U.S. patent application number 09/466799 was filed with the patent office on 2002-04-04 for solid golf ball.
Invention is credited to MARUKO, TAKASHI, MASUTANI, YUTAKA, NAKAMURA, ATSUSHI, YAMAGISHI, HISASHI.
Application Number | 20020039933 09/466799 |
Document ID | / |
Family ID | 12363446 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020039933 |
Kind Code |
A1 |
NAKAMURA, ATSUSHI ; et
al. |
April 4, 2002 |
SOLID GOLF BALL
Abstract
In a solid golf ball comprising a solid core and a cover, the
solid core has a multilayer construction which includes a center
core and an outer core that encloses the center core. The center
core is composed primarily of a resin and has a diameter of 3-20 mm
and a specific gravity of 0.90-1.50. The center core has a surface
Shore D hardness of 40-95 which is at least 10 units greater than
the Shore D hardness of an innermost layer of the outer core. The
ball has an excellent click and feel.
Inventors: |
NAKAMURA, ATSUSHI;
(CHICHIBU-SHI, JP) ; YAMAGISHI, HISASHI;
(CHICHIBU-SHI, JP) ; MARUKO, TAKASHI;
(CHICHIBU-SHI, JP) ; MASUTANI, YUTAKA;
(CHICHIBU-SHI, JP) |
Correspondence
Address: |
SUGHRUE MION ZINN MACPEAK & SEAS
2100 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
200373202
|
Family ID: |
12363446 |
Appl. No.: |
09/466799 |
Filed: |
December 20, 1999 |
Current U.S.
Class: |
473/361 ;
473/370; 473/371; 473/374; 473/377 |
Current CPC
Class: |
A63B 37/06 20130101;
A63B 37/0064 20130101; A63B 37/0075 20130101; A63B 37/0092
20130101; A63B 37/00622 20200801; A63B 37/0065 20130101; A63B 37/04
20130101; A63B 37/00621 20200801; A63B 37/08 20130101; A63B 37/0003
20130101; A63B 37/0066 20130101 |
Class at
Publication: |
473/361 ;
473/370; 473/371; 473/374; 473/377 |
International
Class: |
A63B 037/06; A63B
037/08; A63B 037/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 1999 |
JP |
11-32603 |
Claims
1. A solid golf ball comprising a solid core and a cover that
encloses the solid core, the solid core having a multilayer
construction which includes a center core and an outer core that
encloses the center core, wherein the center core is composed
primarily of a resin and has a diameter d of 3 to 20 mm and a
specific gravity G of 0.90 to 1.50 which satisfy the relationship:
G.gtoreq.0.014 d+0.929, the center core has a Shore D hardness of
40 to 95 at the surface thereon, and the outer core has a Shore D
hardness at an innermost layer thereof which is at least 10 units
lower than the Shore D hardness at the surface of the center
core.
2. The solid golf ball of claim 1, wherein the solid core has a
deflection of 2.2 to 4.3 mm under an applied load of 100 kg.
3. The solid golf ball of claim 1, wherein the innermost layer of
the outer core is composed primarily of a resin or a resin and
rubber mixture.
Description
[0001] The present invention relates to a multi-piece solid golf
ball having an improved "click" and "feel" when hit with a golf
club.
BACKGROUND OF THE INVENTION
[0002] A variety of multi-piece golf balls, including three-piece
and four-piece balls, have been developed over the past few years
in order to improve ball performance.
[0003] Most such golf balls have a center core of about 30 mm in
diameter that is made of a rubber-based material to maintain the
resilience of the golf ball. The rubber center core exerts a large
influence on ball performance when the ball is hit. Balls designed
for golfers with a high golf club head speed generally have a hard
feel when hit, while balls designed for low head speed golfers have
too soft a feel. Hence, there has remained substantial room for
improvement. That is, balls containing a soft center core have a
soft feel while balls containing a hard center core have a hard
feel to the full spectrum of golfers, from players of ordinary
skill to skilled amateurs and professional golfers.
[0004] The clicking sound made when a golf ball is hit, which is an
important feature of the ball, is also strongly affected by the
center core. Again, for the most part, balls containing a soft
center core have a dull "click" when hit, whereas balls containing
a hard center core have a high-pitched "click."
SUMMARY OF THE INVENTION
[0005] Therefore, an object of the present invention is to provide
a solid golf ball having a good feel and an agreeable click.
