U.S. patent application number 10/899091 was filed with the patent office on 2005-03-03 for golf ball.
Invention is credited to Isogawa, Kazuhiko, Iwami, Satoshi, Sajima, Takahiro.
Application Number | 20050049084 10/899091 |
Document ID | / |
Family ID | 34213821 |
Filed Date | 2005-03-03 |
United States Patent
Application |
20050049084 |
Kind Code |
A1 |
Iwami, Satoshi ; et
al. |
March 3, 2005 |
Golf ball
Abstract
A golf ball formed of multiple layers that allows limiting an
uplifting trajectory, providing a trajectory in which the height of
the golf ball is well retained in the latter half of the flight of
the ball thereby increasing travel distance, where at least one
layer is made of a composition of a ternary copolymer ionomer, a
higher fatty acid and an inorganic metal compound mixed together,
at least 80% of the carboxyl group contained in the composition is
neutralized, and the total volume of the dimples (Dv) on the cover
surface ranges from 495 to 575 mm.sup.3. The above composition is
suitable for the cover. The higher fatty acid is a fatty acid with
12 to 40 carbon atoms, and preferably is stearic acid or oleic
acid.
Inventors: |
Iwami, Satoshi; (Kobe-shi,
JP) ; Isogawa, Kazuhiko; (Kobe-shi, JP) ;
Sajima, Takahiro; (Kobe-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
34213821 |
Appl. No.: |
10/899091 |
Filed: |
July 27, 2004 |
Current U.S.
Class: |
473/383 |
Current CPC
Class: |
A63B 37/0074 20130101;
A63B 37/0039 20130101; A63B 37/002 20130101; A63B 37/0024 20130101;
A63B 37/0064 20130101; A63B 37/0012 20130101; A63B 37/0019
20130101; A63B 37/008 20130101; A63B 37/0031 20130101; A63B 37/0075
20130101; A63B 37/0017 20130101; A63B 37/0004 20130101; A63B
37/0033 20130101; A63B 37/0087 20130101; A63B 37/12 20130101; A63B
37/0094 20130101; A63B 37/0003 20130101; A63B 37/0065 20130101 |
Class at
Publication: |
473/383 |
International
Class: |
A63B 037/04; A63B
037/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 2003 |
JP |
2003-300319(P) |
Claims
What is claimed is:
1. A golf ball formed of multiple layers, wherein at least one
layer is made of a composition of a ternary copolymer ionomer, a
higher fatty acid and an inorganic metal compound mixed together,
at least 80% of a carboxyl group contained in the composition is
neutralized, and a total volume of dimples (Dv) on a cover surface
is 495-575 mm.sup.3.
2. A golf ball formed of multiple layers, wherein a cover layer is
made of a composition of a ternary copolymer ionomer, a higher
fatty acid and an inorganic metal compound mixed together, at least
80% of a carboxyl group contained in the composition is
neutralized, and a total volume of dimples (Dv) on a cover surface
is 495-575 mm.sup.3.
3. The golf ball according to claim 2, wherein the higher fatty
acid is a higher fatty acid with 12-40 carbon atoms.
4. The golf ball according to claim 2, wherein said higher fatty
acid is selected from stearic acid or oleic acid, and a metal
component of the inorganic metal compound is selected from the
group consisting of Na, Zn, Mg, Ca, Li and K.
5. The golf ball according to claim 2, wherein said cover is made
of a composition with a Shore D hardness of 40-65.
6. The golf ball according to claim 2, wherein a degree of
neutralization of the carboxyl group contained in said composition
is no less than 90%.
7. The golf ball according to claim 2, wherein a degree of
neutralization of the carboxyl group contained in said composition
is 100%.
Description
[0001] This nonprovisional application is based on Japanese Patent
Application No. 2003-300319 filed with the Japan Patent Office on
Aug. 25, 2003, the entire contents of which are hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a golf ball that eliminates
the decrease in travel distance caused by an uplifting trajectory,
particularly the decrease in distance against an opposing wind.
[0004] 2. Description of the Background Art
[0005] Conventionally, a common resin component for the cover of a
golf ball is ionomer resin of ethylene-(meth-)acrylic acid
copolymer, which possesses good durability against impact and high
cut resistance and thus is widely used as cover material for
two-piece and thread-wound golf balls. However, a golf ball with a
cover made of an ionomer resin has a feel that is harder than that
of a golf ball with a balata cover and allows less control due to
the difficulties in producing spin when struck by an iron club.
Golf balls with a balata cover are widely used by advanced and
professional players because of its superior feel and control. They
are produced, however, in a complex manufacturing process and has a
lower cut resistance. Thus, a variety of alternative soft covers
substituting for balata covers have been proposed in recent
years.
