. The golf ball according to claim 55, wherein each of the
stepped projections comprise a plurality of steps.
57. The golf ball according to claim 56, wherein the plurality of
steps utilize the same geometrical shape.
58. The golf ball according to claim 57, wherein the geometrical
shape is selected from the group consisting of cylinders,
rectangles, squares, rhombuses, pentagons, hexagons, octagons, and
triangles.
59. The golf ball according to claim 58, wherein the geometrical
shape is a cylinder.
60. The golf ball according to claim 59, wherein the steps have a
diameter of from about 0.05 inches to about 0.130 inches.
61. The golf ball according to claim 60, wherein abutting steps
have diameters that differ in an amount of from about 0.005 inches
to about 0.02 inches.
62. The golf ball according to claim 60, wherein the diameter of
ascending steps decreases.
63. The golf ball according to claim 56, wherein each of the steps
have a height of from about 0.005 inches to about 0.003 inches.
64. The golf ball according to claim 63, wherein each of the steps
have the same height.
65. The golf ball according to claim 55, wherein the stepped
projections comprise at least two steps.
66. The golf ball according to claim 65, wherein the stepped
projections comprise two to twelve steps.
67. The golf ball according to claim 66, wherein the stepped
projections comprise three to eight steps.
68. The golf ball according to claim 67, wherein the stepped
projections comprise four to six steps.
Description
FIELD OF THE INVENTION
[0001] This is a continuation-in-part application of U.S. Applicant
Ser. No. 08/998,243, filed Dec. 24, 1997, which is a divisional of
U.S. application Ser. No. 08/920,070 filed Aug. 26, 1997, which in
turn is a continuation of U.S. application Ser. No. 08/542,793,
filed Oct. 13, 1995, now abandoned, which is a continuation-in-part
of U.S. application Ser. No. 08/070,510, filed Jun. 1, 1993, now
abandoned. This application also claims priority from U.S.
Provisional Application Serial No. 60/227,190 filed on Aug. 17,
2000.
BACKGROUND OF THE INVENTION
[0002] Generally, golf balls are one of three types. A first type
is a multi-piece wound ball wherein a vulcanized rubber thread is
wound under tension around a solid or semi-solid core, and
thereafter enclosed in a single or multi-layer covering of a tough,
protective material. A second type of golf ball is a one-piece ball
formed from a solid mass of a resilient material which has been
cured to develop the necessary degree of hardness to provide
utility. One-piece molded balls do not have a second enclosing
cover. A third type of ball is a multi-piece non-wound ball which
includes a liquid, gel or solid core of one or more layers and a
cover having one or more layers formed over the core.
[0003] Attempts to improve and/or optimize performance
characteristics in golf balls are typically directed toward
achieving better feel when the ball is struck with a golf club, and
also allowing for increased or optimum distance while at the same
time adhering to the rules set forth by the United States Golf
Association (U.S.G.A.) regarding the physical characteristics and
performance properties of golf balls. These rules specify that the
weight of a golf ball shall not be greater than 1.620 ounces, the
diameter of the ball shall not be less than 1.680 inches and the
velocity of the ball shall not be greater than 250 feet per second.
The U.S.G.A. rules also specify that the overall distance a golf
ball should travel shall not cover an average distance (in carry
and roll) greater then 280 yards.
[0004] Over the years, attempts to improve characteristics such as
feel and durability have centered around the materials used to form
the various layers of a golf ball.
[0005] Improvements in spin and distance characteristics are
usually directed toward the actual construction and physical makeup
of the golf ball. The use of one or more intermediate layers
between a core and a cover layer to achieve such improvements is
known in the art. The thickness and/or material hardness of each
layer may also be varied in order to achieve a desired
property.
[0006] Attempts at improving spin and distance characteristics have
included employing a core or inner cover layer that utilize an
outer surface with a particular configuration. Specifically, U.S.
Pat. No. 5,836,834 and U.S. Pat. No. 5,984,807 describe golf balls
that use inner cores with certain shaped projections. Both the '834
patent and the '807 patent also describe forming another core layer
around the inner core such that the core is essentially a
concentric, smooth surfaced dual core.
[0007] U.S. Pat. No. 5,820,485 describes a golf ball employing an
inner cover layer having a collection of projections. An outer
cover layer covers the inner layer.
[0008] In general, there is a natural transfer of energy that
occurs within a golf ball when the ball is struck by a golf club.
Energy is transferred from the club face to the golf ball cover,
and then subsequently transferred through each layer beneath the
cover. In solid non-wound golf balls employing spherical layers,
energy transfer is generally a function of the thickness and
material composition of a given layer.
[0009] Therefore, varying either the thickness of a given layer
and/or the material from which a layer is made affects the
efficiency of energy transfer occurring within a golf ball and
consequently affects the overall performance characteristics of
that ball.
[0010] There still exists a need for a golf ball design that
improves the energy transfer occurring within a golf ball, after
being struck by a golf club, such that the design may be varied in
order to achieve different, desirable performance
characteristics.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide a
multi-layer golf ball, in which one or more intermediate layers
have a unique surface configuration.
[0012] Another object of the invention is to provide a multi-layer
golf ball wherein one or more intermediate layers have a
protuberant surface configuration as described herein.
[0013] Yet another object of the invention is to form a multi-layer
golf ball, in which one or more mantle layers have a protuberant
surface configuration formed by a plurality of outwardly extending
projections.
[0014] A further object of the invention is to provide a
multi-layer golf ball having one or more mantle layers in which the
properties of the ball are optimized by the surface configuration
of at least one of the one or more mantle layers and the materials
used to construct the ball.
[0015] Still another object of the invention is to optimize the
transfer of energy occurring within a multi-layer golf ball, when
the ball is struck with a golf club, by providing a surface
interface between adjacent layers that results in an efficient
transfer of energy between the layers.
[0016] Yet another object of the invention is to provide a golf
ball mantle assembly which includes a core and one or more mantle
layers disposed about the core, wherein at least one of the one or
more mantle layers has a protuberant surface provided by a
plurality of projections.
[0017] A further object of the invention is to provide a golf ball
having a cover layer disposed about a mantle assembly described
above.
[0018] The present invention achieves all of the foregoing noted
objectives and provides, in a first aspect, a golf ball mantle
assembly comprising a core and one or more mantle layers disposed
about the core. At least one of the mantle layers has a protuberant
surface that is defined by a plurality of projections extending
outward from the mantle layer.
[0019] In another aspect, the present invention provides a mantle
assembly comprising a core, a first mantle layer disposed about the
core and a second mantle layer disposed about the first mantle
layer. Each of the first mantle layer and the second mantle layer
have a protuberant surface defined by a plurality of
projections.
[0020] In still another aspect, the present invention provides a
golf ball comprising a mantle assembly that includes a core and a
mantle layer disposed about the core. The mantle layer includes a
plurality of outwardly extending projections that define a
protuberant surface. The projections exhibit a geometrical shape
selected from the group consisting of hemispherical, conical,
cylindrical, and angled, having a height of from about 0.02 inches
to about 0.06 inches and a base diameter of from about 0.05 inches
to about 0.200 inches. The ball further comprises a cover layer
disposed about the mantle assembly and immediately adjacent to the
protuberant surface.
[0021] In yet another aspect the present invention provides a golf
ball comprising a core, a first mantle layer disposed about the
core having a protuberant surface defined by a plurality of outward
extending projections, a second mantle layer disposed about the
first mantle layer, and a cover layer disposed about the second
mantle layer. The second mantle layer defines an inner surface
layer comprising a plurality of depressions, and an outer surface
layer having a protuberant surface defined by a plurality of
projections. The cover layer defines an inner surface layer and a
dimpled outer surface layer. The inner surface layer comprises a
plurality of depressions. The depressions on the inner surface
layer of the second mantle layer correspond to the projections of
the first mantle layer, and the depressions on the inner surface of
the cover layer correspond to the projections of the second mantle
layer.
[0022] In a further aspect, the present invention provides a golf
ball comprising a core, a mantle layer disposed about the core and
a cover layer disposed about the mantle layer. The mantle layer
comprises a protuberant surface configuration provided by a
plurality of stepped projections.
[0023] Other objects of the present invention will become apparent
upon a reading and understanding of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a cross-section of a conventional prior art
non-wound multi-layer golf ball having one intermediate layer;
[0025] FIG. 2 is a cross-section of a conventional prior art
non-wound multi-layer golf ball having two intermediate layers;
[0026] FIG. 3a is a schematic cross-section of a cover and a mantle
layer in a conventional prior art golf ball having a smooth
interface therebetween;
[0027] FIG. 3b is a diagram showing the transfer of energy
occurring between the layers of a conventional prior art golf ball
having a smooth interface therebetween;
[0028] FIG. 4a is a schematic cross-section of a cover layer and a
mantle layer in a golf ball having a protuberant interface
therebetween in accordance with the present invention;
[0029] FIG. 4b is a diagram showing the transfer of energy
occurring between the layers of a golf ball having a protuberant
interface therebetween in accordance with the present
invention;
[0030] FIG. 5a is a cross-sectional view of a hemispherical
projection of a protuberant mantle layer;
[0031] FIG. 5b is a top view of the projection in FIG. 5a;
[0032] FIG. 6a is a cross-sectional view of an angled projection of
a protuberant mantle layer;
[0033] FIG. 6b is a top view of the projection of FIG. 6a;
[0034] FIG. 7a is a cross-sectional view of a stepped projection of
a protuberant mantle layer;
[0035] FIG. 7b is a top view of the projection of FIG. 7a;
[0036] FIG. 7c is the cross-sectional view of FIG. 7a, further
illustrating dimensional characteristics of the stepped
projection;
[0037] FIG. 8a is a perspective view of a mantle assembly of a
first preferred embodiment;
[0038] FIG. 8b is a cross-section of the mantle assembly shown in
FIG. 8a;
[0039] FIG. 9a is a perspective view of a mantle assembly of a
second preferred embodiment;
[0040] FIG. 9b is a cross-section of the mantle assembly in FIG.
9a;
[0041] FIG. 10 is a cross-sectional view of a mantle assembly of a
third preferred embodiment;
[0042] FIG. 11 is a cross-sectional view of a mantle assembly of a
fourth preferred embodiment;
[0043] FIG. 12 is a cross-sectional view of a three-piece,
non-wound golf ball employing a mantle assembly of the first
preferred embodiment;
[0044] FIG. 13 is a cross-sectional view of a four-piece, non-wound
golf ball employing a mantle assembly of the first preferred
embodiment;
[0045] FIG. 14 is a cross-sectional view of a three-piece,
non-wound golf ball employing a mantle assembly of the second
preferred embodiment;
[0046] FIG. 15 is a cross-sectional view of a four-piece, non-wound
golf ball employing a mantle assembly of the second preferred
embodiment;
[0047] FIG. 16 is a cross-sectional view of a golf ball employing a
mantle assembly of the third preferred embodiment; and
[0048] FIG. 17 is a cross-sectional view of a golf ball employing a
mantle assembly of the fourth preferred embodiment.
[0049] The above-referenced figures are not to scale, but are
merely illustrative of the enclosed invention. In addition, several
of the figures are schematic in nature. Specifically, the figures
are for purposes of illustrating the enclosed invention, and not to
be construed as limiting the invention described herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0050] The present invention is based on the discovery by the
inventors that by incorporating a particular surface configuration
between adjacent layers of a golf ball, such as between a core and
cover layer or, core and intermediate layer or, between an
intermediate layer and a cover layer or, between adjacent
intermediate layers, desired performance properties may be
obtained. In accordance with the present invention, a golf ball is
provided that utilizes a surface topography at one or more interior
layer interfaces that allows energy to be transferred between
regions of the ball efficiently and in a manner such that desirable
performance characteristics are achieved.
[0051] Multi-layer golf ball constructions are known in the art.
Multi-layer golf balls typically include a core, a dimpled cover
layer and one or more mantle layers disposed therebetween. The term
"mantle layer" as used herein refers to any intermediate layer
disposed between the core and the cover of a golf ball.
[0052] FIGS. 1 and 2 show cross-sectional views of prior art
three-piece and four-piece non-wound golf balls, respectively. FIG.
I represents a three-piece, non-wound golf ball 10 having a core
12, a mantle layer 14 disposed about core 12, and dimpled cover
layer 16. FIG. 2 represents a four-piece, non-wound golf ball 20
having a core 21, two mantle layers 22 and 23 disposed about core
21 and dimpled cover layer 24.
[0053] Mantle layers are often considered to contribute to a
respective layer of a golf ball, i.e., they are typically
considered part of the core or the cover layer. Standard convention
is to consider a mantle layer a member of a respective layer based
on the material from which the mantle layer is constructed. A
mantle layer constructed of the same material, or material similar
to that, as the core and immediately molded over or otherwise
formed about the core would be considered a dual core or core
assembly. Likewise, mantle layers constructed of material similar
to that of a cover layer are typically considered an inner cover
layer.
[0054] Conventional multi-layer golf balls are typically
constructed from uniform spherical layers, i.e., layers having a
smooth round surface. A smooth surface, as used herein refers to a
continuous even surface, i.e., a surface generally free from any
disturbances or protrusions in the surface topography. The inner
layers, i.e., the core and mantle layers, of golf ball 10 and golf
ball 20 shown in FIGS. 1 and 2, respectively, are smooth-surfaced,
spherical layers.
[0055] Interfaces occur at surface boundaries where immediately
adjacent layers adhere to or are in intimate contact with one
another. Inner layers of golf balls 10 and 20 of FIGS. 1 and 2,
respectively, have smooth spherical surfaces. Consequently, a
smooth surface interface is formed between adjacent layers, in each
of the respective golf balls. A smooth interface 17 is formed
between core 12 and mantle layer 14 and another smooth interface 18
is formed between mantle layer 14 and cover layer 16 in the golf
ball of FIG. 1. Similarly, in FIG. 2, smooth interfaces 25, 26, 27
are formed between core 21 and mantle layer 22, between mantle
layer 22 and mantle layer 23, and between mantle layer 23 and cover
layer 24, respectively.
[0056] When a golf ball is struck with a golf club, energy is
transferred from the face of the club to the cover of the ball and
subsequently transferred from the cover to each layer below the
cover. Typically, the cover layer material and the mantle layer
material differ in both their compositions and physical properties.
Therefore, the energy transfer occurring throughout a golf ball
must propagate through different materials via one or more smooth
interfaces, which affects the transfer of energy within a golf
ball. Additionally, different layers typically have different
thicknesses, which also affects the transfer of energy within a
golf ball.
[0057] In addition to differing compositions and physical
properties, the physical arrangement or configuration of the
interface between adjacent layers also affects the transfer of
energy between respective layers. FIG. 3a represents a schematic
cross-section of a golf ball having a cover layer 30 of a
particular thickness and modulus (in terms of a particular type of
material) and a mantle layer 32 of a different thickness and
modulus. A smooth interface 34 is defined between the two layers.
The smooth interface 34 represents any of the smooth interfaces 17,
18, 25, 26, 27 of FIGS. 1 and 2, respectively. FIG. 3b in a graph
illustrating the transfer of energy occurring between adjacent
layers of a golf ball having a smooth interface as represented in
FIG. 3a. The transfer of energy from one layer to another in a ball
having a smooth interface between the respective layers is very
sudden and rather abrupt. It is believed that significant
inefficiencies result from such energy transfers across smooth
interfaces.
[0058] It is desirable, therefore, to incorporate a structural
feature in a golf ball, specifically along the interface between
adjacent layers of a golf ball that allows for an efficient and
less abrupt transfer of energy between adjacent golf ball layers or
interior regions.
Protuberant Surface Configurations
[0059] It has been discovered that changing the surface
configuration of a mantle layer so that the mantle layer no longer
has a uniformly smooth surface, alters the manner in which energy
is transferred between adjacent layers.
[0060] A protuberant surface provides an alternative to a smooth
surface. A protuberant surface contains outwardly extending bulges,
protrusions or projections creating a surface with a unique contour
or topography.
[0061] In a golf ball, a mantle layer having a protuberant surface,
referred to herein as a protuberant mantle layer, contains
outwardly extending, and preferably radially extending bulges,
projections, or protuberances that impart contours or other
irregularities to the surface.
[0062] When a golf ball layer is molded over or otherwise formed
about a protuberant mantle layer, such as a cover or another mantle
layer, the resulting interface between the two layers is not
smooth, but rather conforms to the topography of the surface of the
protuberant mantle layer. An interface occurring between a
protuberant mantle layer and a golf ball layer molded immediately
thereon is referred to herein as a protuberant interface.
[0063] FIG. 4a illustrates a representative embodiment of a
protuberant surface in accordance with the present invention. In
FIG. 4a, mantle layer 42 has a protuberant surface topography
created by projections 44. Projections 44, shown in cross-section
of FIG. 4a, are representative of cylindrical and/or rectangular
projections. A protuberant interface, as illustrated in FIG. 4a,
results from the cover 40 being in intimate contact with the
protuberant surface of mantle layer 42. Surface 46, extends between
the base or side wall of a given projection and the base or side
wall of any next nearest projection. Unless otherwise noted, the
distance between projections is defined in terms of the distance
between the base of a given projection and the base of a next
nearest projection.
[0064] FIG. 4b is a graph demonstrating the transfer of energy that
occurs across the interface between adjacent layers in which the
mantle layer has a protuberant surface topography, thereby
providing a protuberant interface between the mantle layer and
adjacent layer, such as the interface of FIG. 4a. Energy transfer
between adjacent layers having a protuberant interface therebetween
is gradual and more efficient over the total thickness of the
respective layers than the energy transfer occurring across a
smooth interface. FIG. 4b is representative of the typical transfer
of energy that occurs between adjacent layers having a protuberant
surface therebetween. FIG. 4b is merely illustrative, and not to be
considered a limiting example of energy transfer across a
protuberant interface. Energy transfer between adjacent layers of a
golf ball having a protuberant interface therebetween is a function
of several factors including: the thickness of the respective
layers; the material used to construct the respective layers; and
the surface topography which gives rise to the protuberant
interface. A change in any of the noted parameters affects the
energy transfer occurring between adjacent layers.
[0065] A protuberant interface occurs at the surface boundary where
immediately adjacent layers adhere to and/or are in intimate
contact with one another and is created by either of the adjacent
layers having a protuberant surface. Preferably, of the two layers,
the "lower" or underlying layer exhibits a protuberant surface. A
protuberant surface, as previously described herein, is preferably
formed by a plurality of outwardly extending bulges, protrusions or
projections.
[0066] The outwardly extending bulges, contours, or regions on a
protuberant mantle layer according to the present invention are
preferably formed by a plurality of projections. Projections are
preferably in the form of geometrical shapes selected from the
group including, but not limited to, hemispherical, elliptical,
conical, pyramidal, rectangular, hexagonal, pentagonal,
trapezoidal, and cylindrical.
[0067] In one embodiment, projections are preferably hemispherical.
FIG. 5a represents hemispherical projection 50 extending outwardly
from surface 52. Surface 52 is representative of the outer surface
of a mantle layer. FIG. 5b is a top view of projection 50
displaying the circular base of the hemispherical projection.
[0068] The present invention also contemplates angled projections.
Angled projections are substantially conical projections that
extend outwardly from the surface (of a mantle layer) and angle
toward a single point. However, angled projections differ from
conical projections in that angled projections are rounded and/or
curved toward the apex of the projection and do not form a single
point. FIG. 6a displays an embodiment of an angled projection 60
extending outwardly from surface 62. As illustrated in FIG. 6a,
angled projections are substantially conical in that extending the
outer angled walls of projection 60, represented by dashed lines 64
and 66, to a single point 65 provides a cone. FIG. 6b is a top view
of projection 60 displaying the circular base of the angled
projection.
[0069] Protuberant surface configurations may also be provided by
stepped projections, as illustrated in FIG. 7a. Stepped projections
include a step abutting and extending outwardly from the surface of
a mantle layer and at least one step extending therefrom.
