U.S. patent application number 09/814611 was filed with the patent office on 2002-01-24 for golf ball comprising a metal mantle with a cellular or liquid core.
This patent application is currently assigned to SPALDING SPORTS WORLDWIDE, INC.. Invention is credited to Nesbitt, R. Dennis, Sullivan, Michael J..
Application Number | 20020010036 09/814611 |
Document ID | / |
Family ID | 27366060 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020010036 |
Kind Code |
A1 |
Sullivan, Michael J. ; et
al. |
January 24, 2002 |
Golf ball comprising a metal mantle with a cellular or liquid
core
Abstract
A unique golf ball and related methods of manufacturing are
disclosed in which the golf ball comprises one or more metal mantle
layers and a cellular or liquid core component. The golf ball may
also comprise an optional polymeric spherical substrate inwardly
disposed relative to the one or more metal mantle layers. The golf
balls according to the present invention exhibit improved spin,
feel, and acoustic properties. Furthermore, the one or more
interior metal layers prevent, or at least significantly minimize,
coefficient of restitution loss from the golf ball, and
significantly increases the moment of inertia of the golf ball.
Inventors: |
Sullivan, Michael J.;
(Chicopee, MA) ; Nesbitt, R. Dennis; (Westfield,
MA) |
Correspondence
Address: |
Diane F. Covello, Esq.
Division Patent and Trademark Counsel
Spalding Sports Worldwide
425 Meadow Street, P.O. Box 901
Chicopee
MA
01021-0901
US
|
Assignee: |
SPALDING SPORTS WORLDWIDE,
INC.
|
Family ID: |
27366060 |
Appl. No.: |
09/814611 |
Filed: |
March 22, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09814611 |
Mar 22, 2001 |
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08969083 |
Nov 12, 1997 |
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6244977 |
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08969083 |
Nov 12, 1997 |
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08714661 |
Sep 16, 1996 |
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60042120 |
Mar 28, 1997 |
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60042430 |
Mar 28, 1997 |
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Current U.S.
Class: |
473/371 ;
473/378 |
Current CPC
Class: |
A63B 37/0037 20130101;
A63B 37/0024 20130101; A63B 37/0076 20130101; A63B 37/0003
20130101; A63B 2037/085 20130101; A63B 37/0052 20130101; A63B 37/08
20130101; A63B 45/00 20130101; A63B 37/00 20130101; A63B 37/0033
20130101; A63B 37/12 20130101; A63B 2209/08 20130101; A63B 43/00
20130101 |
Class at
Publication: |
473/371 ;
473/378 |
International
Class: |
A63B 037/12; A63B
037/08 |
Claims
I claim:
1. A golf ball comprising: a spherical metal mantle having an inner
surface and an outer surface opposite from said inner surface; a
polymeric outer cover disposed about said mantle and proximate to
said outer surface, said polymeric cover comprising a material
selected from the group consisting of a lower acid ionomer, a
non-ionomeric thermoplastic elastomer, a blend of said low acid
ionomer and said non-ionomeric thermoplastic elastomer, and a
thermoset polymeric material; and a cellular core disposed within
said metal mantle.
2. The golf ball of claim 1 wherein said mantle comprises at least
one metal selected from the group consisting of steel, titanium,
chromium, nickel, and alloys thereof.
3. The golf ball of claim 2 wherein said mantle comprises a nickel
titanium alloy.
4. The golf ball of claim 1 wherein said mantle has a uniform
thickness ranging from about 0.001 inches to about 0.050
inches.
5. The golf ball of claim 4 wherein said thickness ranges from
about 0.005 inches to about 0.050 inches.
6. The golf ball of claim 5 wherein said thickness ranges from
about 0.005 inches to about 0.010 inches.
7. The golf ball of claim 1 wherein said mantle comprises: a first
spherical shell providing said inner surface; and a second
spherical shell providing said outer surface, said second shell
disposed adjacent to said first shell.
8. The golf ball of claim 7 wherein said first shell and said
second shell independently each comprise a metal selected from the
group consisting of steel, titanium, chromium, nickel, and alloys
thereof.
9. The golf ball of claim 8 wherein at least one of said first
shell and said second shell comprise a nickel titanium alloy.
10. The golf ball of claim 1 wherein said outer cover has a modulus
ranging from about 1000 psi to about 10,000 psi.
11. The golf ball of claim 1 wherein said low acid ionomer
comprises less than 16 weight percent acid.
12. The golf ball of claim 1 further comprising: an innermost
polymeric hollow spherical substrate, said spherical substrate
disposed between said mantle and said cellular core.
13. The golf ball of claim 12 wherein said substrate has a
thickness from about 0.005 inches to about 0.010 inches.
14. The golf ball of claim 1 wherein said cellular core comprises
at least one material selected from the group consisting of
polybutadiene/ZDA mixtures, polyurethanes, polyolefins, ionomers,
metallocenes, polycarbonates, nylons, polyesters, and
polystyrenes.
15. The golf ball of claim 14 wherein said cellular core comprises
a crosslinked polybutadiene/ZDA mixture.
16. The golf ball of claim 1 wherein said cellular core is disposed
immediately adjacent to said inner surface of said metal
mantle.
17. A golf ball comprising: a polymeric hollow spherical substrate,
said substrate having an inner surface defining a hollow interior
and an outer surface; a spherical metal mantle having an inner
surface directed toward said outer surface of said spherical
substrate, and an oppositely directed outer surface; a polymeric
outer cover having an inner surface directed toward said outer
surface of said metal mantle, and an oppositely directed outer
surface; and a cellular core disposed within said hollow interior
of said substrate.
18. The golf ball of claim 17 wherein said mantle comprises at
least one metal selected from the group consisting of steel,
titanium, chromium, nickel, and alloys thereof.
19. The golf ball of claim 18 wherein said mantle comprises a
nickel titanium alloy.
20. The golf ball of claim 17 wherein said mantle comprises: a
first spherical metal shell providing said inner surface; and a
second spherical metal shell providing said outer surface, said
second shell disposed adjacent to said first shell.
21. The golf ball of claim 17 wherein said cellular core is
disposed immediately adjacent to said inner surface of said
spherical substrate.
22. A golf ball comprising: a spherical metal mantle having an
inner surface defining an interior region, and an outer surface
opposite from said inner surface, said mantle including a first
spherical metal shell providing said inner surface and a second
spherical metal shell providing said outer surface, said second
shell disposed immediately adjacent to said first shell; a
polymeric outer cover disposed about said mantle and proximate to
said outer surface, said polymeric cover comprising a material
selected from the group consisting of a lower acid ionomer, a
non-ionomeric thermoplastic elastomer, a blend of said low acid
ionomer and said non-ionomeric thermoplastic elastomer, and a
thermoset polymeric material; and a liquid core material disposed
within said interior region of said mantle.
23. The golf ball of claim 22, wherein said mantle comprises at
least one metal selected from the group consisting of steel,
titanium, chromium, nickel, and alloys thereof.
24. The golf ball of claim 23 wherein said mantle comprises a
nickel titanium alloy.
25. The golf ball of claim 23 wherein said mantle has a uniform
thickness ranging from about 0.001 inches to about 0.060
inches.
26. The golf ball of claim 25 wherein said thickness ranges from
about 0.005 inches to about 0.050 inches.
27. The golf ball of claim 26 wherein said thickness ranges from
about 0.005 inches to about 0.010 inches.
28. The golf ball of claim 22 wherein said first shell and said
second shell independently each comprise a metal selected from the
group consisting of steel, titanium, chromium, nickel, and alloys
thereof.