[0006] It has been found that the feel of a golf ball can be varied
and the click improved by dividing the solid core into a center
core and an outer core and optimizing each of these two layers.
More specifically, it has been found that reducing the size of the
center core to a diameter of 3 to 20 mm, which is smaller than in
conventional golf balls, provides an unprecedented click and feel,
particularly when deformation of the ball is large, without
adversely affecting the resilience and other key characteristics of
the ball.
[0007] Moreover, although it is conventional practice to form the
center core of a rubber-based material so as to maintain the ball's
resilience, given the limited hardness achievable with rubber
materials and the loss in productivity encountered when such
materials are used to form small-diameter center cores, a center
core composed primarily of a resin provides certain advantages.
While the use of a resin sphere does give a center core having a
lower resilience than one made of a conventional rubber material,
the decline in the resilience of the ball as a whole is minimized
by setting the diameter of the center core within the
above-indicated range of 3 to 20 mm. The degree of this decline in
the ball's resilience varies with the diameter of the center core,
becoming larger as the diameter of the resin center core increases.
The specific gravity G and the diameter d in millimeters of the
center core are made to satisfy the relationship:
G.gtoreq.0.014+0.929.
[0008] That is, a center core having a larger diameter has a higher
specific gravity. In general, adding a filler to a certain material
to increase its specific gravity has the effect of lowering its
resilience. When the center core is formed so that the specific
gravity rises with increasing diameter, it becomes possible in turn
to lower the specific gravity of the outer core and thus compensate
for the low resilience of the center core. As long as the center
core is given a small diameter and the specific gravity of the
center core is suitably adjusted in accordance with its size, the
center core can be made of resin without compromising the
performance of the ball as a whole.
[0009] It has also been found that when the Shore D hardness of the
center core is set within a relatively hard range of 40 to 95 and
the innermost layer of the outer core is formed so as to be at
least 10 Shore D units softer than the center core, the resulting
soft core containing a small, hard center has the overall effect of
imparting a soft, yet solid feel and an appropriately high-pitched
click to the ball when hit with a golf club.
[0010] Accordingly, the present invention provides a solid golf
ball comprising a solid core and a cover that encloses the solid
core, the solid core having a multilayer construction which
includes a center core and an outer core that encloses the center
core. The center core is composed primarily of a resin and has a
diameter d of 3 to 20 mm and a specific gravity G of 0.90 to 1.50
which satisfy the condition: G.gtoreq.0.014a+0.929. The center core
has a Shore D hardness at the surface thereon of 40 to 95, and the
outer core has a Shore D hardness at an innermost layer portion
thereof which is at least 10 units lower than the Shore D hardness
at the surface of the center core.
[0011] The hardness of the overall ball can be optimized by setting
the deflection of the solid core under a static load of 100 kg
within a range of 2.2 to 4.3 mm. Preferably, the innermost layer of
the outer core is composed primarily of resin or a mixture of resin
and rubber.
[0012] By thus having the solid core of a golf ball contain a
small, hard center core made of resin, there can be obtained a golf
ball having an unprecedented feel and an agreeable click that is
not too low in pitch.
BRIEF DESCRIPTION OF THE DRAWING
[0013] The only figure, FIG. 1 is a sectional view showing a solid
golf ball according to one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring to FIG. 1, the solid golf ball of the invention
has a solid core 1 enclosed within a cover 2. The solid core 1 has
a center core 3 and an outer core 4 which covers the surface of the
center core 3 and is itself enclosed by the cover 2. The solid core
1 shown in FIG. 1 is composed of two layers and the cover 2 is
composed of a single layer. However, if necessary, the outer core 4
of the solid core 1 may itself be composed of two or more layers,
and the cover 2 may be composed of two, three or more layers.
[0015] Unlike prior-art golf balls, the center core 3 in the solid
core 1 of the inventive golf ball is not made of a rubber
composition, but rather is composed primarily of a resin.
[0016] Examples of resins that may be used in the center core 3
include known thermoplastic resins and thermoplastic elastomers,
such as nylons, polyarylates, ionomer resins, polypropylene resins,
thermoplastic polyurethane elastomers and thermoplastic polyester
elastomers. Commercially available resins that are highly suitable
for this purpose include Surlyn AD8512 (an ionomer resin
manufactured by E. I. DuPont de Nemours and Co.), Himilan 1706 and
1707 (ionomer resins manufactured by DuPont-Mitsui Polychemicals
Co., Ltd.), Rilsan BMNO (a nylon resin manufactured by Toray
Industries, Inc.) and U-Polymer U-8000 (a polyarylate resin
manufactured by Unitika, Ltd.).
