U.S. patent application number 16/720955 was filed with the patent office on 2020-06-25 for foam composition, foam member and method of manufacture.
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 Katsunobu MOCHIZUKI.
Application Number | 20200199321 16/720955 |
Document ID | / |
Family ID | 71098276 |
Filed Date | 2020-06-25 |
United States Patent
Application |
20200199321 |
Kind Code |
A1 |
MOCHIZUKI; Katsunobu |
June 25, 2020 |
FOAM COMPOSITION, FOAM MEMBER AND METHOD OF MANUFACTURE
Abstract
A foam composition that includes a polymer material such as
polyurethane or polyurea and a leachable water-soluble fine powder
is provided. This composition can he used in a relatively simple
process to obtain a foam body (porous body) that is uniform only at
the surface or uniform throughout. The foam body can be suitably
used as a golf ball member in golf balls required to have good
controllability on approach shots. Also provided is a method for
producing a foam member, which method includes the steps of to
molding the foam composition to obtain a solid molded body, and
then leaching out and removing the water-soluble fine powder so as
to obtain a foam-molded body.
Inventors: |
MOCHIZUKI; Katsunobu;
(Chichibushi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bridgestone Sports Co., Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Bridgestone Sports Co.,
Ltd.
Tokyo
JP
|
Family ID: |
71098276 |
Appl. No.: |
16/720955 |
Filed: |
December 19, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J 2201/0422 20130101;
C08J 2375/04 20130101; C08J 2201/0446 20130101; C08J 2201/0444
20130101; C08J 2375/08 20130101; A63B 37/0094 20130101; C08J
2207/00 20130101; C08J 9/26 20130101; A63B 37/0024 20130101 |
International
Class: |
C08J 9/26 20060101
C08J009/26; A63B 37/00 20060101 A63B037/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2018 |
JP |
2018-239788 |
Claims
1. A foam composition comprising a polymer material and a leachable
water-soluble fine powder.
2. The foam composition of 1, wherein the polymer material is
polyurethane or polyurea.
3. The foam composition of claim 1, wherein the water-soluble fine
powder has an average particle size of from 1 to 800 .mu.m.
4. The foam composition of claim 1, wherein the water-soluble fine
powder has a melting point of at least 100.degree. C.
5. The foam composition of claim 1, wherein the water-soluble fine
powder is at least one selected from the group consisting of sodium
chloride, calcium chloride, potassium chloride, magnesium chloride,
sodium sulfate, potassium sulfate, magnesium sulfate, sodium
nitrate, calcium nitrate, potassium nitrate, sodium tetraborate,
potassium tetraborate, calcium tetraborate, soluble starch,
monosaccharides, disaccharides, trisaccharides, oligosaccharides,
polysaccharides, and hydrates thereof.
6. The foam composition of claim 1, wherein the content of the
water-soluble fine powder is from 1 to 600 parts by weight per 100
parts by weight of the polymer material.
7. The foam composition of claim 1, wherein the water-soluble
powder has a solubility in water of at least 1 g per 100 g of water
at 20.degree. C.
8. The foam composition of claim 1 which, when molded, yields a
foam-molded body having a specific gravity of from 0,2 to 1.2.
9. The foam composition of claim 1 which, when molded, yields a
foam-molded body having a rebound resilience, as measured in
accordance with JIS-K 6255, of from 9 to 62%.
10. A method for producing a foam member, which method comprises
the steps of, in order: molding the foam composition of claim 1 so
as to obtain a solid molded body; and leaching out and removing the
water-soluble fine powder, thereby giving a foam-molded body.
11. A foam member that can be used as an encasing member formed at
a surface or periphery of a core material, which foam member is a
foam-molded body obtained by the method of claim 10.
12. The foam member of claim 11 which is a golf ball cover.
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. 2018-239788 filed in
Japan on Dec. 21, 2018, the entire contents of which are hereby
incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a foam composition, a foam
member and a method of manufacture thereof. More particularly, the
invention relates to a foam composition, a foam member obtained
from the foam composition that can be suitably used as a golf ball
member such as the intermediate layer or cover of a golf ball, and
a method for manufacturing the foam member.