29. The golf ball of claim 28 wherein at least one of said first
shell and said second shell comprise a nickel titanium alloy.
30. The golf ball of claim 22 wherein said outer cover has a
modulus ranging from about 1000 psi to about 10,000 psi.
31. The golf ball of claim 22 wherein said low acid ionomer
comprises less than 16 weight percent acid.
32. The golf ball of claim 22 further comprising: an innermost
polymeric hollow spherical substrate, said spherical substrate
disposed within said interior region of said mantle and between
said inner surface of said mantle and said liquid core
material.
33. The golf ball of claim 32 wherein said substrate has a
thickness from about 0.005 inches to about 0.010 inches.
34. The golf ball of claim 22 wherein said liquid core comprises at
least one agent selected from the group consisting of water,
alcohol and oil, and at least one agent selected from the group
consisting of an inorganic salt, clay, barytes, and carbon
black.
35. The golf ball of claim 34 wherein said core comprises an
inorganic salt and water.
36. The golf ball of claim 35 wherein said inorganic salt is
calcium chloride.
37. The golf ball of claim 34 wherein said alcohol is
glycerine.
38. A golf ball comprising: a polymeric hollow spherical substrate,
said substrate having an inner surface defining a hollow interior
and an outer surface; a spherical metal mantle having an inner
surface directed toward said outer surface of said spherical
substrate and immediately adjacent to said outer surface of said
spherical substrate, and an oppositely directed outer surface; a
polymeric outer cover having an inner surface directed toward said
outer surface of said metal mantle, and an oppositely directed
outer surface; and a liquid core material disposed within said
hollow interior of said spherical substrate and immediately
adjacent to said inner surface of said spherical substrate.
39. The golf ball of claim 38 wherein said mantle comprises at
least one metal selected from the group consisting of steel,
titanium, chromium, nickel, and alloys thereof.
40. The golf ball of claim 39 wherein said mantle comprises a
nickel titanium alloy.
41. The golf ball of claim 38 wherein said mantle comprises: a
first spherical metal shell providing said inner surface; and a
second spherical metal shell providing said outer surface, said
second shell disposed adjacent to said first shell.
42. A method for producing a golf ball including a spherical metal
mantle having a hollow interior region and a cellular core disposed
within said metal mantle, said method comprising: providing a
spherical metal mantle defining a hollow interior region;
introducing a cellular core material precursor into said hollow
interior region of said mantle; and foaming said cellular core
material precursor while in said hollow interior region of said
mantle.
43. A method for producing a golf ball including a spherical metal
mantle having a hollow interior region and a cellular core disposed
within said metal mantle, said method comprising: providing a first
portion of a spherical metal mantle; providing a spherical cellular
core; providing a second portion of a spherical metal mantle, said
first portion and said second portion adapted to engage each other
and form said spherical metal mantle defining a hollow interior
region; disposing said cellular core between said first portion and
said second portion of said mantle; and engaging said first portion
and said second portion of said mantle together thereby enclosing
said cellular core within said hollow interior region of said
mantle.
44. A method for producing a golf ball including a spherical metal
mantle having a hollow interior region and a cellular core disposed
within said metal mantle, said method comprising: providing a
spherical cellular core having an outer surface; and depositing a
metal upon said outer surface to form said mantle.
45. A method for producing a golf ball including spherical metal
mantle having a hollow interior region and a liquid core disposed
within said metal mantle, said method comprising: providing a
spherical metal mantle defining a hollow interior region; and
introducing a liquid core material within said hollow interior
region of said mantle.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/042,120, filed Mar. 28, 1997; Provisional
Application Ser. No. 60/042,430, filed Mar. 28, 1997; and U.S.
application Ser. No. 08/714,661, filed Sep. 16, 1996.
FIELD OF THE INVENTION
[0002] The present invention relates to golf balls and, more
particularly, to golf balls comprising one or more metal mantle
layers and which further comprise a cellular or liquid core. The
golf balls may comprise an optional polymeric outer cover and/or an
inner polymeric hollow sphere substrate.
BACKGROUND OF THE INVENTION
[0003] Prior artisans have attempted to incorporate metal layers or
metal filler particles in golf balls to alter the physical
characteristics and performance of the balls. For example, U.S.
Pat. No. 3,031,194 to Strayer is directed to the use of a spherical
inner metal layer that is bonded or otherwise adhered to a
resilient inner constituent within the ball. The ball utilizes a
liquid filled core. U.S. Pat. No. 4,863,167 to Matsuki, et al.
describes golf balls containing a gravity filler which may be
formed from one or more metals disposed within a solid rubber-based
core. U.S. Pat. Nos. 4,886,275 and 4,995,613, both to Walker,
disclose golf balls having a dense metal-containing core. U.S. Pat.
No. 4,943,055 to Corley is directed to a weighted warmup ball
having a metal center.
[0004] Prior artisans have also described golf balls having one or
more interior layers formed from a metal, and which feature a
hollow center. Davis disclosed a golf ball comprising a spherical
steel shell having a hollow air-filled center in U.S. Pat. No.
697,816. Kempshall received numerous patents directed to golf balls
having metal inner layers and hollow interiors, such as 704,748;
704,838; 713,772; and 739,753. In U.S. Pat. Nos. 1,182,604 and
1,182,605, Wadsworth described golf balls utilizing concentric
spherical shells formed from tempered steel. U.S. Pat. No.
1,568,514 to Lewis describes several embodiments for a golf ball,
one of which utilizes multiple steel shells disposed within the
ball, and which provide a hollow center for the ball.
[0005] Prior artisans have attempted to provide golf balls having
liquid filled centers. Toland described a golf ball having a liquid
core in U.S. Pat. 4,805,914. Toland describes improved performance
by removing dissolved gases present in the liquid to decrease the
degree of compressibility of the liquid core. U.S. Pat. No.
5,037,104 to Watanabe, et al. and U.S. Pat. No. 5,194,191 to
Nomura, et al. disclose thread wound golf balls having liquid
cores. Similarly, U.S. Pat. No. 5,421,580 to Sugimoto, et al. and
U.S. Pat. No. 5,511,791 to Ebisuno, et al. are both directed to
thread wound golf balls having liquid cores limited to a particular
range of viscosities or diameters. Moreover, Molitor, et al.
described golf balls with liquid centers in U.S. Pat. Nos.
5,150,906 and 5,480,155.
[0006] The only known U.S. patents disclosing a golf ball having a
metal mantle layer in combination with a liquid core are U.S. Pat.
No. 3,031,194 to Strayer and the previously noted U.S. Pat. No.
1,568,514 to Lewis. Unfortunately, the ball constructions and
design teachings disclosed in these patents involve a large number
of layers of different materials, relatively complicated or
intricate manufacturing requirements, and/or utilize materials that
have long been considered unacceptable for the present golf ball
market.
[0007] Concerning attempts to provide golf balls with cellular or
foamed polymeric materials utilized as a core, few approaches have
been proposed. U.S. Pat. No. 4,839,116 to Puckett, et al. discloses
a short distance golf ball. It is believed that artisans considered
the use of foam or a cellular material undesirable in a golf ball,
perhaps from a believed loss or decrease in the coefficient of
restitution of a ball utilizing a cellular core.
[0008] Although satisfactory in at least some respects, all of the
foregoing ball constructions, particularly the few utilizing a
metal shell and a liquid core, are deficient. This is most evident
when considered in view of the stringent demands of the current
golf industry. Moreover, the few disclosures of a golf ball
comprising a cellular or foam material do not motivate one to
employ a cellular material in a regulation golf ball. Specifically,
there is a need for a golf ball that exhibits a high initial
velocity or coefficient of restitution (COR), may be driven
relatively long distances in regulation play, and which may be
readily and inexpensively manufactured.