Preferably stepped projections include a plurality of steps,
wherein each step extends outwardly from an immediately adjacent
underlying step. Preferably each respective step exhibits a
substantially even or flat surface area. FIGS. 7a-7c display
stepped projection 70 extending outwardly from surface 72. Stepped
projection 70 includes a base step 70a extending directly from
surface 72. A plurality of steps (70b-70e) successively extend
outward from disc 70a. Each successive step is preferably smaller,
in terms of diameter, length and/or width, than the immediately
adjacent underlying step from which it extends, i.e., step 70b is
smaller than 70a, step 70c is smaller than step 70b, etc. The
present invention also contemplates an inverted step arrangement
wherein the step abutting the mantle layer is the smallest step and
the size of each successive step increases.
[0070] FIG. 7b is a top view of stepped projection 70. According to
FIG. 7b, stepped projection 70 is comprised of circular discs
70a-70e, wherein the diameter (and/or radius) of each disc
decreases from 70a to 70e, i.e., disc 70e exhibits the smallest
diameter. The present invention also contemplates that stepped
projections may be formed utilizing geometrical shaped steps,
including but not limited to, squares, rectangles, rhombuses,
pentagons, hexagons, octagons, triangles, and the like. Stepped
projections preferably employ steps having the same shape. However,
the present invention contemplates employing different shaped steps
to form a stepped projection.
[0071] Projection size is defined in terms of the dimensions of the
base of the projection and also the height of the projection. For
hemispherical, cylindrical, elliptical, conical and angled
projections, base size refers to the diameter of the base of the
individual projections. In FIG. 5a, 6a and 7a, the diameter d is
defined by the distance between the points at which opposite, i.e.,
polar, ends of the projection base make contact with the outer
surface of a mantle layer. In the case of pyramidal, rectangular,
pentagonal, hexagonal, and trapezoidal projections, base size
refers to the length and/or width of the base of individual
projections, defined by the points at which the base (of each
respective side) of the projection contacts the surface of the
mantle layer. The base diameter or, in the alternative, the length
and/or width is preferably from about 0.05 inches to about 0.20
inches, more preferably from about 0.07 inches to about 0.190
inches, and most preferably from about 0.09 inches to about 0.180
inches.
[0072] Angled projections and conical projections further exhibit
and define a conical angle .phi., as illustrated in FIG. 6a. Angled
projections, as previously described herein, are substantially
conical and therefore may be defined by a conical angle. The
conical angel .phi. is preferably from about 75.degree. to about
110.degree..
[0073] Preferably, particularly with respect to conical, pyramidal,
pentagonal, hexagonal, and trapezoidal projections, the diameter,
length and/or width of the base of a projection is equal to or
greater than the diameter, length, and/or width of the apex, i.e.
the top most point, of the projection. Most preferably, the base
diameter, length and/or width of a projection is greater than the
diameter, length, and/or width of its apex. The present invention
also contemplates forming a protuberant mantle layer comprising a
plurality of projections wherein the base of a projection has a
diameter, length, and/or width less than the diameter, length
and/or width of the apex.
[0074] The height or depth of the projection is defined from the
surface of the mantle layer to the apex of the projection.
Projections reside on or extend outwardly from a curved and/or a
substantially spherical surface. Consequently, a surface arc is
defined between polar ends on the base of a projection, where each
end of the projection makes contact with the outer surface of the
mantle layer. The depths of projections is defined by the distance
h between the apex of the surface arc and the apex of a given
projection, as, for example, is illustrated in FIGS. 5a, 6a and 7a.
The depths of projections are at least about 0.020 inches.
Preferably, the depths of projections are between about 0.020
inches and 0.060 inches.
[0075] Stepped projections are further defined by the number of
steps and the size of each individual step. Steps are defined based
upon the shape of each respective step. Cylindrical projections,
i.e., disc shaped steps, are defined by the diameter or,
alternatively the radius, and the step height. Steps exhibiting
other shapes, i.e., square, rectangle, rhombuses, hexagon,
pentagon, octagon, triangles etc., are defined by the height,
length and/or width of each step. Steps preferably have a diameter,
length and/or width of from about 0.05 inches to about 0.130
inches. Preferably, step size, in terms of diameter, length, and/or
width, decreases from the base step to the outermost step in
uniform increments, i.e., each given step has a diameter, length
and/or width less than the diameter, length and/or width of the
step immediately therebeneath. The present invention also
contemplates stepped projections wherein step size does not
decrease from the base step to the outermost step in uniform
increments. The size difference, in terms of the diameter, length
and/or width, of adjacent steps is preferably from about 0.005
inches to about 0.02 inches.
[0076] Preferably, the height of each respective step, i.e., the
height increments, are equal. The present invention also
contemplates employing steps of different heights in a stepped
projection. Step height increments are preferably from about 0.005
inches to about 0.03 inches.
[0077] Step heights depend upon the number of steps employed in a
stepped projection. Stepped projections employ at least two steps.
Stepped projections preferably employ from about two steps to about
twelve steps, more preferably from about three steps to about eight
steps, and most preferably from about four steps to about six
steps.
[0078] Projections may be arranged in any manner to form a
protuberant surface. Patterns and arrangements of projections are
selected as desired to yield various properties and/or
characteristics in a final golf ball product. Additionally,
projections may be arranged such that the bases of adjacent
projections are in contact with one another or such that the bases
of adjacent projections are not in contact with another. For
example, in FIG. 4a, the base of a given projection does not make
contact with the base of any next nearest projection. Subsequently,
a region of the given mantle layer is exposed. The exposed region
is considered to be a smooth surface region, as would be found in a
mantle construction having a smooth surface. Arrangement of
projections is more fully described in accordance with the
preferred embodiments. Preferably the distance between the bases of
adjacent projections is from about 0.010 inches to about 0.250
inches, and more preferably between about 0.020 inches to about
0.200 inches.
[0079] A protuberant mantle layer preferably comprises projections
of the same shape and having equal dimensions, i.e., having equal
size. When projections of equal dimensions are employed, the apex
of the projections are considered to be co-planar with each other.
However, the present invention encompasses the use of projections
having different dimensions in terms of the height, base diameter,
and/or base length and width of the projection.
[0080] The present invention encompasses protuberant mantle layers
having a protuberant surface formed by projections of different
geometric shapes. Protuberant mantle layers optionally comprise
combinations of two or more geometrical shaped or stepped
projections. Multiple geometric shapes are arranged in any pattern
as desired to provide a mantle layer and/or assembly with a
protuberant surface. A non-limiting example of such an embodiment
is a protuberant mantle layer formed by hemispherical and angled
projections. The projections could be arranged in any manner such
that spherical and/or angled projections were repeating, i.e., a
projection of a given shape would be immediately adjacent to a
projection of the same shape. Additionally, the projections could
be arranged in an alternating or generally non-repeating
fashion.
[0081] Another non-limiting example of utilizing multiple geometric
shapes in accordance with the present invention is a protuberant
mantle assembly formed by pyramidal, hexagonal, and trapezoidal
projections. Accordingly, the projections may be arranged in a
repeating or non-repeating manner, such that desired properties are
achieved.
Mantle Assemblies
[0082] Preferably, a protuberant mantle layer, as previously
described herein, is part of a mantle assembly. A mantle assembly
according to the present invention is comprised of a core and one
or more mantle layers disposed about the core, wherein at least one
of the one or more mantle layers has a protuberant surface. In a
preferred embodiment, the outermost mantle layer of a mantle
assembly comprises a plurality of projections that provide the
outermost mantle layer with a protuberant surface. Projections, as
previously described herein, are most preferably in the form of
repeating geometrical shapes. And, it is preferred that the
plurality of projections are arranged in a uniform or repeating
pattern. However, the present invention encompasses the
simultaneous use of multiple geometric shapes and generally
non-repeating shapes. And, the present invention includes the use
of non-uniform or non-repeating patterns of projections.
[0083] Preferably, a mantle assembly comprising a protuberant
mantle layer is generally spherical. While a protuberant mantle
layer does not have a uniformly smooth or even surface topography
due to the plurality of projections as described herein, in a most
preferred form, the overall shape of the layer is generally
spherical and/or circular.
[0084] FIG. 8a displays a mantle assembly 80 of a first preferred
embodiment mantle assembly in accordance with the present
invention. The mantle assembly 80 comprises a mantle layer 81 on
its outer surface. Hemispherical projections 82 provide the mantle
layer with a protuberant surface. A flat or smooth surface area 84
is formed on the outer mantle layer of the mantle assembly 80 in
the first preferred embodiment, and is defined within the region
between adjacent projections.
[0085] FIG. 8b is a cross-section of the mantle assembly of FIG. 8a
and provides a view of the entire mantle assembly 80 including a
mantle layer 81 and a core 86. Projections 82 and smooth surface 84
generally extending between the projections 82 provide mantle layer
81 with a protuberant surface. The projections 82 of the mantle
assembly 80 can be of any shape or size described herein.
[0086] A second preferred embodiment of a mantle assembly according
to the present invention is illustrated in FIGS. 9a and 9b. FIG. 9a
displays a mantle assembly 90 having a mantle layer 92. Mantle
layer 92 has a protuberant surface configuration provided by a
plurality of hemispherical projections 94. The present invention
contemplates that projections 94 can be of any shape or size
described herein. In the second preferred embodiment, the base of
any selected projection makes contact with the base of each
projection to which it is immediately adjacent. Therefore, no
exposed smooth surfaces exists on the outer surface of the mantle
assembly of the second preferred embodiment.
[0087] FIG. 9b is a cross-section of FIG. 9a and shows mantle
assembly 90 of the second preferred embodiment. Mantle assembly 90
comprises a mantle layer 92 having a plurality of projections 94
molded over a core 96. The projections 94 of the second preferred
embodiment preferably are of equal dimensions.
[0088] FIG. 9b also demonstrates the arrangement of the projections
94, i.e., the base of a projection is in intimate contact with the
base of each immediately adjacent projection.
[0089] A third preferred embodiment of a mantle assembly of the
present invention is shown in FIG. 10. Multi-layer mantle assembly
100 comprises three layers, a core 102, an inner mantle layer 104
and an outer mantle layer 106. The inner mantle layer 104 is
disposed between the core 102 and the outer mantle layer 106.
[0090] The outer mantle layer 106 comprises a plurality of
projections 108, which provide the outer mantle layer with a
protuberant surface. Projections 108 of the third preferred
embodiment exhibit an arrangement similar to the arrangement of the
projections according to the second preferred embodiment, i.e., the
base of a projection is in immediate contact with the base of each
immediately adjacent projection. Alternatively, a smooth surface
may extend between the projections 108. Additionally, projections
108 can be of any shape or size as described herein.
[0091] FIG. 11 a cross-sectional view of a fourth preferred
embodiment of a multi-layer mantle assembly 110 according to the
present invention. Multi-layer mantle assembly 110 comprises core
111, a first protuberant mantle layer 112 having a plurality of
projections 113 disposed about the core 111, and a second
protuberant mantle layer 114 having a plurality of projections 115
disposed about the first protuberant mantle layer 112. First
protuberant mantle layer 112 exhibits a protuberant surface
configuration provided by a plurality of hemispherical projections
113 arranged such that the base of a projection is in immediate
contact with the base of each immediately adjacent projection.
Second protuberant mantle layer 114 exhibits a protuberant surface
provided by a plurality of projections 115 and smooth surface 116
generally extending between the projections.
[0092] Second protuberant mantle layer 114 defines an inner surface
that adheres to or makes contact with the outer surface of mantle
layer 112. Additionally, first protuberant mantle layer 112 defines
an inner surface that adheres to or is in intimate contact with the
outer surface of core 111. Depressions are formed on the inner
surface of second protuberant mantle layer 114 and are defined by
projections 113 on the outer surface of first protuberant mantle
layer 112. Specifically, depressions on the inner surface of second
protuberant mantle layer 114 exhibit a shape that is the negative
shape of a corresponding projection on the outer surface of first
protuberant mantle layer 112.
[0093] Depressions are formed on the inner surface of any layer
formed immediately over a protuberant mantle layer. Depressions are
defined by projections, bulges, or other contours on the surface of
the protuberant mantle layer, i.e., depressions are defined by the
space and/or volume occupied by a projection, bulge, or contour of
the protuberant mantle layer. Consequently, depressions exhibit a
shape that is the negative or corresponding inverse of the shape of
the corresponding projection, bulge or contour from which it is
formed.
[0094] In FIG. 11, for example, the inner surface of outer mantle
layer 114, if removed from mantle assembly 110, exhibits
depressions corresponding to the projections 113 of mantle layer
112. The inner surface of mantle layer 114 is the region of mantle
layer 114 that adheres to or is in contact with the outer surface
of mantle layer 112. Specifically, the depressions on the inner
surface of mantle layer 114 exhibit shapes that are the negative
shapes to a corresponding projection of mantle layer 112.
[0095] The multi-layer mantle assembly 110 is considered to be
spherical, preferably comprised of spherical core and spherical
protuberant mantle layers 112 and 114. Mantle assemblies comprising
two or more protuberant mantle layers are not limited to the mantle
assembly according to the fourth preferred embodiment. The present
invention encompasses numerous variations and alternative
arrangements of a multi-layer mantle assembly comprising two or
more protuberant mantle layers. The present invention contemplates
a mantle assembly comprising two protuberant mantle layers, wherein
the protuberant mantle layers exhibit different surface
configurations. Surface configurations of the mantle layers differ
with respect to any of the arrangement, shape, and/or size of
projections which provide each mantle layer with its respective
surface configuration. Additionally, the present invention
encompasses multi-layer mantle assemblies comprising two or more
protuberant mantle layers wherein each mantle layer exhibits a
surface configuration similar to that of the at least one other
protuberant mantle layer. In such an embodiment, the surface
configurations of each protuberant mantle layer are similar with
respect to the size, shape, and arrangement of projections, which
provide the mantle layers with a protuberant surface
configuration.
[0096] In accordance with the fourth preferred embodiment, the
present invention contemplates, as previously described herein,
protuberant mantle layers having a protuberant surface provided by
projections of different geometric shapes, and optionally
comprising combinations of two or more geometrical shaped
projections. The present invention further contemplates the
arrangement of geometric shapes as desired to provide a mantle
layer and/or assembly with a protuberant surface, optionally
arranged in a repeating or alternating, i.e., a generally
non-repeating fashion.
[0097] A multi-layer mantle assembly according to the present
invention is not limited to three layers. That is, the present
invention includes a multi-layer mantle assembly comprising a core,
and one or more mantle layers disposed about the core, wherein at
least one of the one or more mantle layers has a protuberant
surface as previously described herein. Preferably, the outermost
mantle layer of a multi-layer mantle assembly according to the
present invention has a protuberant surface. The present invention
also contemplates a multi-layer mantle assembly comprising, a core,
an outer mantle layer having a smooth surface, and an inner mantle
layer having a protuberant surface disposed therebetween.
[0098] A mantle assembly according to the present invention is
constructed by forming a spherical core and then molding one or
more mantle layers over the core. At least one of the one or more
mantle layers has a protuberant surface provided by a plurality of
projections.
[0099] A mantle assembly, specifically the constituent components
of a mantle assembly, are formed by any suitable molding method
known in the golf ball art. Such methods include, but are not
limited to, compression molding, injection molding, blow molding,
and reaction injection molding. Preferred methods are described
herein.
[0100] To form a mantle layer having a protuberant surface by the
above-referenced methods, a mold is employed preferably having a
pattern that provides the desired shape, size, and arrangement of
projections, such that a protuberant mantle layer having the
desired surface topography is formed. A mantle layer having a
protuberant surface topography may also be formed by a method
described in copending application, "Method of Making Golf Balls
Having a Protrusion Center", Ser. No. 09/737,067, filed on Dec. 14,
2000, incorporated herein by reference.
[0101] Preferably, the outer surface of a given layer in an mantle
assembly is in adhesive contact with the inner surface of an
immediately adjacent layer. Embodiments comprising a mantle layer
disposed immediately over a protuberant mantle layer also
preferably exhibit adhesive contact between the two respective
layers. Specifically, projections on the outer surface of an
underlying mantle layer are in adhesive contact with the resulting
depression on the inner surface of the layer formed immediately
over the protuberant mantle layer. As previously described herein,
depressions in one layer are the negative shape of the
corresponding projection.
[0102] Materials suitable for forming the core and one or more
mantle layers of a mantle assembly according to the present
invention are described in greater detail herein.
[0103] A mantle assembly, as previously described herein, comprises
a core and one or more mantle layers disposed about the core,
wherein at least one of the one or more mantle layers has a
protuberant surface. Therefore, the core of a present invention
mantle assembly is preferably constructed from any suitable core
material known in the golf ball art. Suitable core materials are
more fully described herein.
[0104] It is recognized that the mantle layers in a mantle assembly
according to the present invention may be constructed from
materials suitable for forming a core, a cover layer, a mantle
layer, or combinations thereof. As previously described herein, a
mantle layer is often considered to be part of a respective layer,
i.e., a core or a cover layer, based on the material from which the
mantle is constructed. A mantle layer constructed from the same
material, or material similar to that, as the core may be
considered a core assembly. Additionally a mantle layer constructed
from material conventionally suitable as a cover material is
typically considered an inner cover layer. Mantle layers, including
protuberant mantle layers, according to the present invention, are
preferably constructed of materials suitable for forming golf ball
covers.
[0105] For example, in one preferred form of a present invention
golf ball, in accordance with FIGS. 8a and 8b, mantle layer 81 is
formed by a material suitable as a golf ball core material. Core 86
and mantle layer 81, which are collectively considered a mantle
assembly according to the present invention, are therefore
considered to be a dual or multi-layer core.
[0106] In an alternative embodiment of a present invention golf
ball, in accordance with FIGS. 8a and 8b, mantle layer 81 is
constructed from a material suitable as a cover material. Mantle
layer 81 is therefore considered to be an inner cover layer.
However, mantle layer 81 and core 86 are still collectively
considered a mantle assembly according to the present
invention.
[0107] The foregoing examples are not to be considered limiting
embodiments. Rather the foregoing examples are merely illustrative
of possible alternative mantle layer constructions, in terms of
materials used to form a mantle layer, and a system for associating
mantle layers with a conventional golf ball layer, i.e., either a
core or a cover layer. The examples, as described in accordance
with FIGS. 8a and 8b, are applicable to any golf ball employing a
mantle assembly according to the present invention.
[0108] A multi-layer mantle assembly of the present invention is
not limited to the particular shapes and/or arrangements of
projections described in the first, second, third, or fourth
preferred embodiments. Additionally, any of the one or more mantle
layers may have a protuberant surface.
Golf Balls
[0109] Preferably, mantle assemblies, as previously described
herein, are utilized to form a golf ball. A golf ball employing a
mantle assembly according to the present invention comprises a
cover layer disposed about the mantle assembly. The cover may be a
single cover layer or optionally a multi-layer cover. The cover
layer is constructed from any suitable cover material, known in the
golf ball art. Suitable cover materials are more fully described
herein. Alternatively, golf balls according to the present
invention include a core, a cover layer, and one or more mantle
layers disposed between the core and the cover, wherein at least
one of the one or more mantle layers exhibits a protuberant surface
configuration as previously described herein. In a preferred form,
a golf ball employing a mantle assembly according to the present
invention has a cover layer molded or otherwise formed immediately
over the outer mantle of a mantle assembly, wherein the outer
mantle layer has a protuberant surface provided by a plurality of
projections. In a most preferred form, a golf ball cover is formed
over a mantle assembly comprising a core and a protuberant mantle
layer.
[0110] FIG. 12 is a cross-section of a three-piece, non-wound golf
ball 120 employing a mantle assembly according to the first
preferred embodiment. A cover layer 122 is molded or otherwise
formed over mantle layer 81. A plurality of outwardly extending
projections 82 and smooth surface 84 extending therebetween are
defined along the outer region of mantle layer 81. Core 86 and
mantle layer 81 are collectively considered to comprise mantle
assembly 80, as described in accordance with FIGS. 8a and 8b. A
protuberant interface is provided where the cover layer adheres to
and is in intimate contact with the protuberant surface of the
mantle assembly.
