U.S. patent application number 16/442639 was filed with the patent office on 2020-01-02 for golf ball.
This patent application is currently assigned to Bridgestone Sports Co., Ltd.. The applicant listed for this patent is Bridgestone Sports Co., Ltd.. Invention is credited to Kae Iizuka, Atsushi Namba, Hirotaka Shinohara.
Application Number | 20200001138 16/442639 |
Document ID | / |
Family ID | 69007506 |
Filed Date | 2020-01-02 |
United States Patent
Application |
20200001138 |
Kind Code |
A1 |
Shinohara; Hirotaka ; et
al. |
January 2, 2020 |
GOLF BALL
Abstract
In a golf ball having a core of at least one layer and a paint
film of at least one layer, at least one layer of the paint film
includes delustering particles and the same or a differing layer of
the paint film includes an effect pigment. The ball is a matte golf
ball that is free of luster and gloss and moreover has a quality
look.
Inventors: |
Shinohara; Hirotaka;
(Chichibushi, JP) ; Iizuka; Kae; (Chichibushi,
JP) ; Namba; Atsushi; (Chichibushi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bridgestone Sports Co., Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Bridgestone Sports Co.,
Ltd.
Tokyo
JP
|
Family ID: |
69007506 |
Appl. No.: |
16/442639 |
Filed: |
June 17, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A63B 37/0077 20130101;
A63B 1/00 20130101; A63B 37/0074 20130101; A63B 37/0022
20130101 |
International
Class: |
A63B 37/00 20060101
A63B037/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 29, 2018 |
JP |
2018-124393 |
Claims
1. A golf ball comprising a core of at least one layer and a paint
film of at least one layer, wherein at least one layer of the paint
film includes delustering particles and the same or a differing
layer of the paint film includes an effect pigment.
2. The golf ball of claim 1, wherein the paint film includes the
effect pigment in the same layer as the layer which includes the
delustering particles.
3. The golf ball of claim 1, wherein the paint film has a two-layer
construction consisting of a white paint film layer and a topcoat
layer formed directly on the white paint film layer, which topcoat
layer includes the delustering particles and the effect
pigment.
4. The golf ball of claim 1, further comprising, as a constituent
member, a white cover layer, wherein the paint film is a single
layer formed directly on the white cover layer and includes the
delustering particles and the effect pigment.
5. The golf ball of claim 1, wherein the paint film has a two-layer
construction consisting of an inner layer and an outer layer, the
inner layer including the effect pigment and the outer layer
including the delustering particles.
6. The golf ball of claim 1, wherein the delustering particles (a)
and the effect pigment (b) included in the paint film have a weight
ratio therebetween, expressed as (a)/(b), which is from 0.3 to
5.0.
7. The golf ball of claim 1, wherein the effect pigment is glass
flakes or mica.
8. The golf ball of claim 1, wherein the paint film has a
reflectance of 2.5 or less, as measured with a glossmeter at an
incident angle of 20.degree..
9. The golf ball of claim 1, wherein the paint film has a
reflectance of 6.0 or less, as measured with a glossmeter at an
incident angle of 60.degree..
10. The golf ball of claim 1, wherein the paint film has a
reflectance of 15.0 or less, as measured with a glossmeter at an
incident angle of 85.degree..
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This non-provisional application claims priority under 35
U.S.C. .sctn. 119(a) on Patent Application No. 2018-124393 filed in
Japan on Jun. 29, 2018, the entire contents of which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a golf ball having a core
of at least one layer and a paint film layer (also referred to as a
"coating layer"). More specifically, the invention relates to a
golf ball that has a matte, gloss-free appearance with a quality
feel.
BACKGROUND ART
[0003] A number of golf balls possessing a distinctive appearance
with a quality feel have been described in the art. One example,
disclosed in JP-A 2016-214326, is a golf ball having a paint film
layer in which an effect pigment for enhancing the appearance
qualities is included within a resin material. However, although
golf balls with such a paint film layer have a quality feel, a
serious drawback is that they are highly light-scattering and
irritate the eyes during putting on the green, which interferes
with concentration.
