U.S. patent application number 12/007856 was filed with the patent office on 2008-07-31 for golf ball.
This patent application is currently assigned to SRI Sports Limited. Invention is credited to Tsutomu Hirau, Kazuhiko Isogawa.
Application Number | 20080182683 12/007856 |
Document ID | / |
Family ID | 39668643 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080182683 |
Kind Code |
A1 |
Hirau; Tsutomu ; et
al. |
July 31, 2008 |
Golf ball
Abstract
The object of the present invention is to provide a golf ball
having excellent luster and durability. The golf ball of the
present invention comprises a golf ball body and a paint film
covering the golf ball body, wherein the golf ball body and the
paint film contains a luster material having a particle size of 5
.mu.m to 100 .mu.m.
Inventors: |
Hirau; Tsutomu; (Kobe-shi,
JP) ; Isogawa; Kazuhiko; (Kobe-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
SRI Sports Limited
|
Family ID: |
39668643 |
Appl. No.: |
12/007856 |
Filed: |
January 16, 2008 |
Current U.S.
Class: |
473/377 |
Current CPC
Class: |
A63B 43/06 20130101;
A63B 37/0033 20130101; A63B 37/0022 20130101; A63B 37/12 20130101;
A63B 37/0003 20130101 |
Class at
Publication: |
473/377 |
International
Class: |
A63B 37/12 20060101
A63B037/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2007 |
JP |
2007-018444(PAT.) |
Claims
1. A golf ball having a golf ball body and a paint film covering
the golf ball body, wherein each of the golf ball body and the
paint film contains a luster material having a particle size of 5
.mu.m to 100 .mu.m.
2. The golf ball according to claim 1, wherein the luster material
comprises mica as a core layer and a light-reflective material
covering a surrounding area of the core layer.
3. The golf ball according to claim 1, wherein the luster material
comprises mica as the core layer and a light-reflective material
consisting of titanium oxide or iron oxide covering a surrounding
area of the core layer.
4. The golf ball according to claim 1, wherein the golf ball body
comprises a cover and the cover contains 0.1 part to 5 parts by
mass of the luster material with respect to 100 parts by mass of
the resin component constituting the cover.
5. The golf ball according to claim 1, wherein the paint film
contains 1 part to 20 parts by mass of the luster material based on
100 parts by mass of the resin component contained in the paint
film.
6. The golf ball according to claim 1, wherein the luster material
has a particle size of 5 .mu.m to 60 .mu.m.
7. The golf ball according to claim 1, wherein the paint film is a
two-component curing type polyurethane resin.
8. The golf ball according to claim 1, wherein the golf ball body
has a cover and the cover contains the luster material, a white
pigment, and a colored pigment other than white.
9. The golf ball according to claim 8, wherein the colored pigment
is a blue pigment or a red pigment.
10. The golf ball according to claim 1, wherein the cover has a
thickness of 0.3 mm to 2.3 mm.
11. A golf ball having a golf ball body consisting of a core and a
cover covering the core and a paint film covering the golf ball
body, wherein each of the cover and the paint film contains a
luster material having a particle size of 5 .mu.m to 100 .mu.m.
12. The golf ball according to claim 11, wherein the luster
material comprises mica as a core layer and a light-reflective
material consisting of titanium oxide or iron oxide covering a
surrounding area of the core layer.
13. The golf ball according to claim 12, wherein the cover contains
0.1 part to 5 parts by mass of the luster material with respect to
100 parts by mass of the resin component constituting the
cover.
14. The golf ball according to claim 13, wherein the paint film
contains 1 part to 20 parts by mass of the luster material based on
100 parts by mass of the resin component contained in the paint
film.
15. The golf ball according to claim 14, wherein the paint film is
a two-component curing type polyurethane resin.
16. The golf ball according to claim 14, wherein the luster
material has a particle size of 5 .mu.m to 60 .mu.m.
17. The golf ball according to claim 14, wherein the golf ball body
has a cover and the cover contains the luster material, a white
pigment, and a colored pigment other than white.
18. The golf ball according to claim 17, wherein the colored
pigment is a blue pigment or a red pigment.
19. The golf ball according to claim 14, wherein the cover has a
thickness of 0.3 mm to 2.3 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to improving an appearance of
a golf ball, more particularly to improving an appearance (luster
and durability of a paint film) of a golf ball.
[0003] 2. Description of the Related Art
[0004] A golf ball is normally colored white, but there has been an
increasing demand for a golf ball with an enhanced quality and an
individualized appearance. In response to such a demand, a golf
ball provided with luster has been proposed.
[0005] For example, Japanese patent publication No. 2004-166719
proposes a golf ball provided with a mark formed on a surface of
the golf ball body and a transparent covering layer covering the
mark, wherein the transparent covering layer comprises a base resin
and a luster material of a glass flake having a surface thereof
covered with a metal oxide, and covers the mark that has a color
tone satisfying L.ltoreq.40 when represented by Lab system. Since
the transparent covering layer covering the mark includes the
luster material, it is possible to provide the golf ball with
luster without lowering durability of the mark and the paint film
itself.
[0006] Japanese patent publication No. 2005-52510 discloses a golf
ball comprising a core and a cover having two or more layers
covering the core, wherein a base material of an outermost layer
cover of the cover is a thermoplastic resin in which 0.2 to 5 parts
by mass of a cholesteric liquid crystal polymer is included based
on 100 parts by mass of the thermoplastic resin, and wherein a base
material of an inner cover adjacent to the outermost layer cover is
a thermoplastic resin in which 1 part by mass or less of titanium
oxide and 1 part by mass or less of a fluorescent pigment are
included respectively based on 100 parts by mass of the
thermoplastic resin.
[0007] Japanese patent publication No. H06-170013 discloses a golf
ball containing a pigment developing color by an interferential
action of reflected lights in a paint layer on a ball surface or a
ball body, the hue of which changes depending on an angle from
which it is viewed.
[0008] Japanese patent publication No. H11-151322 discloses a golf
ball having a pearl color comprising a core and a cover covering
the core, wherein the cover contains 0.02 to 1.5 parts by weight of
a mica pigment, 1.0 to 5.0 parts by weight of titanium oxide and
less than 5 parts by weight of a fluorescent pigment based on 100
parts by weight of the resin.
SUMMARY OF THE INVENTION
[0009] If the luster material is blended only in the cover of the
golf ball, the luster material may not be able to exhibit its
luster sufficiently due to opacity of the cover material.
[0010] If a content of the luster material is increased in order to
allow the luster material to exhibit luster, there arises a problem
of the weld lines becoming conspicuous when the cover is formed.
Additionally, the durability of the golf ball may also be lowered.
On the other hand, when the luster material is blended only in the
paint film of the golf ball, there may be a case where a luster
material clogs a paint line of the paint to generate unevenness of
paint application, resulting in unevenness of appearance.
[0011] The present invention has been achieved in view of the above
circumstances. The object of the present invention is to provide a
golf ball having uniform and excellent luster and excellent
durability.
[0012] The present invention provides a golf ball having a golf
ball body and a paint film covering the golf ball body, wherein
each of the golf ball body and the paint film contains a luster
material having a particle size of 5 .mu.m to 100 .mu.m.
[0013] According to the present invention, since the luster
material is blended in both the paint film and the cover, a golf
ball having a good appearance with luster can be obtained. A
particle size of the luster material is 5 .mu.m to 100 .mu.m, and
when molding the cover, there is no problem of weld line being
conspicuous, and when applying a paint, there occurs no clogging of
a paint line so that unevenness of paint application hardly
occurs.