BACKGROUND ART
[0003] Golf balls are required to have, among other
characteristics, a good flight and stopping performance and a good
scuff resistance. That is, golf balls have been developed so as to
fly well on shots with a driver and also be receptive to backspin
on approach shots. To this end, many cover materials with a high
resilience and a good scuff resistance have been developed as golf
ball members. However, when the resilience and scuff resistance of
a golf ball member such as the cover are increased, the ball ends
up flying too far on approach shots and lacks delicate
controllability. Methods such as that of lowering the molecular
weight of the cover material have been studied as ways of lowering
the rebound resilience of golf ball members such as the cover.
However, when the molecular weight is lowered, the scuff resistance
and moldability of the cover material tend to worsen. Accordingly,
there exists a desire among professional golfers and skilled
amateurs for a golf ball which, in addition to having a cover or
other golf ball member of high resilience and good scuff
resistance, also is endowed with a better controllability on
approach shots.
[0004] Art in which the cover member used in a golf ball is a foam
body (porous body) has hitherto been described in a number of
patent publications, including JP-A 2005-46299 (corresponding to US
2004/266559 A1) and JP-A H01-212577 (corresponding to U.S. Pat. No.
4,274,637 A). However, in such art, a blowing agent such as an
organic blowing agent or sodium hydrogen carbonate (sodium
bicarbonate) is included in the cover-forming material. Molding
methods involving the use of such a chemical blowing agent require
close control of the temperature, pressure and equipment systems
during molding. Also, obtaining a foam body that is uniform
throughout the interior of the cover or other golf ball member is
very difficult. In addition, in most foamed molding processes, a
skin layer to forms at the surface of the member, making it
necessary to, for example, abrade the surface of the foamed golf
ball cover in order to remove the skin layer and expose the foam
face at the ball surface. In golf balls produced by such a process,
the cover surface often is not a uniform foam body, making it
difficult to supply, in golf balls for which close control of the
diameter, weight and the like is required, a stable golf ball
product.
SUMMARY OF THE INVENTION
[0005] It is therefore an object of the present invention to
provide a foam composition from which a foam body (porous body)
that is uniform only at the surface or uniform throughout can be
obtained by a relatively simple method without the use of a blowing
agent. Another object of the invention is to provide a golf ball
member that is made using such a foam composition.
[0006] As a result of extensive investigations. I have discovered
that, in order to obtain a foam body (porous body) which is uniform
only at the surface or uniform throughout without the use of a
blowing agent, by including a leachable water-soluble fine powder
within the polymer material serving as the base material of the
golf ball member and by molding the foam composition and
subsequently leaching out and removing this water-soluble fine
powder, an open-cell or closed-cell porous body is obtained in
which the particulate shape of the water-soluble fine powder
becomes the pores. Moreover, I have found that this method is
relatively simple and industrially advantageous.
[0007] Accordingly, in a first aspect, the invention provides a
foam composition which includes a polymer material and a leachable
water-soluble fine powder.
[0008] In a preferred embodiment of the foam composition according
to the first aspect of the invention, the polymer material is
polyurethane or polyurea.
[0009] In another preferred embodiment of the foam composition, the
water-soluble fine powder has an average particle size of from 1 to
800 .mu.m.
[0010] In yet another preferred embodiment, the water-soluble fine
powder has a melting point of at least 100.degree. C.
[0011] In still another preferred embodiment, the water-soluble
fine powder is at least one selected from the group consisting of
sodium chloride, calcium chloride, potassium chloride, magnesium
chloride, sodium sulfate, potassium sulfate, magnesium sulfate,
sodium nitrate, calcium nitrate, potassium nitrate, sodium
tetraborate, potassium tetraborate, calcium tetraborate, soluble
starch, monosaccharides, disaccharides, trisaccharides,
oligosaccharides, polysaccharides, and hydrates thereof.
[0012] In a further preferred embodiment, the content of the
water-soluble fine powder is from 1 to 600 parts by weight per 100
parts by weight of the polymer material. In a still further
preferred embodiment, the water-soluble powder has a solubility in
water of at least 1 g per 100 g of water at 20.degree. C.
[0013] In a yet further preferred embodiment, the foam composition,
when molded, yields a foam-molded body having a specific gravity of
from 0.2 to 1.2.