[0006] For example, U.S. Pat. No. 4,884,814 discloses a technique
that uses soft ionomer resin for the base resin of a cover. The
technique provides a soft/hard ionomer blend cover made of
ethylene-(meth-)acrylic acid-(meth-)acrylate terpolymer, a
relatively soft ionomer resin, that is blended, to some degree,
with a binary copolymer ionomer resin of ethylene-(meth-)acrylic
acid copolymer. The technique provides improvement in feel and
control, in terms of which a conventional golf ball with a cover
made of ionomer resin of ethylene-(meth-)acrylic acid copolymer
exhibited poor performances.
[0007] The soft/hard ionomer blend cover according to the above
technique is soft and thus facilitates spinning the ball when
struck by an iron club, however, it increases friction between the
club face and the cover such that a ball using a hard core
material, particularly a two piece solid golf ball, may have its
cover surface chipped away by the grooves of an iron club,
resulting in ragged ball surface. This ionomer cover has a low
hardness that reduces the impact resilience of the cover, and thus
of the ball itself.
[0008] To reduce the abrasion of an ionomer cover caused by the
impact by an iron club, GB 2 264 302 proposes a cover made of a
metal salt of two or more kinds of ethylene-unsaturated carboxylic
acid-unsaturated carboxylate ternary copolymer with low flexural
modulus. This technique, however, does not provide a sufficient
abrasion resistance and impact resilience when struck by an iron
club.
[0009] GB 2 311 530 proposes a golf ball characterized in that the
base resin of a cover is mainly formed of the following three
components that are heated and mixed: an ionomer resin; an
acid-modified thermoplastic elastomer with or without an additional
OH group at an end; a styrene-butadiene-styrene block copolymer
containing an epoxy group or a styrene-isoprene-styrene block
copolymer containing an epoxy group, where the covering composition
forming the cover has a flexural rigidity of 50-300 MPa and a Shore
D hardness of 40-60. This technique, although providing improved
feel (when struck) and control and cut resistance, does not provide
satisfactory impact resilience.
[0010] US Publication No. US 2003/0013549A1 uses a composition with
increased degree of neutralization of carboxylic acid in an ionomer
composition for portions of a golf ball other than the cover i.e.
the intermediate layer or center, thereby increasing the
coefficient of restitution of the golf ball. A composition with
increased degree of neutralization of carboxylic acid in an ionomer
composition may be used for the center, intermediate layer or cover
of a golf ball to provide improved resilience, although this causes
increased spin rate, leading to an uplifting trajectory such that
the distance, particularly against an opposing wind, decreases
significantly, especially when the composition is used for the
cover.
SUMMARY OF THE INVENTION
[0011] When the center, intermediate layer-or cover of a golf ball
is made of a composition with increased degree of neutralization of
carboxylic acid in the ionomer composition, especially when the
cover is made of the above composition, the golf ball experiences
an uplifting trajectory, causing decrease in the travel distance,
particularly against an opposing wind. Accordingly, the present
invention provides a golf ball with an intermediate layer or cover
made of a composition with increased degree of neutralization of
carboxylic acid in the ionomer composition and with a total volume
of dimples larger than usual in order to limit an uplifting
trajectory (a larger drag coefficient) providing a trajectory in
which the height of the golf ball is well retained in the latter
half of the flight of the ball, thereby increasing the
distance.
[0012] The present invention provides a golf ball formed of
multiple layers, where at least one layer is made of a composition
of a ternary copolymer ionomer, a higher fatty acid and an
inorganic metal compound mixed together, at least 80% of the
carboxyl group contained in the composition is neutralized, and the
total volume of dimples (Dv) on the cover surface is 495-575
mm.sup.3.
[0013] Further, the present invention provides a golf ball formed
of multiple, layers, where the cover is made of a composition of a
ternary copolymer ionomer, a higher fatty acid and an inorganic
metal compound mixed together, at least 80% of the carboxyl group
contained in the composition is neutralized, and the total volume
of dimples (Dv) on the cover surface is 495-575 mm.sup.3.
[0014] Preferably, the higher fatty acid is a higher fatty acid
with 12-40 carbon atoms, and is stearic acid or oleic acid. It is
desirable that the metal component of the inorganic metal compound
is selected from Na, Zn, Mg, Ca, Li and K.
[0015] Preferably, the cover is made of a composition with a Shore
D hardness of 40-65. The degree of neutralization of the carboxyl
group contained in the composition is no less than 90%,
particularly preferably 100%.
[0016] The present invention provides improved impact resilience by
forming the intermediate layer or the cover from a composition with
increased degree of neutralization of carboxylic acid in the
ionomer composition. The total volume of dimples of a golf ball is
larger than usual to enable minimizing the decrease in the distance
caused by an uplifting trajectory of the golf ball especially
against an opposing wind, providing a trajectory in which the
height of the golf ball is well retained in the latter half of the
flight of the ball, thereby increasing the distance.