[0009] These and other objects and features of the invention will
be apparent from the following summary and description of the
invention, the drawings, and from the claims.
SUMMARY OF THE INVENTION
[0010] The present invention achieves the foregoing objectives and
provides a golf ball comprising one or more metal mantle layers and
which further comprise a cellular or a liquid core component.
Specifically, the present invention provides, in a first aspect, a
golf ball having a cellular or liquid core, and comprising a
spherical metal mantle and a polymeric outer cover disposed about
and adjacent to the metal mantle. The metal mantle is preferably
formed from steel, titanium, chromium, nickel, or alloys thereof.
The metal mantle may comprise one or more layers, each formed from
a different metal. The polymeric outer cover is preferably
relatively soft and formed from a low acid ionomer, a non-ionomer,
or a blend thereof.
[0011] In a second aspect, the present invention provides a golf
ball having a cellular or liquid core component, and comprising an
inner polymeric hollow spherical substrate, a spherical metal
mantle, and a polymeric outer cover. The spherical metal mantle is
disposed between the spherical substrate and the outer cover.
[0012] The cellular core is preferably formed from at least one of
a polybutadiene/ZDA mixture, polyurethanes, polyolefins, ionomers,
metallocenes, polycarbonates, nylons, polyesters, and polystyrenes.
The liquid constituting the liquid core material preferably
comprises at least one of an inorganic salt, clay, barytes, and
carbon black dispersed or mixed with at least one of water, glycol,
and oil.
[0013] The present invention also provides related methods of
forming golf balls having metal mantles and cellular or liquid
cores, with or without an inner polymeric hollow spherical
substrate or an outer cover.
[0014] These and other objects and features of the invention will
be apparent from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a partial cross-sectional view of a first
preferred embodiment golf ball in accordance with the present
invention, comprising a polymeric outer cover, one or more metal
mantle layers, an optional polymeric hollow sphere substrate, and a
cellular core;
[0016] FIG. 2 is a partial cross-sectional view of a second
preferred embodiment golf ball in accordance with the present
invention, the golf ball comprising a polymeric outer cover, one or
more metal mantle layers, and a cellular core;
[0017] FIG. 3 is a partial cross-sectional view of a third
preferred embodiment golf ball in accordance with the present
invention, the golf ball comprising one or more metal mantle layers
and a cellular core;
[0018] FIG. 4 is partial cross-sectional view of a fourth preferred
embodiment golf ball in accordance with the present invention, the
golf ball comprising one or more metal mantle layers, an optional
polymeric hollow sphere substrate, and a cellular core;
[0019] FIG. 5 is a partial cross-sectional view of a fifth
preferred embodiment golf ball in accordance with the present
invention, comprising a polymeric outer cover, one or more metal
mantle layers, an optional polymeric hollow sphere substrate, and a
liquid core;
[0020] FIG. 6 is a partial cross-sectional view of a sixth
preferred embodiment golf ball in accordance with the present
invention, the golf ball comprising a polymeric outer cover, one or
more metal mantle layers, and a liquid core;
[0021] FIG. 7 is a partial cross-sectional view of a seventh
preferred embodiment golf ball in accordance with the present
invention, the golf ball comprising one or more metal mantle layers
and a liquid core; and
[0022] FIG. 8 is partial cross-sectional view of an eighth
preferred embodiment golf ball in accordance with the present
invention, the golf ball comprising one or more metal mantle
layers, an optional polymeric hollow sphere substrate, and a liquid
core.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The present invention relates to golf balls comprising one
or more metal mantle layers and either a liquid or a cellular core
component. The present invention also relates to methods for making
such golf balls.
[0024] FIG. 1 illustrates a first preferred embodiment golf ball
100 in accordance with the present invention. It will be understood
that the referenced drawings are not necessarily to scale. The
first preferred embodiment golf ball 100 comprises an outermost
polymeric outer cover 10, one or more metal mantle layers 20, an
innermost polymeric hollow sphere substrate 30, and a cellular core
40. The golf ball 100 provides a plurality of dimples 104 defined
along an outer surface 102 of the golf ball 100.
[0025] FIG. 2 illustrates a second preferred embodiment golf ball
200 in accordance with the present invention. The golf ball 200
comprises an outermost polymeric outer cover 10, one or more metal
mantle layers 20, and a cellular core 40. The second preferred
embodiment golf ball 200 provides a plurality of dimples 204
defined along the outer surface 202 of the ball 200.
[0026] FIG. 3 illustrates a third preferred embodiment golf ball
300 in accordance with the present invention. The golf ball 300
comprises one or more metal mantle layers 20, and a cellular core
40. The golf ball 300 provides a plurality of dimples 304 defined
along the outer surface 302 of the golf ball 300.
[0027] FIG. 4 illustrates a fourth preferred embodiment golf ball
400 in accordance with the present invention. The golf ball 400
comprises one or more metal mantle layers 20, an optional polymeric
hollow sphere substrate 30, and a cellular core 40. The golf ball
400 provides a plurality of dimples 404 defined along the outer
surface 402 of the golf ball 400.
[0028] FIG. 5 illustrates a fifth preferred embodiment golf ball
500 in accordance with the present invention. The fifth preferred
embodiment golf ball 500 comprises an outermost polymeric outer
cover 10, one or more metal mantle layers 20, an innermost
polymeric hollow sphere substrate 30, and a liquid core 50. The
golf ball 500 provides a plurality of dimples 504 defined along an
outer surface 502 of the golf ball 500.
[0029] FIG. 6 illustrates a sixth preferred embodiment golf ball
600 in accordance with the present invention. The golf ball 600
comprises an outermost polymeric outer cover 10, one or more metal
mantle layers 20, and a liquid core 50. The sixth preferred
embodiment golf ball 600 provides a plurality of dimples 604
defined along the outer surface 602 of the ball 600.
[0030] FIG. 7 illustrates a seventh preferred embodiment golf ball
700 in accordance with the present invention. The golf ball 700
comprises one or more metal mantle layers 20 and a liquid core 50.
The golf ball 700 provides a plurality of dimples 704 defined along
the outer surface 702 of the golf ball 700.
[0031] FIG. 8 illustrates an eighth preferred embodiment golf ball
800 in accordance with the present invention. The golf ball 800
comprises one or more metal mantle layers 20, an optional polymeric
hollow sphere substrate 30 and a liquid core 50. The golf ball 800
provides a plurality of dimples 804 defined along the outer surface
802 of the golf ball 800.
[0032] In all the foregoing noted preferred embodiments, i.e. golf
balls 100, 200, 300, 400, 500, 600, 700, and 800, the golf balls
utilize a cellular or liquid core or core component. In addition,
all preferred embodiment golf balls comprise one or more metal
mantle layers. Details of the materials, configuration, and
construction of each component in the preferred embodiment golf
balls are set forth below.
Polymeric Outer Cover
[0033] The polymeric outer cover layer, such as the cover 10
illustrated in the referenced figures, 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 polyester amide such
as that marketed by Elf Atochem S.A. under the trademark
Pebax.RTM..
[0034] Preferably, the 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
the outer layer comprises a blend of a high modulus (hard) ionomer
with a low modulus (soft) ionomer to form a base ionomer mixture. A
high modulus ionomer as that term is used 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. A low modulus ionomer suitable for use in the
outer layer blend has a flexural modulus measuring from about 1,000
to about 10,000 psi, with a hardness of about 20 to about 40 on the
Shore D scale.