[0004] In addition, so-called matte golf balls which have an
appearance that is colored but are delustered or free of gloss to
such a degree that dimple contours on the surface of the ball
cannot be discerned have been popular recently. Such matte golf
balls are colored golf balls which have a novel coloration and,
although the dimples are not clearly visible, the balls reportedly
have a psychological effect that increases the player's
concentration on the ball when hitting the ball on shots with a
driver and on approach shots, thereby increasing the golf
competitiveness.
[0005] However, although such matte golf balls do have a
psychological effect, they leave something to be desired in terms
of quality feel.
SUMMARY OF THE INVENTION
[0006] It is therefore an object of the present invention to
provide a golf ball which has a quality feel, yet also has a
psychological effect in that it increases the player's
concentration and thus enhances his or her competitiveness.
[0007] As a result of extensive investigations, we have discovered
that, in a golf ball having a core of at least one layer and a
paint film of at least one layer, by including delustering
particles in at least one paint film layer and by including an
effect pigment in the same or a differing layer of the paint film,
the player's concentration on the ball at the time of ball impact
can be increased and the ball can be given a distinctive appearance
with a quality feel.
[0008] Accordingly, the present invention provides a golf ball
having a core of at least one layer and a paint film of at least
one layer, wherein at least one layer of the paint film includes
delustering particles and the same or a differing layer of the
paint film includes an effect pigment.
[0009] In a preferred embodiment of the golf ball of the invention,
the paint film preferably includes the effect pigment in the same
layer as the layer which includes the delustering particles.
[0010] In another preferred embodiment, the paint film has a
two-layer construction consisting of a white paint film layer and a
topcoat layer formed directly on the white paint film layer, which
topcoat layer includes the delustering materials and the effect
pigment.
[0011] In yet another preferred embodiment, the golf ball
additionally has, as a constituent member, a white cover layer, and
the paint film is a single layer formed directly on the white cover
layer and includes the delustering particles and the effect
pigment.
[0012] In still another preferred embodiment of the inventive golf
ball, the paint film has a two-layer construction consisting of an
inner layer and an outer layer, the inner layer including the
effect pigment and the outer layer including the delustering
particles.
[0013] In another preferred embodiment, the delustering particles
(a) and the effect pigment (b) included in the paint film have a
weight ratio therebetween, expressed as (a)/(b), which is from 0.3
to 5.0.
[0014] In a further preferred embodiment, the effect pigment is
glass flakes or mica.
[0015] In a still further preferred embodiment, the paint film has
a reflectance of 2.5 or less, as measured with a glossmeter at an
angle of incidence of 20.degree..
[0016] In a yet further preferred embodiment, the paint film has a
reflectance of 6.0 or less, as measured with a glossmeter at an
angle of incidence of 60.degree..
[0017] In an additional preferred embodiment, the paint film has a
reflectance of 15.0 or less, as measured with a glossmeter at an
angle of incidence of 85.degree..
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0018] The golf ball of the invention, because it is provided with
a matte finish, helps prevent reduced competitiveness due to
diminished player concentration and has a distinctive appearance
with a quality feel.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The objects, features and advantages of the invention will
become more apparent from the following detailed description.
[0020] The golf ball of the invention has a core of at least one
layer and a paint film of at least one layer.
[0021] The core may be formed using a known rubber material as the
base material. Known base rubbers, such as natural rubber or
synthetic rubber, may be used as the base rubber. More
specifically, the use of polybutadiene, especially
cis-1,4-polybutadiene having a cis structure content of at least
40%, is recommended. If desired, natural rubber, polyisoprene
rubber, styrene-butadiene rubber and the like may be used together
with the foregoing polybutadiene in the base rubber. The
polybutadiene may be synthesized with, for example, a
titanium-based, cobalt-based, nickel-based or neodymium-based
Ziegler-type catalyst or with a cobalt, nickel or other metal
catalyst.