[0111] A four-piece, non-wound golf ball 130 employing a mantle
assembly according to the first preferred embodiment is shown in
FIG. 13, wherein a mantle layer 132 is disposed between the mantle
assembly of the first preferred embodiment and a cover layer 134.
Core 86 and mantle layer 81 are collectively considered to comprise
mantle assembly 80, as described in accordance with FIGS. 8a and
8b. A plurality of outwardly extending projections 82 and smooth
surface 84 extending therebetween are defined along the outer
region of mantle 81. A protuberant interface is provided where
mantle layer 132 adheres to and makes intimate contact with
protuberant surface of the mantle assembly.
[0112] A golf ball employing a mantle assembly of the first
preferred embodiment is not limited to the above-described golf
balls. It is contemplated that any number of mantle layers may be
disposed between a cover layer and the mantle assembly.
[0113] Multi-piece, non-wound golf balls employing a mantle
assembly of the second preferred embodiment are shown in FIGS. 14
and 15.
[0114] FIG. 14 is a cross-section of a three-piece, non-wound golf
ball 140 having a mantle assembly according to the second preferred
embodiment. A cover layer 142 is disposed over the mantle layer 92
of the mantle assembly. Core 96 and mantle layer 92 comprise mantle
assembly 90, as described in accordance with FIGS. 9a and 9b. A
protuberant interface is provided by the protuberant surface formed
by projections 94, where the cover layer adheres to and is in
intimate contact with the surface of mantle layer 92 (of the mantle
assembly).
[0115] A cross-section of a four-piece, non-wound golf ball 150
employing a mantle assembly according to the second preferred
embodiment is shown in FIG. 15, wherein a mantle layer 152 is
disposed between mantle layer 92 of the mantle assembly and a cover
154. A plurality of outwardly extending projections 94 are defined
along the outer region of mantle layer 92. Core 96 and mantle layer
92 comprise mantle assembly 90, as described in accordance with
FIGS. 9a and 9b. A protuberant interface is provided, where the
mantle layer 152 adheres to and makes intimate contact with the
protuberant surface of mantle layer 92 (of the mantle
assembly).
[0116] A golf ball employing a mantle assembly according to the
second preferred embodiment is not limited to the above-described
golf balls. It is contemplated that any number of mantle layers may
be disposed between a cover layer and a mantle assembly of the
present invention.
[0117] FIG. 16 shows a multi-layer golf ball 160 employing a
multi-layer mantle assembly according to the third preferred
embodiment. A cover layer 162 is disposed about the outer mantle
layer 106 of the multi-layer mantle assembly. A plurality of
outwardly extending projections 108 are defined along the outer
region of mantle layer 106. Core 102, inner mantle layer 104 and
outer mantle layer 106 comprise mantle assembly 100, as described
in accordance with FIG. 10. A protuberant interface is provided
where the cover layer adheres to and is in intimate contact with
the protuberant surface of mantle layer 106 (of the mantle
assembly).
[0118] FIG. 17 is a cross-sectional view of a golf ball 170
employing a mantle assembly of the fourth preferred embodiment.
Cover layer 172 is disposed about outer mantle layer 114. Outer
mantle 114 exhibits a protuberant surface provided by projections
115 and surface 116 extending between the projections. Core 111,
protuberant inner mantle 112, projections 113, and protuberant
outer mantle layer 114 collectively comprise mantle assembly 110,
as described in accordance with FIG. 11.
[0119] Depressions exist on the inner surface of a cover layer
formed immediately over a protuberant mantle layer. As previously
described herein, depressions are defined on the inner surface of
any layer molded immediately over a protuberant layer by the space
and/or volume occupied by projections extending outwardly from the
protuberant layer. Depressions exhibit a shape that is the negative
of corresponding projections on the surface of the protuberant
mantle layer.
[0120] Preferably, the outer surface of a given layer of a golf
ball according to the present invention is in adhesive contact with
the inner surface of the immediately adjacent layer. Most
preferably, projections of a protuberant mantle layer are in
adhesive contact with the corresponding depressions on the inner
surface of an immediately adjacent layer, which is preferably a
cover layer.
[0121] It is contemplated that a golf ball employing a multi-layer
mantle assembly according to the present invention may have one or
more additional layers disposed between the multi-layer mantle
assembly and the cover. Such additional mantle layers are
preferably constructed of a golf ball cover material and, thus,
would be considered to be part of a multi-layer cover.
[0122] Energy transfer within a golf ball is primarily a function
of the thickness of the respective layers, the size, shape and
placement of projections, and the materials used to form the
respective layers. Physical properties of a golf ball utilizing the
present invention may be adjusted and optimized by varying the
compositions and thickness of individual layers and also by
variations in the surface topography of one or more mantle
layers.
[0123] A selected layer of a golf ball according to the present
invention preferably is formed from a material suitable for that
selected layer. A golf ball core is preferably constructed of any
material known in the art suitable as a golf ball core. A cover
layer preferably includes a material suitable as a golf ball cover.
A mantle layer, including protuberant mantle layers, as previously
described herein may be constructed of a material suitable as any
of a core or a cover layer. Preferably mantle layers are
constructed from materials suitable as a golf ball cover. Suitable
materials are described more fully herein.
[0124] In a preferred form of the invention a golf ball layer
comprises a selected material in combination with an adjacent layer
having another selected material. The selected materials of
adjacent layers preferably exhibit different physical properties
such as hardness and flexural modulus, and more preferably include
different composition. Materials are chosen to provide a particular
layer with a desired physical property, and subsequently to
contribute to the overall performance of the golf ball.
[0125] Materials are selected such that satisfactory adhesion is
obtained between adjacent layers. Specifically, it is preferable
that the outer surface of an underlying layer is in adhesive
contact with the inner surface of the immediate overlying layer.
Adhesive properties between materials of adjacent layers are
preferred for a core and an adjacent mantle layer, for adjacent
mantle layers, and for a mantle layer and a cover layer adjacent
thereto. Adhesive properties between materials is especially
preferred when an underlying layer exhibits a protuberant surface
configuration as previously described herein.
[0126] A selected layer preferably comprises a material dissimilar
from a material of an adjacent layer. A material of one type is
considered dissimilar to a material of one another type if the
selected materials i) exhibit different chemical compositions; ii)
exhibit different physical properties; or iii) exhibit a
combination of i and ii. Adjacent layers that utilize materials
having the same primary chemical composition most preferably
exhibit different physical properties, i.e., hardness, flexural
modulus, etc.
[0127] A golf ball according to the present invention preferably
utilizes a cover layer of material A in combination with an
underlying protuberant mantle layer of material B. More preferably,
the golf ball further includes utilizing protuberant mantle layer
having material B in combination with a core having material C. As
previously described herein, materials A, B, and C preferably
exhibit different physical properties and may have comparatively
similar or unique compositions. Preferably material A exhibits a
flexural modulus from about 1,000 psi to about 100,000 psi,
material B exhibits a flexural modulus of from about 1,000 psi to
about 400,000 psi, and material C exhibits a flexural modulus of
from about 1,000 psi to about 200,000 psi. More preferably material
A exhibits a flexural modulus from about 1,000 psi to about 50,000
psi, material B exhibits a flexural modulus from about 10,000 psi
to about 200,000 psi, and material C exhibits a flexural modulus
from about 1,000 psi to about 150,000 psi. Most preferably material
A exhibits a flexural modulus of from about 1,000 psi to about
10,000 psi, material B exhibits a flexural modulus of from about
40,000 psi to about 100,000 psi, and material C exhibits a flexural
modulus of from about 1,000 psi to about 100,000 psi.
[0128] In another form of the present invention, a golf ball
utilizes a cover of material A in combination with a protuberant
mantle layer of material B, and protuberant mantle layer of
material B is utilized in combination with a second protuberant
mantle layer having material D. The second protuberant mantle layer
of material D is preferably used in combination with a core having
material C.
[0129] As previously described herein, materials A, B, C and D
preferably exhibit different physical properties and may have
comparatively similar or unique compositions. Preferably material A
exhibits a flexural modulus from about 1,000 psi to about 100,000
psi, material B exhibits a flexural modulus of from about 1,000 psi
to about 400,000 psi, material D exhibits a flexural modulus of
from about 1,000 psi to about 400,000 psi, and material C exhibits
a flexural modulus of from about 1,000 psi to about 200,000 psi.
More preferably material A exhibits a flexural modulus from about
1,000 psi to about 50,000 psi, material B exhibits a flexural
modulus from about 10,000 psi to about 200,000 psi, material D
exhibits a flexural modulus of from about 20,000 psi to about
200,000 psi, and material C exhibits a flexural modulus from about
1,000 psi to about 150,000 psi. Most preferably material A exhibits
a flexural modulus of from about 1,000 psi to about 10,000 psi,
material B exhibits a flexural modulus of from about 40,000 psi to
about 100,000 psi, material D exhibits a flexural modulus of from
about 50,000 psi to about 150,000 psi, and material C exhibits a
flexural modulus of from about 1,000 psi to about 100,000 psi.
[0130] Any suitable golf ball material may be utilized as materials
A, B, C, and D. Materials A, B, and D preferably include any of a
low-acid ionomer, a high-acid ionomer, a polyamide-ionomer
composition, a polyurethane, and combinations thereof. Material C,
i.e., a core material, preferably includes a polybutadiene
material, a metallocene polyolefin, a polyurethane and combinations
thereof. Materials for a core (material C), a cover layer (material
A), and/or one or more protuberant mantle layers (materials B and
D) are discussed in greater detail herein with respect to cores,
mantle layers, and cover layers.
[0131] In one embodiment according to the present invention, a golf
ball comprises a polybutadiene core, a protuberant mantle layer
comprising a high acid ionomer, and a cover layer comprising a low
acid ionomer.
[0132] In another embodiment according to the present invention, a
golf ball comprises a polybutadiene core, a protuberant mantle
layer high acid ionomer composition, and a cover layer comprising a
blend of a high acid ionomer and a low acid ionomer.
[0133] In a further embodiment, a golf ball according to the
present invention comprises a polybutadiene core, a protuberant
mantle layer comprising a high acid ionomer, and a cover layer
comprising a blend of a polyamide and ionomer.
[0134] Still another embodiment of the present invention is a golf
ball comprising a polybutadiene core, a protuberant mantle layer
comprising a high acid ionomer and a cover layer comprising a
polyurethane.
[0135] In another embodiment, a golf ball according to the present
invention comprises a polybutadiene core, a protuberant mantle
layer comprising a polyurethane, and a cover layer comprising a low
acid ionomer.
[0136] Still a further example of an embodiment according to the
present invention is a golf ball comprising a polybutadiene core, a
polyurethane protuberant mantle layer, and a cover layer comprising
a blend of a high acid ionomer and a low acid ionomer.
[0137] Yet another embodiment of the present invention is a golf
ball comprising a polybutadiene core, a protuberant mantle layer
comprising a polyurethane material, and a cover layer comprising a
polyamide-ionomer composition.
[0138] In a further embodiment according to the present invention,
a golf ball comprises a polybutadiene core, a protuberant mantle
layer comprising a polyurethane material, and a cover layer
comprising a polyurethane material.
[0139] Another embodiment of the present invention is a golf ball
comprising a core which includes a metallocene polyolefin, a
protuberant mantle layer comprising a high acid ionomer, and a
cover layer comprising a low acid ionomer.
[0140] Yet another embodiment according to the present invention is
a golf ball comprising a core that comprises a metallocene
polyolefin, a protuberant mantle layer comprising a high acid
ionomer, and a cover layer including a blended composition
comprising a high acid ionomer and a low acid ionomer.
[0141] In a further embodiment, a golf ball according to the
present invention comprises a core which includes a metallocene
polyolefin, a protuberant mantle layer comprising a high acid
ionomer, and a cover layer comprising a composition which includes
a polyamide and ionomer blend.
[0142] In yet a further embodiment, a golf ball according to the
present invention comprises a metallocene polyolefin core, a
protuberant mantle layer that includes a high acid ionomer, and a
polyurethane cover.
[0143] Yet another embodiment of the present invention, is a golf
ball that comprises a metallocene polyolefin core, a polyurethane
protuberant mantle layer, and a cover layer comprising a low acid
ionomer.
[0144] A further embodiment of a golf ball according to the present
invention comprises a metallocene polyolefin core, a protuberant
mantle layer comprising a polyurethane, and a cover layer
comprising a high acid/low acid ionomer blend.
[0145] In another embodiment according to the present invention, a
golf ball comprises a metallocene polyolefin core, a protuberant
mantle layer comprising a polyurethane, and a cover layer
comprising a polyamide-ionomer composition.
[0146] Yet another embodiment of a golf ball according to the
present invention includes a metallocene polyolefin core, a
protuberant mantle layer comprising a polyurethane, and a cover
layer comprising a polyurethane.
[0147] In yet another preferred embodiment, a golf ball according
to the present invention includes a polyurethane core, a
protuberant mantle layer comprising a high acid ionomer, and a
cover layer comprising a low acid ionomer.
[0148] In another preferred embodiment, a golf ball according to
the present invention comprises a polyurethane core, a high acid
ionomer protuberant mantle layer, and a cover layer comprising a
blend of a high acid and a low acid ionomer.
[0149] Still another embodiment according to the present invention
is a golf ball comprising a polyurethane core, a high acid ionomer
protuberant mantle layer, and a high acid ionomer cover.
[0150] In another embodiment according to the present invention, a
golf ball comprises a polyurethane core, protuberant mantle layer
comprising a high acid ionomer, and a polyurethane cover.
[0151] Another embodiment according to the present invention is a
golf ball comprising a polyurethane core, a protuberant mantle
layer comprising a polyurethane, and a polyamide-ionomer cover
layer.
[0152] Still another embodiment according to the present invention
is a golf ball comprising a polyurethane core, a protuberant mantle
layer comprising a polyurethane, and a cover layer comprising a
polyurethane.
[0153] In another embodiment, a golf ball according to the present
invention comprises a polybutadiene core, a first protuberant
mantle layer comprising a polyurethane material, a second
protuberant mantle comprising a high acid ionomer, and a cover
layer comprising a low acid ionomer.
[0154] Still another embodiment according to the present invention
is a golf ball comprising a polybutadiene core, a protuberant
mantle layer comprising a polyurethane material, a second
protuberant mantle layer comprising a high acid ionomer, and a
cover layer comprising a blend of a high acid ionomer and a low
acid ionomer.
[0155] Yet another embodiment according to the present invention is
a golf ball comprising a polybutadiene core, a first mantle layer
comprising a polyurethane material, a second mantle layer
comprising a polyurethane material, and a cover layer comprising a
polyamide ionomer composition, wherein both the first and second
mantle layers have a protuberant surface configuration.
[0156] A further embodiment according to the present invention is a
golf ball comprising a polybutadiene core, a protuberant mantle
layer comprising a high acid ionomer, a second protuberant mantle
layer comprising a high acid ionomer, and a cover layer comprising
a low acid ionomer.
[0157] Still another embodiment according to the present invention
is a golf ball comprising a polybutadiene core, a protuberant
mantle layer comprising a polyurethane material, another
protuberant mantle layer comprising a polyurethane material, and a
polyurethane cover.
[0158] In another embodiment according to the present invention, a
golf ball includes a metallocene polyolefin core, a first
protuberant mantle layer comprising a high acid ionomer, a second
protuberant mantle layer comprising a high acid ionomer, and a
cover layer comprising a low acid ionomer.
[0159] Still a further embodiment according to the present
invention, is a golf ball including a core which comprises a
metallocene polyolefin, a first protuberant mantle layer comprising
a high acid ionomer, a second protuberant mantle layer comprising a
high acid ionomer, and a cover layer comprising a blend of a high
acid ionomer with a low acid ionomer.
[0160] Yet another embodiment according to the present invention is
a golf ball comprising a metallocene polyolefin core, a protuberant
mantle layer comprising a polyamide-ionomer composition, another
protuberant mantle layer comprising a high acid ionomer, and a
cover layer comprising a low acid ionomer.
[0161] A further embodiment according to the present invention is a
golf ball comprising a metallocene polyolefin core, a first
protuberant mantle layer comprising a polyamide-ionomer
composition, a second protuberant mantle layer comprising a
polyurethane, and a polyurethane cover.
[0162] In another embodiment, a golf ball according to the present
invention comprises a polyurethane core, a first protuberant mantle
layer comprising a polyurethane, a second protuberant mantle layer
comprising a high acid ionomer, and a cover layer comprising a low
acid ionomer.
[0163] In another embodiment according to the present invention, a
golf ball comprises a polyurethane core, a first protuberant mantle
layer comprising a polyamide-ionomer composition, a second
protuberant mantle layer comprising a polyurethane material, and a
cover layer comprising a polyamide-ionomer composition.
[0164] Yet another embodiment according to the present invention is
a golf ball comprising a polyurethane core, a first protuberant
mantle layer comprising a polyamide-ionomer composition, a second
protuberant mantle layer comprising a polyurethane composition, and
a cover layer comprising a polyurethane composition.
[0165] Still another embodiment according to the present invention
is a golf ball comprising a polyurethane core, a first protuberant
mantle layer comprising a polyurethane material, a second
protuberant mantle layer comprising a polyurethane material, and a
cover layer comprising a polyurethane material.
[0166] Mantle assembly cores according to the present invention may
be formed from any suitable core material known in the golf ball
art. The core and/or mantle layers may be formed from a thermoset
material, a thermoplastic material, or combinations thereof.
[0167] A wide array of thermoset materials can be utilized in a
core and/or mantle layers of the present invention. Examples of
suitable thermoset materials include butadiene or any natural or
synthetic elastomer, including metallocene polyolefins,
polyurethanes, silicones, polyamides, polyureas, or virtually any
irreversibly cross-linked resin system. Similarly a polybutadiene
elastomer could be further used. It is also contemplated that
epoxy, phenolic, and an array of unsaturated polyester resins could
be utilized.
[0168] The thermoplastic material used in the present invention
cores and/or mantle layers includes a wide assortment of
thermoplastic materials. Examples of typical thermoplastic
materials for incorporation in the golf balls of the present
invention include, but are not limited to, ionomers, polyurethane
thermoplastic elastomers, and combinations thereof. It is also
contemplated that a wide array of other thermoplastic materials
could be utilized, such as polysulfones, fluoropolymers,
polyamide-imides, polyarylates, polyaryletherketones, polyaryl
sulfones/polyether sulfones, polybenzimidazoles, polyether-imides,
polyamides, liquid crystal polymers, polyphenylene sulfides; and
specialty high-performance resins, which would include
fluoropolymers, polybenzimidazole, and ultrahigh molecular weight
polyethylenes.
[0169] Additional examples of suitable thermoplastics include
metallocenes, polyvinyl chlorides,
acrylonitrile-butadiene-styrenes, acrylics, styrene-acrylonitriles,
styrene-maleic anhydrides, polyamides (nylons), polycarbonates,
polybutylene terephthalates, polyethylene terephthalates,
polyphenylene ethers/polyphenylene oxides, reinforced
polypropylenes, and high-impact polystyrenes.
[0170] Preferably, the thermoplastic materials have relatively high
melting points, such as a melting point of at least about
300.degree. F. Several examples of these preferred thermoplastic
materials and which are commercially available include, but are not
limited to, Capron.RTM. (trademarked by Allied Signal Plastics for
a blend of nylon and ionomer), Lexan.RTM. (trademarked by General
Electric for polycarbonate), Pebax.RTM. (trademarked by Elf Atochem
for a polyether block amide), and Hytrel.RTM. (trademarked by
DuPont for a series of polyester elastomers). The polymers or resin
system may be cross-linked by a variety of means such as by
peroxide agents, sulphur agents, radiation or other cross-linking
techniques.