[0014] In still another preferred embodiment, the foam composition,
when molded, yields a foam-molded body having a rebound resilience,
as measured in accordance with JIS-K 6255, of from 9 to 62%.
[0015] In a second aspect, the invention provides a method for
producing a foam member, which method includes the steps of:
molding the foam composition according to the first aspect of the
invention so as to obtain a solid molded body; and then leaching
out and removing the water-soluble fine powder, thereby giving a
foam-molded body.
[0016] In a third aspect, the invention provides a foam member that
can be used as an encasing member formed at a surface or periphery
of a core material, which foam member is a foam-molded body
obtained by the method according to the second aspect of the
invention.
[0017] In a preferred embodiment of the third aspect of the
invention, the foam member is a golf ball cover.
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0018] With the foam composition of the invention, it is possible
to obtain a foam body (porous body) that is uniform only at the
surface or uniform throughout by a relatively simple process
without using a blowing agent. The foam body can be suitably used
in particular as a golf ball member for obtaining a golf ball which
has a good controllability on approach shots.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The objects, features and advantages of the invention will
become more apparent to from the following detailed
description.
[0020] The foam composition of the invention includes a polymer
material and a leachable water-soluble fine powder.
[0021] In the present invention, the polymer material is not
particularly limited. However, the polymer material required for
satisfying the desired properties in the target product having a
foam body (foam member) that is molded using a foam composition can
be suitably selected from among known thermoplastic resins,
thermoplastic elastomers, thermoset resins and thermoset
elastomers.
[0022] For example, in cases where the foam body is to be used as a
golf ball member, the polymer material that serves as the base
material may be, for example, a rubber material or a thermoplastic
or thermoset polyurethane elastomer, polyester elastomer, ionomeric
resin, polyolefin elastomer or polyurea. These may be used singly
or two or more may be used in admixture. In those cases in
particular where the foam body is to be used as an encasing member
such as a golf ball cover, preferred use can be made of
polyurethane or polyurea.
[0023] The rubber material can be obtained by vulcanizing a rubber
composition containing a base rubber as the chief component. This
rubber material is formed using a rubber composition containing,
for example, a base rubber, a co-crosslinking agent, a crosslink
initiator, a metal oxide and an antioxidant. It is preferable to
use polybutadiene as the base rubber of the rubber composition.
[0024] The polyurethane and polyurea are described in detail
below.
Polyurethane
[0025] The polyurethane has a structure which includes soft
segments composed of a polymeric polyol (polymeric glycol) that is
a long-chain polyol, and hard segments composed of a chain extender
and a polyisocyanate. Here, the polymeric polyol serving as a
starting material may be any that has hitherto been used in the art
relating to polyurethane materials, and is not particularly
limited. This is exemplified by polyester polyols, polyether
polyols, polycarbonate polyols, polyester polycarbonate polyols,
polyolefin polyols, conjugated diene polymer-based polyols, castor
oil-based polyols, silicone-based polyols and vinyl polymer-based
polyols. Specific examples of polyester polyols that may to be used
include adipate-type polyols such as polyethylene adipate glycol,
polypropylene adipate glycol, polybutadiene adipate glycol and
polyhexa methylene adipate glycol; and lactone-type polyols such as
polycaprolactone polyol. Examples of polyether polyols include
poly(ethylene glycol), polypropylene glycol), poly(tetramethylene
glycol) and poly(methyltetramethylene glycol). Such long-chain
polyols may be used singly, or two or more may be used in
combination.
[0026] The long-chain polyol preferably has a number-average
molecular weight in the range of 1,000 to 5,000. By using a
long-chain polyol having a number-average molecular weight in this
range, golf balls made with a polyurethane composition that have
excellent properties, including a good rebound and a good
productivity can be reliably obtained. The number-average molecular
weight of the long-chain polyol is more preferably in the range of
1,500 to 4,000, and even more preferably in the range of 1,700 to
3,500.
[0027] Here and below, "number-average molecular weight" refers to
the number-average molecular weight calculated based on the
hydroxyl value measured in accordance with JIS-K 1557.