[0022] Co-crosslinking agents such as unsaturated carboxylic acids
and metal salts thereof, inorganic fillers such as zinc oxide,
barium sulfate and calcium carbonate, and organic peroxides such as
dicumyl peroxide and 1,1-bis(t-butylperoxy)cyclohexane may be
included in the base rubber. If necessary, commercial antioxidants
and the like may also be suitably added.
[0023] A cover of at least one layer may be formed over the core as
a core-encasing member. In the case of a two-layer cover, the inner
layer is called the intermediate layer and the outer layer is
called the outermost layer. In the case of a three-layer cover, the
respective layers are called, in order from the inner side: the
envelope layer, the intermediate layer and the outermost layer.
[0024] The materials making up the cover layers are exemplified by,
without particular limitation, resins that have hitherto been used
as golf ball materials, such as ionomeric resins, polyester resins,
polyurethane resins, polyamide resins, polyolefin resins,
olefin-based thermoplastic elastomers and styrene-based
thermoplastic elastomers. Ionomeric resins are especially suitable
and preferably include, for example, either of (a) and (b) below:
(a) an ethylene-.alpha.,.beta.-unsaturated carboxylic acid
copolymer and/or a metal salt thereof, (b) an
ethylene-.alpha.,.beta.-unsaturated carboxylic
acid-.alpha.,.beta.-unsaturated carboxylic acid ester copolymer
and/or a metal salt thereof.
[0025] Specific examples of the .alpha.,.beta.-unsaturated
carboxylic acid in components (a) and (b) include acrylic acid,
methacrylic acid, maleic acid and fumaric acid. Acrylic acid and
methacrylic acid are especially preferred. The
.alpha.,.beta.-unsaturated carboxylic acid ester in component (b)
is preferably a lower alkyl ester of the above unsaturated
carboxylic acid, specific examples of which include methyl
methacrylate, ethyl methacrylate, propyl methacrylate, butyl
methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate and
butyl acrylate. Butyl acrylate (butyl n-acrylate, butyl i-acrylate)
is especially preferred.
[0026] Metal ion neutralization products of the copolymers in
components (a) and (b) can be obtained by partially neutralizing
acid groups on the olefin-unsaturated carboxylic acid copolymer or
the olefin-unsaturated carboxylic acid-unsaturated carboxylic acid
ester copolymer with metal ions. Illustrative examples of metal
ions which neutralize the acid groups include Na.sup.+, K.sup.+,
Li.sup.+, Zn.sup.++, Cu.sup.++, Mg.sup.++, Ca.sup.++, Co.sup.++,
Ni.sup.++ and Pb.sup.++. Preferred use can be made of Na.sup.+,
Li.sup.+, Zn.sup.++, Mg.sup.-+ and Ca.sup.-+ in particular. Such
neutralization products may be obtained by a known method. For
example, a neutralization product may be obtained by using, for
reaction with the above copolymer, a compound such as a formate,
acetate, nitrate, carbonate, bicarbonate, oxide, hydroxide or
alkoxide of the above metal ion.
[0027] Known substances may be used as components (a) and (b).
Illustrative examples include commercial products such as the
following acid copolymers: Nucrel.RTM. N1560, Nucrel.RTM. N1214,
Nucrel.RTM. N1035, Nucrel.RTM. AN4221C, Nucrel.RTM. AN4311,
Nucrel.RTM. AN4318 and Nucrel.RTM. AN4319 (all products of
DuPont-Mitsui Polychemicals Co., Ltd.). Illustrative examples of
metal ion neutralization products of acid copolymers include
Himilan.RTM. 1554, Himilan.RTM. 1557, Himilan.RTM. 1601,
Himilan.RTM. 1605, Himilan.RTM. 1706, Himilan.RTM. AM7311,
Himilan.RTM. 1855, Himilan.RTM. 1856 and Himilan.RTM. AM7316 (all
products of DuPont-Mitsui Polychemicals Co., Ltd.), and Surlyn.RTM.