[0017] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a partial cross sectional view of a golf ball.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The present invention provides a golf ball formed of
multiple layers, where at least one layer is made of a composition
of a ternary copolymer ionomer, a higher fatty acid and an
inorganic metal compound mixed together, at least 80% of the
carboxyl group contained in the composition is neutralized, and the
total volume of dimples (Dv) on the cover surface is 495-575
mm.sup.3.
[0020] Particularly, the composition may be used for the cover to
provide a golf ball with excellent resilience.
[0021] <Ternary Copolymer Ionomer Composition with Higher Degree
of Neutralization>
[0022] The present invention uses a ternary copolymer ionomer
composition with higher degree of neutralization for at least one
of a center, intermediate layer and cover layer of a golf ball.
[0023] A ternary copolymer ionomer with higher degree of
neutralization as used herein means a composition including a
ternary copolymer ionomer, a higher fatty acid and an inorganic
metal compound that are heated and mixed together, where all the
carboxyl group contained in the composition (the carboxyl group in
the ternary copolymer ionomer together with the carboxyl group in
the higher fatty acid) is neutralized, with the total degree of
neutralization being 80% or more. Since a degree of neutralization
less than 80% provides an insufficient resilience, the degree of
neutralization is preferably 85% or more and more preferably 90% or
more, and particularly 100% is optimal.
[0024] The degree of neutralization can be determined from the
amount of remaining carboxyl group ([COOH]) and the amount of metal
salt of carboxylic acid ([COOM]) in accordance with the following
formula:
The degree of neutralization (%)={[COOM]
([COOH]+[COOM])}.times.100
[0025] The amount of remaining carboxyl group ([COOH]) is measured
by heating and melting the ionomer composition into tetrahydrofuran
and titrating it in the heated state with a predetermined
concentration of potassium hydroxide. The amount of metal salt of
carboxylic acid ([COOM]) is measured by analyzing the neutralizing
metal. The metal may be analyzed by Hitachi, Ltd. polarized Zeeman
atomic absorption spectrophotometer, model 180-80, for example, for
monovalent metals such as sodium, and by Seiko Electronics, Ltd.,
sequential ICP emission spectrophotometer, model SPS1100, for
example, for bivalent metals such as zinc.
[0026] In the ternary copolymer ionomer composition, higher fatty
acid accounts for 20-50 parts by mass, and preferably 25-45 parts
by mass per 100 parts of the ternary copolymer ionomer. A loading
of higher fatty acid less than 20 parts provides insufficient
fluidity of the composition, while a loading more than 50 parts
means a decrease in the proportion of the ternary copolymer ionomer
component, resulting in low resilience.
[0027] Inorganic metal compound accounts for 0.5-10 parts by mass,
preferably 1-8 parts. When the inorganic metal compound accounts
for less than 0.5 parts, the degree of neutralization is small and
cannot provide desired properties. More than 10 parts thereof
result in insufficient fluidity of the composition.
[0028] The ternary copolymer ionomer composition with higher degree
of neutralization may be prepared by mixing a ternary copolymer
ionomer, a higher fatty acid and an inorganic metal compound, and
heating and mixing them at a temperature of 100-250.degree. C. for
1-10 minutes. The ternary copolymer ionomer composition with higher
degree of neutralization has a Shore D hardness of 45-60, more
preferably 50-58.
[0029] <Ternary Copolymer Ionomer>
[0030] The ternary copolymer ionomer used in the present invention
is an ionomer made of a ternary copolymer of ethylene and .alpha.,
.beta. unsaturated carboxylic acid and .alpha., .beta. unsaturated
carboxylate. Preferably, it is a ternary copolymer of ethylene and
(meth-) acrylic acid and (meth-) acrylate.
[0031] The .alpha., .beta. unsaturated carboxylate may be a methyl,
ethyl, propyl, n-butyl or isobutyl ester of .alpha., .beta.
unsaturated carboxylic acid, for example.
[0032] The ternary copolymer ionomer has the ethylene component in
45-92 percent by mass, preferably 55-85 percent by mass, and the
.alpha., .beta. unsaturated carboxylic acid component in 3-25
percent by mass, preferably 5-20 percent by mass, and the .alpha.,
.beta. unsaturated carboxylate component in 5-30 percent by mass,
preferably 10-25 percent by mass.
[0033] In the ternary copolymer of ethylene and (meth-) acrylic
acid and (meth-) acrylate, the preferred proportions of the three
components in the copolymer composition is: ethylene in 70-85
percent by weight, (meth-) acrylic acid in 5-20 percent by weight,
and (meth-) acrylate in 10-25 percent by weight.