[0035] The hard ionomer resins utilized to produce the outer cover
layer composition 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.
The carboxylic acid groups of the copolymer may be totally or
partially (i.e. approximately 15-75 percent) neutralized.
[0036] The hard ionomeric resins may include 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.
[0037] The hard ionomeric resins developed by Exxon Corporation and
introduced under the designation Escor.RTM. and sold under the
designation "Iotek" are somewhat similar to the hard ionomeric
resins developed by E.I. DuPont de Nemours & Company and sold
under the Surlyn.RTM. trademark. However, since the "Iotek"
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" resins (i.e., the acrylic acid based
hard ionomer resins) are the more preferred hard resins for use in
formulating the outer cover layer blends for use in the present
invention. In addition, various blends of "Iotek" and Surlyn.RTM.
hard ionomeric resins, as well as other available ionomeric resins,
may be utilized in the present invention in a similar manner.
[0038] Examples of commercially available hard ionomeric resins
which may be used in the present invention in formulating the 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 percent 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 1:
1TABLE 1 Typical Properties of Commercially Available Hard Surlyn
.RTM. Resins Suitable for Use in the Outer Layer Blends of the
Preferred Embodiments ASTM D 8940 9910 8920 8528 9970 9730 Cation
Type Sodium Zinc Sodium Sodium Zinc Zinc Melt flow index, D-1238
2.8 0.7 0.9 1.3 14.0 1.6 gms/b mm. Specific Gravity, D-792 0.95
0.97 0.95 0.94 0.95 0.95 g/cm.sup.3 Hardness, Shore D D-2240 66 64
66 60 62 63 Tensile Strength, D-638 (4.8) (3.6) (5.4) (4.2) (3.2)
(4.1) (kpsi), MPa 33.1 24.8 37.2 29.0 22.0 28.0 Elongation, % D-638
470 290 350 450 460 460 Flexural Modulus, D-790 (51) (48) (55) (32)
(28) (30) (kpsi) MPa 350 330 380 220 190 210 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
[0039] Examples of the more pertinent acrylic acid based hard
ionomer resin suitable for use in the present outer cover
composition sold under the "Iotek" trade name by the Exxon
Corporation include Iotek 4000, Iotek 4010, Iotek 8000, Iotek 8020
and Iotek 8030. The typical properties of these and other Iotek
hard ionomers suited for use in formulating the outer layer cover
composition are set forth below in Table 2:
2TABLE 2 Typical Properties of Iotek Ionomers Resin ASTM Properties
Method Units 4000 4010 8000 8020 8030 Cation type zinc zinc sodium
sodium sodium Melt index D-1238 g/10 min. 2.5 1.5 0.8 1.6 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 30 40
cation neutralized Plaque ASTM 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 % 395 420 350 410 395 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 Blow-up ratio) 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 % 360 340 280 340 345 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 Resin ASTM
Properties Method Units 7010 7020 7080 Cation type zinc zinc zinc
Melt Index D-1238 g/10 min. 0.8 1.5 2.5 Density D-1505 kg/m.sup.3
960 960 960 Melting Point D-3417 .degree. C. 90 90 90
Crystallization D-3417 .degree. C. -- -- -- Point Vicat Softening
D-1525 .degree. C. 60 63 62.5 Point % Weight Acrylic Acid -- -- --
% of Acid Groups -- -- -- Cation Neutralized Plaque ASTM Properties
Method Units 7010 7020 7080 (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 1% Secant modulus
D-638 MPa -- -- -- Shore Hardness D D-2240 -- 57 55 55
[0040] Comparatively, soft ionomers are used in formulating the
hard/soft blends of the outer cover composition. 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 and 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 and a flexural modulus from about 1,000 to about
10,000, as measured in accordance with ASTM method D-790.
[0041] Certain ethylene-acrylic acid based soft ionomer resins
developed by the Exxon Corporation under the designation "Iotek
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 outer cover. The combination produces higher COR's
(coefficient of restitution) 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
outer layer 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.
[0042] While the exact chemical composition of the resins to be
sold by Exxon under the designation Iotek 7520 is considered by
Exxon to be confidential and proprietary information, Exxon's
experimental product data sheet lists the following physical
properties of the ethylene acrylic acid zinc ionomer developed by
Exxon:
3TABLE 3 Property ASTM Method Units Typical Value Physical
Properties of Iotek 7520 Melt Index D-1238 g/10 min. 2 Density
D-1505 kg/m.sup.3 0.962 Cation Zinc Melting Point D-3417 .degree.
C. 66 Crystallization D-3417 .degree. C. 49 Point Vicat Softening
D-1525 .degree. C. 42 Point 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 Mattie Flex Resistance
D-430 Cycles >5000
[0043] In addition, test data collected by the inventor indicates
that Iotek 7520 resins have Shore D harnesses 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 7520 resins are generally zinc salts of a
terpolymer of ethylene, acrylic acid, and methyl acrylate.
[0044] Furthermore, the inventor has found that a newly developed
grade of an acrylic acid based soft ionomer available from the
Exxon Corporation under the designation Iotek 7510, is also
effective, when combined with the hard ionomers indicated above in
producing golf ball covers exhibiting higher COR values at equal or
softer hardness than those produced by known hard-soft ionomer
blends. In this regard, Iotek 7510 has the advantages (i.e.
improved flow, higher COR values at equal hardness, increased
clarity, etc.) produced by the Iotek 7520 resin when compared to
the methacrylic acid base soft ionomers known in the art (such as
the Surlyn 8625 and the Surlyn 8629 combinations disclosed in U.S.
Pat. No. 4,884,814).
[0045] In addition, Iotek 7510, when compared to Iotek 7520,
produces slightly higher COR values at equal softness/hardness due
to the Iotek 7510's higher hardness and neutralization. Similarly,
Iotek 7510 produces better release properties (from the mold
cavities) due to its slightly higher stiffness and lower flow rate
than Iotek 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.
[0046] According to Exxon, Iotek 7510 is of similar chemical
composition as Iotek 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 7520 is estimated to
be about 30-40 weight percent neutralized and Iotek 7510 is
estimated to be about 40-60 weight percent neutralized. The typical
properties of Iotek 7510 in comparison with those of Iotek 7520 are
set forth below:
4TABLE 4 Physical Properties of Iotek 7510 in Comparison to Iotek
7520 IOTEK 7520 IOTEK 7510 MI, g/10 min 2.0 0.8 Density, g/cc 0.96
0.97 Melting Point, .degree. F. 151 149 Vicat Softening Point,
.degree. F. 108 109 Flex Modulus, psi 3800 5300 Tensile Strength,
psi 1450 1750 Elongation, % 760 690 Hardness, Shore D 32 35
[0047] 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 60 percent soft ionomer resin.
[0048] 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, both patents herein incorporated by
reference. The present invention is in no way limited to those
examples.
[0049] 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 following
properties:
5TABLE 5 Properties of Estane .RTM. X-4517 Tensile 1430 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. F. (>177.degree. C.)
Specific Gravity (H.sub.2O = 1) 1.1-1.3
[0050] 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 travel distance
characteristic produced by the high acid ionomer resin composition.
These include, but are not limited to thermoplastic polyurethanes
such as: Texin thermoplastic polyurethanes from Mobay Chemical Co.
and the Pellethane 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, all of which are herein
incorporated by reference; and, Hytrel polyester elastomers from
DuPont and Pebax polyester amides from Elf Atochem S.A.