7930, Surlyn.RTM. 6320, Surlyn.RTM. 8320, Surlyn.RTM. 9320 and
Surlyn.RTM. 8120 (E.I. DuPont de Nemours and Company).
[0028] The resin material for the outermost layer of the cover may
include a colorant comprising a fluorescent dye or fluorescent
pigment and a white pigment such as titanium oxide. That is, in
order to finish the ball to a colored ball whose surface is free of
luster and soft-toned, a colorant comprising a fluorescent dye or
fluorescent pigment may be included in the outermost layer-forming
resin material. Color is imparted to the outermost layer of the
cover by suitably including a known fluorescent dye or fluorescent
pigment as the colorant. Examples include solvent yellow, solvent
orange, anthraquinone and phthalocyanine (all of which are dyes),
and also yellow fluorescent pigments, pink fluorescent pigments and
orange fluorescent pigments. Known commercial products may be used
as these colorants.
[0029] In cases where such a colorant is used, it is preferable to
employ a fluorescent colorant that is light harvesting.
Light-harvesting fluorescent colorants are materials which have the
ability to collect sunlight and convert the wavelength to the
long-wavelength side as fluorescent light. These materials are
characterized in that they collect light by totally reflecting it
at the interior of the colored material and guiding it to the
dimple edges, where the light is emitted in a concentrated state
and intensely colored.
[0030] Such light-harvesting fluorescent colorants include systems
that generate orange, pink, red, yellow, blue or violet colors.
Commercial products may be used in any of these chromogenic
systems. Examples of light-harvesting fluorescent dyes that may be
used include those available from BASF under the trade names
Lumogen F Yellow 083, Lumogen F Orange 240, Lumogen F Red 305 and
Lumogen F Blue 650, and those available from Kashinomoto
Technologies Co., Ltd. under the trade names Lumicolor Red, Smart
Color LP Green, Smart Color LP Yellow and Smart Color LP
Orange.
[0031] The amount of the above colorant included per 100 parts by
weight of the outermost layer-forming resin material is from 0.001
to 0.2 part by weight, and preferably from 0.005 to 0.1 part by
weight. When this amount is low, the fluorescence may weaken and
the desired decorativeness may not be obtained. On the other hand,
when this amount is high, migration of the colorants, especially
dyes, may arise, staining objects that come into contact with the
golf ball.
[0032] When a white pigment is used, illustrative examples of such
pigments include titanium oxide, zinc oxide and barium sulfate.
From the standpoint of hiding power and corrosion resistance, the
use of titanium oxide is preferred. In this invention, as
subsequently discussed, an effect pigment is included in the paint
film (coating layer). However, when the cover outermost layer
underlying the paint film (coating layer) has a color other than
white, the coexistence of that color with the color of the effect
pigment makes it difficult to achieve the desired color at the
ball's surface. Also, depending on the amount of delusterant such
as silica that is included, the paint film may become milky white.
Here too, when the color of the substrate underlying the paint film
is a color other than white, achieving the desired color at the
ball surface is difficult. Accordingly, the cover outermost layer
underlying the paint film (coating layer) is preferably white in
color.
[0033] Also, when a white pigment is used, the amount included per
100 parts by weight of the resin material in the outermost layer is
from 1.0 to 10.0 parts by weight, and preferably from 2.0 to 5.0
parts by weight. When this amount is low, the desired white color
may not be obtained. On the other hand, when this amount is high,
the durability of the layer containing the white pigment may
decrease.
[0034] An inorganic filler or organic filler may be included in the
outermost layer-forming resin material. When an inorganic filler is
used, examples of such materials include, without particular
limitation, calcium carbonate and silica.
[0035] When an organic filler is used, examples of such materials
include, without particular limitation, fine particles of
crosslinked polymethyl methacrylate (crosslinked PMMA), crosslinked
polybutyl methacrylate, crosslinked polyacrylate ester, crosslinked
acrylic-styrene copolymer, melamine resin or polyurethane.