[0171] Any or all of the previously described components in the
cores and/or mantle layers of the preferred embodiment golf balls
of the present invention may be formed in such a manner, or have
suitable fillers added, so that their resulting density is
decreased or increased. For example, any of the components in the
cores and/or mantle layers could be formed or otherwise produced to
be light in weight. For instance, the components could be foamed,
either separately or in situ. Related to this, a foamed light
weight filler agent may be added. In contrast, any of these
components could be mixed with, or otherwise receive, various high
density filler agents or other weighting components such as
relatively high density fibers or particulate agents in order to
increase their mass or weight.
[0172] The following commercially available thermoplastic resins
are particularly preferred for use in the noted mantle layers
employed in the preferred embodiment golf balls of the present
invention: Capron.RTM. 8351 (available from Allied Signal
Plastics), Lexan.RTM. ML5776 (from General Electric), Pebax.RTM.
3533 (a polyether block amide from Elf Atochem), and Hytrel.RTM.
G4074 (from DuPont). Properties of these four preferred
thermoplastics are set forth below in Tables 1-4. When forming a
golf ball in accordance with the present invention, if the mantle
layer is to comprise a thermoplastic material, it is most preferred
to utilize Pebax.RTM. thermoplastic resin.
1TABLE 1 Capron .RTM. 8351 50% ASTM Mechanical DAM RH Test Tensile
Strength, Yield, psi (MPa) 7,800 (54) -- D-638 Flexural Strength,
psi (MPa) 9,500 (65) -- D-790 Flexural Modulus, psi (MPa) 230,000
-- D-790 (1,585) Ultimate Elongation, % 200 -- D-638 Notched Izod
Impact, ft-lbs/in (J/M) No Break -- D-256 Drop Weight Impact,
ft-lbs (J) 150 (200) -- D-3029 Drop Weight Impact, @ -40.degree.
F., ft-lbs (J) 150 (200) -- D-3029 Physical Specific Gravity 1.07
-- D-792 Thermal Melting Point, .degree. F. (.degree. C.) 420 (215)
-- D-789 Heat Deflection @ 264 psi .degree. F. (.degree. C.) 140
(60) -- D-648
[0173]
2TABLE 2 Lexan .RTM. ML5776 Typical ASTM Property Data Unit Method
Mechanical Tensile Strength, Yield, 8500 psi ASTM D-638 Type 1,
0.125" Tensile Strength, Break 9500 psi ASTM D-638 Type 1, 0.125"
Tensile Elongation, Yield, 110.0 % ASTM D-638 Type 1, 0.125"
Flexural Strength, Yield, 12000 psi ASTM D-790 0.125" Flexural
Modulus, 310000 psi ASTM D-790 0125" Impact Izod Impact, Unnotched,
73 F. 60.0 ft-lbs/ins ASTM D-4812 Izod Impact, Notched, 73 F. 15.5
ft-lbs/ins ASTM D-256 Izod Impact, Notches, 73 F., 12.0 ft-lbs/ins
ASTM D-256 0.250" Instrumented Impact 48.0 ft-lbs ASTM D-3763
Energy @ Peak, 73 F. Thermal HDT, 264 psi, 0.250", 257 deg F. ASTM
D-648 Unannealed Thermal Index, Elec Prop 80 deg C. UL 7468 Thermal
Index, Mech Prep with 80 deg C. UL 7468 Impact Thermal Index, Mech
Prop 80 deg C. UL 7468 without Impact Physical Specific Gravity,
Solid 1.19 -- ASTM D-792 Water Absorption, 0.150 % ASTM D-570 24
hours @ 73 F. Mold Shrinkage, Flow, 0.125" 5.7 in/in E-3 ASTM D-955
Melt Flow Rate, Nom'l, 7.5 g/10 min ASTM D-1238 30.degree. C./1.2
kgf (0) Flame Characteristics UL File Number, USA E121562 -- --
94HB Rated (tested thickness) 0.060 inch UL 94
[0174]
3TABLE 3 Pebax .RTM. 3533 Resin ASTM Property Test Method Units
3533 Specific Gravity D792 1.01 Water Absorption Equilibrium D570
(20.degree. C., 50% RH.>) 0.5 24 Hr. Immersion 1.2 Hardness
D2240 35D Tensile Strength, Ultimate D638 psi 5600 Elongation,
Ultimate D638 % 580 Flexural Modulus D790 psi 2800 Izod Impact,
Notched D256 ft 20.degree. C. lb/in NB -40.degree. C. NB Abrasion
Resistance D1044 Mg/100 104 H18/1000 g Cycles Tear Resistance
Notched D624C lb/in 260 Melting Point D3418 .degree. F. 306 Vicat
Softening Point .degree. F. 165 HDT 66 psi D648 .degree. F. 115
Compression Set (24 hr., 160.degree. F.) D395A % 54
[0175]
4TABLE 4 Hytrel .RTM. G4074 Thermoplastic Elastomer ASTM Physical
Test Method Dens/Sp Gr ASTM D792 1.1800 sp gr 23/23C Melt Flow ASTM
D1238 5.20 @ E-190 C/2.16 kg g/10/min Wat Abs ASTM D570 2.100%
Mechanical Elong @ Brk ASTM D638 230.0% Flex Mod ASTM D790 9500 psi
TnStr @ Brk ASTM D638 2000 psi Impact Notch Izod ASTM D256 No Break
@ 73.0 F. @ 0.250 inft-lb/in 0.50 @ -40.0 F. @ 0.2500 inft-lb/in
Shore ASTM D2240 40 Shore D DTUL @ 66 ASTM D648 122 F. Melt Point
338.0 F. Vicat Soft ASTM D1525 248 F. Melt Point
[0176] The cores have a weight of about 25 to 40 grams and
preferably about 30 to 40 grams. The cores can be molded from
materials noted herein. For example the core can be molded from a
slug of uncured or lightly cured elastomer composition comprising a
high cis content polybutadiene and a metal salt of an 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 increase the
amount of zinc diacrylate co-agent. In addition, larger amounts of
metal oxide such as zinc oxide 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. Non-limiting
examples of other materials which may be used in the core
composition include compatible rubbers or ionomers, and low
molecular weight fatty acids such as stearic acid. Free radical
initiator catalysts such as peroxides are admixed with the core
composition so that on the application of heat and pressure, a
curing or crosslinking reaction takes place.
[0177] The cores and mantle layers of the present invention are
preferably formed by compression molding techniques. However, it is
fully contemplated that liquid injection molding, blow molding or
transfer molding techniques could be utilized.
[0178] Additionally, the core and/or mantle layer compositions of
the invention may be based on polybutadiene, natural rubber,
metallocene catalyzed polyolefins such as Exact.RTM. (Exxon Chem.
Co.) and Engage.RTM. (Dow Chem. Co.), polyurethanes, other
thermoplastic or thermoset elastomers, and mixtures of one or more
of the above materials with each other and/or with other
elastomers.
[0179] It is preferred that the base elastomer have a relatively
high molecular weight. Polybutadiene has been found to be
particularly useful because it imparts to the golf balls a
relatively high coefficient of restitution. Polybutadiene can be
cured using a free radical initiator such as a peroxide, or it can
be sulfur cured. A broad range for the molecular weight of
preferred base elastomers is from about 50,000 to about 500,000. A
more preferred range for the molecular weight of the base elastomer
is from about 100,000 to about 500,000. As a base elastomer for the
core composition, cis-1-4-polybutadiene is preferably employed, or
a blend of cis-1-4-polybutadiene with other elastomers may also be
utilized. Most preferably, cis-1-4-polybutadiene having a
weight-average molecular weight of from about 100,000 to about
500,000 is employed. Along this line, it has been found that the
high cis-1-4-polybutadienes manufactured and sold by Bayer
Corporation, Germany, under the trade name Taktene.RTM. 220 or 1220
are particularly preferred. Furthermore, the core may be comprised
of a cross linked natural rubber, EPDM, metallocene catalyzed
polyolefin, or another crosslinkable elastomer.
[0180] When polybutadiene is used for golf ball cores, it commonly
is cross linked with an unsaturated carboxylic acid co-crosslinking
agent. The unsaturated carboxylic acid component of the core
composition typically is the reaction product of the selected
carboxylic acid or acids and an oxide or carbonate of a metal such
as zinc, magnesium, barium, calcium, lithium, sodium, potassium,
cadmium, lead, tin, and the like. Preferably, the oxides of
polyvalent metals such as zinc, magnesium and cadmium are used, and
most preferably, the oxide is zinc oxide.
[0181] Exemplary of the unsaturated carboxylic acids which find
utility in the core compositions are acrylic acid, methacrylic
acid, itaconic acid, crotonic acid, sorbic acid, and the like, and
mixtures thereof. Preferably, the acid component is either acrylic
or methacrylic acid. Usually, from about 5 to about 40, and
preferably from about 15 to about 30 parts by weight of the
carboxylic acid salt, such as zinc diacrylate, is included in the
core composition. The unsaturated carboxylic acids and metal salts
thereof are generally soluble in the elastomeric base, or are
readily dispersible.
[0182] The free radical initiator included in the core composition
is any known polymerization initiator (a co-crosslinking agent)
which decomposes during the cure cycle. The term "free radical
initiator" as used herein refers to a chemical which, when added to
a mixture of the elastomeric blend and a metal salt of an
unsaturated, carboxylic acid, promotes cross linking of the
elastomers by the metal salt of the unsaturated carboxylic acid.
The amount of the selected initiator present is dictated only by
the requirements of catalytic activity as a polymerization
initiator. Suitable initiators include peroxides, persulfates, azo
compounds and hydrazides. Peroxides, which are readily commercially
available, are conveniently used in the present invention,
generally in amounts of from about 0.1 to about 10.0 and preferably
in amounts of from about 0.3 to about 3.0 parts by weight per each
100 parts of elastomer.
[0183] Exemplary of suitable peroxides for the purposes of the
present invention are dicumyl peroxide, n-butyl 4,4'-bis
(butylperoxy) valerate, 1,1-bis(t-butylperoxy)-3,3,5-trimethyl
cyclohexane, di-t-butyl peroxide and 2,5-di-(t-butylperoxy)-2,5
dimethyl hexane and the like, as well as mixtures thereof. It will
be understood that the total amount of initiators used will vary
depending on the specific end product desired and the particular
initiators employed.
[0184] The core compositions of the present invention may
additionally contain any other suitable and compatible modifying
ingredients including, but not limited to, metal oxides, fatty
acids, and diisocyanates and polypropylene powder resin. For
example, Papi.RTM. 94, a polymeric diisocyanate, commonly available
from Dow Chemical Co., Midland, Mich., is an optional component in
the rubber compositions. It can range from about 0 to 5 parts by
weight per 100 parts by weight rubber (phr) component, and acts as
a moisture scavenger. In addition, it has been found that the
addition of a polypropylene powder resin results in a core which is
hard (i.e., exhibits high PGA compression) and thus allows for a
reduction in the amount of cross linking co-agent utilized to
soften the core to a normal or below normal compression.
[0185] Furthermore, because polypropylene powder resin can be added
to a core composition without an increase in weight of the molded
core upon curing, the addition of the polypropylene powder allows
for the addition of higher specific gravity fillers, such as
mineral fillers. Since the cross linking agents utilized in the
polybutadiene core compositions are expensive and/or the higher
specific gravity fillers are relatively inexpensive, the addition
of the polypropylene powder resin substantially lowers the cost of
the golf ball cores while maintaining, or lowering, weight and
compression.
[0186] Various activators may also be included in the compositions
of the present invention. For example, zinc oxide and/or magnesium
oxide are activators for the polybutadiene. The activator can range
from about 2 to about 30 parts by weight per 100 parts by weight of
the rubbers (phr) component.
[0187] Moreover, reinforcement agents may be added to the core
compositions of the present invention. Since the specific gravity
of polypropylene powder is very low, and when compounded, the
polypropylene powder produces a lighter molded core, when
polypropylene is incorporated in the core compositions, relatively
large amounts of higher specific gravity fillers may be added so
long as the specific core weight limitations are met. As indicated
above, additional benefits may be obtained by the incorporation of
relatively large amounts of higher specific gravity, inexpensive
mineral fillers such as calcium carbonate. Such fillers as are
incorporated into the core compositions should be in finely divided
form, as for example, in a size generally less than about 30 mesh
and preferably less than about 100 mesh U.S. standard size. The
amount of additional filler included in the core composition is
primarily dictated by weight restrictions and preferably is
included in amounts of from about 10 to about 100 parts by weight
per 100 parts rubber.
[0188] The preferred fillers are relatively inexpensive and heavy
and serve to lower the cost of the ball and to increase the weight
of the ball to closely approach the U.S.G.A. weight limit of 1.620
ounces. However, if thicker cover compositions are to be applied to
the core to produce larger than normal (i.e., greater than 1.680
inches in diameter) balls, use of such fillers and modifying agents
will be limited in order to meet the U.S.G.A. maximum weight
limitations of 1.620 ounces. Limestone is ground calcium/magnesium
carbonate and is used because it is an inexpensive, heavy filler.
Ground flash filler may be incorporated and is preferably 20 mesh
ground up center stock from the excess flash from compression
molding. It lowers the cost and may increase the hardness of the
ball.
[0189] Fatty acids or metallic salts of fatty acids may also be
included in the compositions, functioning to improve moldability
and processing. Generally, free fatty acids having from about 10 to
about 40 carbon atoms, and preferably having from about 15 to about
20 carbon atoms, are used. Exemplary of suitable fatty acids are
stearic acid and linoleic acids, as well as mixtures thereof. An
example of a suitable metallic salt of a fatty acid is zinc
stearate. When included in the core compositions, the metallic
salts of fatty acids are present in amounts of from about 1 to
about 25, preferably in amounts from about 2 to about 15 parts by
weight based on 100 parts rubber (elastomer). It is preferred that
the core compositions include stearic acid as the fatty acid
adjunct in an amount of from about 2 to about 5 parts by weight per
100 parts of rubber.
[0190] Diisocyanates may also be optionally included in the core
compositions. When utilized, the diisocyanates are included in
amounts of from about 0.2 to about 5.0 parts by weight based on 100
parts rubber. Exemplary of suitable diisocyanates is
4,4'-diphenylmethane diisocyanate and other polyfunctional
isocyanates known in the art.
[0191] Furthermore, the dialkyl tin difatty acids set forth in U.S.
Pat. No. 4,844,471, the dispensing agents disclosed in U.S. Pat.
No. 4,838,556, and the dithiocarbamates set forth in U.S. Pat. No.
4,852,884 may also be incorporated into the polybutadiene
compositions of the present invention. The specific types and
amounts of such additives are set forth in the above identified
patents, which are incorporated herein by reference.
[0192] Cores according to the present invention can be manufactured
using relatively conventional techniques, such as injection
molding, blow molding, compression molding and reaction injection
molding.
[0193] The covers of golf balls according to the present invention
may comprise any material suitable for use as a golf ball cover.
Examples of preferred materials include, but are not limited to,
ionomer resins, nylon compositions, and polyurethane materials.
[0194] It is appreciated that the following described materials may
be used in a multi-layer cover as any of an outer cover layer or an
inner cover layer.
[0195] Additionally, the cover materials described herein are also
suitable for forming a mantle layer. A mantle layer as presently
used includes a mantle layer that is a member of a mantle assembly
according to the present invention including a mantle layer having
a textured surface topography.
[0196] It is appreciated that the following described materials,
while referred with respect to cover layers, are also suitable to
form any mantle layer in a mantle assembly according to the present
invention.
[0197] A. Ionomer Resins
[0198] With respect to a preferred ionomeric cover composition of
the invention, ionomeric resins are polymers containing interchain
ionic bonding. As a result of their toughness, durability, and
flight characteristics, various ionomeric resins sold by E. I.
DuPont de Nemours & Company under the trademark Surlyn.RTM. and
more recently, by the Exxon Corporation (see U.S. Pat. No.
4,911,451, incorporated herein by reference) under the trademarks
Escor.RTM. and Iotek.RTM., have become the materials of choice for
the construction of golf ball covers over the traditional "balata"
(transpolyisoprene, nature or synthetic) rubbers.
[0199] Ionomeric resins are generally ionic copolymers of an
olefin, such as ethylene, and a metal salt of an unsaturated
carboxylic acid, such as acrylic acid, methacrylic acid or maleic
acid. In some instances, an additional softening comonomer such as
an acrylate can also be included to form a terpolymer. The pendent
ionic groups in the ionomeric resins interact to form ion-rich
aggregates contained in a non-polar polymer matrix. The metal ions,
such as sodium, zinc, magnesium, lithium, potassium, calcium, etc.
are used to neutralize some portion of the acid groups in the
copolymer resulting in a thermoplastic elastomer exhibiting
enhanced properties, i.e., improved durability, etc., for golf ball
construction over balata.
[0200] The ionomeric resins utilized to produce cover compositions
can be formulated according to known procedures such as those set
forth in U.S. Pat. No. 3,421,766 or British Patent No. 963,380,
with neutralization effected according to procedures disclosed in
Canadian Patent Nos. 674,595 and 713,631, all of which are hereby
incorporated by reference, wherein the ionomer is produced by
copolymerizing the olefin and carboxylic acid to produce a
copolymer having the acid units randomly distributed along the
polymer chain. Broadly, the ionic copolymer generally comprises one
or more .alpha.-olefins and from about 9 to about 20 weight percent
of .alpha.,.beta.-ethylenically unsaturated mono- or dicarboxylic
acid, the basic copolymer neutralized with metal ions to the extent
desired.
[0201] At least about 20% of the carboxylic acid groups of the
copolymer are neutralized by the metal ions (such as sodium,
potassium, zinc, calcium, magnesium, and the like) and exist in the
ionic state. Suitable olefins for use in preparing the ionomeric
resins include ethylene, propylene, butene-1, hexene-1 and the
like. Unsaturated carboxylic acids include acrylic, methacrylic,
ethacrylic, .alpha.-chloroacrylic, crotonic, maleic, fumaric,
itaconic acids, and the like. The ionomeric resins utilized in the
golf ball industry are generally copolymers of ethylene with
acrylic (i.e., Escor.RTM.) and/or methacrylic (i.e., Surlyn.RTM.)
acid. In addition, two or more types of ionomeric resins may be
blended into the cover compositions in order to produce the desired
properties of the resulting golf balls.
[0202] The cover compositions which may be used in making the
preferred embodiment golf balls of the present invention are set
forth in detail but not limited to those in U.S. Pat. No.
5,688,869, incorporated herein by reference. In short, the cover
material is comprised of hard, high stiffness ionomer resins,
preferably containing relatively high amounts of acid (i.e.,
greater than 16 weight percent acid, preferably from about 17 to
about 25 weight percent acid, and more preferably from about 18.5
to about 21.5 weight percent) and at least partially neutralized
with metal ions (such as sodium, zinc, potassium, calcium,
magnesium and the like). The high acid resins are blended and melt
processed to produce compositions exhibiting hardness and
coefficient of restitution values when compared to low acid
ionomers, or blends of low acid ionomer resins containing 16 weight
percent acid or less.
[0203] The preferred cover compositions may also be prepared from
specific blends of two or more high acid ionomers with other cover
additives which do not exhibit the processing, playability,
distance and/or durability limitations demonstrated by the prior
art. However, as more particularly indicated below, the cover
composition can also be comprised of one or more low acid ionomers
so long as the molded covers exhibit a hardness of 65 or more on
the Shore D scale. These include lithium ionomers or blends of
ionomers with harder non-ionic polymers such as nylon,
polyphenylene oxide and other compatible thermoplastics. Examples
of cover compositions which may be used are set forth in detail in
copending U.S. Ser. No. 07/776,803 filed Oct. 15, 1991, and Ser.
No. 07/901,660 filed Jun. 19, 1992, now having matured into U.S.
Pat. No. 5,688,869, incorporated herein by reference. Of course,
the cover compositions are not limited in any way to those
compositions set forth in said copending applications.