[0034] Examples of the ternary copolymer ionomer are Hi-milan 1856
(Na), Hi-milan 1855 (Zn), Hi-milan AM 7316 (Zn) and the like,
commercially available from Mitsui-Dupont Chemical Co. Ltd. Dupont
Co. Ltd. also sells Surlyn 8120 (Na), Surlyn 8320 (Na), Surlyn 9320
(Zn), Surlyn 6320 (Mg), and the like. Also, Exxon Mobil Corp. sells
IOTEC 7510 (Zn), IOTEC 7520 (Zn), and the like. With respect to
improvement in resilience, Surlyn 6320 (Mg) is preferred. The
metals set forth in the parentheses indicate neutralizing metals of
the ionomer. The ternary copolymer ionomer preferably has a Shore D
hardness in the range from 30 to 60, more preferably from 40 to
58.
[0035] <Higher Fatty Acid>
[0036] Higher fatty acids used in the present invention are
preferably those with 12-40 carbon atoms. A higher fatty acid with
less than 12 carbon atoms has an insufficient molecular weight that
results in lower resilience, though providing a better fluidity. A
higher fatty acid with more than 40 carbon atoms has an excessive
molecular weight so that the fluidity tends to be low at high
degrees of neutralization. Accordingly, the present invention
preferably has 12-40 carbon atoms, and more preferably 14-30, and
still more preferably 16-24. Stearic acid, oleic acid and linoleic
acid, which have 18 carbon atoms, are particularly preferable. The
higher fatty acid may be a saturated or unsaturated fatty acid.
[0037] <Inorganic Metal Compound>
[0038] The inorganic metal compounds used in the present invention
include magnesium oxide, magnesium hydroxide, magnesium carbonate,
zinc oxide, sodium oxide, sodium carbonate, calcium oxide, calcium
hydroxide and lithium hydroxide. Magnesium oxide and magnesium
hydroxide are particularly preferable.
[0039] The preferred combinations of a higher fatty acid and an
inorganic metal compound in the present invention include stearic
acid, oleic acid, and magnesium oxide, magnesium hydroxide to
improve moldability and resilience.
[0040] <Polymer Components in Composition>
[0041] The ternary copolymer ionomer composition with higher degree
of neutralization of the present invention is preferably mixed with
other resin and/or rubber components as required to provide needed
properties of the center, intermediate layer, cover.
[0042] For example, as for the compositions for the cover, a
ternary copolymer ionomer composition with higher degree of
neutralization can be constructed of a ternary copolymer ionomer
component only, while a ternary copolymer ionomer with a lower
degree of neutralization or a binary copolymer ionomer may be used.
Examples of binary copolymer ionomers in trade names are Hi-milan
1555 (Na), Hi-milan 1557 (Zn), Hi-milan 1605 (Na), Hi-milan 1706
(Zn), Hi-milan 1707 (Na), Hi-milan AM 7318 (Na), Hi-milanAM7315
(Zn), Hi-milanAM7317 (Zn), Hi-milan AM 7311 (Mg), Hi-milan MK 7320
(K) and the like, all commercially available from Mitsui-Dupont
Chemical Co., Ltd.
[0043] Dupont Co., Ltd also sells Surlyn 8945 (Na), Surlyn 8940
(Na), Surlyn 9910 (Zn), Surlyn 9945 (Zn), Surlyn 7930 (Li), Surlyn
7940 (Li) and the like.
[0044] Also, Exxon Mobil Corp. sells IOTEC 7010 (Zn), IOTEC 8000
(Na), IOTEC 7030 (Zn), IOTEC 8030 (Na) and the like. Na, Zn, K, Li
and Mg in the parentheses indicate the metals of these neutralizing
metal ions.
[0045] According to the present invention, one or more of these
ionomer resins may be mixed with the above composition. Also, two
or more of ionomer resins neutralized with the illustrated
monovalent metal ions and ionomer resins neutralized with the
illustrated bivalent metal ions may be mixed for use in the present
invention.
[0046] Moreover, the polymer components to be mixed with the above
composition may include one or more of polyolefin-based elastomers,
polyurethane-based elastomers and polyester-based elastomers, for
example, that are mixed together. Examples of polyolefin-based
elastomers in trade names are Milastomer M4800NW from Mitsui
Chemicals, Inc., and Sumitomo TPE3682, 9455 from Sumitomo Chemicals
Co., Ltd. Examples of polyurethane-based elastomers in trade names
are KU ON 9195, KURAMIRON 9180 from Kuraray Co., Ltd., Elastollan
ET880 and ET 890 from BASF Polyurethane Elastomers Ltd. Examples of
polyester-based elastomers in trade names are Hytrel 4047, 4767,
5557 from Toray-Dupont Co., Ltd.