[0028] The chain extender is not particularly limited; any chain
extender that has hitherto been employed in the art relating to
polyurethanes may be suitably used in this invention,
low-molecular-weight compounds with a molecular weight of 2,000 or
less which have on the molecule two or more active hydrogen atoms
capable of reacting with isocyanate groups may be used. Of these,
preferred use can be made of aliphatic diols having from 2 to 12
carbon atoms. Specific examples include 1,4-butylene glycol,
1,2-ethylene glycol, 1,3-hutanediol, 1,6-hexanediol and
2,2-dimethyl-1, 3-propanediol. Of these, the use of 1,4-butylene
glycol is especially preferred.
[0029] Any polyisocyanate hitherto employed in the art relating to
polyurethanes may he suitably used without particular limitation as
the polyisocyanate. For example, use can he made of one or more
selected from the group consisting of 4,4'-diphenylmethane
diisocyanate:, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,
p-phenylene diisocyanate, xylylene diisocyanate, 1,5-naphthylene
diisocyanate, tetramethylxylene diisocyanate, hydrogenated xylylene
diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene
diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate,
norhomene diisocyanate, trimethylhexamethylene diisocyanate,
1,4-bis(isocyanatomethyl)cyclohexane and dimer acid diisocyanate.
However, depending on the type of isocyanate, crosslinking to
reactions during injection molding may be difficult to control.
[0030] The ratio of active hydrogen atoms to isocyanate groups in
the polyurethane-forming reaction may be suitably adjusted within a
preferred range. Specifically, in preparing a polyurethane by
reacting the above long-chain polyol, polyisocyanate and chain
extender, it is preferable to use the respective components in
proportions such that the amount of isocyanate groups included in
the polyisocyanate per mole of active hydrogen atoms on the
long-chain polyol and the chain extender is from 0.95 to 1.05
moles.
[0031] The method for preparing the polyurethane is not
particularly limited. Preparation using the long-chain polyol,
chain extender and polyisocyanate may be carried out by either a
prepolymer process or a one-shot process via a known
urethane-forming reaction. Of these, melt polymerization in the
substantial absence of solvent is preferred. Production by
continuous melt polymerization using a multiple screw extruder is
especially preferred.
[0032] It is preferable to use a thermoplastic polyurethane
material as the polyurethane. The thermoplastic polyurethane
material may be a commercial product, examples of which include
those available under the trade name Pandex from DIC Covestro
Polymer, Ltd., and those available under the trade name Resamine
from Dainichiseika Color & Chemicals Mfg. Co., Ltd.
Polyurea
[0033] The polyurea is a resin composition composed primarily of
urea linkages formed by reacting (i) an isocyanate with (ii) an
amine-terminated compound. This resin composition is described in
detail below.
(i) Isocyanate
[0034] Suitable use can be made here of an isocyanate that is used
in the prior art relating to polyurethanes, although the isocyanate
is not particularly limited. Use may be made of isocyanates similar
to those mentioned above in connection with the polyurethane
material.
(ii) Amine-Terminated Compound
[0035] An amine-terminated compound is a compound having an amino
group at the end of the molecular chain. In this invention, the
long-chain polyamines and/or amine curing agents shown below may be
used.
[0036] A long-chain polyamine is an amine compound which has on the
molecule at least two amino groups capable of reacting with
isocyanate groups, and which has a number-average molecular weight
of from 1,000 to 5,000. In this invention, the number-average
molecular weight is more preferably from 1,500 to 4,000, and even
more preferably from 1,900 to 3,000, Examples of such long-chain
polyamines include, but are not limited to, amine-terminated
hydrocarbons, amine: terminated polyethers, amine-terminated
polyesters, amine-terminated polycarbonates, amine-terminated
polycaprolactones, and mixtures thereof. These long-chain
polyamines may be used singly, or two or more may be used in
combination.