[0204] The high acid ionomers suitable for use in the preferred
embodiment golf balls are ionic copolymers which are the metal,
i.e., 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 (i.e., iso- or
n-butylacrylate, etc.) can also be included to produce a softer
terpolymer. The carboxylic acid groups of the copolymer are
partially neutralized (i.e., approximately 10-75%, preferably
30-70%) by the metal ions. Each of the high acid ionomer resins
included in the cover compositions of the invention contains
greater than about 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.
[0205] Although an ionomeric cover composition preferably includes
a high acid ionomeric resin and the scope of the patent embraces
all known high acid ionomeric resins falling within the parameters
set forth above, only a relatively limited number of these high
acid ionomeric resins are currently available. In this regard, the
high acid ionomeric resins available from E. I. DuPont de Nemours
Company under the trademark Surlyn.RTM., and the high acid ionomer
resins available from Exxon Corporation under the trademarks
Escor.RTM. or Iotek.RTM. are examples of available high acid
ionomeric resins which may be utilized in the present
invention.
[0206] The high acid ionomeric resins available from Exxon under
the designation Escor.RTM. and/or Iotek.RTM., are somewhat similar
to the high acid ionomeric resins available under the Surlyn.RTM.
trademark. However, since the Escor.RTM./Iotek.RTM. ionomeric
resins are sodium or zinc 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.
[0207] Examples of the high acid methacrylic acid-based ionomers
found suitable for use in accordance with this invention include
Surlyn.RTM. AD-8422 (sodium cation), Surlyn.RTM. 8162 (zinc
cation), Surlyn.RTM. SEP-503-1 (zinc cation), and Surlyn.RTM.
SEP-503-2 (magnesium cation). According to DuPont, all of these
ionomers contain from about 18.5 to about 21.5% by weight
methacrylic acid.
[0208] More particularly, Surlyn.RTM. AD-8422 is currently
commercially available from DuPont in a number of different grades
(i.e., Surlyn.RTM. AD-8422-2, Surlyn.RTM. AD-8422-3, Surlyn.RTM.
AD-8422-5, etc.) based upon differences in melt index. According to
DuPont, Surlyn.RTM. AD-8422 offers the following general
properties, listed in Table 5, when compared to Surlyn.RTM. 8920,
which is the stiffest, hardest of all on the low acid grades
(referred to as "hard" ionomers in U.S. Pat. No. 4,884,814,
incorporated herein by reference):
5 TABLE 5 Low Acid High Acid (15 wt % Acid) (>20 wt % Acid)
Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. 8920 8422-2 8422-3 Ionomer
Cation Na Na Na Melt Index 1.2 2.8 1.0 Sodium, Wt % 2/3 1.9 2.4
Base Resin MI 60 60 60 MP.sup.1, .degree. C. 88 86 85 FP.sup.1,
.degree. C. 47 48.5 45 Compression Molding.sup.2 Tensile Break, psi
4350 4190 5330 Yield, psi 2280 3670 3590 Elongation, % 315 263 289
Flex Mod, K psi 53.2 76.4 88.3 Shore D hardness 66 67 68 .sup.1DSC
second heat, 10.degree. C./min heating rate. .sup.2Samples
compression molded at 150.degree. C. annealed 24 hours at
60.degree. C. Surlyn .RTM. 8422-2, -3 were homogenized at
190.degree. C. before molding.
[0209] In comparing Surlyn.RTM. 8920 to Surlyn.RTM. 8422-2 and
Surlyn.RTM. 8422-3, it is noted that the high acid Surlyn.RTM.
ionomers yield, lower elongation, slightly higher Shore D hardness
and much higher flexural modulus. Surlyn.RTM. 8920 contains 15%
weight methacrylic acid and is 59% neutralized with sodium.
[0210] In addition, Surlyn.RTM. SEP-503-1 (zinc cation) and
Surlyn.RTM. SEP-503-2 (magnesium cation) are high acid zinc and
magnesium versions of the Surlyn.RTM. AD 8422 high acid ionomers.
When compared to the Surlyn.RTM. AD 8422 (sometimes referred to
herein as Surlyn.RTM. 8422 or as 8422) high acid ionomers, the
Surlyn.RTM. SEP-503-1 and SEP-503-2 ionomers can be defined as
follows in Table 6:
6TABLE 6 Surlyn .RTM. Ionomer Ion Melt Index Neutralization % AD
8422-3 Na 1.0 45 SEP 503-1 Zn 0.8 38 SEP 503-2 Mg 1.8 43
[0211] Furthermore, Surlyn.RTM. 8162 is a zinc cation ionomer resin
containing approximately 20% by weight (i.e., 18.5-21.5% weight)
methacrylic acid copolymer that has been 30-70% neutralized.
Surlyn.RTM. 8162 is currently commercially available from
DuPont.
[0212] Examples of the high acid acrylic acid-based ionomers
suitable for use in the present invention include the Escor.RTM. or
Iotek.RTM. high acid ethylene acrylic acid ionomers produced by
Exxon. In this regard, Escor.RTM. or Iotek.RTM. 959 is a sodium ion
neutralized ethylene-acrylic acid copolymer. According to Exxon,
Iotek.RTM.s 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. The physical properties of these high acid acrylic
acid-based ionomers are as follows in Table 7:
7 TABLE 7 Escor .RTM. Escor .RTM. Property (Iotek .RTM. 959) (Iotek
.RTM. 960) Melt Index, g/10 min 2.0 1.8 Cation Sodium Zinc Melting
Point, .degree. F. 172 174 Vicat Softening Point, .degree. F. 130
131 Tensile @ Break, psi 4600 3500 Elongation @ Break, % 325 430
Hardness, Shore D 66 57 Flexural Modulus, psi 66,000 27,000
[0213] Furthermore, as a result of the development by the inventors
of a number of new 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
new high acid ionomers and/or high acid ionomer blends besides
sodium, zinc and magnesium high acid ionomers or ionomer blends are
now available for golf ball cover production. It has been found
that these new cation neutralized high acid ionomer blends produce
cover compositions exhibiting enhanced hardness and resilience due
to synergies which occur during processing. Consequently, the metal
cation neutralized high acid ionomer resins recently produced can
be blended to produce substantially harder covered golf balls
having higher C.O.R.'s than those produced by the low acid ionomer
covers presently commercially available.
[0214] More particularly, several new metal cation neutralized high
acid ionomer resins have been produced by the inventors 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. application Ser. No. 901,680, incorporated
herein by reference. It has been found that numerous new 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 (i.e., from about 10% to
90%).
[0215] 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.
[0216] The softening comonomer that can be optionally included in
the covers of the preferred embodiment golf balls 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.
[0217] Consequently, examples of a number of copolymers suitable
for use to produce the high acid ionomers included in the preferred
embodiment balls of 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 30 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.
[0218] Along these lines, examples of the preferred high acid base
copolymers which fulfill the criteria set forth above, are a series
of ethylene-acrylic acid copolymers which are commercially
available from The Dow Chemical Company, Midland, Mich., under the
Primacor.RTM. designation. These high acid base copolymers exhibit
the typical properties set forth in Table 8 below:
8TABLE 8 Typical Properties of Primacor .RTM. Ethylene-Acrylic Acid
Copolymers Melt Tensile Flexural Vicat Percent Density, Index, YD.
St Modulus Soft PT Shore D Grade Acid glcc g/10 min (psi) (psi)
(.degree. C.) Hardness ASTM D-792 D-1238 D-638 D-790 D-1525 D-2240
5980 20.0 0.958 300.0 -- 4800 43 50 5990 20.0 0.955 1300.0 650 2600
40 42 5990 20.0 0.955 1300.0 650 3200 40 42 5981 20.0 0.960 300.0
900 3200 46 48 5981 20.0 0.960 300.0 900 3200 46 48 5983 20.0 0.958
500.0 850 3100 44 45 5991 20.0 0.953 2600.0 635 2600 38 40
[0219] Due to the high molecular weight of the Primacor.RTM. 5981
grade of the ethylene-acrylic acid copolymer, this copolymer is the
more preferred grade utilized in the invention.
[0220] 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.
[0221] 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.
[0222] The new 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%.
[0223] As indicated below in Table 9, and more specifically in
Example 1 in U.S. application Ser. No. 901,680, a number of new
types of metal cation neutralized high acid ionomers can be
obtained from the above indicated process. These include new 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 new cation
neutralized acrylic acid based high acid ionomer resins are
produced.
9TABLE 9 Formulation Wt-% Cation Wt-% Melt Shore D No. Salt
Neutralization Index C.O.R. Hardness 1 (NaOH) 6.98 67.5 0.9 .804 71
2 (NaOH) 5.66 54.0 2.4 .806 73 3 (NaOH) 3.84 35.9 12.2 .612 69 4
(NaOH) 2.91 27.0 17.5 .812 (brittle) 5 (MnAc) 19.6 71.7 7.5 .809 73
6 (MnAc) 23.1 883 3.5 .814 77 7 (MnAc) 15.3 53.0 7.5 .810 72 8
(MnAc) 26.5 106 0.7 .813 (brittle) 9 (LiOH) 4.54 71.3 0.6 .610 74
10 (LiOH) 3.38 52.5 4.2 .818 72 11 (LiOH) 2.34 35.9 18.6 .815 72 12
(KOH) 5.30 36.0 19.3 Broke 70 13 (KOH) 8.26 57.9 7.18 .804 70 14
(KOH) 10.7 77.0 4.3 .801 67 15 (ZnAc) 17.9 71.5 0.2 .806 71 16
(ZnAc) 13.9 53.0 0.9 .797 69 17 (ZnAc) 9.91 36.1 3.4 .793 67 18
(MgAC) 17.4 70.7 2.8 .814 74 19 (MgAC) 20.6 87.1 1.5 .815 76 20
(MgAC) 13.8 53.8 4.1 .614 74 21 (CaAc) 13.2 69.2 1.1 .813 74 22
(CaAc) 7.12 34.9 10.1 .808 70 Control: 50/50 Blend of loteks .RTM.
8000/7030 C.O.R. = .810/65 Shore D Hardness DuPont High Acid Surlyn
.RTM. 8422 (Na) C.O.R. = .811/70 Shore D Hardness DuPont High Acid
Surlyn .RTM. 8162 (Zn) C.O.R. = .807/65 Shore D Hardness Exxon High
Acid Iotek .RTM. EX-960 (Zn) C.O.R. = .796/65 Shore D Hardness
Formulation Wt-%/Cation Wt-% Melt No. Salt Neutralization Index
C.O.R. 23 (MgO) 2.91 53.5 2.5 .813 24 (MgO) 3 85 71.5 2.8 .808 25
(MgO) 4.76 89.3 1.1 .809 26 (MgO) 1.96 35.7 7.5 .815 Control for
Formulation Nos. 23-26 is 50/50 Iotek .RTM. 8000/7030, C.O.R. =
.814, Formulation 26 C.O.R. was normalized to that control
accordingly Formulation Wt-% Cation Wt-% Melt Shore D No. Salt
Neutralization Index C.O.R. Hardness 27 (NiAc) 13.04 61.1 0.2 .802
71 28 (NiAc) 10.71 48.9 0.5 799 72 29 (NiAc) 8.26 36.7 1.8 .796 69
30 (NiAc) 5.66 24.4 7.5 .786 64 17 (ZnAc) 9.91 36.1 3.4 .793 67
Control for Formulation Nos. 27-30 is 50/50 Iotek .RTM. 8000/7030,
C.O.R. = .807
[0224] When compared to low acid versions of similar cation
neutralized ionomer resins, the new metal cation neutralized high
acid ionomer resins exhibit enhanced hardness, modulus and
resilience characteristics.
[0225] When utilized in golf ball cover construction, it has been
found that the new acrylic acid based high acid ionomers extend the
range of hardness beyond that previously obtainable while
maintaining the beneficial properties (i.e., durability, click,
feel, etc.) of the softer low acid ionomer covered balls, such as
balls produced utilizing the low acid ionomers disclosed in U.S.
Pat. Nos. 4,884,814 and 4,911,451, and the recently produced high
acid blends disclosed in U.S. Pat. No. 5,688,869, all of which, as
previously noted, are herein incorporated by reference.
[0226] Moreover, as a result of the development of a number of new
acrylic acid based high acid ionomer resins neutralized to various
extents by several different types of metal cations, such as
manganese, lithium, potassium, calcium and nickel cations, several
new ionomers or ionomer blends are now available for golf ball
production. By using these high acid ionomer resins harder, stiffer
golf balls having higher C.O.R.s, and thus longer distance, can be
obtained.
[0227] Other ionomer resins may be used in the cover compositions,
such as low acid ionomer resins, preferably such that the molded
cover produces a Shore D hardness of 65 or more.
[0228] The low acid ionomers which may be suitable for use in
formulating cover layer compositions are ionic copolymers which are
the metal, i.e., 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
(i.e., iso- or n-butylacrylate, etc.) can also be included to
produce a softer terpolymer. The carboxylic acid groups of the
copolymer are partially neutralized (i.e., approximately 10-75%,
preferably 30-70%) 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.
[0229] Suitable low acid ionomers include, but are not limited to,
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 Iotek.RTM., or blends thereof.
[0230] The low acid ionomeric resins available from Exxon under the
designation Escor.RTM. and/or Iotek.RTM., are somewhat similar to
the low acid ionomeric resins available under the Surlyn.RTM.
trademark. However, since the Escor.RTM./Iotek.RTM. ionomeric
resins are sodium or zinc 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.
[0231] When utilized in the construction of an inner layer of a
multi-layered golf ball, it has been found that the low acid
ionomer blends extend the range of compression and spin rates
beyond that previously obtainable. More preferably, it has been
found that when two or more low acid ionomers, particularly blends
of sodium and zinc low acid ionomers, are processed to produce the
covers of multi-layered golf balls, (i.e., the inner cover layer
herein) the resulting golf balls will travel further and at an
enhanced spin rate than previously known multi-layered golf balls.
Such an improvement is particularly noticeable in enlarged or
oversized golf balls.
[0232] For example, the normal size, multi-layer golf ball taught
in U.S. Pat. No. 4,650,193 does not incorporate blends of low acid
ionomeric resins of the present invention in the inner cover layer.
In addition, the multi-layered ball disclosed in the '193 patent
suffers substantially in durability in comparison with the present
invention.
[0233] Furthermore, use of an inner layer formulated from blends of
lower acid ionomers produces multi-layer golf balls having enhanced
compression and spin rates. These are the properties desired by the
more skilled golfer.
[0234] Regarding multi-layer cover constructions, the outer cover
layer is preferably softer than the low acid ionomer blend based
inner layer. The softness provides for the enhanced feel and
playability characteristics typically associated with balata or
balata-blend balls. The outer layer or ply is comprised of a
relatively soft, low modulus (about 1,000 psi to about 10,000 psi)
and low acid (less than 16 weight percent acid) ionomer, ionomer
blend or a non-ionomeric thermoplastic elastomer such as, but not
limited to, a polyurethane, a polyester elastomer such as that
marketed by DuPont under the trademark Hytrel.RTM., or a polyether
amide such as that marketed by Elf Atochem S.A. under the trademark
Pebax.RTM.. The outer layer is fairly thin (i.e., from about 0.010
to about 0.070 in thickness, more desirably 0.03 to 0.06 inches in
thickness for a 1.680 inch ball and 0.04 to 0.07 inches in
thickness for a 1.72 inch ball), but thick enough to achieve
desired playability characteristics while minimizing expense
[0235] Preferably, an outer layer includes a blend of hard and soft
(low acid) ionomer resins such as those described in U.S. Pat. Nos.
4,884,814 and 5,120,791, both incorporated herein by reference.
Specifically, a desirable material for use in molding an outer
layer comprises a blend of a high modulus (hard), low acid, ionomer
with a low modulus (soft), low acid, ionomer to form a base ionomer
mixture.
[0236] A high modulus ionomer herein is one which measures from
about 15,000 to about 70,000 psi as measured in accordance with
ASTM method D-790. The hardness may be defined as at least 50 on
the Shore D scale as measured in accordance with ASTM method
D-2240.
[0237] The hard ionomer resins utilized to produce an outer cover
layer composition comprised of hard/soft blends include ionic
copolymers which are the sodium, zinc, magnesium or lithium salts
of the reaction product of an olefin having from 2 to 8 carbon
atoms and an unsaturated monocarboxylic acid having from 3 to 8
carbon atoms.
[0238] The carboxylic acid groups of the copolymer may be totally
or partially (i.e., approximately 15-75%) neutralized.
[0239] The hard ionomeric resins are likely copolymers of ethylene
and either acrylic and/or methacrylic acid, with copolymers of
ethylene and acrylic acid being the most preferred. Two or more
types of hard ionomeric resins may be blended into the outer cover
layer compositions in order to produce the desired properties of
the resulting golf balls.
[0240] As discussed earlier herein, the hard ionomeric resins
introduced under the designation Escor.RTM. and sold under the
designation Iotek.RTM. are somewhat similar to the hard ionomeric
resins sold under the Surlyn.RTM. trademark. However, since the
Iotek.RTM. ionomeric resins are sodium or zinc salts of
poly(ethylene-acrylic acid) and the Surlyn.RTM. resins are zinc or
sodium salts of poly(ethylene-methacrylic acid) some distinct
differences in properties exist. As more specifically indicated in
the data set forth below, the hard Iotek.RTM. resins (i.e., the
acrylic acid based hard ionomer resins) are the more preferred hard
resins for use in formulating the outer layer blends for use in the
present invention. In addition, various blends of Iotek.RTM. and
Surlyn.RTM. hard ionomeric resins, as well as other available
ionomeric resins, may be utilized in the present invention in a
similar manner.
[0241] Examples of commercially available hard ionomeric resins
which may be used in the present invention in formulating the inner
and outer cover blends include the hard sodium ionic copolymer sold
under the trademark Surlyn.RTM. 8940 and the hard zinc ionic
copolymer sold under the trademark Surlyn.RTM. 9910. Surlyn.RTM.
8940 is a copolymer of ethylene with methacrylic acid and about 15
weight percent acid which is about 29% neutralized with sodium
ions. This resin has an average melt flow index of about 2.8.
Surlyn.RTM. 9910 is a copolymer of ethylene and methacrylic acid
with about 15 weight percent acid which is about 58 percent
neutralized with zinc ions. The average melt flow index of
Surlyn.RTM. 9910 is about 0.7. The typical properties of
Surlyn.RTM. 9910 and 8940 are set forth below in Table 10:
10TABLE 10 Typical Properties of Commercially Available Hard Surlyn
.RTM. Resins Suitable for Use in the Inner and Outer Layer Blends
of the Present Invention ASTM D 8940 9910 8920 8526 9970 9730
Cation Type Sodium Zinc Sodium Sodium Zinc Zinc Melt flow index,
gms/10 min. D-1238 28 0.7 0.9 1.3 14.0 1.6 Specific Gravity,
g/cm.sup.3 D-792 0.95 0.97 0.95 0.94 0.95 .095 Hardness, Shore D
D-2240 66 64 66 60 62 63 Tensile Strength, (kpsi), MPa D-638 (4.8)
(3.6) (5.4) (4.2) (3.2) (4.1) Elongation, % D-638 470 290 350 450
460 460 Flexural Modulus, (kpsi) MPa D-790 (51) (48) (55) (32) (28)
(30) Tensile Impact (23.degree. C.) D-18225 1020 1020 865 1160 760
1240 KJ/m.sub.2 (ft.-lbs./in.sup.2) (485) (485) (410) (550) (360)
(590) Vicat Temperature, .degree. C. D-1525 63 62 58 73 61 73
[0242] Examples of the more pertinent acrylic acid based hard
ionomer resin suitable for use as an inner and outer cover
composition sold under the Iotek.RTM. tradename by the Exxon
Corporation include Iotek.RTM. 4000, Iotek.RTM. 4010, Iotek.RTM.