[0047] Further, polystyrene-based elastomers, such as thermoplastic
elastomers containing a styrene block may be used. Thermoplastic
elastomers containing a styrene block may be a block copolymer
including a styrene block and a unit derived from a conjugated
diene compound, and the conjugated diene compound may be one or
more of butadiene, isoprene, 1,3-pentadiene,
2,3-dimethyl-1,3-butadiene and the like, where butadiene, isoprene
and a combination thereof is preferred.
[0048] Examples of thermoplastic elastomers containing a styrene
block are styrene-butadiene-styrene block copolymer (SBS),
styrene-ethylene-butylen- e-styrene block copolymer (SEBS) where
the double bond portion of the butadiene in SBS is hydrogenated,
styrene-isoprene-styrene block copolymer (SIS),
styrene-ethylene-propylene-styrene block copolymer (SEPS) where the
double bond portion of the isoprene in SIS is hydrogenated,
styrene-isoprene-butadiene-styrene block copolymer (SIBS),
styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS)
where the double bond portion of the butadiene or isoprene in SIBS
is hydrogenated and modifications thereof.
[0049] For the cover or intermediate layer, the polymer components
stated above may be mixed in 80 parts by mass or less, particularly
50 parts by mass or less, per 100 parts of the ternary copolymer
ionomer with higher degree of neutralization.
[0050] For the center, conventional center compositions may
simultaneously be used. For example, a rubber component may be
mixed in 80 parts by mass or less per 100 parts of the ternary
copolymer ionomer with higher degree of neutralization. Then, one
or more co-crosslinking agents in 10-50 parts by mass in total per
100 parts of the rubber component may be added that are made of a,
P-monoethyleric unsaturated carboxylic acid such as acrylic acid,
methacrylic acid and the like or its metal salt, or
trimethylolpropane trimethacrylate polyfunctional monomer and the
like. The rubber component may be polybutadiene, polyisoprene or
the like. Further, a filler such as zinc oxide, barium sulfate or
the like in 10-30 parts by mass, a peroxide such as dicumyl
peroxide in 0.5-5 parts by mass and, if necessary, an antioxidant
in 0.1-1 part by mass may be added.
[0051] <Other Ingredients>
[0052] To the cover composition forming the cover and the like in
the present invention may be added a variety of additives as
required, such as pigment, weight conditioner, dispersant,
ultraviolet absorbent, photo-stabilizer or the like.
[0053] <Total Volume of Dimples Dv>
[0054] According to the present invention, the total volume of
dimples ranges from 495 to 575 mm.sup.3. A total volume of dimples
less than 495 mm.sup.3 cannot limit the uplifting trajectory due to
the increased spin rate. More preferably, the total volume is 505
mm.sup.3 or more, yet more preferably 515 mm.sup.3 or more,
particularly preferably 525 mm.sup.3 or more. A total volume more
than 575 mm.sup.3 excessively lowers the trajectory leading to the
tendency of the ball to drop, reducing the travel distance. The
total volume is more preferably 565 mm.sup.3 or less.
[0055] "Total volume of dimples-Dv" will now be explained referring
to FIG. 1 which is a partial cross section of a golf ball showing a
dimple area. "Volume of dimple" means a volume defined by, in FIG.
1, an imaginary spherical surface of a golf ball (i.e. the
spherical surface imagined when assuming that dimple 2 does not
exist) and the surface of dimple 2. "Volume of dimple" is the sum
of an upper volume w and a lower volume V, which are separated from
each other by the plane connecting the points P--P at which the
imaginary spherical surface crosses the dimple surface. "Total
volume of dimples Dv" is defined as the sum of volumes of the
dimples provided on the surface of a golf ball, each being
represented as "volume of dimple (w+v)". The diameter of a dimple,
d, is defined as the distance between the points P--P at which the
imaginary spherical surface crosses the dimple surface. Finally, in
FIG. 1, the sphere depth of a dimple is defined as D.sub.0, the
dimple depth as D.sub.1.
[0056] <Cover Hardness>
[0057] According to the present invention, the cover preferably has
a Shore D hardness of 40-55, more preferably 42-60, particularly
45-55. A Shore D hardness less than 40 produces an excessively soft
cover which results in low resiliency, as well as increased spin
rate, causing the travel distance to be decreased. A Shore D
hardness more than 65 produces a cover that is excessively hard,
which means an inferior feel.
[0058] <Structure of Golf Ball and Compositions of its
Layers>
[0059] According to the present invention, ternary copolymer
ionomer with higher degree of neutralization may be used for at
least one of the center, intermediate layer and cover. Any of the
following modes can achieve the objectives of the present
invention.