[0017] If desired, an inorganic filler such as barium sulfate,
titanium dioxide or zinc oxide may be included as a weight modifier
in the resin material. The weight of the center core 3 can be
increased by incorporating a large amount of such a filler. This in
turn allows the proportion of the rubber component in the outer
core 4 (subsequently described) to be increased, enabling a
remarkable improvement in the resilience of the golf ball. The use
of a high specific gravity filler is advantageous in production as
well in that it allows the degree of center core eccentricity to be
easily determined nondestructively by x-ray inspection. The amount
of weight modifier included is preferably 0 to about 115 parts by
weight, and especially about 5 to about 100 parts by weight per 100
parts by weight of resin.
[0018] The center core made primarily of the above type of resin
has a diameter of from 3 to 20 mm, preferably 5 to 18 mm, and
especially 8 to 15 mm. Too small a center core fails to achieve the
intended effects, whereas one that is too large may adversely
affect the resilience of the ball.
[0019] The center core has a specific gravity of from 0.90 to 1.50,
and especially 1.00 to 1.45. Moreover, it is formed such as to
satisfy the relationship:
G.gtoreq.0.014 d+0.929,
[0020] wherein G represents the specific gravity of the center core
3 and d represents the diameter (in millimeters) of the center
core.
[0021] The center core at the surface thereof has a Shore D
hardness within a range of 40 to 95, preferably 43 to 90, and
especially 45 to 87. If the center core 3 has too low a hardness,
i.e., is excessively soft, improvements in the click and feel
cannot be achieved.
[0022] The center core can be produced by injection molding a
center core material composed primarily of the above-described
resin.
[0023] Next, the outer core 4 which encloses the center core 3 may
be composed of a single layer or have a multilayer construction
composed of two or more layers. The innermost layer of the outer
core which contiguously encloses the center core must have a Shore
D hardness which is lower than the Shore D hardness of the center
core. Specifically, the innermost layer of the outer core must have
a Shore D hardness that is at least 10 units, preferably at least
12 units, and most preferably at least 15 units lower than the
Shore D hardness of the center core. A hardness difference of less
than 10 will not allow sufficient improvement to be achieved in the
click and feel of the ball. If the innermost layer of the outer
core is made of a rubber material or the like and has a hardness
distribution, all areas of the innermost layer, and thus the
hardest area thereof, must have a Shore D hardness which is at
least 10 units lower than the Shore D hardness of the center
core.
[0024] So long as the outer core 4 has the above-described hardness
difference with the center core 3, the outer core 4 is not subject
to any other limitation. The material used to make the outer core 4
may be a rubber base conventionally used for the same purpose, a
thermoplastic resin base material, or a mixture of rubber with a
thermoplastic resin.
[0025] The larger the diameter of the center core 3 and the greater
its hardness, the more desirable it becomes for achieving good
adhesion between the center core 3 and the outer core 4 to enclose
the center core 3 with a thermoplastic resin or a mixture of a
thermoplastic resin and rubber.
[0026] When the center core 3 is enclosed in this way within a
resin or a resin-rubber mixture, the outer core 4 preferably has a
two-layer construction in which the resin or resin-rubber mixture
is enclosed as the inside layer within an outside layer formed of a
rubber composition. However, the ball may be composed entirely of
resin materials so long as the materials used are capable of
ensuring the resilience of the ball.
[0027] The thermoplastic resin making up the outer core 4 may be
the same as that used in the center core 3. Suitable examples
include ionomer resins, thermoplastic polyurethane elastomers and
thermoplastic polyester elastomers.
[0028] If a mixture of the resin with rubber is to be used, this
mixture may be formulated by dispersing a diene rubber such as
butadiene rubber in an ionomer resin and effecting crosslinkage as
described in JP-A 10-113406. Alternatively, the mixture may be a
blend of an ionomer resin with a functional rubbery copolymer such
as a crosslinked rubber having carboxyl groups incorporated
therein, as described in JP-A 10-314341.