[0051] In addition, or instead of the following thermoplastics, one
or more thermoset polymeric materials may be utilized for the outer
cover. Preferred thermoset polymeric materials include, but are not
limited to, polyurethanes, metallocenes, diene rubbers such as
trans polyisoprene EDPM or EPR. It is also preferred that all
thermoset materials be crosslinked. Crosslinking may be achieved by
chemical crosslinking and/or initiated by free radicals generated
from peroxides, gamma or election beam radiation.
[0052] The polymeric outer cover layer is about 0.020 inches to
about 0.120 inches in thickness. The outer cover layer is
preferably about 0.050 inches to about 0.075 inches in thickness.
Together, the mantle and the outer cover layer combine to form a
ball having a diameter of 1.680 inches or more, the minimum
diameter permitted by the rules of the United States Golf
Association and weighing about 1.620 ounces.
Multilayer Metal Mantle
[0053] The preferred embodiment golf balls of the present invention
comprise one or more metal mantle layers disposed inwardly and
proximate to, and preferably adjacent to, the outer cover layer. A
wide array of metals can be used in the mantle layers or shells as
described herein. Table 6, set forth below, lists suitable metals
for use in the preferred embodiment golf balls.
6TABLE 6 Metals for Use in Mantle Layer(s) Young's Bulk Shear
Poisson's modulus, modulus, modulus, ratio, Metal E, 10.sup.6 psi
K, 10.sup.6 psi G, 10.sup.6 psi v Aluminum 10.2 10.9 3.80 0.345
Brass, 30 Zn 14.6 16.2 5.41 0.350 Chromium 40.5 23.2 16.7 0.210
Copper 18.8 20.0 7.01 0.343 Iron (soft) 30.7 24.6 11.8 0.293 (cast)
22.1 15.9 8.7 0.27 Lead 2.34 6.64 0.811 0.44 Magnesium 6.48 5.16
2.51 0.291 Molybdenum 47.1 37.9 18.2 0.293 Nickel (soft) 28.9 25.7
11.0 0.312 (hard) 31.8 27.2 12.2 0.306 Nickel-silver, 19.2 19.1
4.97 0.333 55Cu-18Ni-27Zn Niobium 15.2 24.7 5.44 0.397 Silver 12.0
15.0 4.39 0.367 Steel, mild 30.7 24.5 11.9 0.291 Steel, 0.75 C 30.5
24.5 11.8 0.293 Steel, 0.75 C, hardened 29.2 23.9 11.3 0.296 Steel,
tool 30.7 24.0 11.9 0.287 Steel, tool, hardened 29.5 24.0 11.4
0.295 Steel, stainless, 2Ni-18Cr 31.2 24.1 12.2 0.283 Tantalum 26.9
28.5 10.0 0.342 Tin 7.24 8.44 2.67 0.357 Titanium 17.4 15.7 6.61
0.361 Titanium/Nickel alloy Tungsten 59.6 45.1 23.3 0.280 Vanadium
18.5 22.9 6.77 0.365 Zinc 15.2 10.1 6.08 0.249
[0054] Preferably, the metals used in the one or more mantle layers
are steel, titanium, chromium, nickel, or alloys thereof.
Generally, it is preferred that the metal selected for use in the
mantle be relatively stiff, hard, dense, and have a relatively high
modulus of elasticity.
[0055] The thickness of the metal mantle layer depends upon the
density of the metals used in that layer, or if a plurality of
metal mantle layers are used, the densities of those metals in
other layers within the mantle. Typically, the thickness of the
mantle ranges from about 0.001 inches to about 0.050 inches. The
preferred thickness for the mantle is from about 0.005 inches to
about 0.050 inches. The most preferred range is from about 0.005
inches to about 0.010 inches. It is preferred that the thickness of
the mantle be uniform and constant at all points across the
mantle.
[0056] As noted, the thickness of the metal mantle depends upon the
density of the metal(s) utilized in the one or more mantle layers.
Table 7, set forth below, lists typical densities for the preferred
metals for use in the mantle.
7 TABLE 7 Metal Density (grams per cubic centimeter) Chromium 6.46
Nickel 7.90 Steel (approximate) 7.70 Titanium 4.13
[0057] There are at least two approaches in forming a metal mantle
utilized in the preferred embodiment golf balls. In a first
embodiment, two metal half shells are stamped from metal sheet
stock. The two half shells are then arc welded or otherwise
together and heat treated to stress relieve. It is preferred to
heat treat the resulting assembly since welding will typically
anneal and soften the resulting hollow sphere resulting in "oil
canning," i.e. deformation of the metal sphere after impact, such
as may occur during play.
[0058] In a second embodiment, a metal mantle is formed via
electroplating over a thin hollow polymeric sphere, described in
greater detail below. This polymeric sphere may correspond to the
previously described optional polymeric hollow sphere substrate 30.
There are several preferred techniques by which a metallic mantle
layer may be deposited upon a non-metallic substrate. In a first
category of techniques, an electrically conductive layer is formed
or deposited upon the polymeric or non-metallic sphere.
Electroplating may be used to fully deposit a metal layer after a
conductive salt solution is applied onto the surface of the
non-metallic substrate. Alternatively, or in addition, a thin
electrically conducting metallic surface can be formed by flash
vacuum metallization of a metal agent, such as aluminum, onto the
substrate of interest. Such surfaces are typically about
3.times.10.sup.-6 of an inch thick. Once deposited, electroplating
can be utilized to form the metal layer(s) of interest. It is
contemplated that vacuum metallization could be employed to fully
deposit the desired metal layer(s). Yet another technique for
forming an electrically conductive metal base layer is chemical
deposition. Copper, nickel, or silver, for example, may be readily
deposited upon a non-metallic surface. Yet another technique for
imparting electrical conductivity to the surface of a non-metallic
substrate is to incorporate an effective amount of electrically
conductive particles in the substrate, such as carbon black, prior
to molding. Once having formed an electrically conductive surface,
electroplating processes can be used to form the desired metal
mantle layers.
[0059] Alternatively, or in addition, various thermal spray coating
techniques can be utilized to form one or more metal mantle layers
onto a spherical substrate. Thermal spray is a generic term
generally used to refer to processes for depositing metallic and
non-metallic coatings, sometimes known as metallizing, that
comprise the plasma arc spray, electric arc spray, and flame spray
processes. Coatings can be sprayed from rod or wire stock, or from
powdered material.
[0060] A typical plasma arc spray system utilizes a plasma arc
spray gun at which one or more gasses are energized to a highly
energized state, i.e. a plasma, and are then discharged typically
under high pressures toward the substrate of interest. The power
level, pressure, and flow of the arc gasses, and the rate of flow
of powder and carrier gas are typically control variables.
[0061] The electric arc spray process preferably utilizes metal in
wire form. This process differs from the other thermal spray
processes in that there is no external heat source, such as from a
gas flame or electrically induced plasma. Heating and melting occur
when two electrically opposed charged wires, comprising the spray
material, are fed together in such a manner that a controlled arc
occurs at the intersection. The molten metal is atomized and
propelled onto a prepared substrate by a stream of compressed air
or gas.
[0062] The flame spray process utilizes combustible gas as a heat
source to melt the coating material. Flame spray guns are available
to spray materials in rod, wire, or powder form. Most flame spray
guns can be adapted for use with several combinations of gases.
Acetylene, propane, mapp gas, and oxygen-hydrogen are commonly used
flame spray gases.
[0063] Another process or technique for depositing a metal mantle
layer onto a spherical substrate in the preferred embodiment golf
balls is chemical vapor deposition (CVD). In the CVD process, a
reactant atmosphere is fed into a processing chamber where it
decomposes at the surface of the substrate of interest, liberating
one material for either absorption by or accumulation on the work
piece or substrate. A second material is liberated in gas form and
is removed from the processing chamber, along with excess
atmosphere gas, as a mixture referred to as off-gas.