[0060] a. For a two-layer structure of center (or core)/cover
layer, ternary copolymer ionomer with higher degree of
neutralization may be used for one or both of the center and the
cover.
[0061] b. For a three-layer structure of center/intermediate
layer/cover layer, it may be used for one, two or all of the
center, intermediate layer and cover layer.
[0062] Further, it may be used for at least one layer of a golf
ball formed of four layers. Particularly, it may be most
advantageously used for the cover.
[0063] <Method of Manufacturing Golf Ball>
[0064] A generally used technique may be applied without limitation
to manufacture inventive golf balls. For example, a method that
involves preparing ingredients in desired weights and then
injection-molding them, or a method that involves press-molding may
be used.
[0065] <Ball Weight and Ball Outer Diameter>
[0066] The diameter of an inventive golf ball ranges from 40 to 45
mm, particularly from 42 to 44 mm. Since the air resistance may be
decreased within the range provided in the specifications regulated
by the United States Golf Association (USGA), the diameter is
preferably 42.67-42.80 mm. The mass of a golf ball according to the
present invention ranges from 44 to 46 g, particularly 45.00 g to
45.93 g.
EXAMPLES
[0067] Table 1 sets forth center and intermediate layer
formulations, while Table 2 sets forth cover formulations. Ternary
copolymer ionomer compositions with higher degree of neutralization
used for the examples (shown below Tables 1 and 2) are
provided.
1 TABLE 1 A B C D E Center Formulation BR18 1 100.0 100.0 100.0
100.0 zinc acrylate 33.0 33.0 33.0 33.0 zinc oxide 12.0 7.5 7.5 7.5
diphenyl disulfide 2 0.5 0.5 0.5 0.5 dicumyl peroxide 3 0.8 0.8 0.8
0.8 ternary copolymer ionomer 100.0 (Mg 100%) 7 curing condition
170.degree. C. .times. 15 min. 170.degree. C. .times. 15 min.
170.degree. C. .times. 15 min. 170.degree. C. .times. 15 min.
center diameter (mm) 40 32.5 37 37 40 Intermediate Formulation BR11
1 none 100 none layer zinc acrylate 36 zinc oxide 11 diphenyl
disulfide 2 0.5 dicumyl peroxide 3 0.7 ternary copolyrner ionomer
100 (Mg 100%) 7 Hi-milan 1605 4 30 Hi-milan 1706 5 30 Surlyn 6320 6
40 curing condition 170.degree. C. .times. 15 min. core diameter
(center/intermediate layer) (mm) 40 40 40 40 40 98-1275N
deformation (mm) 3 2.9 2.9 2.8 3 1 High cis-polybutadiene from JSR
Corporation 2 From Sumitomo Seika Chemicals Co., Ltd. 3 From NOF
Corporation 4 Na neutralized binary ionomer from Mitsui-Dupont
Chemical Co., Ltd. 5 Zn neutralized binary ionomer from
Mitsui-Dupont Chemical Co., Ltd. 6 Mg neutralized ternary ionomer
from Du Pont Co., Ltd. 7 Surlyn 6320 mixed with stearic acid,
magnesium oxide while heated, and 100% of carboxyl group in stearic
acid neutralized by Mg
[0068]
2TABLE 2 1 2 Cover Hi-milan 1605 4 50 Formulation Hi-milan 1706 5
Surlyn 6320 6 50 ternary copolymer ionomer (Mg 100%) 7 100 titanium
oxide 3 3 Shore D Hardness 57D 55D 5 Zn neutralized binary ionomer
from Mitsui-DuPont Chemical Co., Ltd. 6 Mg neutralized ternary
ionomer from Du Pont Co., Ltd. 7 Surlyn 6320 mixed with stearic
acid, magnesium oxide while heated, and 100% of carboxyl group in
stearic acid neutralized with Mg Surlyn 6320: 100 parts by mass
Stearic acid: 40 parts by mass Magnesium oxide: 3.9 parts by
mass
[0069] Tables 3 and 4 set forth dimple characteristics. The shown
formulations and dimple characteristics were used to fabricate the
golf balls of the examples and comparative examples. The golf balls
of the examples are illustrated in Table 5 and those of the
comparative examples in FIG. 6, each with its property
evaluation.