[0029] The rubber composition for use in the outer core is
preferably one comprising polybutadiene as the base. The use of
cis-1,4-polybutadiene having a cis structure of at least 40% is
especially suitable. Where desired, other suitable rubber
ingredients such as natural rubber, polyisoprene rubber or
styrene-butadiene rubber may be compounded with the polybutadiene
to give the base rubber. The resilience of the golf ball can be
improved by increasing the proportion of the polybutadiene
component. Up to about 10 parts by weight of the other rubber
ingredients may be compounded per 100 parts by weight of the
polybutadiene.
[0030] A crosslinking agent may be included in the rubber
composition. Exemplary crosslinking agents are the zinc and
magnesium salts of unsaturated fatty acids, such as zinc
dimethacrylate and zinc diacrylate, and ester compounds such as
trimethylpropane methacrylate. Zinc diacrylate is especially
preferred for achieving a high resilience. The crosslinking agent
is preferably included in an amount of about 10 to 30 parts by
weight per 100 parts by weight of the base rubber.
[0031] In the practice of the invention, a vulcanizing agent is
generally compounded in the rubber composition. It is recommended
that the vulcanizing agent include a peroxide having a one minute
half-life temperature of lower than 155.degree. C. in an amount of
at least 30% by weight, and especially 40 to 70% by weight based on
the overall vulcanizing agent. Examples of suitable peroxides
include commercially available products such as Perhexa 3M
(manufactured by Nippon Oils and Fats Co., Ltd.). The amount of
vulcanizing agent included in the rubber composition is preferably
from about 0.6 to 2 parts by weight per 100 parts by weight of the
base rubber.
[0032] If necessary, other suitable ingredients may also be blended
in the rubber composition, such as an antioxidants and specific
gravity-modifying fillers (e.g., zinc oxide, barium sulfate). The
amount of such specific gravity modifiers blended is typically from
about 1 to 30 parts by weight per 100 parts by weight of the base
rubber.
[0033] The solid core 1 composed of a center core 3 enclosed within
an outer core 4 as described above preferably has a diameter of 36
to 41.5 mm. If the outer core is formed of a resin or a
resin-rubber mixture on the inside and of a rubber composition on
the outside, the inside layer preferably has a thickness of 0.5 to
5.0 mm, and especially 1.0 to 4.0 mm, while the outside layer
preferably has a thickness of 4 to 17 mm, and especially 6 to 15
mm.
[0034] The specific gravity of the outer core is not critical. The
(outer core) layer composed primarily of resin will have a specific
gravity of 0.90 to 1.30, and preferably 0.95 to 1.25, while the
(outer core) layer composed primarily of rubber will have a
specific gravity of 1.00 to 1.30, and preferably 1.05 to 1.25.
[0035] Preferably the solid core has a deflection of 2.2 to 4.3 mm,
more preferably 2.4 to 4.1 mm, and most preferably 2.5 to 4.0 mm
under an applied load of 100 kg. A deflection of less than 2.2 mm
may give the golf ball too hard a feel when hit, whereas a
deflection of more than 4.3 mm may result in a feel that is so soft
as to detract from the performance of the ball.
[0036] Production of the solid core may be carried out using a
known method to vulcanize and cure the rubber composition. For
example, one highly suitable method is a two-step process in which
the rubber composition is first subjected to primary vulcanization
(semi-vulcanization) in a mold to form a pair of hemispherical
cups. A preformed center core is then placed in one of the
hemispherical cups, the other cup is closed over the center core,
and secondary vulcanization (complete vulcanization) is carried
out. That is, formation of the outer core also completes production
of the solid core. Since the above method requires vulcanization to
form the outer core, the center core is exposed to an elevated
temperature. Hence, it is advantageous for the center core to have
a melting point of at least 150.degree. C. When a resin or a
resin-rubber mixture is used in the outer core, it may be injection
molded.
[0037] An adhesive is typically applied to the center core before
it is placed in the hemispherical cup. The adhesive provides a
secure bond at the interface between the center core and the outer
core, thereby enhancing the durability of the golf ball and helping
to achieve a high resilience. To increase adhesion between the
center core and the outer core, it is also advisable to roughen the
surface of the center core in an apparatus such as a tumbler so as
to form minute irregularities thereon before placing it in the
outer core.
[0038] The golf ball of the invention is made by forming a cover 2
around the solid core 1. The cover may be made of a known cover
stock material. Preferably the cover has a thickness of 0.5 to 3.5
mm, and especially 1 to 2.5 mm, and a Shore D hardness of 40 to 75,
more preferably 45 to 70, and most preferably 50 to 65. A hardness
that is too low may result in a poor ball resilience, whereas
excessive hardness may compromise the durability of the ball. It is
recommended that the cover have a specific gravity of 0.95 to 1.25.