[0064] The reactant atmosphere that is typically used in CVD
includes chlorides, fluorides, bromides and iodides, as well as
carbonyls, organometallics, hydrides and hydrocarbons. Hydrogen is
often included as a reducing agent. The reactant atmosphere must be
reasonably stable until it reaches the substrate, where reaction
occurs with reasonably efficient conversion of the reactant.
Sometimes it is necessary to heat the reactant to produce the
gaseous atmosphere. A few reactions for deposition occur at
substrate temperatures below 200 degrees C. Some organometallic
compounds deposit at temperatures of 600 degrees C. Most reactions
and reaction products require temperatures above 800 degrees C.
[0065] Common CVD coatings include nickel, tungsten, chromium, and
titanium carbide. CVD nickel is generally separated from a nickel
carbonyl, Ni(CO).sub.4, atmosphere. The properties of the deposited
nickel are equivalent to those of sulfonate nickel deposited
electrolytically. Tungsten is deposited by thermal decomposition of
tungsten carbonyl at 300 to 600 degrees C., or may be deposited by
hydrogen reduction of tungsten hexachloride at 700 to 900 degrees
C. The most convenient and most widely used reaction is the
hydrogen reduction of tungsten hexafluoride. If depositing chromium
upon an existing metal layer, this may be done by pack cementation,
a process similar to pack carbonizing, or by a dynamic,
flow-through CVD process. Titanium carbide coatings may be formed
by the hydrogen reduction of titanium tetrafluoride in the presence
of methane or some other hydrocarbon. The substrate temperatures
typically range from 900 to 1010 degrees C., depending on the
substrate.
[0066] Surface preparation for CVD coatings generally involve
de-greasing or grit blasting. In addition, a CVD pre-coating
treatment may be given. The rate of deposition from CVD reactions
generally increases with temperature in a manner specific to each
reaction. Deposition at the highest possible rate is preferable,
however, there are limitations which require a processing
compromise.
[0067] Vacuum coating is another category of processes for
depositing metals and metal compounds from a source in a high
vacuum environment onto a substrate, such as the spherical
substrate used in several of the preferred embodiment golf balls.
Three principal techniques are used to accomplish such deposition:
evaporation, ion plating, and sputtering. In each technique, the
transport of vapor is carried out in an evacuated, controlled
environment chamber and, typically, at a residual air pressure of 1
to 10.sup.-5 Pascals.
[0068] In the evaporation process, vapor is generated by heating a
source material to a temperature such that the vapor pressure
significantly exceeds the ambient chamber pressure and produces
sufficient vapor for practical deposition. To coat the entire
surface of a substrate, such as the inner spherical substrate
utilized in several of the preferred embodiment golf balls, it must
be rotated and translated over the vapor source. Deposits made on
substrates positioned at low angles to the vapor source generally
result in fibrous, poorly bonded structures. Deposits resulting
from excessive gas scattering are poorly adherent, amorphous, and
generally dark in color. The highest quality deposits are made on
surfaces nearly normal or perpendicular to the vapor flux. Such
deposits faithfully reproduce the substrate surface texture. Highly
polished substrates produce lustrous deposits, and the bulk
properties of the deposits are maximized for the given deposition
conditions.
[0069] For most deposition rates, source material should be heated
to a temperature so that its vapor pressure is at least 1 Pascal or
higher. Deposition rates for evaporating bulk vacuum coatings can
be very high. Commercial coating equipment can deposit up to
500,000 angstroms of material thickness per minute using large
ingot material sources and high powered electron beam heating
techniques.
[0070] As indicated, the directionality of evaporating atoms from a
vapor source generally requires the substrate to be articulated
within the vapor cloud. To obtain a specific film distribution on a
substrate, the shape of the object, the arrangement of the vapor
source relative to the component surfaces, and the nature of the
evaporation source may be controlled.
[0071] Concerning evaporation sources, most elemental metals,
semi-conductors, compounds, and many alloys can be directly
evaporated in vacuum. The simplest sources are resistance wires and
metal foils. They are generally constructed of refractory metals,
such as tungsten, molybdenum, and tantalum. The filaments serve the
dual function of heating and holding the material for evaporation.
Some elements serve as sublimation sources such as chromium,
palladium, molybdenum, vanadium, iron, and silicon, since they can
be evaporated directly from the solid phase. Crucible sources
comprise the greatest applications in high volume production for
evaporating refractory metals and compounds. The crucible materials
are usually refractory metals, oxides, and nitrides, and carbon.
Heating can be accomplished by radiation from a second refractory
heating element, by a combination of radiation and conduction, and
by radial frequency induction heating.
[0072] Several techniques are known for achieving evaporation of
the evaporation source. Electron beam heating provides a flexible
heating method that can concentrate heat on the evaporant. Portions
of the evaporant next to the container can be kept at low
temperatures, thus minimizing interaction. Two principal electron
guns in use are the linear focusing gun, which uses magnetic and
electrostatic focusing methods, and the bent-beam magnetically
focused gun. Another technique for achieving evaporation is
continuous feed high rate evaporation methods. High rate
evaporation of alloys to form film thicknesses of 100 to 150
micrometers requires electron beam heating sources in large
quantities of evaporant. Electron beams of 45 kilowatts or higher
are used to melt evaporants in water cooled copper hearths up to
150 by 400 millimeters in cross section.
[0073] Concerning the substrate material of the spherical shell
upon which one or more metal layers are formed in several of the
preferred embodiment golf balls, the primary requirement of the
material to be coated is that it be stable in vacuum. It must not
evolve gas or vapor when exposed to the metal vapor. Gas evolution
may result from release of gas absorbed on the surface, release of
gas trapped in the pores of a porous substrate, evolution of a
material such as plasticizers used in plastics, or actual
vaporization of an ingredient in the substrate material.
[0074] In addition to the foregoing methods, sputtering may be used
to deposit one or more metal layers onto, for instance, an inner
hollow sphere substrate such as substrate 30 utilized in some of
the preferred embodiment golf balls. Sputtering is a process
wherein material is ejected from the surface of a solid or liquid
because of a momentum exchange associated with bombardment by
energetic particles. The bombarding species are generally ions of a
heavy inert gas. Argon is most commonly used. The source of ions
may be an ion beam or a plasma discharge into which the material
can be bombarded is immersed.
[0075] In the plasma-discharge sputter coating process, a source of
coating material called a target is placed in a vacuum chamber
which is evacuated and then back filled with a working gas, such as
Argon, to a pressure adequate to sustain the plasma discharge. A
negative bias is then applied to the target so that it is bombarded
by positive ions from the plasma.
[0076] Sputter coating chambers are typically evacuated to
pressures ranging from 0.001 to 0.00001 Pascals before back filling
with Argon to pressures of 0.1 to 10 Pascals. The intensity of the
plasma discharge, and thus the ion flux and sputtering rate that
can be achieved, depends on the shape of the cathode electrode, and
on the effective use of a magnetic field to confine the plasma
electrons. The deposition rate in sputtering depends on the target
sputtering rate and the apparatus geometry. It also depends on the
working gas pressure, since high pressures limit the passage of
sputtered flux to the substrates.
[0077] Ion plating may also be used to form one or more metal
mantle layers in the golf balls of the present invention. Ion
plating is a generic term applied to atomistic film deposition
processes in which the substrate surface and/or the depositing film
is subjected to a flux of high energy particles (usually gas ions)
sufficient to cause changes in the interfacial region or film
properties. Such changes may be in the film adhesion to the
substrate, film morphology, film density, film stress, or surface
coverage by the depositing film material.