[0014] The luster material preferably, for example, comprises mica
as a core layer and a light-reflective material covering a
surrounding area of the core layer. More preferably, the luster
material comprises mica as the core layer and the light-reflective
material consisting of a titanium oxide or an iron oxide covering a
surrounding area of the core layer. Additionally, it is also a
preferred embodiment that the golf ball body has a cover and the
cover contains 0.1 part to 5 parts by mass of the luster material
based on 100 parts by mass of the resin component constituting the
cover. Further, it is preferred that the paint film contains 1 part
or more and 20 parts or less of the luster material based on 100
parts of the resin component included in the paint film by
mass.
[0015] The present invention can provide a golf ball having
excellent luster and durability. The golf ball also has good
coating workability, and the paint film to be formed has no
unevenness of paint application and has good durability. According
to the present invention, there is no problem of weld line becoming
conspicuous when molding the cover.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] A golf ball of the present invention comprises a golf ball
body and a paint film covering the golf ball body, wherein each of
the golf ball body and the paint film contains a luster material
having a particle size of 5 .mu.m to 100 .mu.m.
[0017] First, the luster material used in the present invention
will be explained. The present invention contains a luster material
having a particle size of 5 .mu.m to 100 .mu.m (hereinafter simply
referred to as "luster material" occasionally).
[0018] In the present invention, having a particle size of 5 .mu.m
to 100 .mu.m means that the particles of 80% or more of the total
volumes of the particles have a particle size in a range of 5 .mu.m
to 100 .mu.m. In the present invention, preferably used is a luster
material having a particle size of 5 .mu.m to 80 .mu.m, more
preferably a luster material having a particle size of 5 .mu.m to
60 .mu.m.
[0019] If the particle size is outside the above range, when
forming a cover, a weld line becomes conspicuous so that the
appearance of the resultant golf ball will be undermined. In
forming the paint film, clogging of a paint line including a spray
gun and the like becomes more likely to occur, causing unevenness
of paint application.
[0020] The particle size can be measured by, for example, a laser
diffraction method using a mastersizer manufactured by Marvern.
[0021] Examples of the luster material used in the present
invention include a luster material having a core layer covered
with one or more layers of a light-reflective material, such as the
luster material having a core layer consisting of mica, a pearl
flake, a glass flake, a metal or a metal oxide, and a
light-reflective material consisting of a metal, a metal oxide, or
a metal nitride and covering the surrounding area of the core
layer. Examples of the metal of the core layer include at least one
kind selected from the group consisting of aluminum, chromium,
cobalt, gold, silver, nickel, and iron. Examples of the metal oxide
used for the core layer and the light-reflective material include
titanium dioxide, iron oxide and the like.
[0022] Specific examples of the luster material include, for
example, a luster material having a core layer consisting of mica
and a metal oxide consisting of titanium oxide or iron oxide
covering a surrounding area of the core layer ("Iriodin"
manufactured by Merck Ltd.), a luster material having a core layer
consisting of a glass flake and a metal oxide consisting of
titanium dioxide or iron oxide or a metal such as gold, silver, and
nickel covering a surrounding area of the core layer ("Metashine"
manufactured by Nippon Sheet Glass Co., Ltd.), and a luster
material having a core layer consisting of aluminum or an iron
oxide and a metal oxide consisting of silicon dioxide or iron oxide
covering a surrounding area of the core layer ("Variocrom"
manufactured by BASF).
[0023] In the present invention, a photochromic laminated body
formed by laminating polymer layers having different refractive
index, preferably a photochromic laminated body formed by
laminating two kinds of polymer layers having different refractive
indexes alternately may be used as the luster material. The
photochromic laminated body is considered to exhibit the excellent
luster due to the following mechanism. Namely, incident lights
entering into the photochromic laminated body from the outside
reflects at the surface of the laminated body and at the interface
of the multi layer structure, and these reflected lights interfere
with each other. Then, since polymers having different refractive
indexes are laminated, a reflected light having a specific color is
strengthened depending on a film thickness of the polymer layer and
the number of laminated layers and the like, and thus the metallic
luster having a subtly different colors are developed depending on
an angle from which they are viewed. Specific examples of the
photochromic laminated body include, for example, "Morphotone"
manufactured by TEIJIN FIBERS LIMITED.
[0024] The golf ball of the present invention is a golf ball
comprising a golf ball body and a paint film covering the golf ball
body, wherein each of the golf ball body and the paint film
comprises the luster material having a particle size of 5 to 100
.mu.m. Namely, a golf ball having the excellent luster can be
obtained by including the luster material in both of the golf ball
body and the paint film covering the golf ball body.
[0025] Hereinafter, a paint film containing the luster material
will be explained.
[0026] The paint film may be provided in a manner that it covers
the golf ball body. The paint film may be what is called a clear
paint layer containing a resin component and the luster material
without another pigment, or may be what is called an enamel paint
layer containing a resin component, the luster material and another
pigment. It is preferably the clear paint layer.
[0027] The resin component constituting the paint film is not
particularly limited, and an acrylic resin, an epoxy resin, a
polyurethane resin, a polyester-based resin, a cellulose-based
resin and the like may be used, but a two-component curing type
polyurethane resin to be mentioned later is preferably used. If the
two-component curing type polyurethane resin is used, a paint film
which is further excellent in durability can be obtained.
[0028] The two-component curing type polyurethane resin is a
polyurethane resin obtained by reacting a base resin and a curing
agent. Such examples include one obtained by curing a base resin
containing a polyol component with a polyisocyanate compound or a
derivative thereof.
[0029] The base resin containing the polyol component preferably
contains a specific urethane polyol as shown in the following. The
urethane polyol is synthesized by a reaction between a
polyisocyanate and a polyol. The polyisocyanate used for the
synthesis is not particularly limited as long as it has two or more
isocyanate groups. Such examples include an aromatic polyisocyanate
such as 2,4-toluene diisocyanate, 2,6-tolylene diisocyanate, the
mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate
(TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene
diisocyanate (NDI), 3,3'-bitolylene-4,4'-diisocyanate (TODI),
xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate
(TMXDI), and paraphenylene diisocyanate (PPDI); and an alicyclic or
aliphatic polyisocyanate such as 4,4'-dicyclohexylmethane
diisocyanate (H.sub.12MDI), hydrogenated xylylenediisocyanate
(H.sub.6XDI), hexamethylene diisocyanate (HDI), isophorone
diisocyanate (IPDI), norbornene diisocyanate (NBDI). These may be
used either alone or as a mixture of at least two of them. Among
them, in view of weather resistance, a non-yellowing type
polyisocyanate such as TMXDI, XDI, HD.sub.1, H.sub.6XDI, IPD.sub.1,
H.sub.12MDI, and NBDI is preferably used. The polyisocyanate may
also be used as a curing agent for curing the urethane polyol.
[0030] The polyol used for preparing the urethane polyol is not
particularly limited as long as it has a plurality of hydroxyl
groups. Such examples include a polyol having a low-molecular
weight and a polyol having a high molecular weight. Examples of the
polyol having a low-molecular weight include a diol such as
ethylene glycol, diethylene glycol, triethylene glycol,
1,3-butanediol, 1,4-butanediol, neopentyl glycol, and
1,6-hexanediol; and a triol such as glycerin, trimethylol propane,
and hexanetriol. Examples of the polyol having a high molecular
weight include a polyether polyol such as polyoxyethylene glycol
(PEG), polyoxypropylene glycol (PPG), polyoxytetramethylene glycol
(PTMG); a condensed polyester polyol such as polyethylene adipate
(PEA), polybutylene adipate (PBA), and polyhexamethylene adipate
(PHMA); a lactone polyester polyol such as
poly-.epsilon.-caprolactone (PCL); a polycarbonate polyol such as
polyhexamethylene carbonate; an acrylic polyol and the like. Among
the polyols described above, a polyol having a weight average
molecular weight of 50 to 2,000, particularly a polyol having a
weight average molecular weight of about 100 to 1,000 is preferably
used. These polyols may be used either alone or as a mixture of at
least two of them.