As already noted, the cover 2 may be composed of one layer or a
plurality of layers.
[0039] A known cover stock material may be used to form the cover.
Examples include ionomer resins, balata rubber, and thermoplastic
polyurethane, polyamide and polyester elastomers. The cover is
preferably formed by a conventional injection molding process.
[0040] It is recommended that the solid golf ball thus formed have
a deflection of 2.2 to 3.8 mm, and especially 2.4 to 3.5 mm under a
static load of 100 kg.
[0041] As in conventional golf balls, the golf ball of the
invention has numerous dimples formed on the surface of the cover.
The total number of dimples is preferably from 350 to 500, more
preferably from 370 to 480, and most preferably from 390 to 450.
The dimples may be distributed in a geometrical arrangement that is
octahedral or icosahedral, for example. Nor is the dimple pattern
limited to a circular pattern, the use of any other suitable
pattern, such as a square, hexagonal, pentagonal or triangular
pattern, also being acceptable.
[0042] It is recommended to optimize the diameter, depth, and
cross-sectional shape of dimples for improving the distance of the
ball. Dimples may be provided so that the dimple surface coverage,
which is defined as the ratio: (surface area of ball occupied by
dimples)/(total surface area of ball) and expressed as a
percentage, is preferably at least 65%, and more preferably 70% to
80%. A dimple surface coverage of less than 65% will sometimes fail
to achieve an increased carry. The dimple volume ratio, which is
defined as (total volume of dimples)/(volume of ball) and expressed
as a percentage, may be set within a range of preferably 0.76% to
1.0%, and especially 0.78% to 0.94%. A dimple volume ratio less
than 0.76% may result in too high a trajectory and a dimple volume
ratio greater than 1.0% may result in too low a trajectory, the
effect of either being a decrease in the carry of the ball.
[0043] The golf ball of the invention should be formed so as to
have a diameter and weight which conform with the Rules of Golf.
That is, the ball should have a diameter of not less than 42.67 mm
and a weight of not greater than 45.93 g.
[0044] The solid golf ball of the invention, as described herein,
provides an excellent click and feel when hit with a golf club.
EXAMPLE
[0045] Examples of the invention and comparative examples are given
below by way of illustration, and are not intended to limit the
invention.
Examples and Comparative Examples
[0046] In each example, a center core having the characteristics
indicated in Table 1 was produced by injection molding a resin
compound having the composition shown in the table in a mold. In
some of the examples, a resin blend having the composition shown in
the table was injection molded over the center core. In addition, a
rubber composition was intimately mixed in a roll mill, then
subjected to 6 minutes of primary vulcanization
(semi-vulcanization) at 130.degree. C. to form a pair of
hemispherical cups. The pair of cups was either closed over the
resin blend that had been injection molded about the center core or
was closed directly over the center core, following which the outer
core was subjected to 15 minutes of secondary vulcanization
(complete vulcanization) at 155.degree. C. to give a solid core
having a two- or three-layer construction.
[0047] The cover stock material shown in Table 1 was then injection
molded over the solid core in each example to form a cover having a
thickness of 2.1 mm and bearing 392 dimples (dimple surface
coverage, 78%; dimple volume ratio, 0.88%) to give a solid golf
ball having the characteristics shown in the table.
[0048] The properties of the resulting golf balls were measured and
evaluated as described below. The results are presented in Table
1.
Flight Performance
[0049] The golf balls obtained in each example were measured for
carry and total distance when hit with a driver (No. 1 wood) at a
head speed of 40 m/s (HS40) using a swing robot.
Click and Feel
[0050] The click and feel of the golf balls in each example when
hit with a No. 1 wood were rated as follows by three professional
golfers.
[0051] Feel
[0052] Good: All three golfers thought ball had an appropriately
soft, yet solid feel.
[0053] Poor: All three golfers thought ball had too soft a
feel.
[0054] Click
[0055] Good: All three golfers thought click was appropriate.
[0056] Fair: Two of the golfers thought click sounded dull.
[0057] Poor: All three golfers thought click sounded dull.