[0078] Ion plating is typically done in an inert gas discharge
system similar to that used in sputtering deposition except that
the substrate is the sputtering cathode and the bombarded surface
often has a complex geometry. Basically, the ion plating apparatus
is comprised of a vacuum chamber and a pumping system, which is
typical of any conventional vacuum deposition unit. There is also a
film atom vapor source and an inert gas inlet. For a conductive
sample, the work piece is the high voltage electrode, which is
insulated from the surrounding system. In the more generalized
situation, a work piece holder is the high voltage electrode and
either conductive or non-conductive materials for plating are
attached to it. Once the specimen to be plated is attached to the
high voltage electrode or holder and the filament vaporization
source is loaded with the coating material, the system is closed
and the chamber is pumped down to a pressure in the range of 0.001
to 0.0001 Pascals. When a desirable vacuum has been achieved, the
chamber is back filled with Argon to a pressure of approximately 1
to 0.1 Pascals. An electrical potential of -3 to -5 kilovolts is
then introduced across the high voltage electrode, that is the
specimen or specimen holder, and the ground for the system. Glow
discharge occurs between the electrodes which results in the
specimen being bombarded by the high energy Argon ions produced in
the discharge, which is equivalent to direct current sputtering.
The coating source is then energized and the coating material is
vaporized into the glow discharge.
[0079] Another class of materials, contemplated for use in forming
the one or more metal mantle layers is nickel titanium alloys.
These alloys are known to have super elastic properties and are
approximately 50 percent (atomic) nickel and 50 percent titanium.
When stressed, a super elastic nickel titanium alloy can
accommodate strain deformations of up to 8 percent. When the stress
is later released, the super elastic component returns to its
original shape. Other shape memory alloys can also be utilized
including alloys of copper zinc aluminum, and copper aluminum
nickel. Table 8 set forth below presents various physical,
mechanical, and transformation properties of these three preferred
shape memory alloys.
8TABLE 8 Properties of Shape Memory Alloys Cu-Zn-Al Cu-Al-Ni Ni-Ti
PHYSICAL PROPERTIES Density (g/cm.sup.3) 7.64 7.12 6.5 Resistivity
(.mu..OMEGA.-cm) 8.5-9.7 11-13 80-100 Thermal Conductivity
(J/m-s-K) 120 30-43 10 Heat Capacity (J/Kg-K) 400 373-574 390
MECHANICAL PROPERTIES Young's Modulus (GPa) .beta.-Phase 72 85 83
Martensite 70 80 34 Yield Strength (MPa) .beta.-Phase 350 400 690
Martensite 80 130 70-150 Ultimate Tensile Strength (Mpa) 600
500-800 900 TRANSFORMATION PROPERTIES Heat of Transformation
(J/mole) Martensite 160-440 310-470 R-Phase 55 Hysteresis (K)
Martensite 10-25 15-20 30-40 R-Phase 2-5 Recoverable Strain (%)
One-Way (Martensite) 4 4 8 One-Way (R-Phase 0.5-1 Two-Way
(Martensite) 2 2 3
[0080] In preparing the preferred embodiment golf balls, the
polymeric outer cover layer, if utilized, is molded (for instance,
by injection molding or by compression molding) about the metal
mantle.
Core
[0081] The preferred embodiment golf ball may comprise one of two
types of cores--a cellular core comprising a material having a
porous or cellular configuration; or a liquid core. Suitable
materials for a cellular core 10 include, but are not limited to,
foamed elastomeric materials such as, for example, crosslinked
polybutadiene/ZDA mixtures, polyurethanes, polyolefins, ionomers,
metallocenes, polycarbonates, nylons, polyesters, and polystyrenes.
Preferred materials include polybutadiene/ZDA mixtures, ionomers,
and metallocenes. The most preferred materials are foamed
crosslinked polybutadiene/ZDA mixtures.
[0082] The shape and configuration of the foamed core is spherical.
The diameter of the cellular core typically ranges from about 1.340
inches to about 1.638 inches, and most preferably from about 1.500
inches to about 1.540 inches. It is generally preferred that the
core, whether a cellular core or a liquid core, be immediately
adjacent to, and thus next to, the inner surface of either the
metal mantle layer or the polymeric hollow sphere.
[0083] If the cellular core is used in conjunction with a metal
mantle, the selection of the type of metal for the mantle will
determine the size and density for the cellular core. A hard, high
modulus metal will require a relatively thin mantle so that ball
compression is not too hard. If the mantle is relatively thin, the
ball may be too light in weight so a cellular core will be required
to add weight and, further, to add resistance to oil canning or
deformation of the metal mantle. In contrast, a solid core would
likely also add too much weight to the finished ball and,
therefore, a cellular core is preferred to provide proper weight
and resilience.
[0084] The weight of the cellular core can be controlled by the
cellular density. The cellular core typically has a specific
gravity of from about 0.10 to about 1.0. The coefficient of
restitution of the cellular core should be at least 0.500.
[0085] The structure of the cellular core may be either open or
closed cell. It is preferable to utilize a closed cell
configuration with a solid surface skin that can be metallized or
receive a conductive coating. The preferred cell size is that
required to obtain an apparent specific gravity of from about 0.10
to about 1.0.
[0086] In a preferred method, a cellular core is fabricated and a
metallic cover applied over the core. The metallic cover may be
deposited by providing a conductive coating or layer about the core
and electroplating one or more metals on that coating to the
required thickness. Alternatively, two metallic half shells can be
welded together and a flowable cellular material, for example a
foam, or a cellular core material precursor, injected through an
aperture in the metallic sphere using a two component liquid system
that forms a semi-rigid or rigid material or foam. The fill hole in
the metal mantle may be sealed to prevent the outer cover stock
from entering into the cellular core during cover molding.
[0087] If the cellular core is prefoamed or otherwise formed prior
to applying the metallic layer, the blowing agent may be one or
more conventional agents that release a gas, such as nitrogen or
carbon dioxide. Suitable blowing agents include, but are not
limited to, azodicarbonamide,
N,N-dinitros-opentamethylene-tetramine, 4-4 oxybis
(benzenesulfonyl-hydrazide), and sodium bicarbonate. The preferred
blowing agents are those that produce a fine closed cell structure
forming a skin on the outer surface of the core.
[0088] A cellular core may be encapsulated or otherwise enclosed by
the metal mantle, for instance by affixing two hemispherical halves
of a metal shell together about a cellular core. It is also
contemplated to introduce a foamable cellular core material
precursor within a hollow spherical metal mantle and subsequently
foaming that material in situ.
[0089] In yet another variant embodiment, an optional polymeric
hollow sphere, such as for example, the hollow sphere substrate 30,
may be utilized to receive a cellular material. One or more metal
mantle layers, such as metal mantle layers 20, can then be
deposited or otherwise disposed about the polymeric sphere. If such
a polymeric sphere is utilized in conjunction with a cellular core,
it is preferred that the core material be introduced into the
hollow sphere as a flowable material. Once disposed within the
hollow sphere, the material may foam and expand in volume to the
shape and configuration of the interior of the hollow sphere.
[0090] As noted, the preferred embodiment golf ball may include a
liquid core. In one variant, the liquid filled core disclosed in
U.S. Pat. Nos. 5,480,155 and 5,150,906, both herein incorporated by
reference, is suitable. Suitable liquids for use in the present
invention golf balls include, but are not limited to, water,
alcohol, oil, combinations of these, solutions such as glycol and
water, or salt and water. Other suitable liquids include oils or
colloidal suspensions, such as clay, barytes, or carbon black in
water or other liquid. A preferred liquid core material is a
solution of inorganic salt in water. The inorganic salt is
preferably calcium chloride. The preferred glycol is glycerine.