[0031] The urethane polyol is a polyol wherein a urethane bond is
formed by a reaction between the polyisocyanate and a polyol,
having a hydroxyl group at a terminal thereof. Herein, a ratio of
the urethane bonds in the urethane polyol is preferably 0.1 mmol to
5 mmol in 1 g of the urethane polyol. A ratio of the urethane bonds
is related to rigidity of the paint film to be formed, and if it is
less than 0.1 mmol/g, urethane concentration of the paint film to
be formed becomes low so that abrasion-resistance may become
insufficient. On the other hand, if it is more than 5 mmol/g, the
paint film becomes too hard, so that flexibility of the film with
the deformation of the golf ball body becomes lowered and more
susceptible to cracking.
[0032] A weight average molecular weight of the urethane polyol is
preferably 4,000 or more, more preferably 4,500 or more, and
preferably less than 10,000, more preferably 9,000 or less. If it
is less than 4,000, it takes a long time to dry, so that
workability and productivity becomes lowered. On the other hand, if
the urethane polyol has a high molecular weight of 10,000 or more,
the hydroxyl value of the urethane polyol becomes relatively small,
so that an amount to be reacted after coating becomes small and
thus adhesion to a base (golf ball body) tends to be lowered.
Additionally, if a weight average molecular weight is 9,000 or
less, a dense paint film (or a clear paint layer) which is less in
lowering of adhesion even in a state of being wet in water can be
formed.
[0033] A hydroxyl group value of the urethane polyol is preferably
15 mgKOH/g or more, particularly preferably 25 mgKOH/g or more, and
preferably 130 mgKOH/g or less, particularly preferably 120 mgKOH/g
or less. If it is less than 15 mgKOH/g, a reaction with the curing
agent becomes insufficient, so that adhesion strength with the ball
body may become difficult to obtain. On the other hand, if it is
more than 130 mgKOH/g, a reaction with the curing agent requires a
long time so that a drying time becomes longer to lower the
productivity and, at the same time, the ball becomes susceptible to
cracking at the time of impact.
[0034] The urethane polyol as described above can be obtained by
reacting a polyol and a polyisocyanate which are to be raw
materials in such a proportion that the hydroxyl groups of the
polyol component is in excess relative to the isocyanate groups of
the polyisocyanate component by molar ratio. In the above described
reaction, a solvent or a catalyst (e.g., dibutyl tin dilaurylate)
publicly known for use in a urethane reaction may be used. A ratio
of the urethane bond may be adjusted by adjusting a molecular
weight of the polyol which is to be a raw material, a blending
ratio of the polyol and the polyisocyanate and the like.
[0035] The polyol component constituting the base resin is
preferably the specific urethane polyol itself; that is,
preferably, the base resin is substantially the specific urethane
polyol, but, apart from the urethane polyol, may include a polyol
which is compatible with the urethane polyol and devoid of the
urethane bond, too. In such a case, the polyol devoid of the
urethane bond is not particularly limited, and the above-mentioned
raw material polyol for syntheizing the urethane polyol may be
used. If the base resin contains a polyol devoid of the urethane
bond, a content of the urethane polyol in the base resin is
preferably 50 mass % or more, more preferably 80 mass % or more. If
the content of the urethane polyol in the base resin is less than
50 mass %, the content of the urethane polyol becomes relatively
small, so that a drying time becomes longer.
[0036] A content of the luster material in the paint film is not
particularly limited, but it is preferably 1 part by mass or more,
more preferably 3 parts by mass or more, even more preferably 5
parts by mass or more and 20 parts by mass or less, more preferably
15 parts by mass or less, even more preferably 13 parts by mass or
less based on 100 parts by mass of the resin component. There is a
tendency that luster becomes insufficient if the content of the
luster material is less than the lower limit, while if it is more
than the upper limit, durability of the paint film becomes
lowered.
[0037] Besides the abovementioned base resin, the paint film may
further contain an additive which is included in a paint for a
conventional golf ball such as an ultraviolet absorber, an
antioxidant, a light stabilizer, a fluorescent brightener, an
antiblocking agent, and a pigment.
[0038] A mark is normally formed on a surface of the golf ball
body. The mark formed on the surface of the golf ball body may be
formed by using an ink composition which is normally used for an
ink composition for marking a golf ball, for example, one
containing a pigment, a solvent, a base resin, other additives and
the like. The base resin for the ink composition for marking is not
particularly limited, and may include a polyester resin, an epoxy
resin, nitrocellulose, an acrylic resin, a vinyl chloride-vinyl
acetate copolymer, a polyurethane resin, and a polyamide resin; the
epoxy resin, the polyester resin, the nitrocellulose and the like
are preferred since they are excellent in adhesion. When the epoxy
resin is used as the base resin, for example, it is preferred to
use a polyisocyanate such as hexamethylene diisocyanate, isophorone
diisocyanate, and tolylene diisocyanate as a curing agent. The
solvent of the ink composition for marking is not particularly
limited, and may include cyclohexanone, acetylacetone,
propyleneglycol monomethylether acetate, methoxymethylbutylacetate,
ethylacetate, and aromatic hydrocarbon, or a mixture solvent of at
least two of them. The other additives may include a delustering
agent, a defoamer and the like, and as a delustering agent,
colloidal silica, a low density polyethylene particle, a medium
density polyethylene particle and the like may be used. As the
defoamer, methyl siloxane and the like may be used.
[0039] The golf ball of the present invention has no limitation on
its structure and includes a one-piece golf ball, a two-piece golf
ball, a three-piece golf ball, a multi-piece golf ball comprising
at least four layers, and a wound-core golf ball. The present
invention can be applied for all types of the golf ball. Luster of
the golf ball can be further enhanced by including the
above-mentioned luster material in a one-piece golf ball body in a
case of one-piece golf ball, and in an outermost layer cover in a
case of a golf ball body having a core and a cover. In a more
preferred embodiment of the present invention, the above mentioned
luster material is included in an outermost layer cover of the golf
ball body having a core and a cover.
[0040] Hereinafter, the cover composition forming the cover will be
explained. However, components included in the cover composition
and the content thereof are same as the components included in the
cover and the content thereof unless explained otherwise.
[0041] The resin component of the cover composition forming the
cover is not particularly limited, and such examples include a
polyurethane resin, an ionomer resin, a polyamide resin, a
polyester resin, or a mixture of these. Particularly, it is a
preferred embodiment that a main component of the resin component
is a polyurethane resin or an ionomer resin, and a content of the
polyurethane resin or the ionomer resin is preferably 50 mass % or
more, more preferably 70 mass % or more, even more preferably 90
mass % or more. Further, it is also a preferred embodiment that the
resin component essentially consists of the polyurethane resin or
the ionomer resin. If the polyurethane resin or the ionomer resin
is employed as the resin component of the cover composition, a
cover having excellent durability can be obtained.
[0042] The polyurethane resin which can be used for the resin
component for the cover composition is not particularly limited as
long as it has a plurality of urethane bonds in a molecule. It is,
for example, a product in which the urethane bonds are formed in
the molecule by reacting a polyisocyanate with a polyol, if
necessary, further reacting with a polyamine and the like. Examples
of the polyurethane resin include a thermoplastic polyurethane
resin, and a thermosetting (two-component curing type) polyurethane
resin.
[0043] In general, the polyurethane resin preferably contains a
polyisocyanate component and a polyol component, and, as necessary,
a polyamine component. The polyisocyanate component is not
particularly limited as long as it has 2 or more isocyanate groups.