1TABLE 1 Composition (parts by weight) EX 1 EX 2 EX 3 EX 4 CE 1 CE
2 CE 3 Center core Surlyn AD-8512 (ionomer) -- -- -- 100 -- 100 --
Rilsan BMNO (polyamide) 100 100 100 -- 100 -- -- Hytrel 3548 -- --
-- -- -- -- 100 Barium sulfate 10.0 -- -- 15.0 20.0 -- -- Outer
core 1 Himilan 1557 50 50 -- -- -- 50 -- Surlyn 8120 50 50 -- -- --
50 -- XER91P* -- 10 -- -- -- 10 -- cis-1,4-Polybutadiene -- -- 100
100 100 -- 100 Zinc oxide -- -- 5 5 5 -- 5 Barium sulfate -- --
17.5 20.5 9.0 -- 20.5 Zinc diacrylate -- -- 29.0 22.0 29.0 -- 22.0
Dicumyl peroxide -- -- 1.2 1.2 1.2 -- 1.2 Outer core 2
cis-1,4-Polybutadiene 100 100 -- -- -- 100 -- Zinc oxide 5 5 -- --
-- 5 -- Barium sulfate 21.0 19.5 -- -- -- 30.5 -- Zinc diacrylate
29.0 28.5 -- -- -- 28.5 -- Dicumyl peroxide 1.2 1.2 -- -- -- 1.2 --
Cover Himilan 1605 -- -- -- 50 50 50 50 formulation Himilan 1706 --
-- -- 50 50 50 50 Himilan 1557 50 50 50 -- -- -- -- Himilan 1601 50
50 50 -- -- -- -- Center core Diameter (mm) 18.0 10.0 13.0 5.0 25.0
18.0 10.0 Weight (g) 3.7 0.6 1.3 0.1 10.6 3.0 0.6 Specific gravity
1.22 1.14 1.14 1.08 1.30 0.98 1.15 Surface Shore D 80 80 80 64 81
64 35 hardness Outer core 1 Diameter (mm) 23.0 15.0 38.5 38.5 38.5
23.0 38.5 Weight (g) 7.0 1.8 35.0 35.0 35.0 6.3 35.0 Specific
gravity of 0.98 0.98 1.17 1.17 1.12 0.98 1.17 material Shore D
hardness 50 49 45-53 40-44 45-53 49 40-44 Primary -- -- 130.degree.
C., 130.degree. C., 130.degree. C., -- 130.degree. C.,
vulcanization 6 min 6 min 6 min 6 min conditions Secondary -- --
155.degree. C., 155.degree. C., 155.degree. C., -- 155.degree. C.,
vulcanization 15 min 15 min 15 min 15 min conditions Outer core 2
Diameter (mm) 38.5 38.5 -- -- -- 38.5 -- Weight (g) 35.0 35.0 -- --
-- 35.0 -- Specific gravity of 1.19 1.18 -- -- -- 1.22 -- material
Primary 130.degree. C., 130.degree. C., -- -- -- 130.degree. C., --
vulcanization 6 min 6 min 6 min conditions Secondary 155.degree.
C., 155.degree. C., -- -- -- 155.degree. C., -- vulcanization 15
min 15 min 15 min conditions Deflection of solid core under 100 2.5
2.9 2.7 3.5 2.1 2.5 3.2 kg load (mm) Golf ball Weight (g) 45.3 45.3
45.3 45.3 45.3 45.3 45.3 Diameter (mm) 42.7 42.7 42.7 42.7 42.7
42.7 42.7 Shore D hardness of 58 58 58 64 64 64 64 cover Cover
thickness (mm) 2.1 2.1 2.1 2.1 2.1 2.1 2.1 Performance Carry (m)
195.0 193.5 193.0 192.0 187.0 187.5 193.0 at HS40 Total distance
(m) 211.0 209.0 208.5 210.0 201.0 202.0 209.0 Feel good good good
good good good poor Click good good good good fair good poor
[0058] XER91P is a resin modifier supplied by Japan Synthetic
Rubber Co., Ltd. which is composed of a functional rubbery
copolymer obtained by conferring a crosslinked
acrylonitrile-butadiene rubber with carboxyl functionality.
[0059] Japanese Patent Application No. 11-032603 is incorporated
herein by reference.
[0060] Although some preferred embodiments have been described,
many modifications and variations may be made thereto in light of
the above teachings. It is therefore to be understood that the
invention may be practiced otherwise than as specifically described
without departing from the scope of the appended claims.
* * * * *