8000, Iotek.RTM. 8020 and Iotek.RTM. 8030. The typical properties
of these and other Iotek.RTM. hard ionomers suited for use in
formulating an inner and/or outer layer cover compositions are
listed in Table 11:
11TABLE 11 Typical Properties of lotek .RTM. lonomers ASTM Resin
Properties Method Units 4000 4010 8000 8020 8030 Cation type zinc
zinc sodium sodium sodium Melt index D-1238 g/10 min. 25 1.5 0.8 16
2.8 Density D-1505 kg/m.sup.3 963 963 954 960 960 Melting Point
D-3417 .degree. C. 90 90 90 87.5 87.5 Crystallization Point D-3417
.degree. C. 62 64 56 53 55 Vicat Softening Point D-1525 .degree. C.
62 63 61 64 67 % Weight Acrylic Acid 16 -- 11 -- -- % of Acid
Groups Cation 30 -- 40 -- -- Neutralized ASTM Plaque Properties
Method Units 4000 4010 8000 8020 8030 (3 mm thick, compression
molded) Tensile at Break D-638 MPa 24 26 36 31.5 28 Yield Point
D-638 MPa none none 21 21 23 Elongation at Break D-638 % 420 420
350 410 395 1% Secant Modulus D-638 MPa 160 160 300 350 390 Shore
Hardness D D-2240 -- 55 55 61 58 59 Film Properties (50 Micron Film
2.2:1 ASTM Blow-Up Ratio) Method Units 4000 4010 8000 8020 8030
Tensile at Break MD D-882 MPa 41 39 42 52 47.4 TD D-882 MPa 37 38
38 38 40.5 Yield Point MD D-882 MPa 15 17 17 23 21.6 TD D-882 MPa
14 15 15 21 20.7 Elongation at Break MD D-882 % 310 270 260 295 305
TD D-882 % 360 240 280 340 345 1% Secant Modulus MD D-882 MPa 210
215 390 380 380 TD D-882 MPa 200 225 380 350 345 Dart Drop Impact
D-1709 g/micron 12.4 12.5 20.3 ASTM Resin Properties Method Units
7010 7020 7030 Cation type zinc zinc zinc Melt index D-1238 g/10
min. 0.8 0.8 2.5 Density D-1505 kg/m.sup.3 960 960 960 Melting
Point D-3417 .degree. C. 90 90 90 Vicat Softening Point D-1525
.degree. C. 60 63 62.5 ASTM Plaque Properties Method Units 7010
7020 7030 (3 mm thick, compression molded) Tensile at Break D-638
MPa 38 38 38 Yield Point D-638 MPa none none none Elongation at
Break D-638 % 500 420 395 Shore Hardness D D-2240 -- 57 55 55
[0243] Comparatively, soft ionomers are used in formulating the
hard/soft blends of inner and outer cover compositions. These
ionomers include acrylic acid based soft ionomers. They are
generally characterized as comprising sodium or zinc salts of a
terpolymer of an olefin having from about 2 to 8 carbon atoms,
acrylic acid, and an unsaturated monomer of the acrylate ester
class having from 1 to 21 carbon atoms. The soft ionomer is
preferably a zinc-based ionomer made from an acrylic acid base
polymer in an unsaturated monomer of the acrylate ester class. The
soft (low modulus) ionomers have a hardness from about 20 to about
40 as measured on the Shore D scale, as measured in accordance with
ASTM method D-2240, and a flexural modulus from about 1,000 to
about 10,000, as measured in accordance with ASTM method D-790.
[0244] Certain ethylene-acrylic acid based soft ionomer resins
developed by the Exxon Corporation under the designation Iotek.RTM.
7520 (referred to experimentally by differences in neutralization
and melt indexes as LDX 195, LDX 196, LDX 218 and LDX 219) may be
combined with known hard ionomers such as those indicated above to
produce the inner and outer cover layers. The combination produces
higher C.O.R.s at equal or softer hardness, higher melt flow (which
corresponds to improved, more efficient molding, i.e., fewer
rejects) as well as significant cost savings versus the inner and
outer layers of multi-layer balls produced by other known hard-soft
ionomer blends as a result of the lower overall raw materials costs
and improved yields.
[0245] While the exact chemical composition of the resins to be
sold by Exxon under the designation Iotek.RTM. 7520 is considered
by Exxon to be confidential and proprietary information, Exxon's
experimental product data sheet and Table 12 lists the following
physical properties of the ethylene acrylic acid zinc ionomer
developed by Exxon:
12TABLE 12 Physical Properties of Iotek .RTM. 7520 Property ASTM
Method Units Typical Value Melt Index D-1238 g/10 min. 2 Density
D-1505 kg/m.sup.3 0.962 Cation zinc Melting Point D-3417 66
Crystallization Point D-3417 .degree. C. 49 Vicat Softening D-1525
.degree. C. 42 Plaque Properties (2 mm thick Compression Molded
Plaques) Tensile at Break D-638 MPa 10 Yield Point D-638 MPa None
Elongation at Break D-638 % 760 1% Secant Modulus D-638 MPa 22
Shore D Hardness D-2240 32 Flexural Modulus D-790 MPa 26 Zwick
Rebound ISO 4862 % 52 De Mattia Flex D-430 Cycles >5000
Resistance
[0246] In addition, test data collected by the inventor indicates
that Iotek.RTM. 7520 resins have Shore D hardnesses of about 32 to
36 (per ASTM D-2240), melt flow indexes of 3.+-.0.5 g/10 min (at
190.degree. C. per ASTM D-1288), and a flexural modulus of about
2500-3500 psi (per ASTM D-790). Furthermore, testing by an
independent testing laboratory by pyrolysis mass spectrometry
indicates that Iotek.RTM. 7520 resins are generally zinc salts of a
terpolymer of ethylene, acrylic acid, and methyl acrylate.
[0247] Furthermore, a newly developed grade of an acrylic acid
based soft ionomer available from the Exxon Corporation under the
designation Iotek.RTM. 7510, is also effective, when combined with
the hard ionomers indicated above in producing golf ball covers
exhibiting higher C.O.R. values at equal or softer hardness than
those produced by known hard-soft ionomer blends. In this regard,
Iotek.RTM. 7510 has the advantages (i.e., improved flow, higher
C.O.R. values at equal hardness, increased clarity, etc.) produced
by the Iotek.RTM. 7520 resin when compared to the methacrylic acid
base soft ionomers known in the art (such as the Surlyn.RTM. 8625
and the Surlyn.RTM. 8629 combinations disclosed in U.S. Pat. No.
4,884,814).
[0248] In addition, Iotek.RTM. 7510, when compared to Iotek.RTM.
7520, produces slightly higher C.O.R. valves at equal
softness/hardness due to the Iotek.RTM. 7510's higher hardness and
neutralization. Similarly, Iotek.RTM. 7510 produces better release
properties (from the mold cavities) due to its slightly higher
stiffness and lower flow rate than Iotek.RTM. 7520. This is
important in production where the soft-covered balls tend to have
lower yields caused by sticking in the molds and subsequent punched
pin marks from the knockouts.
[0249] According to Exxon, Iotek.RTM. 7510 is of similar chemical
composition as Iotek.RTM. 7520 (i.e., a zinc salt of a terpolymer
of ethylene, acrylic acid, and methyl acrylate) but is more highly
neutralized. Based upon FTIR analysis Iotek.RTM. 7520 is estimated
to be about 30-40 wt. -% neutralized and Iotek.RTM. 7510 is
estimated to be about 40-60 wt.-% neutralized. The typical
properties of Iotek.RTM. 7510 in comparison of those of Iotek.RTM.
7520 are set forth below in Table 13:
13TABLE 13 Physical Properties of Iotek .RTM. 7510 in Comparison to
Iotek .RTM. 7520 Iotek .RTM. 7520 Iotek .RTM. 7514 MI, g/10 min 2.0
0.8 Density, g/cc 0.96 0.97 Melting Point, of 151 149 Vicat
Softening Point, .degree. F. 108 109 Flex Modulus, psi 3800 5300
Tensile Strength, psi 1450 1750 Elongation, % 760 690 Shore D
Hardness 32 35
[0250] It has been determined that when hard/soft ionomer blends
are used for the outer cover layer, good results are achieved when
the relative combination is in a range of about 90 to about 10
percent hard ionomer and about 10 to about 90 percent soft ionomer.
The results are improved by adjusting the range to about 75 to 25
percent hard ionomer and 25 to 75 percent soft ionomer. Even better
results are noted at relative ranges of about 60 to 90 percent hard
ionomer resin and about 40 to 10 percent soft ionomer resin.
[0251] Specific formulations which may be used in the cover
composition are included in the examples set forth in U.S. Pat.
Nos. 5,120,791 and 4,884,814. The present invention is in no way
limited to those examples.
[0252] Moreover, in alternative embodiments, the outer cover layer
formulation may also comprise a soft, low modulus non-ionomeric
thermoplastic elastomer including a polyester polyurethane such as
B. F. Goodrich Company's Estane.RTM. polyester polyurethane X-4517.
According to B. F. Goodrich, Estane.RTM. X-4517 has the properties
listed in Table 14:
14TABLE 14 Properties of Estane .RTM. X-4517 Tensile 143 100% 815
200% 1024 300% 1193 Elongation 641 Youngs Modulus 1826 Hardness A/D
88/39 Bayshore Rebound 59 Solubility in Water Insoluble Melt
Processing Temperature >350.degree. (>177.degree. C.)
Specific Gravity (H.sub.2O = 1) 1.1-1.3
[0253] In addition to the above noted ionomers, compatible additive
materials may also be added to produce the cover compositions of
the present invention. These additive materials include dyes (for
example, Ultramarine Blue.TM. sold by Whitaker, Clark, and Daniels
of South Painsfield, N.J.), and pigments, i.e., white pigments such
as titanium dioxide (for example Unitane.TM. 0-110) zinc oxide, and
zinc sulfate, as well as fluorescent pigments. As indicated in U.S.
Pat. No. 4,884,814, the amount of pigment and/or dye used in
conjunction with the polymeric cover composition depends on the
particular base ionomer mixture utilized and the particular pigment
and/or dye utilized. The concentration of the pigment in the
polymeric cover composition can be from about 1% to about 10% as
based on the weight of the base ionomer mixture. A more preferred
range is from about 1% to about 5% as based on the weight of the
base ionomer mixture. The most preferred range is from about 1% to
about 3% as based on the weight of the base ionomer mixture. The
most preferred pigment for use in accordance with this invention is
titanium dioxide.
[0254] Moreover, since there are various hues of white, i.e., blue
white, yellow white, etc., trace amounts of blue pigment may be
added to the cover stock composition to impart a blue white
appearance thereto. However, if different hues of the color white
are desired, different pigments can be added to the cover
composition at the amounts necessary to produce the color
desired.
[0255] In addition, it is within the purview of this invention to
add to the cover compositions of this invention compatible
materials which do not affect the basic novel characteristics of
the composition of this invention. Among such materials are
antioxidants (i.e., Santonox.RTM. R), antistatic agents,
stabilizers and processing aids. The cover compositions of the
present invention may also contain softening agents, such as
plasticizers, etc., 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.
[0256] Furthermore, optical brighteners, such as those disclosed in
U.S. Pat. No. 4,679,795, herein incorporated by reference, may also
be included in the cover composition of the invention. Examples of
suitable optical brighteners which can be used in accordance with
this invention are Uvitex.RTM. OB as sold by the Ciba-Geigy
Chemical Company, Ardsley, N.Y. Uvitex.RTM. OB is thought to be
2,5-Bis(5-tert-butyl-2-benzoxazoly)t- hiophene. Examples of other
optical brighteners suitable for use in accordance with this
invention are as follows: Leucopure.RTM. EGM as sold by Sandoz,
East Hanover, N.J. 07936. Leucopure.RTM. EGM is thought to be
7-(2n-naphthol(1,2-d)-triazol 2yl)-3phenyl-coumarin. Phorwhite.RTM.
K-20G2 is sold by Mobay Chemical Corporation, P.O. Box 385, Union
Metro Park, Union, N.J. 07083, and is thought to be a pyrazoline
derivative. Eastobrite.RTM. OB-1 as sold by Eastman Chemical
Products, Inc. Kingsport, Tenn., is thought to be
4,4-Bis(-benzoxazoly)stilbene. The above-mentioned Uvitex.RTM. and
Eastobrite.RTM. OB-1 are preferred optical brighteners for use in
accordance with this invention.
[0257] Moreover, since many optical brighteners are colored, the
percentage of optical brighteners utilized must not be excessive in
order to prevent the optical brightener from functioning as a
pigment or dye in its own right.
[0258] Other soft, relatively low modulus non-ionomeric
thermoplastic elastomers may also be utilized to produce the outer
cover layer as long as the non-ionomeric thermoplastic elastomers
produce the playability and durability characteristics desired
without adversely effecting the enhanced spin characteristics
produced by the low acid ionomer resin compositions. These include,
but are not limited to thermoplastic polyurethanes such as:
Texin.RTM. thermoplastic polyurethanes from Mobay Chemical Co. and
the Pellethane.RTM. thermoplastic polyurethanes from Dow Chemical
Co.; 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.
[0259] B. Nylon Compositions
[0260] Furthermore, examples of cover compositions for use as inner
or outer cover layers include a graft copolymer or blend of a
polyamide homopolymer with one or both of an ionomeric terpolymer
and an ionomeric copolymer with two types of monomers. Preferred
polyamides for use according to the invention are polymers of
caprolactam such as polyepsiloncaprolactam (nylon 6),
polyhexamethyleneadipamide (nylon 6,6), and copolymers of nylon 6
and nylon 6,6. The ionomeric component of the invention preferably
is a copolymer formed from an alpha-olefin having 2 to 8 carbon
atoms and an acid which is selected from the group consisting of
alpha, beta-ethylenically unsaturated mono- or dicarboxylic acids
and is neutralized with cations which include at least one member
selected from the group consisting of zinc, lithium, sodium,
manganese, calcium, chromium, nickel, aluminum, potassium, barium,
tin, copper, and magnesium ions. Preferred cations are zinc, sodium
and lithium, and combinations thereof. The copolymer may further be
formed from an unsaturated monomer of the acrylate ester class
having from 1 to 21 carbon atoms.
[0261] The Shore D hardness of a hard nylon-containing cover layer
according to the invention is typically in the range of 65 to 84.
Shore D hardness is measured generally in accordance with ASTM
D-2240, but measured on the curved surface of the ball. The Shore D
hardness of a soft nylon-containing cover layer according to the
present invention typically is in the range of 50 to 65. Both hard
and soft nylon-containing cover layers preferably are made from
resin compositions which have a melt index of from about 0.5 to
about 20 g/10 min., more preferably from about 0.5 to about 8 g/10
min., and most preferably from about 1 to about 4 g/10 mins.
[0262] Golf balls according to the invention typically have a
coefficient of restitution of at least 0.780 and more preferably at
least 0.800, and a PGA compression of 85 to 117, more preferably 90
to 105, and most preferably 90 to 97. High spin golf balls
according to the invention typically have a PGA compression of 70
to 100, more preferably 75 to 95, and most preferably 75 to 85.
[0263] An "ionomeric copolymer" as this term is used herein is a
copolymer of alpha-olefin and an alpha, beta-ethylenically
unsaturated mono- or dicarboxylic acid with at least 3% and
preferably at least 10% of the carboxylic acid groups being
neutralized with metal ions. The alpha-olefin preferably has 2 to 8
carbon atoms, the carboxylic acid preferably is acrylic acid,
methacrylic acid, maleic acid, or the like and the metal ions
include at least one cation selected from the group consisting of
ions of zinc, magnesium, lithium, barium, potassium, calcium,
manganese, nickel, chromium, tin, aluminum, sodium, copper, or the
like. Preferably the cation is zinc, sodium or lithium or a
combination thereof. The term "copolymer" includes (1) copolymers
having two types of monomers which are polymerized together, (2)
terpolymers (which are formed by the polymerization of three types
of monomers), and (3) copolymers which are formed by the
polymerization of more than three types of monomers.
[0264] A "polyamide component" as used herein is a polyamide
homopolymer, a polyamide copolymer containing two or more types of
amide units, e.g., nylon 6, nylon 12, or a combination of both a
polyamide homopolymer and a polyamide copolymer. The polyamide
component preferably is a long chain polymer, not an oligomer,
which typically is a short chain polymer of 2 to 10 units. An
"ionomeric component" is (a) a non-polyamide-containing ionomeric
copolymer which is capable of being mixed or blended with the
polyamide component, (b) the ionomeric portion of a
polyamide-containing ionomeric copolymer, or a combination of both
(a) and (b). If the polyamide component and ionomeric component are
bonded to one another, the acid portion of the ionomeric component
preferably is neutralized before the reaction of the polyamide and
ionomeric components, but could also be neutralized after the
reaction of the polyamide and ionomeric components.
[0265] The details of interaction between a polyamide and an
ionomeric copolymer are not fully understood. A polyamide and an
ionomer could, for example, be intimately mixed without any bonding
but with specific intermolecular interactions. Furthermore, it is
possible, in combining a specific quantity of polyamide with a
specific quantity of ionomeric copolymer that portions of the
overall quantities of the polyamide component and ionomeric
component could be bonded to each other, as in a graft reaction,
while other portions of the polyamide component and ionomeric
component could form a blend which may have specific intermolecular
interactions. Thus, this application is not intended to be limited
by the degree of bonding versus intermolecular interaction of the
polyamide component and ionomeric component unless specifically
indicated.
[0266] Golf balls of the present invention may employ a composition
that is the reaction product ("RP") of a reactive mixture of
polyamide, ionomeric copolymer, and an ester. The RP preferably is
formed from a reactive mixture of at least one of
polyepsiloncaprolactam (Nylon 6) and polyhexamethyleneadipamide
(Nylon 6,6), zinc neutralized ethylene/methacrylic acid ionomer
copolymer, and ethylene (meth)acrylate. As used herein, the term
"(meth)acrylate" includes both acrylates and methacrylates. The
polyamide preferably is about 50 wt % to about 90 wt % of the
reactive mixture, the ionic copolymer is about 5 to about 50 wt %
of the reactive mixture, and the copolymer is about 1 to 20 wt % of
the reactive mixture. More preferably, the polyamide is about 60 to
about 72 wt % of the reactive mixture, the ionic copolymer is about
26-34 wt % of the reactive mixture, and the ester copolymer,
preferably olefin ester copolymer, is about 2-6 wt % of the
reactive mixture.
[0267] Commercially available products which are the reaction
products of reactive mixtures of polyamide, ionic copolymer, and
olefin ester copolymer include Capron.RTM. 8351, available from
Allied Signal. This reactive mixture, and the processing thereof,
is believed to be described in U.S. Pat. No. 4,404,325, the
teachings of which are incorporated herein by reference in their
entirety. As described therein, the preferred polyamide is
polyespiloncaprolactam or polyhexamethyleneadipami- de, and most
preferably polyespiloncaprolactam. The preferred olefin ester
copolymer is ethylene/ethyl acrylate. The preferred ionic copolymer
is a zinc neutralized copolymer of ethylene/methacrylic acid
available from DuPont under the trade name Surlyn.RTM. 9721 (1801).
According to claim 7 of U.S. Pat. No. 4,404,325, the polyamide is
present in the reactive mixture in an amount of about 60 to about
72 wt %, the ionomeric copolymer is present in an amount of about
26 wt % to about 34 wt %, and the olefin ester copolymer is present
in an amount of about 2 to about 6 wt %, based on the total weight
of the reactive mixture. It is believed that Capron.RTM. 8351 has a
nylon backbone with ionomer grafted thereto. Allied Signal
indicates that Capron.RTM. 8351 is a graft copolymer which has the
properties set forth below in Table 15:
15TABLE 15 Test Property Method (ASTM) Value Specific Gravity D-792
1.07 Yield Tensile Strength, psi (MPa) D-638 7800 (54) Ultimate
Elongation % D-638 200.00 Flexural Strength, psi (MPa) D-790 9500
(65) Flexural Modulus, psi (MPa) D-790 230,000 (1585) Notched Izod
Impact ft-lbs/in D-256 No Break Drop Weight Impact ft-lbs/in D-3029
150 (200) Drop Weight Impact @-40 F, D-3029 150 (200) ft-lbs (J)
Heat Deflection Temperature D-648 60.00 @264 psi, .degree. C.