Such examples include an aromatic polyisocyanate such as
2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of
2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI),
4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene
diisocyanate (NDI), 3,3'-bitolylene-4,4'-diisocyanate (TODI),
xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate
(TMXDI), paraphenylene diisocyanate (PPDI); and an alicyclic or
aliphatic polyisocyanate such as 4,4'-dicyclohexylmethane
diisocyanate (H.sub.12MDI), hydrogenated xylylenediisocyanate
(H.sub.6XDI), hexamethylene diisocyanate (HDI), isophorone
diisocyanate (IPDI), andnorbornene diisocyanate (NBDI). These may
be used either alone or as a mixture of at least two of them.
[0044] In view of improving the abrasion-resistance, an aromatic
polyisocyanate is preferably used as the polyisocyanate component
of the polyurethane resin. By using the aromatic polyisocyanate,
the mechanical property of the resultant polyurethane resin will be
improved, and thus the cover excellent in the abrasion-resistance
is obtained. In view of improving the weather resistance, a
non-yellowing type polyisocyanate such as TMXDI, XDI, HDI,
H.sub.6XDI, IPDI, H.sub.12MDI, and NBDI is preferably used as the
polyisocyanate component of the polyurethane resin, more preferably
4,4'-dicyclohexylmethane diisocyanate (H.sub.12MDI) is used.
4,4'-dicyclohexylmethane diisocyanate (H.sub.12MDI) has a rigid
structure, so that the mechanical property of the polyurethane
resin is improved and thus a cover which is excellent in the
abrasion-resistance can be obtained.
[0045] The polyol component constituting the polyurethane resin is
not particularly limited as long as it has a plurality of hydroxyl
groups. Such examples include a polyol having a low-molecular
weight, a polyol having a high molecular weight and the like.
Examples of the polyol having a low-molecular weight include a diol
such as ethylene glycol, diethylene glycol, triethylene glycol,
1,3-butanediol, 1,4-butanediol, neopentyl glycol, and
1,6-hexanediol; and a triol such as glycerin, trimethylol propane,
and hexanetriol. Examples of the high molecular weight polyol
include a polyether polyol such as polyoxyethylene glycol (PEG),
polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol
(PTMG); a condensed polyester polyol such as polyethylene adipate
(PEA), polybutylene adipate (PBA), and polyhexamethylene adipate
(PHMA); a lactone polyester polyol such as
poly-.epsilon.-caprolactone (PCL); polycarbonate polyol such as
polyhexamethylene carbonate; and an acrylic polyol. A mixture of at
least two kinds of the polyols described above may also be
used.
[0046] An average molecular weight of the polyol having high
molecular weight is not particularly limited, but it is, for
example, preferably 400 or more, more preferably 1000 or more. If
the average molecular weight of the high molecular weight polyol
becomes too small, the resultant polyurethane becomes hard,
resulting in lowering of shot feeling of the golf ball. An upper
limit of the average molecular weight of the high molecular weight
polyol is not particularly limited, but it is preferably 10000 or
less, more preferably 8000 or less.
[0047] The polyamine constituting the polyurethane as necessary is
not particularly limited as long as it comprises at least two or
more amino groups. Examples of the polyamine include an aliphatic
polyamine such as ethylenediamine, propylenediamine, butylene
diamine, hexamethylenediamine, an alicyclic polyamine such as
piperazine and isophoronediamine, and an aromatic polyamine.
[0048] The aromatic polyamine has no limitation as long as it has
at least two amino groups directly or indirectly bonded to an
aromatic ring. Herein, the "indirectly bonded to the aromatic
ring", for example, means that the amino group is bonded to the
aromatic ring via a lower alkylene bond. Further, the aromatic
polyamine includes, for example, a monocyclic aromatic polyamine
having at least two amino groups bonded to one aromatic ring or a
polycyclic aromatic polyamine having at least two aminophenyl
groups each having at least one amino group bonded to one aromatic
ring.
[0049] Examples of the monocyclic aromatic polyamine include a type
such as phenylenediamine, toluenediamine, diethyltoluenediamine,
and dimethylthiotoluenediamine wherein amino groups are directly
bonded to an aromatic ring; and a type such as xylylenediamine
wherein amino groups are bonded to an aromatic ring via a lower
alkylene group. Further, the polycyclic aromatic polyamine may
include a poly(aminobenzene) having two aminophenyl groups directly
bonded to each other or a compound having at least two aminophenyl
groups bonded via a lower alkylene group or an alkylene oxide
group. Among them, a diaminodiphenylalkane having two aminophenyl
groups bonded to each other via a lower alkylene group is
preferable. Typically preferred are 4,4'-diaminodiphenylmethane and
the derivatives thereof.
[0050] In the present invention, the thermoplastic polyurethane
resin is preferably used, and the thermoplastic polyurethane
elastomer is more preferably used as the resin component of the
cover composition. The thermoplastic polyurethane elastomer used
herein is the polyurethane resin having so-called "rubber
elasticity." The use of the thermoplastic polyurethane elastomer
provides the cover with high resilience. The thermoplastic
polyurethane elastomer is not limited as long as it can be molded
into the cover by injection-molding or compression molding.
Examples of the thermoplastic polyurethane elastomer are
"ELASTOLLAN XNY 90A", "ELASTOLLAN XNY 97A", and "ELASTOLLAN XNY585"
available from BASF Japan.
[0051] In the present invention, it is also a preferred embodiment
to use a thermosetting (two-component curing type) polyurethane
resin as a resin component of the cover composition. The
thermosetting (two-component curing type) polyurethane resin can
generate a great amount of three-dimensional crosslinks, so that a
cover which is excellent in durability can be obtained. Examples of
the thermosetting (two-component curing type) polyurethane resin
may include a type in which the isocyanate group terminated
urethane prepolymer is cured using a curing agent such as
polyamine, polyol and the like, or a type in which a hydroxyl group
or an amino group-terminated urethane prepolymer is cured by a
curing agent such as a polyisocyanate. The polyamine, the polyol,
and the polyisocyanate to be used as the curing agent can be
suitably selected from the above described compounds. Among them,
as a thermosetting (two-component curing type) polyurethane resin,
one obtained by curing the isocyanate group terminated urethane
prepolymer with a polyamine is preferred. In such a case, a molar
ratio of the amino group of the curing agent with respect to the
isocyanate group of the urethane prepolymer (NH.sub.2/NCO) is 0.70
or more, more preferably 0.80 or more, even more preferably 0.85 or
more, 1.20 or less, more preferably 1.05 or less, even more
preferably 1.00 or less. If it is less than 0.70, an amount of the
isocyanate group terminated urethane prepolymer with respect to the
polyamine becomes excessive, so that a production reaction of an
allophanate cross-linkage and a burette cross-linkage becomes more
likely to occur, resulting in insufficient flexibility of the
polyurethane to be obtained as a final product. On the other hand,
if it is more than 1.20, the isocyanate group becomes insufficient,
so that a reaction of the allophanate or a biuret cross-linkage
becomes less likely to occur. As a result, there is a tendency that
the number of three-dimensional crosslinks becomes too small and a
strength of the thermosetting polyurethane resin to be obtained as
a final product becomes lowered.