3TABLE 3 Total Sphere Volume Upper Total upper Sum Ball Diameter
Depth depth Curvature V volume V + W volume volume (V + W) diameter
Type Number d(mm) D.sub.1(mm) D.sub.0(mm) (mm) (mm.sup.3) W
(mm.sup.3) (mm.sup.3) (mm.sup.3) (mm.sup.3) (mm.sup.3) I 42.70 A
132 4.100 0.1325 0.2311 15.92 0.876 0.652 1.528 115.6 86.0 201.6
42.70 B 180 3.550 0.1320 0.2059 12.00 0.654 0.366 1.020 117.8 65.9
183.7 42.70 C 60 3.400 0.1300 0.1978 11.18 0.591 0.308 0.899 35.5
18.5 54.0 42.70 D 60 3.200 0.1300 0.1900 9.91 0.524 0.242 0.765
31.4 14.5 45.9 432 300.3 184.9 485.2 II 42.70 A 132 4.100 0.1410
0.2396 14.97 0.932 0.652 1.584 123.1 86.0 209.1 42.70 B 180 3.550
0.1400 0.2139 11.32 0.694 0.366 1.060 125.0 65.9 190.9 42.70 C 60
3.400 0.1400 0.2078 10.39 0.637 0.308 0.945 38.2 18.5 56.7 42.70 D
60 3.200 0.1400 0.2000 9.21 0.564 0.242 0.806 33.9 14.5 48.4 432
320.1 184.9 505.0 III 42.70 A 132 4.100 0.1500 0.2486 14.08 0.992
0.652 1.644 130.9 86.0 217.0 42.70 B 180 3.550 0.1500 0.2239 10.58
0.744 0.366 1.110 133.9 65.9 199.8 42.70 C 60 3.400 0.1475 0.2153
9.87 0.671 0.308 0.979 40.3 18.5 58.8 42.70 D 60 3.200 0.1450
0.2050 8.90 0.585 0.242 0.826 35.1 14.5 49.6 432 340.2 184.9
525.1
[0070]
4TABLE 4 Total Sphere Volume Upper Total upper Sum Ball Diameter
Depth depth Curvature V volume V + W volume volume (V + W) diameter
Type Number d(mm) D.sub.1(mm) D.sub.0(mm) (mm) (mm.sup.3) W
(mm.sup.3) (mm.sup.3) (mm.sup.3) (mm.sup.3) (mm.sup.3) IV 42.70 A
132 4.100 0.1600 0.2588 13.21 1.058 0.652 1.710 139.7 86.0 225.7
42.70 B 180 3.550 0.1575 0.2314 10.08 0.782 0.366 1.148 140.7 65.9
206.6 42.70 C 60 3.400 0.1550 0.2228 9.40 0.706 0.308 1.013 42.3
18.5 60.8 42.70 D 60 3.200 0.1550 0.2150 8.34 0.625 0.242 0.867
37.5 14.5 52.0 432 360.2 184.9 545.1 V 42.70 A 132 4.100 0.1675
0.2661 12.63 1.108 0.652 1.760 146.3 86.0 232.3 42.70 B 180 3.550
0.1675 0.2414 9.49 0.831 0.366 1.197 149.7 65.9 215.5 42.70 C 60
3.400 0.1650 0.2328 8.84 0.751 0.308 1.059 45.1 18.5 63.6 42.70 D
60 3.200 0.1625 0.2225 7.96 0.656 0.242 0.897 39.3 14.5 53.8 432
380.4 184.9 565.2 VI 42.70 A 132 4.100 0.1760 0.2746 12.03 1.165
0.652 1.816 153.7 86.0 239.8 42.70 B 180 3.550 0.1750 0.2489 9.09
0.869 0.366 1.235 156.4 65.9 222.3 42.70 C 60 3.400 0.1750 0.2428
8.34 0.797 0.308 1.105 47.8 18.5 66.3 42.70 D 60 3.200 0.1750
0.2350 7.40 0.707 0.242 0.948 42.4 14.5 56.9 432 400.4 184.9
585.2
[0071]
5 TABLE 5 Examples 1 2 3 4 5 6 Ball Specification Core (center +
intermediate layer) formulation A A A A C E Core diameter (mm) 40
40 40 40 40 40 Core 98-1274N deformation (mm) 3.0 3.0 3.0 3.0 2.9
3.0 Cover formulation 2 2 2 2 1 1 Cover thickness (mm) 1.4 1.4 1.4
1.4 1.4 1.4 Cover Shore D hardness 55D 55D 55D 55D 57D 57D Ball
98-1274N deformation (mm) 2.75 2.75 2.75 2.75 2.65 2.75 Ball
diameter D (mm) 42.7 42.7 42.7 42.7 42.7 42.7 Dimple specification
III II IV V III III Total volume of dimples (mm.sup.3) 525 505 545
565 525 525 Ball Resilience 103 103 103 103 102 100 Properties
Launch angle (.degree.) 11.5 11.5 11.5 11.5 11.6 11.4 Angle of
trajectory (.degree.) 12.7 12.8 12.6 12.5 12.7 12.7 Angle of
trajectory - Launch angle (.degree.) 1.2 1.3 1.1 1 1.1 1.3 Total
distance 101 101 102 103 101 100
[0072]
6 TABLE 6 Comparative Examples 1 2 3 4 5 Ball Specification Core
(center + intermediate layer) formulation A B D A A Core diameter
(mm) 40 40 40 40 40 Core 98-1274N deformation (mm) 3.0 2.9 2.8 3.0
3.0 Cover formulation 1 1 1 2 2 Cover thickness (mm) 1.4 1.4 1.4
1.4 1.4 Cover Shore D hardness 57D 57D 57D 55D 55D Ball 98-1274N
deformation (mm) 2.75 2.65 2.55 2.75 2.75 Ball diameter D(mm) 42.7
42.7 42.7 42.7 42.7 Dimple specification III III III I VI Total
volume of dimples (mm.sup.3) 525 525 525 485 585 Ball Resilience 99
98 97 103 103 Properties Launch angle (.degree.) 11.5 11.4 11.3
11.4 11.6 Angle of trajectory (.degree.) 12.8 12.7 12.6 13 12.1
Angle of trajectory - Launch angle (.degree.) 1.3 1.3 1.3 1.6 0.5
Total distance 99 98 97 98 97
[0073] In the examples of the present invention, ingredients were
regulated to produce a center, intermediate layer and cover of
desired weights, and the outer diameter and thickness were
regulated by injection molding.