Melting Point, .degree. C. D-789 215.00
[0268] Capron.RTM. 8351 is the most preferred RP for use in the
invention. Variations of Capron.RTM. 8351 also may be used. For
example, variations of Capron.RTM. 8351 which may be used include
those which employ polyepsiloncaprolactam or
polyhexamethyleneadipamide with olefin ester copolymers such as
ethylene/methyl acrylate, ethylene/ethyl methacrylate, and
ethylene/methyl methacrylate. Ionic copolymers which may be used in
variations of Capron.RTM. 8351 include ionic copolymers of an alpha
olefin of the formula RCH.dbd.CH.sub.2 where R is H or alkyl
radicals having 1-8 carbons, and an alpha, beta-ethylenically
unsaturated carboxylic acid having from 3-8 carbons. The ionic
copolymer has at least about 10 wt % of the COOH groups neutralized
with metal cations, preferably zinc. Examples of these ionic
copolymers include zinc neutralized ethylene/methacrylic acid. In
variations of Capron.RTM. 8351, the reactive mixture neutralized to
produce such variations may include from about 50 wt % to about 90
wt % polyamide, from about 5 wt % to about 50 wt % ionic copolymer,
and from about 1 wt % to about 20 wt % olefin ester copolymer, all
percents based on the weight of the reactive mixture.
[0269] In another preferred embodiment, golf balls of the invention
employ preferably as an inner and/or outer cover layer, a
composition that includes RP and at least one terpolymer.
Terpolymers which may be employed include olefin/alkyl
(meth)acrylate/carboxylic acid terpolymers. These terpolymers
typically have from about 50 wt % to about 98 wt % olefin, from
about 1 wt % to about 30 wt % alkyl acrylate, and from about 1 wt %
to about 20 wt % carboxylic acid. The olefin may be any of
ethylene, propylene, butene-1, hexene-,1 and the like, preferably
ethylene. The alkyl (meth)acrylate may be any of methyl acrylate,
methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl
acrylate, butyl methacrylate, butyl vinyl ether, methyl vinyl
ether, and the like, preferably methyl acrylate. The carboxylic
acid may be any one of acrylic acid, methacrylic acid, maleic acid,
and fumaric acid. Monoesters of diacids such as methyl hydrogen
maleate, methyl hydrogen fumarate, ethyl hydrogen fumarate, and
maleic anhydride which is considered to be a carboxylic acid may
also be used. Preferably, the carboxylic acid is acrylic acid.
Useful ethylene/methyl acrylate/acrylic acid terpolymers may
comprise from about 50 wt % to about 98 wt %, preferably from about
65 wt % to about 85 wt %, and most preferably about 76 wt %
ethylene; from about 1 wt % to about 30 wt % preferably from about
15 wt % to about 20 wt %, and most preferably about 18 wt % methyl
acrylate; and about 1 wt % to about 20 wt %, preferably from about
4 wt % to about 10 wt %, and most preferably about 6 wt % acrylic
acid.
[0270] Olefin/alkyl(meth)acrylate/carboxylic acid terpolymers which
are preferred for use in the compositions employed in the invention
are ethylene/methyl acrylate/acrylic acid terpolymers such as those
marketed by Exxon Chemical Co. under the name Escor.RTM.. Examples
of these terpolymers include Escor.RTM. ATX 320 and Escor.RTM. ATX
325. The properties of Escor.RTM. ATX 320 and Escor.RTM. ATX 325 as
provided by Exxon are set forth below in Table 16:
16TABLE 16 Property/Resin ESCOR .RTM. ATX-320 ESCOR .RTM. ATX-325
Melt Index.sup.1 5.0 g/10 min 20.0 g/10 min Density.sup.1 0.950
g/cc 0.950 g/cc Melting Point.sup.1 69 C. 67 C. Crystallization 51
C. 50 C. Temperature.sup.1 Vicat Softening 66 C. 60 C. Temperature
200 g.sup.2 Tensile Strength @ 12 MPa 7.8 MPa Yield.sup.3
Hardness.sup.4 34.00 30.00 Elongation @ Break.sup.3 >800%
>800% .sup.1Exxon Method .sup.2ASTM D 1525 .sup.3ASTM 638
.sup.4Shore D
[0271] Other olefin/alkyl (meth)acrylate/carboxylic acid
terpolymers which may be employed with RP in the compositions
employed in the invention include but are not limited to:
[0272] ethylene/n-butyl acrylate/acrylic acid,
[0273] ethylene/n-butyl acrylate/methacrylic acid,
[0274] ethylene/2-ethoxyethyl acrylate/acrylic acid,
[0275] ethylene/2-ethoxyethyl acrylate/methacrylic acid,
[0276] ethylene/n-pentyl acrylate/acrylic acid,
[0277] ethylene/n-pentyl acrylate/methacrylic acid,
[0278] ethylene/n-octyl acrylate/acrylic acid,
[0279] ethylene/2-ethyhexyl acrylate/acrylic acid,
[0280] ethylene/n-propyl acrylate/acrylic acid,
[0281] ethylene/n-propyl acrylate/methacrylic acid,
[0282] ethylene/n-heptyl acrylate/acrylic acid,
[0283] ethylene/2-methoxylethyl acrylate/acrylic acid,
[0284] ethylene/3-methoxypropyl acrylate/acrylic acid,
[0285] ethylene/3-ethoxypropyl acrylate/acrylic acid, and
[0286] ethylene/acrylate/acrylic acid.
[0287] Compositions which may be employed to provide golf balls
according to this embodiment of the invention include from about 1
wt % to about 90 wt %, preferably from about 1 wt % to about 30 wt
%, and most preferably about 15 wt % RP; and from about 99 wt % to
about 10 wt % terpolymer, preferably from about 99 wt % to about 70
wt % and most preferably about 85 wt % terpolymer.
[0288] Golf balls of the present invention also employ, preferably
as a cover, compositions which include RP and an olefin/alkyl
acrylate/carboxylic acid terpolymer ionomer. Typically, the
carboxylic acid groups of the terpolymer ionomer are partially
(i.e., approximately 5% to 80%) neutralized by metal ions such as
lithium, sodium, zinc, manganese, nickel, barium, tin, calcium,
magnesium, copper and the like, preferably zinc, sodium or lithium
or a combination thereof, and most preferably zinc or lithium or a
combination thereof. These terpolymer ionomers usually have a
relatively high molecular weight, e.g., a melt index of about 0.1
to 1000 g/10 min., and/or a weight average molecular weight of 5000
up to one million. The ethylene/methyl acrylate/acrylic acid
terpolymer ionomer may comprise from about 50 wt % to about 98 wt
%, preferably from about 65 wt % to about 85 wt %, and most
preferably about 76 wt % ethylene; from about 1 to about 30 wt %,
preferably from about 15 to about 20 wt %, and most preferably
about 18 wt % methyl acrylate; and from about 1 wt % to about 20 wt
%, preferably from about 4 wt % to about 10 wt %, and most
preferably about 6 wt % acrylic acid. Useful terpolymer ionomers
include, for example, ethylene/methyl acrylate/acrylic acid
terpolymer ionomers sold by Exxon Chemical Co. under the
designation Iotek.RTM.. Preferred terpolymer ionomers for use in
the invention include zinc neutralized ethylene/methyl
acrylate/acrylic acid terpolymer ionomers such as Iotek.RTM. 7520
and Iotek.RTM. 7510, and lithium neutralized ionomers such as
Escor.RTM. ATX-320-Li-80.
[0289] Escor.RTM. ATX320 Li-80 is produced by utilizing a 6.0 wt %
acrylic acid/18.0 wt % methyl acrylate 76 wt % ethylene terpolymer
produced by Exxon Chemical Co. under the designation Escor.RTM. ATX
320. The acid groups present in the terpolymer then are neutralized
to 80 mol % by using lithium hydroxymonohydrate. Neutralization is
performed by adding lithium hydroxymonohydrate and Escor.RTM. ATX
320 terpolymer to an intensive mixer (Banbury.RTM. type). The
lithium salt solubilizes in the ATX 320 terpolymer above the
melting temperature of the terpolymer, and a vigorous reaction
occurs with foaming as the lithium cation reacts with the acid
groups of the terpolymer, and volatile byproducts are evaporated.
The reaction is continued until foaming ceases (i.e., about 30 to
about 45 minutes at 250.degree. F. to 350.degree. F.) and the batch
is removed from the Banbury.RTM. mixer. Mixing continues on a hot
two-roll mill (175.degree. F. to 250.degree. F.) to complete the
neutralization reaction.
[0290] For the purpose of determining the weight percent of
neutralization of the acrylic acid groups in the terpolymer ionomer
after reacting with the lithium salt, it is assumed that one mol of
lithium neutralizes one mol of acrylic acid. The calculations of
neutralization are based upon an acrylic acid molecular weight of
72 g/mol, giving 0.067 mols of lithium per 100 grams of the
terpolymer.
[0291] Although Escor.RTM. ATX 320 terpolymer can be 80 mol %
neutralized by lithium, it is to be understood that other degrees
of neutralization with lithium, ranging from about 3 mol % to about
90 mol %, may be employed to provide useful ionomers. Thus, for
example, ATX 320 that is 20 mol % neutralized by lithium,
hereinafter referred to as ATX 320-Li-20 may be employed. In
addition, various cation salts such as salts of sodium, potassium,
magnesium, manganese, calcium and nickel may be employed in a
manner similar to lithium salts to provide various other Escor.RTM.
ATX 320 type terpolymer ionomers.
[0292] Other terpolymer ionomers which may be used in the
compositions employed in this embodiment of the invention include
ethylene/alkyl ester/methacrylic acid terpolymer ionomers; such as
those disclosed in U.S. Pat. No. 4,690,981, the teachings of which
are incorporated by reference in its entirety herein, and which are
available from DuPont Corp. under the trade name Surlyn.RTM..
Properties of various Surlyn.RTM. terpolymer ionomers which may be
used in the invention are set forth in Table 17. The terpolymer
ionomer may be from about 1 wt % to about 99 wt %, preferably from
about 50 wt % to about 99 wt %, and most preferably about 85 wt %,
all amounts based on the total weight of the RP-terpolymer ionomer
composition. RP may be from about 1 wt % to about 99 wt %,
preferably about 1 wt % to about 50 wt %, and most preferably about
15 wt %, all amounts based on the total weight of the
composition.
17TABLE 17 Resin/ Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Surlyn
.RTM. Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Property
ASTM 7930 7940 8020 8528 8550 8660 8120 8320 Cation Li Li Na Na Na
Na Na Na Meld Flow Index D-1238 1.80 2.60 1.00 1.30 3.90 10.00 0.90
0.90 (g/10 min) Density D-792 0.94 0.94 0.95 0.94 0.94 0.94 0.94
0.94 Notched Izod D-256 NB.sup.1 NB.sup.1 NB.sup.1 11.40 -- 16.00
-- -- Tensile Impact (23 C) D-1822S 140.00 220.00 630.00 550.00
795.00 345.00 235.00 213.00 ft-lb/in.sup.2 Flexural Mod (23 C)
D-790 67.00 61.00 14.00 32.00 31.70 34.00 49.10 19.30 kpsi Yield
Strength (kpsi) D-838 2.80 2.20 -- 1.80 1.60 1.90 2.20 2.30
Elongation (%) D-838 290.00 285.00 530.00 450.00 419.00 470.00
660.00 770.00 Hardness, Shore D D-2240 68.00 68.00 56.00 60.00
60.00 62.00 38.00 25.00 Vicat Temperature D-152 (C) 5-70 62.00
63.00 61.00 73.00 78.00 71.00 51.00 48.00 Rate B Resin/ Surlyn
.RTM. Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Surlyn
.RTM. Surlyn .RTM. Surlyn .RTM. Surlyn .RTM. Property 9020 9320
9520 9650 9720 9730 9910 9950 9970 Cation Zn Zn Zn Zn Zn Zn Zn Zn
Zn Meld Flow Index (g/10 1.10 0.60 1.10 5.00 1.00 1.60 0.70 5.50
1.40 min) Density 0.96 0.94 0.95 0.95 0.95 0.95 0.97 0.95 0.95
Notched Izod NB.sup.2 10.10 14.50 NB.sup.1 NB.sup.1 6.60 NB.sup.1
NB.sup.1 Tensile Impact (23 C) ft- 610.00 570.00 460.00 600.00
590.00 485.00 485.00 360.00 lb/in.sup.2 Flexural Mod (23 C) kpsi
14.00 3.70 38.00 32.00 36.00 30.00 48.00 37.00 28.00 Yield Strength
(kpsi) -- 3.50 1.80 1.80 1.70 1.60 2.00 1.80 1.60 Elongation (%)
510.00 500.00 410.00 410.00 440.00 460.00 290.00 490.00 480.00
Hardness, Shore D 55.00 40.00 60.00 63.00 61.00 63.00 64.00 62.00
62.00 Vicat Temperature (C) 57.00 454.00 74.00 71.00 71.00 73.00
62.00 68.00 61.00 .sup.1Terpolymer ionomers .sup.2No Break
[0293] Other suitable nylon containing compositions include
compositions of olefin/carboxylic acid copolymer ionomers made from
two types of monomers and RP. Olefin/carboxylic acid copolymer
ionomers which may be employed with RP include those wherein the
carboxylic acid groups of the copolymer ionomer are partially
(i.e., approximately 5% to 80%) neutralized by metal ions such as
but not limited to lithium, sodium, zinc and magnesium, and
preferably zinc, and/or sodium. Ionic copolymers may be zinc
neutralized ethylene/methacrylic acid ionomer copolymer, sodium
neutralized ethylene/acrylic acid copolymer ionomers, and mixtures
thereof. The zinc neutralized ethylene/acrylic acid copolymer
ionomer can be the reaction product of zinc neutralization of an
ethylene/acrylic acid copolymer having from about 15 wt % to about
20 wt % acrylic acid and a melt index of about 37 to about 100.
These copolymer ionomers usually have a relatively high molecular
weight, e.g., a melt index of about 0.1 to 1000 g/10 min., and/or a
weight average molecular weight of 5000 up to one million. Useful
copolymer ionomers include, for example, ethylene/acrylic acid
copolymer ionomers sold by Exxon Chemical Co. under the designation
Iotek.RTM. such as Iotek.RTM. 7030, Iotek.RTM. 7020, Iotek.RTM.
7010, Iotek.RTM. 8030, Iotek.RTM. 8020, and Iotek.RTM. 8000.
Non-limiting examples of preferred Iotek.RTM. copolymer ionomers
for use in the invention include Iotek.RTM. 7010, Iotek.RTM. 7030
and Iotek.RTM. 8000. Properties of various Iotek.RTM. copolymer
ionomers are shown in Tables 18 and 19.
18TABLE 18 ASTM Iotek .RTM. Iotek .RTM. Iotek .RTM. Iotek .RTM.
Iotek .RTM. Method 4000 4010 7010 7020 7030 Resin/ Property Cation
Zn Zn Zn Zn Zn Melt Flow Index g/10 min D-1238 2.50 1.50 0.80 1.50
2.50 Density Point, C. D-792 964.00 966.00 968.00 966.00 964.00
Melting Point, C. D-2240 85.00 84.00 83.50 84.00 85.00
Crystallization Point, C. D-638 58.00 56.00 55.00 56.00 58.00 Vicat
Softening Point, C. D-638 60.00 60.00 60.00 60.00 60.00 Flexural
Mod, MPa D-790 155.00 175.00 190.00 175.00 155.00 Tensile Impact at
23 C., KJ/m.sup.2 D-1822 480.00 520.00 550.00 520.00 480.00 (Type S
Dumbbell, 2 mm Thick Compression Plaques) Plaque Properties (2 mm
thick compression molding) Tensile Strength at Break D-638 22.60
23.50 24.50 23.50 22.60 MPa Yield Point MPa D-638 12.00 13.00 14.00
13.00 12.00 Elongation at Break % D-638 460.00 450.00 440.00 450.00
460.00 1% Secant Modulus MPa D-638 125.00 135.00 150.00 135.00
125.00 Shore D Hardness D-2240 52.00 53.00 54.00 53.00 52.00 IOTEK
.TM. Iotek .RTM. Iotek .RTM. Iotek .RTM. Iotek .RTM. Iotek .RTM.
8000 8020 8030 7520 7510 3110 Resin/ Property Cation Na Na Na Zn Zn
Na Melt Flow Index g/10 min 0.80 1.60 2.80 2.00 0.80 1.30 Density
Point, C. 957.00 0.96 956.00 962.00 970.00 939.00 Melting Point, C.
83.00 84.00 87.00 67.00 67.00 95.00 Crystallization Point, C. 45.00
47.00 49.00 39.00 38.00 58.00 Vicat Softening Point, C. 54.00 54.50
55.50 40.00 40.00 75.00 Flexural Mod, MPa 320.00 340.00 355.00
30.00 35.00 260.00 Tensile Impact at 23 C., KJ/m.sup.2 570.00
550.00 500.00 780.00 950.00 580.00 (Type S Dumbbell, 2 mm Thick
Compression Plaques) Plaque Properties (2 mm thick compression
molding) Tensile Strength at Break 33.00 32.50 32.00 12.00 15.00
28.00 MPa Yield Point MPa 19.00 18.50 18.00 4.00 4.00 14.00
Elongation at Break % 370.00 380.00 410.00 680.00 570.00 510.00 1%
Secant Modulus MPa 280.00 280.00 280.00 22.00 27.00 210.00 Shore D
Hardness 60.00 60.00 60.00 30.00 35.00 55.00 *Terpolymer
ionomer
[0294]
19TABLE 19 ASTM EX EX EX EX Method 1001 1004 1006 1007
Resin/Property Cation Exxon Na Zn Na Zn Melt Flow Index D-1238 1.00
2.00 1.30 g/10 min Melting Point (C.) D-3417 83.70 82.50 86.00
Crystallization Point (C.) D-3417 41.30 52.50 47.50 52.30 Plaque
Properties (2 mm thick compression molding Tensile Strength at
Break D-638 34.40 20.60 33.50 24.10 MPa Yield Point MPa D-638 21.30
14.00 19.30 13.80 Elongation at Break % D-638 341.00 437.00 421.00
472.00 1% Secant Modulus MPa D-638 356.00 128.00 314.00 154.00 1%
Secant Modulus MPa D-790 365.00 130.00 290.00 152.00 Shore D
Hardness D-2240 63.00 53.00 58.00 51.00 Vicat Softening Point
D-1525 51.50 55.00 57.00 60.50
[0295] Compositions of nylon homopolymer and/or copolymer and one
or more olefin/alkyl acrylate/carboxylic acid terpolymer ionomers
are also suitable cover materials in a golf ball according to the
present invention. Terpolymer ionomers which may be used with the
nylon homopolymers preferably are ethylene/methyl acrylate/acrylic
acid terpolymer ionomers. Nylon homopolymers for use in any of the
compositions employed in the invention include but are not limited
to nylon 6, nylon 6,6, and mixtures or copolymers thereof. Other
nylons such as nylon 11, nylon 12, nylon 6,12, nylon 6,6/6 and
nylon 46 also can be used as long as sufficient durability is
achieved. In the case of nylon 6, a polyamide chain of about 140 to
about 222 repeating units is typically useful, but lower and higher
molecular weight material may be employed. Capron.RTM. 8202, a
nylon 6 type polymer available from Allied Signal, is preferred.
According to Allied Signal, Capron.RTM. 8202 has the properties set
forth below in Table 20.