[0036] The amount of the inorganic filler or organic filler added
per 100 parts by weight of the above resin material is from 0.01 to
1.0 part by weight, and preferably from 0.02 to 0.2 part by weight.
When too much is added, the hiding properties may become excessive,
detracting from a ball design having a quality feel, or the change
in color when color fading occurs due to sunlight exposure may
increase.
[0037] In addition, various additives may be optionally included in
the resin composition. For example, pigments, dispersants,
antioxidants, light stabilizers, ultraviolet absorbers and
lubricants may be suitably added.
[0038] The resin composition can be obtained by mixing together the
above ingredients using, for example, any of various types of
mixers, such as a kneading-type single-screw or twin-screw
extruder, a Banbury mixer or a kneader.
[0039] Numerous dimples of one, two or more types may be formed on
the surface of the outermost layer. The shapes, diameters, depths,
number, surface occupancy and other characteristics of the dimples
may be suitably selected.
[0040] The golf ball of the invention has a paint film (coating
layer) which is formed using a paint composition containing
delustering particles.
[0041] The paint composition is not particularly limited, although
it is preferable to use a urethane-based paint. Because the paint
film must be capable of enduring the harsh conditions of golf ball
use, a two-part curable urethane paint, especially a non-yellowing
urethane paint, is preferred.
[0042] In the case of a two-part curable urethane paint, various
polyols such as saturated polyester polyols, acrylic polyols or
polycarbonate polyols may be used as the base resin, and
non-yellowing polyisocyanates such as adducts, biurets or
isocyanurates of hexamethylene diisocyanate, isophorone
diisocyanate or hydrogenated xylylene diisocyanate, or mixtures
thereof, may be used as the isocyanate.
[0043] Exemplary delustering particles include silica particles,
melamine particles and acrylic particles. Specific examples include
silica, polymethyl methacrylate, polybutyl methacrylate,
polystyrene and polybutyl acrylate. The delustering particles may
be organic particles or inorganic particles, with the use of silica
particles being especially preferred.
[0044] From the standpoint of light-quenching properties and
coating properties, the delustering particles have a specific
surface area, expressed as the BET specific surface area, of
preferably from 200 to 400 m.sup.2/g.
[0045] Also, from the standpoint of the spin performance of the
ball and the light-quenching properties, the delustering particles
have an average primary particle size of preferably from 1.0 to 3.0
.mu.m. When this value exceeds 3.0 .mu.m, the ball surface becomes
rough, which has an adverse effect on the spin performance and may
even lower the performance. On the other hand, when this value is
too small, the light-quenching effect may diminish.
[0046] The content of such delustering particles per 100 parts by
weight of the base resin (combined amount of resin ingredients and
solvent) in the paint composition may be set to preferably from 5
to 10 parts by weight. When this content is too high, the viscosity
of the paint composition rises and the painting operation tends to
become more difficult to carry out. When it is too low, the
light-quenching effect may diminish.
[0047] The effect pigment is included in the same layer of the
paint film as that containing the delustering particles or is
included in a different layer of the paint film. It is especially
preferable for the effect pigment to be included in the same layer
as that containing the delustering particles.
[0048] Various types of effect pigments may be used, although
preferred effect pigments include, for example, metal powder
pigments, glass flakes, mica and pearlescent pigments. Specific
examples of metal powder pigments that can be used include aluminum
powder, bronze powder, stainless steel powder and nickel powder. Of
these, aluminum powder is preferred because, when used together
with a color pigment or dye, the color tone is easily adjusted.