[0052] In one preferable embodiment, the ionomer resin is used as
the resin component for the cover composition. Examples of the
ionomer resin are one prepared by neutralizing at least a part of
carboxyl groups in a copolymer composed of ethylene and
.alpha.,.beta.-unsaturated carboxylic acid with a metal ion, or one
prepared by neutralizing at least a part of carboxyl groups in a
terpolymer composed of ethylene, .alpha.,.beta.-unsaturated
carboxylic acid and .alpha.,.beta.-unsaturated carboxylic acid
ester with a metal ion. Examples of the .alpha.,.beta.-unsaturated
carboxylic acid are acrylic acid, methacrylic acid, fumaric acid,
maleic acid, and crotonic acid. Among them, acrylic acid and
methacrylic acid are preferable. Examples of the
.alpha.,.beta.-unsaturated carboxylic acid ester are methyl ester,
ethyl ester, propyl ester, n-butyl ester, isobutyl ester and the
like of acrylic acid, methacrylic acid, fumaric acid, maleic acid,
and the like. Especially, the ester of acrylic acid and methacrylic
acid are preferable. Examples of the metal ion for neutralizing at
least a part of the carboxyl groups include alkali metal ions such
as sodium, potassium, and lithium ions; divalent metal ions such as
magnesium, calcium, zinc, barium, and cadmium ions; trivalent metal
ions such as aluminum ion, or other metal ions such as tin, and
zirconium ions. Among them, sodium, zinc, and magnesium ions are
preferably used to improve the resilience and the durability.
[0053] Examples of the ionomer resin include, but not limited to,
HIMILAN 1555, HIMILAN 1557, HIMILAN 1605, HIMILAN 1652, HIMILAN
1702, HIMILAN 1705, HIMILAN 1706, HIMILAN 1707, HIMILAN 1855, and
HIMILAN 1856 available from MITSUI-DUPONT POLYCHEMICAL CO.; SURLYN
8945, SURLYN 9945, and SURLYN 6320 available from DUPONT CO.; and
IOTEK 8000, and IOTEK 7010 available from Exxon Co. These ionomer
resins exemplified above may be used alone, or as a mixture of two
or more.
[0054] It is also a preferred embodiment to use another
thermoplastic elastomer as a resin component of the cover
composition of the present invention in addition to the base resin
such as the thermoplastic polyurethane resin or the ionomer
resin.
[0055] Specific examples of the other thermoplastic elastomers
include a thermoplastic polyamide elastomer having a commercial
name of "PEBAX (e.g. "PEBAX 2533")" available from ARKEMA Inc, a
thermoplastic polyester elastomer having a commercial name of
"HYTREL (e.g. "HYTREL 3548" and "HYTREL 4047")" available from DU
PONT-TORAY Co, a thermoplastic polystyrene elastomer having a
commercial name of "Rabalon" available from Mitsubishi Chemical
Corporation, and the like. Among them, the thermoplastic
polystyrene elastomer is preferred. Examples of the thermoplastic
polystyrene elastomer include a polystyrene-diene type block
copolymer which contains a polystyrene block component as a hard
segment and a diene block component such as polybutadiene,
isoprene, hydrogenated polybutadiene, and hydrogenated polyisoprene
as a soft segment. The polystyrene-diene type block copolymer is
one having a double bond derived from a conjugated diene compound
of a block copolymer or a partially hydrogenated block copolymer.
Examples of the polystyrene-diene type block copolymer include a
block copolymer of SBS (styrene-butadiene-styrene) structure having
a polybutadiene block, or a block copolymer of SIS
(styrene-isoprene-styrene) structure. An amount of the
thermoplastic elastomer to be blended is preferably 1 to 60 parts
by mass, more preferably 1 to 35 parts by mass based on 100 parts
by mass of the base resin.
[0056] When the luster material is blended in the cover, a content
of the luster material in the cover composition is preferably 0.1
part by mass or more, more preferably 0.2 part by mass or more,
even more preferably 0.3 part by mass or more and preferably 5
parts by mass or less, more preferably 3.0 parts by mass or less,
even more preferably 2.0 parts by mass or less based on 100 parts
by mass of the resin component. If the content of the luster
material is more than 5 parts by mass, a weld line appears clearly
after the molding, so that an appearance and durability may be
lowered. If the content of the luster material is less than 0.1
part by mass, sufficient luster cannot be obtained.
[0057] It is also a preferred embodiment to add a pigment, in
addition to the luster material, to the cover, so that a cover
having various colors and the luster can be obtained. The pigment
may be an organic pigment or an inorganic pigment.
[0058] Examples of the pigment include a black pigment such as
carbon black; a white pigment such as titanium oxide; a blue
pigment such as ultramarine blue, cobalt blue, and phthalocyanine
blue; a purple pigment such as anthraquinone violet, dioxane
violet, and methyl violet; a yellow pigment such as titanium yellow
(20TiO.sub.2--NiO-Sb.sub.2O.sub.3), lead oxide (PbO), chrome yellow
(PbCrO.sub.4), yellow iron oxide (FeO(OH)), cadmium yellow, pigment
yellow-1, and pigment yellow-12; and a red pigment such as iron
oxide red (Fe.sub.2O.sub.3), red lead (Pb.sub.3O.sub.4), molybdenum
red, cadmium red, pigment red-3, pigment red-57, pigment orange-13.
These pigments may be used alone or as a mixture of two or more
kinds.
[0059] Specific examples of the pigment include a red pigment such
as ZQ-13 commercially available from DAYGLO, a blue pigment such as
ZQ-19 commercially available from DAYGLO, an orange pigment such as
ZQ-14 commercially available from DAYGLO, a pink pigment such as
ZQ-11 commercially available from DAYGLO, and a green pigment such
as ZQ-18 commercially available from DAYGLO.
[0060] A content of the pigment in the cover composition is
preferably 0.001 part by mass or more, more preferably 0.005 part
by mass or more, even more preferably 0.01 part by mass or more
based on 100 parts by mass of the resin component, and preferably
10 parts by mass or less, more preferably 7 parts by mass or less,
even more preferably 5 parts by mass or less. If the content of the
pigment is more than 10 parts by mass, the durability of the cover
may be lowered. If the content of the pigment is less than 0.001
part by mass, a desired color will not be obtained clearly.
[0061] It is also a preferred embodiment of the present invention
to use a white pigment together with a colored pigment other than
white. In such a case, the content of the colored pigment other
than white in the cover composition is preferably 0.001 part by
mass or more, more preferably 0.005 part by mass or more and 5
parts by mass or less, more preferably 3 parts by mass or less
based on 100 parts by mass of the resin component. If the content
of the pigment is more than 5 parts by mass, the durability of the
cover may become lowered. On the other hand, if the content of the
pigment is less than 0.001 part by mass, a desired color cannot be
obtained clearly.
[0062] A content of the white pigment (preferably titanium oxide)
in the cover composition is 0.005 part by mass or more, more
preferably 0.05 part by mass or more, even more preferably 0.1 part
by mass or more based on 100 parts by mass of the resin component.
If the content of the white pigment (preferably titanium oxide) is
0.005 part by mass or more, a contour of a dimple of the cover
becomes clear. The content of the white pigment (preferably
titanium oxide) in the cover composition is preferably 5 parts by
mass or less, more preferably 4 parts by mass or less, even more
preferably 3 parts by mass or less based on 100 parts by mass of
the resin component. If the content of the white pigment
(preferably titanium oxide) becomes too large, there may be a case
in which opacity becomes too high, so that the luster of the luster
material in the cover is undermined.
[0063] The cover composition of the present invention may further
contain a gravity adjusting agent such as calcium carbonate and
barium sulfate, a dispersant, an antioxidant, an ultraviolet
absorber, a light stabilizer, a fluorescent brightener or the like
to the extent that the performance of the cover is not
undermined.
[0064] A thickness of the cover of the present invention is not
particularly limited, and it is preferably 0.3 mm or more, more
preferably 0.5 mm or more, even more preferably 0.8 mm or more, and
preferably 2.3 mm or less, more preferably 2.0 mm or less, even
more preferably 1.6 mm or less. If it is less than 0.3 mm, molding
of the cover may become difficult. If it is more than 2.3 mm, the
cover becomes too thick and thus the resilience of the resultant
golf ball may become lowered.