[0091] The most inexpensive liquid is a salt water solution. All of
the liquids noted in the previously-mentioned, '155 and '906
patents are suitable. The density of the liquid can be adjusted to
achieve the desired final weight of the golf ball.
[0092] The most preferred technique for forming a ball having a
liquid core is to form a thin, hollow polymeric sphere by blow
molding or forming two half shells and then joining the two half
shells together. The hollow sphere is then filled with a suitable
liquid and sealed. These techniques are described in the '155 and
'906 patents.
[0093] The liquid filled sphere is then preferably metallized, such
as via electroplating, to a suitable thickness of from about 0.001
inches to about 0.050 inches. The resulting metal mantle may
further receive one or more other metal mantle layers. The
metallized sphere is then optionally covered with a polymeric
dimpled cover by injection or compression molding and then finished
using conventional methods.
[0094] A liquid core is preferable over a solid core in that it
develops less spin initially and has greater spin decay resulting
in a lower trajectory with increased total distance.
Optional Polymeric Sphere
[0095] A wide array of polymeric materials can be utilized to form
the thin hollow sphere or shell as referred to herein and generally
depicted in the accompanying drawings as the sphere 30.
Thermoplastic materials are generally preferred for use as
materials for the shell. Typically, such materials should exhibit
good flowability, moderate stiffness, high abrasion resistance,
high tear strength, high resilience, and good mold release, among
others.
[0096] Synthetic polymeric materials which may be used for the thin
hollow sphere include homopolymeric and copolymer materials which
may include: (1) Vinyl resins formed by the polymerization of vinyl
chloride, or by the copolymerization of vinyl chloride with vinyl
acetate, acrylic esters or vinylidene chloride; (2) Polyolefins
such as polyethylene, polypropylene, polybutylene, and copolymers
such as polyethylene methylacrylate, polyethylene ethylacrylate,
polyethylene vinyl acetate, polyethylene methacrylic or
polyethylene acrylic acid or polypropylene acrylic acid or
terpolymers made from these and acrylate esters and their metal
ionomers, polypropylene/EPDM grafted with acrylic acid or anhydride
modified polyolefins; (3) Polyurethanes, such as are prepared from
polyols and diisocyanates or polyisocyanates; (4) Polyamides such
as poly(hexamethylene adipamide) and others prepared from diamines
and dibasic acids, as well as those from amino acid such as
poly(caprolactam), and blends of polyamides with SURLYN,
polyethylene, ethylene copolymers, EDPA, etc; (5) Acrylic resins
and blends of these resins with polyvinyl chloride, elastomers,
etc.; (6) Thermoplastic rubbers such as the urethanes, olefinic
thermoplastic rubbers such as blends of polyolefins with EPDM,
block copolymers of styrene and butadiene, or isoprene or
ethylene-butylene rubber, polyether block amides; (7) Polyphenylene
oxide resins, or blends of polyphenylene oxide with high impact
polystyrene; (8) Thermoplastic polyesters, such as PET, PBT, PETG,
and elastomers sold under the trademark HYTREL by E. I. DuPont De
Nemours & Company of Wilmington, Del.; (9) Blends and alloys
including polycarbonate with ABS, PBT, PET, SMA, PE elastomers,
etc. and PVC with ABS or EVA or other elastomers; and (10) Blends
of thermoplastic rubbers with polyethylene, polypropylene,
polyacetal, nylon, polyesters, cellulose esters, etc.
[0097] It is also within the purview of this invention to add to
the compositions employed for the thin hollow shell agents which do
not affect the basic characteristics of the shell. Among such
materials are antioxidants, antistatic agents, and stabilizers.
Other Aspects of Preferred Embodiment Ball Construction
[0098] Additional materials may be added to the outer cover 10
including dyes (for example, Ultramarine Blue sold by Whitaker,
Clark and Daniels of South Plainsfield, N.J.) (see U.S. Pat. No.
4,679,795 herein incorporated by reference); pigments such as
titanium dioxide, zinc oxide, barium sulfate and zinc sulfate; UV
absorbers; antioxidants; antistatic agents; and stabilizers.
Further, the cover compositions may also contain softening agents,
such as plasticizers, processing aids, etc. and reinforcing
material such as glass fibers and inorganic fillers, as long as the
desired properties produced by the golf ball covers are not
impaired.
[0099] The outer cover layer may be produced according to
conventional melt blending procedures. In the case of the outer
cover layer, 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 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 an 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 high acid ionomer
resin compositions.
[0100] In place of utilizing a single outer cover, a plurality of
cover layers may be employed. For example, an inner cover can be
formed about the metal mantle, and an outer cover then formed about
the inner cover. The thickness of the inner and outer cover layers
are governed by the thickness parameters for the overall cover
layer. The inner cover layer is preferably formed from a relatively
hard material, such as, for example, the previously described high
acid ionomer resin. The outer cover layer is preferably formed from
a relatively soft material having a low flexural modulus.
[0101] In the event that an inner cover layer and an outer cover
layer are utilized, these layers can be formed as follows. An inner
cover layer may be formed by injection molding or compression
molding an inner cover composition about a metal mantle to produce
an intermediate golf ball having a diameter of about 1.50 to 1.67
inches, preferably about 1.620 inches. The outer layer is
subsequently molded over the inner layer to produce a golf ball
having a diameter of 1.680 inches or more.
[0102] In compression molding, the inner cover 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 mantle in a mold having the desired inner
cover thickness and subjected to compression molding at 200.degree.
to 300.degree. F. for about 2 to 10 minutes, followed by cooling at
50.degree. to 70.degree. F. for about 2 to 7 minutes to fuse the
shells together to form a unitary intermediate ball. In addition,
the intermediate balls may be produced by injection molding wherein
the inner cover layer is injected directly around the mantle placed
at the center of an intermediate ball mold for a period of time in
a mold temperature of from 50.degree. F. to about 100.degree. F.
Subsequently, the outer cover layer is molded about the core and
the inner layer by similar compression or injection molding
techniques to form a dimpled golf ball of a diameter of 1.680
inches or more.
[0103] After molding, the golf balls produced may undergo various
further processing steps such as buffing, painting and marking as
disclosed in U.S. Pat. No. 4,911,451 herein incorporated by
reference.
[0104] The resulting golf ball produced from the high acid ionomer
resin inner layer and the relatively softer, low flexural modulus
outer layer exhibits a desirable coefficient of restitution and
durability properties while at the same time offering the feel and
spin characteristics associated with soft balata and balata-like
covers of the prior art.
[0105] In yet another embodiment, a metal shell is disposed along
the outermost periphery of the golf ball and hence, provides an
outer metal surface. Similarly, a metal shell may be deposited on
to a dimpled molded golf ball. The previously described metal
mantle may be used without a polymeric outer cover, and so, provide
a golf ball with an outer metal surface. Providing a metal outer
surface produces a scuff resistant, cut resistant, and very hard
surface ball. Furthermore, positioning a relatively dense and heavy
metal shell about the outer periphery of a golf ball produces a
relatively low spinning, long distance ball. Moreover, the high
moment of inertia of such a ball will promote long rolling
distances.
[0106] The invention has been described with reference to the
preferred embodiments. Obviously, modifications and alterations
will occur to others upon reading and understanding the foregoing
detailed description. It is intended that the invention be
construed as including all such modifications and alterations
insofar as they come within the scope of the appended claims or the
equivalents thereof.
* * * * *