Examples of such aluminum pigments that may be used include the
commercial products available under the trade names "Aluminum Paste
Highprint TD200T" and "Metasheen Slurry KM100" (both manufactured
by Toyo Aluminum K.K.). Pearlescent pigments are broadly divided
into metal oxide-coated mica, basic lead carbonate, bismuth
oxychloride and natural pearl essence. Of these, the selection of a
metal oxide-coated mica is preferred because such pigments are
nontoxic and have the best chemical stability. In general, titanium
dioxide and iron oxide are commonly used as the metal oxide; by
varying the coverage (thickness of the metal oxide coating),
various colors and interference effects can be achieved. The larger
the particle size of these pigments, the greater the degree of
luster that can be achieved. However, at a larger pigment particle
size, the luster has a tendency to subside. Hence, it is necessary
to select a pigment having a suitable particle size within a range
that does not detract from the advantageous effects of the
invention.
[0049] The content of effect pigment per 100 parts by weight of the
base resin (combined amount of resin ingredients and solvent) in
the paint composition for the paint film may be set to preferably
from 1.0 to 10.0 parts by weight. When this content is too high,
during spray painting, for example, the paint propelling ability of
the spray gun decreases, which may make the painting operation more
difficult to carry out. When this content is too low, it may not be
possible to obtain the quality ball appearance that is desired.
[0050] The delustering particles (a) and effect pigment (b)
included in the paint film have a weight ratio therebetween,
expressed as (a)/(b), which, to achieve a good balance between the
ball surface luster-suppressing effect and a quality feel, is
preferably from 0.3 to 5.0, and more preferably from 1.0 to 2.5. At
a weight ratio below this range, it may not be possible to suppress
the luster of the golf ball surface; at a weight ratio above this
range, a quality feel may not be achieved.
[0051] Specific paint film configurations include embodiments in
which the paint film consists of a single layer, in which case the
effect pigment is included in the same layer as that which includes
the delustering particles; and embodiments in which the paint film
consists of two layers, in which case the effect pigment is
included in the inner layer and the delustering particles are
included in the outer layer.
[0052] The layer structure of the paint film may be a two-layer
structure consisting of a white paint film layer and a topcoat
layer formed directly on the white paint film layer. In this case,
the delustering particles and the effect pigment may both be
included in the topcoat layer.
[0053] When the paint film is a single layer, the golf ball in a
preferred embodiment includes, as a constituent member, a white
cover layer, and a single-layer or multilayer paint film is formed
directly on the white cover layer. Depending on the content of
delusterant such as silica, the paint film may become milky white.
When the color of the substrate underlying the paint film is a
color other than white, it may be difficult to achieve the desired
color at the ball surface. Hence, it is preferable for the
outermost layer of the cover serving as the underlying substrate of
the paint film to be white.
[0054] The paint film (coating layer) has a reflectance, as
measured with a glossmeter, which is 2.5 or less at an angle of
incidence of 20.degree., 6.0 or less at an angle of incidence of
60.degree., and 15.0 or less at an angle of incidence of
85.degree.. With a coating layer optimized so that these
reflectances satisfy the indicated ranges, a delustering effect can
be imparted. The conditions for measuring the reflectance with a
glossmeter involve measurement with the instrument used in the
subsequently described examples on an ABS resin plate to which the
coating layer has been applied to a thickness of 20 .mu.m.
[0055] Ball specifications such as the ball weight and diameter may
be suitably set in accordance with the Rules of Golf.
EXAMPLES
[0056] The following Working Examples and Comparative Examples are
provided to illustrate the invention, and are not intended to limit
the scope thereof.
Working Examples 1 to 5, Comparative Examples 1 to 3
[0057] As shown in Table 1 below, the solid core in each Example
was produced by using the following rubber composition, which is
common to all the Examples, and vulcanizing for 15 minutes at
155.degree. C.
TABLE-US-00001 TABLE 1 Common to all Rubber composition for core
Working and (parts by weight) Comparative Examples Polybutadiene
rubber 100 Organic peroxide 1 Barium sulfate 16 Zinc oxide 4 Zinc
acrylate 30 Zinc salt of pentachlorothiophenol 0.3
[0058] Details on the above core materials are given below. [0059]
Polybutadiene: Available under the trade name "BRO1" from JSR
Corporation [0060] Organic peroxide: Dicumyl peroxide, available as
"Percumyl D" from NOF Corporation [0061] Barium sulfate: Available
from Sakai Chemical Co., Ltd. [0062] Zinc oxide: Available from
Sakai Chemical Co., Ltd. [0063] Zinc acrylate: Available from
Nippon Shokubai Co., Ltd. [0064] Zinc salt of
pentachlorothiophenol: Available from Wako Pure Chemical
Industries, Ltd.