[0065] The core for the golf ball of the present invention is
preferably a core (preferably spherical core) molded by
heat-pressing the rubber composition for the core containing a base
rubber, a crosslinking initiator, a co-crosslinking agent, and, as
necessary, a filler.
[0066] As the base rubber, a natural rubber and/or a synthetic
rubber such as a polybutadiene rubber, a natural rubber, a
polyisoprene rubber, a styrene polybutadiene rubber, and
ethylene-propylene-diene terpolymer (EPDM) may be used. Among them,
typically preferred is the high cis-polybutadiene having cis-1,4
bond in a proportion of 40% or more, more preferably 70% or more,
even more preferably 90% or more in view of its superior repulsion
property.
[0067] The crosslinking initiator is blended to crosslink the base
rubber component. As the crosslinking initiator, an organic
peroxide is preferably used. Examples of the organic peroxide for
use in the present invention are dicumyl peroxide,
1,1-bis(t-butylperoxy)-3,5-trimethylcyclohexane,
2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide.
Among them, dicumyl peroxide is preferable. The amount of the
organic peroxide to be blended in the rubber composition is
preferably 0.2 part by mass or more, more preferably 0.3 part by
mass or more, and preferably 3 parts by mass or less, more
preferably 2 parts by mass or less based on 100 parts by mass of
the base rubber. If the content is less than 0.2 part by mass, the
core becomes too soft, and the resilience tends to be lowered, and
if the content is more than 3 parts by mass, the amount of
co-crosslinking agent needs to be increased in order to obtain an
appropriate hardness, so that the resilience tends to be
insufficient.
[0068] The co-crosslinking agent is not particularly limited as
long as it has the effect of crosslinking a rubber molecule with a
base rubber molecular chain by graft polymerization; for example,
.alpha.,.beta.-unsaturated carboxylic acid having 3 to 8 carbon
atoms or a metal salt thereof, more preferably, acrylic acid,
methacrylic acid or a metal salt thereof may be used. As the metal
constituting the metal salt, for example, zinc, magnesium, calcium,
aluminum and sodium may be used, and among them, zinc is preferred
because it provides high resilience. The amount of the
co-crosslinking agent to be used is preferably 10 parts or more,
more preferably 20 parts or more, and preferably 50 parts or less,
more preferably 40 parts or less based on 100 parts of the base
rubber by mass. If the amount of the co-crosslinking agent to be
used is less than 10 parts by mass, the amount of the organic
peroxide must be increased to obtain an appropriate hardness which
tends to lower the resilience. On the other hand, if the amount of
the co-crosslinking agent to be used is more than 50 parts by mass,
the core becomes too hard, so that the shot feeling may be
lowered.
[0069] The filler contained in the rubber composition for the core
is mainly blended as a gravity adjusting agent in order to adjust
the specific gravity of the golf ball obtained as the final product
in the range of 1.0 to 1.5, and may be blended as required.
Examples of the filler include an inorganic filler such as zinc
oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten
powder, and molybdenum powder. The amount of the filler to be
blended in the rubber composition is preferably 2 parts or more,
more preferably 3 parts or more, and preferably 50 parts or less,
more preferably 35 parts or less based on 100 parts of the base
rubber by mass. If the amount of filler to be blended is less than
2 parts by mass, it becomes difficult to adjust the weight, while
if it is more than 50 parts by mass, the weight ratio of the rubber
component becomes small and the resilience tends to be lowered.
[0070] The rubber composition for the core may further include an
organic sulfur compound, an antioxidant, or a peptizing agent as
required in addition to the base rubber, the crosslinking
initiator, the co-crosslinking agent, and the filler.
[0071] As the organic sulfur compound, a diphenyl disulfide or a
derivative thereof may be preferably used. The amount of the
diphenyl disulfide or the derivative thereof to be blended is
preferably 0.1 part or more, more preferably 0.3 part or more, and
preferably 5.0 parts or less, more preferably 3.0 parts or less
based on 100 parts of the base rubber by mass. Examples of the
diphenyl disulfide or the derivative thereof include diphenyl
disulfide, a mono-substituted diphenyl disulfide such as
bis(4-chlorophenyl) disulfide, bis(3-chlorophenyl) disulfide,
bis(4-bromophenyl) disulfide, bis(3-bromophenyl) disulfide,
bis(4-fluorophenyl) disulfide, bis(4-iodophenyl) disulfide and
bis(4-cyanophenyl) disulfide; a di-substituted diphenyl disulfide
such as bis(2,5-dichlorophenyl) disulfide, bis(3,5-dichlorophenyl)
disulfide, bis(2,6-dichlorophenyl) disulfide,
bis(2,5-dibromophenyl) disulfide, bis (3,5-dibromophenyl)
disulfide, bis(2-chloro-5-bromophenyl) disulfide, and
bis(2-cyano-5-bromophenyl) disulfide; tri-substituted diphenyl
disulfide such as bis (2,4,6-trichlorophenyl) disulfide, and bis
(2-cyano-4-chloro-6-bromophenyl) disulfide; a tetra-substituted
diphenyl disulfide such as bis (2,3,5,6-tetra chlorophenyl)
disulfide; a penta-substituted diphenyl disulfide such as
bis(2,3,4,5,6-pentachlorophenyl) disulfide and bis(2,3,4,5,6-penta
bromophenyl) disulfide. These diphenyl disulfide or the derivatives
thereof can enhance resilience by having some influence on the
state of vulcanization of vulcanized rubber. Among them, diphenyl
disulfide and bis(penta bromophenyl) disulfide are preferably used
since the golf ball having particularly high resilience can be
obtained.
[0072] An amount of the antioxidant to be blended is preferably 0.1
part by mass or more and 1 part by mass or less based on 100 parts
by mass of the base rubber. An amount of the peptizing agent is
preferably 0.1 part by mass or more and 5 parts by mass or less
based on 100 parts by mass of the base rubber.
[0073] The conditions for press-molding the rubber composition
should be determined depending on the rubber composition. The
press-molding is preferably carried out for 10 to 60 minutes at the
temperature of 130 to 200.degree. C. Alternatively, the
press-molding is preferably carried out in a two-step heating, for
example, for 20 to 40 minutes at the temperature of 130 to
150.degree. C., and continuously for 5 to 15 minutes at the
temperature of 160 to 180.degree. C.
[0074] If the golf ball of the present invention is a three-piece
golf ball or a multi-piece golf ball, the core consists of a center
made from the above-mentioned rubber composition for the core and
at least one intermediate layer covering the center. Examples of
the intermediate layer include a thermoplastic resin such as a
polyurethane resin, an ionomer resin, nylon, and polyethylene; and
a thermoplastic elastomer such as a polystyrene-based elastomer, a
polyolefin-based elastomer, a polyurethane-based elastomer, a
polyester-based elastomer and the like. Among them, the ionomer
resin is preferable.
[0075] The intermediate layer may further contain a gravity
adjusting agent such as tungsten, and barium sulfate, an
antioxidant, a pigment and the like, in addition to the resin
component.
[0076] When preparing a wound-core golf ball in the present
invention, a wound core may be used as the core. In that case, for
example, a wound core comprising a center formed by curing the
above rubber composition for the core and a rubber thread layer
which is formed by winding a rubber thread around the center in an
elongated state can be used. In the present invention, the rubber
thread, which is conventionally used for winding around the center,
can be adopted for winding around the center. The rubber thread,
for example, is obtained by vulcanizing a rubber composition
including a natural rubber, or a mixture of a natural rubber and a
synthetic polyisoprene, a sulfur, a vulcanization auxiliary agent,
a vulcanization accelerator, and an antioxidant. The rubber thread
is wound around the center in elongation of about 10 times length
to form the wound core.