[0074] <Test Method>
[0075] (1) Coefficient of Restitution
[0076] The golf balls were struck by a cylindrical aluminum object
of 200 g at a speed of 45 m/sec, and the speeds of the cylindrical
object and each golf ball before and after the impact were
measured, and their speeds and weights were used to calculate the
coefficient of restitution of the golf ball. Five measurements were
made for each golf ball to determine an average that was used as
the value of the ball. Values relative to Example 6 which has the
value 100 are shown. A greater value indicates better
resilience.
[0077] (2) 98-1274N Deformation
[0078] Deformation (mm) of a golf ball, core or center was measured
beginning with an initial load of 98N applied thereto and ending
with a final load of 1274N. A greater number indicates more
softness.
[0079] (3) Flight Performance
[0080] A metal head wood No. 1, a driver, was attached to a swing
robot from True Temper. Each golf ball was struck by the golf club
at a head speed of 45 m/sec, and launch angle immediately after the
shot, angle of trajectory, total travel distance (the distance all
the way to the stopping point) were measured. Five measurements
were made for each golf ball to determine an average that was used
as the value of the ball. The units for the launch angle and the
angle of trajectory are "degree", and total distances relative to
Example 6 which has the value 100 are shown, where a greater value
indicates greater total distance.
[0081] (4) Shore D Hardness
[0082] Measurement was conducted in accordance with ASTM-D2240. A
heat press-molded sheet with a thickness of about 2 mm made of the
above composition was preserved at 23.degree. C. for 2 weeks.
Thereafter, three or more stacked sheets were measured using a
spring type hardness meter (Shore D type), by an automatic rubber
hardness meter model LA1 from Kobunshi Keiki Co., Ltd.
[0083] <Test Results>
[0084] Comparative Examples 1 to 3 do not contain ternary copolymer
ionomer with higher degree of neutralization and therefore exhibit
lower resiliencies and shorter distances. Comparative Examples 4
and 5 have total volumes of dimples that lie outside the range
according to the invention. As a result, Comparative Example 4
cannot limit an uplifting trajectory, while Comparative Example 5
does so in excess and leads to the tendency of the ball to drop,
both resulting in shorter distances.
[0085] Examples 1 to 4, however, have a cover made of ternary
copolymer ionomer with higher degree of neutralization, and
produced excellent results in both resilience and travel distance.
Example 5 uses ternary copolymer ionomer with higher degree of
neutralization for the intermediate layer, producing excellent
results in both resilience and distance. Example 6 uses ternary
copolymer ionomer with higher degree of neutralization for the
center with excellent results in both resilience and distance. The
results in Table 5 also indicate that ternary copolymer ionomer
with higher degree of neutralization is used for the cover with
better results in resilience than it is used for the center or the
intermediate layer.
[0086] The present invention provides a center, an intermediate
layer or a cover of a golf ball made of a composition with
increased degree of neutralization of carboxylic acid in an ionomer
composition to limit an uplifting trajectory of the golf ball that
would cause the travel distance to be decreased, thereby preventing
decrease in the distance against an opposing wind. The total volume
of dimples of a golf ball is larger than usual to limit an
uplifting trajectory of the ball (a larger drag coefficient),
providing a trajectory in which the height of the golf ball is well
retained in the latter half of the flight of the ball, thereby
increasing the distance, providing a valuable golf ball that can
meet needs of golfers.
[0087] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
* * * * *