Formation of Cover (Intermediate Layer and Outermost Layer)
[0065] Next, an intermediate layer-encased sphere having a diameter
of 40 mm was produced by injection molding the intermediate
layer-forming resin material shown in Table 2 below, which is
common to all the Examples, to a thickness of 1.35 mm over the 37.3
mm diameter core obtained as described above. A three-piece golf
ball having a ball diameter of 42.7 mm was then manufactured by
injection-molding the outermost layer-forming material shown in the
same table to a thickness of 1.35 mm over the intermediate
layer-encased sphere. A common dimple configuration was formed at
this time on the surface of the outermost layer in each Working
Example and Comparative Example.
TABLE-US-00002 TABLE 2 Common to all Working and Resin material
(parts by weight) Comparative Examples Cover Intermediate layer HPF
1000 100 Outermost layer Himilan 1601 50 Himilan 1557 50 Magnesium
stearate 1 Titanium oxide 2.8
[0066] Details on the materials in the table are given below.
[0067] HPF 1000: An ionomeric resin material available from E.I.
DuPont de Nemours and Company [0068] Himilan 1605, Himilan 1557:
Ionomeric resins from DuPont-Mitsui Polychemicals Co., Ltd. [0069]
Titanium oxide: A white pigment
[0070] Next, in each Working Example and Comparative Example, using
the two-part curable urethane paint made of a base resin and a
curing agent shown in Table 3 below, the surface of the outermost
layer of the golf ball was coated to a thickness of 15 .mu.m,
thereby forming a single-layer paint film (coating layer).
TABLE-US-00003 TABLE 3 Common to all Working and Resin composition
of paint (pbw) Comparative Examples Base resin Saturated polyester
polyol 27.5 (m.w., 28,000) Solvent 72.5 (Combined amount of resin
(100) ingredients and solvent) Delustering particles Amounts shown
in Table 4 (silica) for respective Examples Effect pigment Curing
agent HMDI isocyanurate 42.0 (low-molecular weight) Solvent
58.0
[0071] Details on the base resin and curing agent are given in (i)
to (iv) below. [0072] (i) First, a reactor equipped with a reflux
condenser, a dropping funnel, a gas inlet and a thermometer was
charged with 140 parts by weight of trimethylolpropane, 95 parts by
weight of ethylene glycol, 157 parts by weight of adipic acid and
58 parts by weight of 1,4-cyclohexanedimethanol, following which
the temperature was raised to between 200 and 240.degree. C. under
stirring and the reaction was effected by 5 hours of heating. This
yielded a saturated polyester polyol having an acid value of 4, a
hydroxyl value of 170 and a weight-average molecular weight (Mw) of
28,000. [0073] (ii) Next, the polyester polyol synthesized above
was dissolved in butyl acetate, thereby preparing a varnish having
a nonvolatiles content of 70 wt %. [0074] (iii) The base resin was
prepared by dissolving 27.5 parts by weight of the saturated
polyester polyol with the butyl acetate (the nonvolatiles content
of this solution was 27.5 wt %), and mixing in silica ("Finesil
X-35" available from Maruo Calcium Co., Ltd.; average primary
particle size, 2.4 .mu.m; BET specific surface area, 262 m.sup.2/g)
as the delustering particles and natural mica (Iriodin 7205, from
Sano Paint Co., Ltd.) as the effect pigment. [0075] (iv) Next, the
isocyanate shown in Table 3 was dissolved in an organic solvent and
used as the curing agent. That is, HDI isocyanurate (available as
Duranate.TM. TPA-100 from Asahi Kasei Corporation; NCO content,
23.1 wt %; nonvolatiles content, 100 wt %) and, as organic
solvents, ethyl acetate and butyl acetate were added in the
proportions shown in Table 3, thereby preparing a resin composition
for use as a paint.