EXAMPLES
[0077] The following examples illustrate the present invention;
however, these examples are intended to illustrate the invention
and are not to be construed to limit the scope of the present
invention. Many variations and modifications of such examples will
exist without departing from the scope of the inventions. Such
variations and modifications are intended to be within the scope of
the invention.
[Evaluation]
(1) Evaluation of Weld Line
[0078] Thirty golfers visually examined the golf ball bodies formed
with the paint films to evaluate the appearance of the weld line
based on the following evaluation standards.
None: Weld lines are inconspicuous and appearance was good.
Present: Weld lines are clearly discernible, and appearance is
unfavorable.
(2) Luster
[0079] Thirty golfers visually examined the golf balls formed with
a paint film to evaluate the luster based on following evaluation
standards.
E(Excellent): There is a marked pearl luster quality, and
appearance is very beautiful. G(Good): There is a pearl luster
quality, and appearance is beautiful. F(Fair): There is a poor
pearl luster quality, and appearance is not very good. P(Poor):
There is essentially no pearl luster quality, and appearance is
poor.
(3) Coating Workability and Unevenness of Paint Application
[0080] A spray gun (SA-100 manufactured by Fuji Toryo) was
connected to a paint line having a strainer provided with a metal
mesh of 120 .mu.m in a middle thereof to evaluate workability when
applying the paint and unevenness of the formed paint film based on
following evaluation standards.
Coating Workability
[0081] G(Good): There is no clogging of the strainer and the spray
gun on the paint line. P(Poor): Clogging of the strainer and the
spray gun on the paint line is occasionally found, resulting in
unstable state of application.
Unevenness of the Paint Film
[0082] G(Good): There is no unevenness of the paint film, and
appearance of the golf ball is good. P(Poor): Unevenness of the
paint film was found at some portions, resulting in poor appearance
of the golf ball.
(4) Durability of the Golf Ball
[0083] Each golf ball was repeatedly hit with a metal head driver
(W#1) attached to a swing robot manufactured by TRUETEMPER CO, at
the head speed of 45 m/sec. to make the golf ball collide with a
collision board. Times up to which the golf balls are cracked were
measured. In addition, each value obtained was reduced to an index
number relative to the measured value obtained in Golf ball No. 11
being assumed 100. The larger number indicates better
durability.
(5) Durability of the Paint Film of Golf Ball
[0084] Each golf ball was repeatedly hit 50 times with a metal head
driver (#W1) attached to a swing robot manufactured by TRUETEMPER
CO, at the head speed of 45 m/sec. to evaluate appearance of the
golf ball after being hit based on following evaluation
standards.
G(Good): No crack is present on a surface of the golf ball.
F(Fair): Cracks are found at some portions of the surface of the
golf ball, but the paint film is not peeled off. P(Poor): Cracks
are found on the surface of the golf ball, and the paint film is
peeled off.
[Preparation of Golf Ball Body]
(1) Preparation of Core
[0085] The rubber composition shown in Table 1 was kneaded and
pressed with upper and lower molds each having a spherical cavity
at the heating condition of 160.degree. C. for 20 minutes to obtain
the core in a spherical shape having a diameter of 38.5 mm.
TABLE-US-00001 TABLE 1 Rubber composition for the core Part by mass
Polybutadiene rubber 100 Zinc oxide 20 Zinc acrylate 22.0 Barium
sulfate Appropriate amount*.sup.) Dicumyl peroxide 1 Formulation:
parts by mass Barium sulfate: prepared such that a mass of the golf
ball becomes 45.5 g Notes on Table 1 Polybutadiene rubber: BR730
manufactured by JSR Corporation Zinc acrylate: ZNDA-90S
manufactured by NIHON JYORYU KOGYO Co., LTD. Zinc oxide: "Ginrei R"
manufactured by Toho-Zinc Co. Barium sulfate: Barium sulfate BD
manufactured by Sakai Chemical Industry Co., Ltd. Dicumyl peroxide:
Percumyl D manufactured by NOF Corporation
(2) Preparation of Cover Composition
[0086] The materials shown in Table 2 were mixed using a twin-screw
kneading extruder to obtain the cover composition in the form of
pellet. The extrusion was conducted in the following conditions:
screw diameter=45 mm, screw revolutions=200 rpm, screw L/D=35, and
the cover composition was heated to from 160.degree. C. to
230.degree. C. at the die position of the extruder.
(3) Preparation of the Golf Ball Body
[0087] The cover composition thus prepared was directly
injection-molded onto the core to form the cover covering the core,
thereby obtaining the two-piece golf ball having a diameter of 42.
7 mm. The upper and lower molds for forming the cover have a
spherical cavity with dimples. The part of the dimples can serve as
a hold pin which is retractable. When forming the golf ball body,
the hold pins were protruded to hold the core, and the resin heated
at 210.degree. C. was charged into the mold held under the pressure
of 80 tons for 0.3 seconds. After the cooling for 30 seconds, the
molds were opened and then the golf ball was discharged.
TABLE-US-00002 TABLE 2 Golf ball No. 1 2 3 4 5 6 7 8 9 10 Cover
layer Himilan 1605 50 50 50 50 50 50 50 50 50 50 Himilan 1706 50 50
50 50 50 50 50 50 50 50 Pigment: white pigment (titanium dioxide)
-- -- -- -- -- -- 2 -- -- -- Pigment: blue pigment ZQ-19 0.02 0.02
0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 Iriodin 201 (particle size
of 5 to 25 .mu.m) 0.5 0.1 0.5 0.5 0.5 0.05 0.5 -- -- -- Iriodin 215
(particle size of 10 to 60 .mu.m) -- -- -- -- -- -- -- 0.5 -- --
Iriodin 351 (particle size of 5 to 100 .mu.m) -- -- -- -- -- -- --
-- 0.5 -- Iriodin 355 (particle size of 10 to 100 .mu.m) -- -- --
-- -- -- -- -- -- 0.5 Iriodin 163 (particle size of 20 to 180
.mu.m) -- -- -- -- -- -- -- -- -- -- Iriodin 249 (particle size of
10 to 125 .mu.m) -- -- -- -- -- -- -- -- -- -- Iriodin 183
(particle size of 45 to 500 .mu.m) -- -- -- -- -- -- -- -- -- --
Paint film layer Two-component curing type polyurethane 100 100 100
100 100 100 100 100 100 100 resin Iriodin 201 (particle size of 5
to 25 .mu.m) 10 10 1 20 22 10 1 10 10 10 Iriodin 215 (particle size
of 10 to 60 .mu.m) -- -- -- -- -- -- -- -- -- -- Iriodin 351
(particle size of 5 to 100 .mu.m) -- -- -- -- -- -- -- -- -- --
Iriodin 355 (particle size of 10 to 100 .mu.m) -- -- -- -- -- -- --
-- -- -- Iriodin 163 (particle size of 20 to 180 .mu.m) -- -- -- --
-- -- -- -- -- -- Iriodin 249 (particle size of 10 to 125 .mu.m) --
-- -- -- -- -- -- -- -- -- Iriodin 183 (particle size of 45 to 500
.mu.m) -- -- -- -- -- -- -- -- -- -- Evaluation Luster E E G E E G
G E E E Weld line None None None None None None None None None None
Coating workability G G G G G G G G G G Unevenness of paint film G
G G G P G G G G G Durability of paint film G G G G F G G G G G
Durability of golf ball 100 101 100 100 100 102 100 101 101 100
Golf ball No. 11 12 13 14 15 16 17 18 Cover layer Himilan 1605 50
50 50 50 50 50 50 50 Himilan 1706 50 50 50 50 50 50 50 50 Pigment:
white pigment (titanium dioxide) -- -- 0.2 -- -- -- -- -- Pigment:
blue pigment ZQ-19 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 Iriodin
201 (particle size of 5 to 25 .mu.m) 0.5 -- 0.5 0.5 -- -- -- 0.5
Iriodin 215 (particle size of 10 to 60 .mu.m) -- -- -- -- -- -- --
-- Iriodin 351 (particle size of 5 to 100 .mu.m) -- -- -- -- -- --
-- -- Iriodin 355 (particle size of 10 to 100 .mu.m) -- -- -- -- --
-- -- -- Iriodin 163 (particle size of 20 to 180 .mu.m) -- -- -- --
-- 0.5 -- -- Iriodin 249 (particle size of 10 to 125 .mu.m) -- --
-- -- -- -- 0.5 -- Iriodin 183 (particle size of 45 to 500 .mu.m)
-- 0.5 -- -- -- -- -- -- Paint film layer Two-component curing type
polyurethane 100 100 100 100 100 100 100 100 resin Iriodin 201
(particle size of 5 to 25 .mu.m) -- 10 10 -- 10 10 10 -- Iriodin
215 (particle size of 10 to 60 .mu.m) -- -- -- -- -- -- -- --
Iriodin 351 (particle size of 5 to 100 .mu.m) -- -- -- -- -- -- --
-- Iriodin 355 (particle size of 10 to 100 .mu.m) -- -- -- -- -- --
-- -- Iriodin 163 (particle size of 20 to 180 .mu.m) -- -- -- -- --
-- -- -- Iriodin 249 (particle size of 10 to 125 .mu.m) -- -- -- --
-- -- -- 10 Iriodin 183 (particle size of 45 to 500 .mu.m) 10 -- --
-- -- -- -- -- Evaluation Luster E G E F F G G G Weld line None
Present None Present None Present Present None Coating workability
P G G G G G G G Unevenness of paint film P G G G G G G P Durability
of paint film P G G G G G G F Durability of golf ball 100 97 100
100 100 98 100 100 Formulation: parts by mass
Notes on Table 2
[0088] Himilan 1605: a sodium ion-neutralized ethylene-methacrylic
acid copolymer-based ionomer resin manufactured by MITSUI-DUPONT
POLYCHEMICAL Himilan 1706: a zinc ion-neutralized
ethylene-methacrylic acid copolymer ionomer resin manufactured by
MITSUI-DUPONT POLYCHEMICAL Iriodin 201: a pearl pigment
manufactured by MERCK (a luster material comprising mica as a core
layer and titanium oxide covering a surrounding area of the core
layer; a particle size of 5 .mu.m to 25 .mu.m) Iriodin 215: a pearl
pigment manufactured by MERCK (a luster material comprising mica as
a core layer and titanium oxide covering a surrounding area of the
core layer; a particle size of 10 .mu.m to 60 .mu.m) Iriodin 351: a
pearl pigment manufactured by MERCK (a luster material comprising
mica as a core layer and titanium oxide covering a surrounding area
of the core layer; a particle size of 5 .mu.m to 100 .mu.m) Iriodin
355: a pearl pigment manufactured by MERCK (a luster material
comprising mica as a core layer and titanium oxide covering a
surrounding area of the core layer; a particle size of 10 .mu.m to
100 .mu.m) Iriodin 163: a pearl pigment manufactured by MERCK (a
luster material comprising mica as a core layer and titanium oxide
covering a surrounding area of the core layer; a particle size of
20 .mu.m to 180 .mu.m) Iriodin 249: a pearl pigment manufactured by
MERCK (a luster material comprising mica as a core layer and
titanium oxide covering a surrounding area of the core layer; a
particle size of 10 .mu.m to 125 .mu.m) Iriodin 183: a pearl
pigment manufactured by MERCK (a luster material comprising mica as
a core layer and titanium oxide covering a surrounding area of the
core layer; a particle size of 45 .mu.m to 500 .mu.m) Titanium
dioxide: a titanium oxide A-220 manufactured by ISHIHARA SANGYO
KAISHA, LTD. ZQ-19: a blue pigment manufactured by DAYGLO
[Formation of the Paint Film]
[0089] A mark was pad-printed on a surface of the golf ball body
and subsequently, the composition for forming paint film shown in
Table 2 was applied thereto to cover the golf ball body, followed
by drying in an oven at 40.degree. C. for 4 hours, thereby
preparing a golf ball. The composition for forming a paint film was
prepared in a following manner.
[Preparation of the Composition for Forming the Paint Film]
[0090] 1) Base resin: urethane polyol
[0091] Into 120 parts by mass of a solvent (toluene and methylethyl
ketone), 60 parts by mass of PTMG250 (polyoxytetramethylene glycol
having a molecular weight of 250 manufactured by BASF) and 54 parts
by mass of 550 U (branched polyol having a molecular weight of 550
manufactured by Sumika Bayer Urethane Co., Ltd.) were dissolved,
and then dibutyl tin dilaurylate was added to the mixture in a
ratio of 0.1 mass % relative to a total base resin. While the
polyol was maintained at 80.degree. C., 66 parts by mass of
isophorone diisocyanate was dropped thereto, thereby preparing a
urethane polyol (having a solid content of 60 mass %, a hydroxyl
group value of 75 mgKOH/g, and a weight average molecular weight of
7808).
2) Curing agent: isophorone diisocyanate (manufactured by Sumika
Bayer Urethane Co., Ltd.) 3) Blending ratio: NCO of curing agent/OH
of base resin=1.2 (molar ratio) 4) A luster material was added to
100 parts by mass of the two-component curing type urethane resin
component as shown in Table 2, thereby preparing a composition for
forming a paint film.
[0092] Table 2 shows the results of evaluation of luster, presence
of weld line, coating workability, unevenness of paint film, and
durability of the resultant golf balls.
[0093] Golf ball Nos. 1 to 4, Nos. 6 to No. 10, and No. 13 are golf
balls having a golf ball body and a paint film covering the golf
ball body, wherein the golf ball body and the paint film contains a
luster material having a particle size of 5 .mu.m to 100 .mu.m. In
any case, a golf ball having luster and good appearance and
durability without a conspicuous weld line was obtained. Coating
workability was also good and there was no unevenness of the paint
film.
[0094] Golf ball No. 5 is a case in which the paint film contains
more than 20 parts by mass of the luster material based on 100
parts by mass of the resin component constituting the paint film,
in which there was a tendency that unevenness of the paint film was
formed. Golf ball No. 6 is a case in which the cover contains less
than 0.1 part by mass of the luster material based on 100 parts by
mass of the resin component constituting the cover, in which there
was a tendency that the luster was lowered compared with Golf ball
No. 2.
[0095] Golf balls No. 11 and No. 18 are cases in which the paint
film contains a luster material having a particle size of 45 .mu.m
to 500 .mu.m and 10 .mu.m to 125 .mu.m respectively, where
unevenness of the paint film occurred. Golf ball No. 12 is a case
in which the cover contains a luster material having a particle
size of 45 .mu.m to 500 .mu.m, where weld lines were conspicuous
and appearance was poor. Golf ball No. 14 is a case where only the
cover contained the luster material, while Golf ball No. 15 is a
case where only the paint film contained the luster material. In
both cases, the luster was insufficient. Golf ball Nos. 16 and No.
17 are cases in which the cover contained a luster material having
a particle size which is outside the range of 5 .mu.m to 100 .mu.m,
where weld lines were conspicuous and appearance was poor.
[0096] The present invention provides a golf ball having luster and
durability.
[0097] This application is based on Japanese Patent application No.
2, 007-18,444 filed on Jan. 29, 2007, the contents of which are
hereby incorporated by reference.
* * * * *