20TABLE 20 Test Method Property (ASTM) Value Specific Gravity D-792
1.13 Yield Tensile Strength, psi (MPa) D-638 11500 (80) Ultimate
Elongation % D-638 70.00 Flexural Strength, psi (MPa) D-790 15700
(110) Flexural Modulus, psi (MPa) D-790 410,000 (2825) Notched Izod
Impact, ft-labs/in D-256 1.0 (55) Heat Deflection Temperature @ 264
psi, C. D-648 65.00 Melting Point, C. D-789 215.00 Rockwell
Hardness, R Scale D-785 119.00
[0296] Terpolymer ionomers which may be employed include but are
not limited to those having from about 50 wt % to about 98 wt %,
preferably from about 65 wt % to about 85 wt %, and most preferably
about 76 wt % ethylene; from about 1 wt % to about 30 wt %,
preferably from about 15 wt % to about 20 wt %, and most preferably
about 18 wt % methyl acrylate, and from about 1 wt % to about 20 wt
%, preferably from about 4 wt % to about 10 wt %, and most
preferably about 6 wt % acrylic acid, wherein the acrylic acid has
been neutralized by zinc, lithium or sodium or combinations
thereof. Preferred terpolymer ionomers include Iotek.RTM. 7520,
Iotek.RTM. 7510, Escor.RTM. ATX 320-Li-80, or a mixture thereof.
The nylon homopolymer may be present in the compositions in an
amount of from about 1 wt % to about 99 wt %, preferably from about
1 wt % to about 50 wt %, and most preferably about 15 wt % of the
composition. The terpolymer ionomer may be from about 99 wt % to
about 1 wt %, preferably from about 90 wt % to about 50 wt %, and
most preferably about 85 wt %, all amounts based on total weight of
the composition.
[0297] Zytel.RTM. 408 is a nylon 66 modified molding compound
containing ionomer. It is believed that Zytel.RTM. 408 is an
intimate mixture of polyamide and an ionomeric terpolymer of an
alpha-olefin, an acrylate ester, and an alpha, beta-ethylenically
unsaturated mono- or dicarboxylic acid with a portion of the
carboxylic acid groups being neutralized with metal ions. It is
unknown to the present inventors whether Zytel.RTM. 408 is a graft
copolymer or a blend; however, Zytel.RTM. 408 is believed to be a
blend of nylon 6,6 and an ethylene alkylmethacrylate methacrylic
acid terpolymer ionomer neutralized with zinc. The properties of
Zytel.RTM. 408, as provided by DuPont, are shown below in Table
21:
21TABLE 21 Test Method Property (ASTM) Value Specific Gravity D-792
1/09 Tensile Strength (-40.degree. F.) D-638 15100 psi Tensile
Strength (-40.degree. C.) D-638 104.1 MPa Flexural Modulus
(-40.degree. F.) D-790 410,000 psi Flexural Modulus (-40.degree.
C.) D-790 2827 MPa Izod Impact Strength at -40.degree. F. D-256 1.3
ft.lb/in. Izod Impact Strength at -40.degree. C. D-256 69 J/m
Gardner Impact at -30.degree. F. D-3029 >320 ft. lbs. Heat
Deflection temperature @@ D-648 75 C. 1.810.sup.6 Pa Melting Point
D-789 255 C. .sup.1Dry as molded, with about 0.2% water
[0298] Other suitable nylon compositions include compositions of
polyamide homopolymers or copolymers, and olefin/carboxylic acid
copolymer ionomers made from two types of monomers such as
Iotek.RTM.. The polyamides which can be used in the compositions
employed in the invention include but are not limited to nylon 6,
nylon 6,6, nylon 11, nylon 12, nylon 6,12, nylon 6,6/6, nylon 46
and mixtures thereof, as long as sufficient durability is achieved.
Preferably, the nylon polymer is any of nylon 6 and nylon 6,6, most
preferably nylon 6. In the case of nylon 6, a polyamide chain of
about 140 to about 222 repeating units is typically useful, but
lower and higher molecular weight material may be employed. A
preferred polyamide homopolymer is Capron.RTM. 8202 available from
Allied Signal. Useful copolymer ionomers include copolymer ionomers
having from about 99 wt % to about 70 wt %, preferably from about
90 wt % to about 80 wt %, and most preferably 85 wt % ethylene; and
from about 1 wt % to about 30 wt %, preferably from about 10 wt %
to about 20 wt %, and most preferably 15 wt % acrylic acid. A
preferred ethylene/acrylic acid copolymer ionomer is Iotek.RTM.
7010 from Exxon Chemical Co. The copolymer ionomer may be present
in the composition in an amount of from about 99 wt % to about 1 wt
%, preferably from about 95 wt % to about 70 wt %, and most
preferably about 80 wt % of the composition. The polyamide
homopolymer may be from about 1 wt % to about 99 wt %, preferably
from about 5 wt % to about 30 wt %, and most preferably about 20 wt
%, wherein all amounts are based on the total weight of the
composition.
[0299] Two or more copolymer ionomers may be preblended prior to
blending with polyamide homopolymers and/or RP to provide
compositions which may be used in the invention. Thus, preblends of
hard and soft copolymer ionomers, as well as preblends of high
carboxylic acid copolymer ionomers and low carboxylic acid
copolymer ionomers may be utilized to provide compositions for use
in the invention. An example of such a preblend is a mixture of
Iotek.RTM. 8000 and Iotek.RTM. 7010.
[0300] Cover materials may also be nylon compositions of polyamide
homopolymers or copolymers, and olefin/alkyl acrylate/carboxylic
acid terpolymers. Useful terpolymers include terpolymers having
about from 50 wt % to about 98 wt %, preferably from about 65 wt %
to about 85 wt %, and most preferably about 76 wt % olefin,
preferably ethylene; from about 1 wt % to about 30 wt %, preferably
from about 15 wt % to about 20 wt %, and most preferably about 18
wt % alkyl acrylate, preferably methyl acrylate; and from about 1
wt % to about 20 wt %, preferably from about 4 wt % to about 10 wt
%, and most preferably about 6 wt % carboxylic acid, preferably
acrylic acid. The terpolymer may be present in the composition in
an amount of from about 1 wt % to about 99 wt %, preferably from
about 50 wt % to about 99 wt %, and most preferably about 85 wt %
of the composition. The polyamide homopolymer may be from about 1
wt % to about 99 wt %, preferably from about 1 wt % to about 50 wt
%, and most preferably about 15 wt % wherein all amounts are based
on the total weight of the composition. Useful polyamides may be of
polyepsiloncaprolactam and polyhexamethyleneadipamide, more
preferably nylon 6, nylon 6,6, nylon 11, nylon 12, nylon 6,12,
nylon 6,6/6, nylon 46 and mixtures thereof. Preferably, the nylon
polymer is any of nylon 6 and nylon 6,6, still more preferably
nylon 6, and most preferably the nylon homopolymer sold by Allied
Signal under the trade name Capron.RTM. 8202. A preferred
ethylene/methyl acrylate/acrylic acid terpolymer is Escor.RTM. ATX
320 from Exxon Chemical Co.
[0301] Two or more terpolymers may be preblended prior to blending
with any of RP or the polyamide homopolymers to provide
compositions which may be used in the invention. Thus, preblends of
hard and soft terpolymers, as well as preblends of high carboxylic
acid terpolymers and low carboxylic acid terpolymers may be
utilized to provide compositions for use in the invention.
[0302] C. Polyurethanes
[0303] Polyurethanes are polymers which 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, diphenyl methane diisocyanate monomer ("MDI") and
toluene diisocyanate ("TDI") and their derivatives) and a polyol
(for example, a polyester polyol or a polyether polyol).
[0304] 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, i.e., whether the material is thermoset
(crosslinked molecular structure) or thermoplastic (linear
molecular structure).
[0305] Crosslinking 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). Consequently, a great variety of
polyurethanes are suitable for different end uses.
[0306] Polyurethane has been used for golf balls and other game
balls as a cover material. Commercially available polyurethane golf
balls have been made of thermoset polyurethanes. A polyurethane
becomes irreversibly "set" when a polyurethane prepolymer is cross
linked with a polyfunctional curing agent, such as polyamine and
polyol. The prepolymer typically is made from polyether or
polyester. Diisocyanate polyethers are preferred because of their
water resistance.
[0307] The physical properties of thermoset polyurethanes are
controlled substantially by the degree of cross linking. 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
purely by physical means. The crosslinkings bonds can be reversibly
broken by increasing temperature, as occurs during molding or
extrusion. In this regard, thermoplastic polyurethanes can be
injection molded, and extruded as sheet and blown film. They can be
used up to about 350.degree. F. and are available in a wide range
of hardnesses.
[0308] Polyurethane materials suitable for the present invention
are formed by the reaction of a polyisocyanate, a polyol, and
optionally one or more chain extending diols. The polyisocyanate is
selected, for example, from the group including diphenyl methane
diisocyanate ("MDI"); toluene diisocyanate ("TDI"); xylene
diisocyanate ("XDI"); methylene bis-(4-cyclohexyl isocyanate)
("HMDI"); hexamethylene diisocyanate; and
naphthalene-1,5,-diisocyanate ("NDI").
[0309] One polyurethane component which can be used in the present
invention incorporates meta-tetramethylxylylene diisocyanate
(TMXDI)("META") aliphatic isocyanate (Cytec Industries, West
Paterson, N.J.). Polyurethanes based on meta-tetramethylxylylene
diisocyanate 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.
[0310] A non-limiting example of a suitable polyurethane is
Estane.RTM. X4517 from B. F. Goodrich.
[0311] Further examples of suitable polyurethanes include
polyurethane systems formed via reaction injection molding (RIM).
RIM processing to form various layers of a golf ball is described
in detail in pending application U.S. Ser. No. 09/411,690,
incorporated herein by reference.
[0312] 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 Corporation
(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 Bayflex.RTM. MP-10000 and Bayflex.RTM. 110-50,
filled and unfilled. Further preferred examples are polyols,
polyamines and isocyanates formed by processes for recycling
polyurethanes and polyureas. Peroxides, such as MEK-peroxide and
dicumyl peroxide can be used. Furthermore, catalysts or activators
such as cobalt octoate 6% can be used.
[0313] The golf balls of the present invention can be produced, at
least in part, by molding processes currently known in the golf
ball art. Specifically, multi-layer golf balls can be produced by
injection molding or compression molding a mantle layer about wound
or solid molded cores to produce an intermediate golf ball having a
diameter of about 1.50 to 1.67 inches, preferably about 1.620
inches. The cover layer is subsequently molded over the mantle
layer to produce a golf ball having a diameter of 1.680 inches or
more. Although 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.
[0314] In compression molding, the mantle layer composition is
formed via injection at about 380.degree. F. to about 450.degree.
F. into smooth surfaced hemispherical shells which are then
positioned around the core in a mold having the desired mantle
layer thickness and subjected to compression molding at 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 mantle layer is injected directly around the
core placed at the center of an intermediate ball mold for a period
of time at a mold temperature of from 50.degree. F. to about
100.degree. F. An outer layer is molded about the core and the
inner layer by similar compression or injection molding techniques
to form a dimpled golf ball of a diameter of 1.680 inches or
more.
[0315] A preferred method of forming a golf ball according to the
present invention is forming one or more layers via a
fast-chemical-reaction process.
[0316] A preferred method of forming a polyurethane component for a
golf ball according to the invention is by reaction injection
molding ("RIM"). 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 processes usually
involve a rapid reaction between one or more reactive components
such as polyether- 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. 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, e.g., 1500-3000
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.
[0317] 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 which occur in a
conventional injection molding. 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 50,000 to 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. In contrast, in a RIM process,
the chemical reaction typically takes place in less than about two
minutes, preferably in under one minute, and in many cases in about
30 seconds or less.
[0318] 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. Failure can occur at this location because this
interfacial region is intrinsically different from the remainder of
the cover layer and can be weaker or more stressed. The
developments described herein 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 eliminates knit-lines and other molding
deficiencies which can be caused by temperature difference and/or
reaction difference in the injected materials. The process of the
invention results in generally uniform molecular structure, density
and stress distribution as compared to conventional
injection-molding processes.
[0319] The various cover composition layers of the present
invention may be produced according to conventional melt blending
procedures. When a blend of hard and soft, low acid ionomer resins
are utilized, the hard ionomer resins are blended with the soft
ionomeric resins and with a masterbatch containing the desired
additives in a Banbury.RTM. mixer, two-roll mill, or extruder prior
to molding. The blended composition is then formed into slabs and
maintained in such a state until molding is desired. Alternatively,
a simple dry blend of the pelletized or granulated resins and color
masterbatch 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. A
similar process is utilized to formulate the low acid ionomer resin
compositions.
[0320] Preferably, in a golf ball, according to the invention, at
least one layer of the golf ball contains at least one part by
weight of a filler. Fillers preferably are used to adjust the
density, flex modulus, mold release, and/or melt flow index of a
layer. More preferably, at least when the filler is for adjustment
of density or flex modulus of a layer, it is present in an amount
of at least five parts by weight based upon 100 parts by weight of
the layer composition. With some fillers, up to about 200 parts by
weight probably can be used.
[0321] A density adjusting filler according to the invention
preferably is a filler which has a specific gravity which is at
least 0.05 and more preferably at least 0.1 higher or lower than
the specific gravity of the layer composition. Particularly
preferred density adjusting fillers have specific gravities which
are higher than the specific gravity of the resin composition by
0.2 or more, even more preferably by 2.0 or more.
[0322] A flex modulus adjusting filler according to the invention
is a filler which, when used in an amount of, e.g., 1 to 100 parts
by weight based upon 100 parts by weight of resin composition, will
raise or lower the flex modulus (ASTM D-790) of the resin
composition by at least 1% and preferably at least 5% as compared
to the flex modulus of the resin composition without the inclusion
of the flex modulus adjusting filler.
[0323] A mold release adjusting filler is a filler which allows for
the easier removal of a part from a mold, and eliminates or reduces
the need for external release agents which otherwise could be
applied to the mold. A mold release adjusting filler typically is
used in an amount of up to about 2 weight percent based upon the
total weight of the layer.
[0324] A melt flow index adjusting filler is a filler which
increases or decreases the melt flow, or ease of processing of the
composition.
[0325] The layers may contain coupling agents that increase
adhesion of materials within a particular layer, e.g., to couple a
filler to a resin composition, or between adjacent layers.
Non-limiting examples of coupling agents include titanates,
zirconates and silanes. Coupling agents typically are used in
amounts of 0.1 to 2 weight percent based upon the total weight of
the composition in which the coupling agent is included.
[0326] A density adjusting filler is used to control the moment of
inertia, and thus the initial spin rate of the ball and spin decay.
The addition in one or more layers, and particularly in the outer
cover layer of a filler with a lower specific gravity than the
resin composition results in a decrease in moment of inertia and a
higher initial spin rate than would result if no filler were used.
The addition in one or more of the cover layers, and particularly
in the outer cover layer of a filler with a higher specific gravity
than the resin composition, results in an increase in moment of
inertia and a lower initial spin rate. High specific gravity
fillers are preferred as less volume is used to achieve the desired
inner cover total weight. Non-reinforcing fillers are also
preferred as they have minimal effect on C.O.R. Preferably, the
filler does not chemically react with the resin composition to a
substantial degree, although some reaction may occur when, for
example, zinc oxide is used in a shell layer which contains some
ionomer.
[0327] The density-increasing fillers for use in the invention
preferably have a specific gravity in the range of 1.0 to 20. The
density-reducing fillers for use in the invention preferably have a
specific gravity of 0.06 to 1.4, and more preferably 0.06 to 0.90.
The flex modulus increasing fillers have a reinforcing or
stiffening effect due to their morphology, their interaction with
the resin, or their inherent physical properties. The flex modulus
reducing fillers have an opposite effect due to their relatively
flexible properties compared to the matrix resin. The melt flow
index increasing fillers have a flow enhancing effect due to their
relatively high melt flow versus the matrix. The melt flow index
decreasing fillers have an opposite effect due to their relatively
low melt flow index versus the matrix.
[0328] Fillers which may be employed in layers other than the outer
cover layer may be or are typically in a finely divided form, for
example, in a size generally less than about 20 mesh, preferably
less than about 100 mesh U.S. standard size, except for fibers and
flock, which are generally elongated. Flock and fiber sizes should
be small enough to facilitate processing. Filler particle size will
depend upon desired effect, cost, ease of addition, and dusting
considerations. The filler preferably is selected from the group
consisting of precipitated hydrated silica, clay, talc, asbestos,
glass fibers, aramid fibers, mica, calcium metasilicate, barium
sulfate, zinc sulfide, lithopone, silicates, silicon carbide,
diatomaceous earth, polyvinyl chloride, carbonates, metals, metal
alloys, tungsten carbide, metal oxides, metal stearates,
particulate carbonaceous materials, micro balloons, and
combinations thereof. Non-limiting examples of suitable fillers,
their densities, and their preferred uses are listed in Table
22:
22 TABLE 22 Filler Type Spec. Grav. Comments Precipitated hydrated
silica 2.00 1,2 Clay 2.62 1,2 Talc 2.85 1,2 Asbestos 2.50 1,2 Glass
fibers 2.55 1,2 Aramid fibers (KEVLAR .RTM.) 1.44 1,2 Mica 2.80 1,2
Calcium metasilicate 2.90 1,2 Barium sulfate 4.60 1,2 Zinc sulfide
4.10 1,2 Lithopone 4.2-4.3 1,2 Silicates 2.10 1,2 Silicon carbide
platelets 3.18 1,2 Silicon carbide whiskers 3.20 1,2 Tungsten
carbide 15.60 1 Diatomaceous earth 2.30 1,2 Polyvinyl chloride 1.41
1,2 Carbonates Calcium carbonate 2.71 1,2 Magnesium carbonate 2.20
1,2 Metals and Alloys (Powders) Titanium 4.51 1 Tungsten 19.35 1
Aluminum 2.70 1 Bismuth 9.78 1 Nickel 8.90 1 Molybdenum 10.20 1
Iron 7.86 1 Steel 7.8-7.9 1 Lead 11.40 1,2 Copper 8.94 1 Brass
8.2-8.4 1 Boron 2.34 1 Boron carbide whiskers 2.52 1,2 Bronze
8.70-8.74 1 Cobalt 8.92 1 Beryllium 1.84 1 Zinc 7.14 1 Tin 7.31 1
Metal Oxides Zinc oxide 5.57 1,2 Iron oxide 5.10 1,2 Aluminum oxide
4.00 Titanium oxide 3.9-4.1 1,2 Magnesium oxide 3.3-3.5 1,2
Zirconium oxide 5.73 1,2 Metal Stearates Zinc stearate 1.09 3,4
Calcium stearate 1.03 3,4 Barium stearate 1.23 3,4 Lithium stearate
1.01 3,4 Magnesium stearate 1.03 3,4 Particulate Carbonaceous
Materials Graphite 1.5-1.8 1,2 Carbon black 1.80 1,2 Natural
bitumen 1.2-1.4 1,2 Cotton flock 1.3-1.4 1,2 Cellulose flock
1.15-1.5 1,2 Leather fiber 1.2-1.4 1,2 Micro Balloons Glass
0.15-1.1 1,2 Ceramic 0.2-0.7 1,2 Fly ash 0.6-0.8 1,2 Coupling
Agents Adhesion Promoters Titanates 0.95-1.17 Zirconates 0.92-1.11
Silane 0.95-1.2 Comments 1. Particularly useful for adjusting
density of the cover layer. 2. Particularly useful for adjusting
flex modulus of the cover layer. 3. Particularly useful for
adjusting mold release of the cover layer. 4. Particularly useful
for increasing melt flow index of the cover layer. All fillers
except for metal stearates would be expected to reduce the melt
flow index of an injection molded cover layer. The amount of filler
employed is primarily a function of weight requirements and
distribution.
[0329] 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. 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.
* * * * *