[0076] The glossiness and quality feel of the golf balls thus
obtained in each Working Example and Comparative Example were
measured and evaluated. The results are shown in Table 4 below.
Glossiness
[0077] The glossiness of the paint film (coating layer) at the golf
ball surface was evaluated as follows. The degrees of gloss at
incident angles of 20.degree./60.degree./85.degree. were measured
with the BYK Micro-TRI-Gloss Meter. When the numerical values for
degree of gloss at the respective measurement angles were 2.5 or
less at an incident angle of 20.degree., 6.0 or less at an incident
angle of 60.degree. and 15.0 or less at an incident angle of
85.degree., the glossiness was sufficiently suppressed and thus
rated as excellent ("Exc"). When the degree of gloss was from 2.6
to 5.0 at an incident angle of 20.degree., from 6.1 to 20.0 at an
incident angle of 60.degree. and from 15.1 to 40.0 at an incident
angle of 85.degree., the glossiness was somewhat suppressed and
thus rated as "Good." Otherwise, the glossiness was rated as
"NG."
Quality Feel
[0078] The quality feel was visually assessed by 30 golfers and
rated according to the following criteria.
[0079] Exc: At least 25 out of 30 golfers thought the ball had a
quality feel.
[0080] Good: From 15 to 24 out of 30 golfers thought the ball had a
quality feel.
[0081] Fair: From 6 to 14 out of 30 golfers thought the ball had a
quality feel.
[0082] NG: Five or fewer out of 30 golfers thought the ball had a
quality feel.
TABLE-US-00004 TABLE 4 Comparative Working Example Example 1 2 3 4
5 1 2 3 Coating Formulation Base Saturated polyester 27.5 27.5 27.5
27.5 27.5 27.5 28.0 27.5 layer (pbw) resin polyol (m.w., 28,000)
Solvent 72.5 72.5 72.5 72.5 72.5 72.5 72.0 72.5 Combined amount 100
100 100 100 100 100 100 100 (resin ingredients + solvent)
Delustering particles (a) 9.0 6.0 15.0 2.0 9.0 9.0 Effect pigment
(b) 6.0 6.0 6.0 9.0 2.0 6.0 (a)/(b) 1.5 1.0 2.5 0.2 4.5 -- -- --
Curing HMD isocyanurate 42.0 42.0 42.0 42.0 42.0 42.0 42.0 42.0
agent (low-molecular-weight) Glossiness Solvent 58.0 58.0 58.0 58.0
58.0 58.0 58.0 58.0 Glossmeter incident 1.9 2.1 1.5 3.5 1.3 1.2
60.0 80.6 angle, 20.degree. Glossmeter incident 3.7 5.8 3.0 12.3
2.5 2.1 80.0 96.9 angle, 60.degree. Glossmeter incident 9.8 12.2
6.8 35.0 4.8 3.2 95.0 98.0 angle, 85.degree. Rating Exc Exc Exc
Good Exc Exc NG NG Ball appearance: quality feel Exc Exc Exc Exc
Good NG NG Exc
[0083] The results in Table 4 show that the golf balls obtained in
Working Examples 1 to 5 according to the invention were matte golf
balls in which the paint film had substantially no luster, which
balls had a quality feel.
[0084] By contrast, the golf ball in Comparative Example 1 was a
golf ball that had a matte look but lacked a quality feel.
[0085] The golf ball in Comparative Example 2 had an appearance
that lacked both a matte look and a quality feel.
[0086] The golf ball in Comparative Example 3 had a quality feel
but a matte appearance.
[0087] Japanese Patent Application No. 2018-124393 is incorporated
herein by reference.
[0088] 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.
* * * * *