[0037] An amine curing agent is an amine compound which has on the
molecule at least two amino groups capable of reacting with
isocyanate groups and which has a number-average molecular weight
of less than 1,000, In this invention, the number-average molecular
weight is more preferably less than 800, and even more preferably
less than 600. Specific examples of such amine curing agents
include, but are not limited to, ethylenediamine,
hexamethylenediamine, 1-methyl-2,6-cyclohexyldiamine,
tetrahydroxypropylene ethylenediamine, 2,2,4- and
2,4,4-trimethyl-1,6-hexanediamine,
4,4'-bis(sec-butylamino)dicyclohexylmethane, 1,4-bis sec-butylamino
cyclohexane, 1,2-bis(sec-butylamino)cyclohexane, derivatives of
4,4'-butylamino)dicyclohexyl methane,
4,4'-dicyclohexylmethanediamine, 1,4-cyclohexane bis(methylamine),
1,3-cyclohexane bis(methylamine), diethylene glycol
di(aminopropyl)ether, 2-methylpentamethylenediamine,
diaminocyclohexane, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine, propylenediamine, 1,3-diaminopropane,
dimethylaminopropylamine, diethylaminopropylamine,
dipropylenetriamine, imidobis(propylamine), monoethanolamine,
diethanolamine, triethanolamine, monoisopropanolamine,
diisopropanolamine, isophoronediamine,
4,4'-methylenebis(2-chloroaniline),
3,5-dimethylthio-2,4-toluenediamine,
3,5-dimethylthio-2,6-toluenediamine,
3,5-diethylthio-2,4-toluenediamine,
3,5-diethylthio-2,6-toluenediamine,
4,4'-bis(sec-butylamino)diphenylmethane and derivatives thereof,
1,4-bis(sec-butylamino)benzene, 1,2-bis(sec-butylamino)benzene,
N,N'-dialkylaminodiphenylmethane,
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, trimethylene
glycol di-p-aminobenzoate, polytetramethylene oxide
di-p-aminobenzoate,
4,4'-methylenebis(3-chloro-2,6-diethyleneaniline),
4,4'-methylenebis(2,6-diethylaniline), m-phenylenediamine,
p-phenylenediamine and mixtures thereof. These amine curing agents
may be used singly or two or more may be used in combination.
(iii) Polyol
[0038] Although not an essential ingredient, in addition to the
above-described components (i) and (ii), a polyol may also be
included in the polyurea. The polyol is not particularly limited,
but is preferably one that has hitherto been used in the art
relating to polyurethanes. Specific examples include the long-chain
polyols and/or polyol curing agents mentioned below.
[0039] The long-chain polyol may be any that has hitherto been used
in the art relating to polyurethanes. Examples include, but are not
limited to, polyester polyols, polyether polyols, polycarbonate
polyols, polyester polycarbonate polyols, polyolefin-based polyols,
conjugated diene polymer-based polyols, castor oil-based polyols,
silicone-based polyols and vinyl polymer-based polyols. These
long-chain polyols may be used singly or two or more may be used in
combination.
[0040] The long-chain polyol has a number-average molecular weight
of preferably from 1,000 to 5,000, and more preferably from 1,700
to 3,500. In this average molecular weight range, an even better
resilience and productivity are obtained.
[0041] The polyol curing agent is preferably one that has hitherto
been used in the art relating to polyurethanes, but is not subject
to any particular limitation. In this invention, use may be made of
a low-molecular-weight compound having on the molecule at least two
active hydrogen atoms capable of reacting with isocyanate groups,
and having a molecular weight of less than 1,000. Of these, the use
of aliphatic diols having from 2 to 12 carbon atoms is preferred.
Specific examples include 1,4-butylene glycol, 1,2-ethylene glycol,
1,3-butanediol, 1,6-hexanediol and 2,2-dimethyl-1,3-propanediol.
The use of 1,4-butylene glycol is especially preferred. The polyol
curing agent has a number-average molecular weight of preferably
less than 800, and more preferably less than 600.
[0042] A known method may be used to produce the polyurea. A
prepolymer process, a one-shot process or some other known method
may be suitably selected for this purpose.
[0043] When the above polyurethane or other resin is used as the
base resin, the content to thereof is suitably selected according
to the required properties of the manufactured article that is
desired. The lower limit is at least 50 wt %, preferably at least
60 wt %, and more preferably at least 80 wt %, per 100 wt % of the
composition.
[0044] This invention, along with using the above polymer material,
includes a leachable water-soluble fine powder within the foam
composition. The water-soluble fine powder has an average particle
size of preferably from 1 to 800 .mu.m, more preferably from 2 to
600 .mu.m, and even more preferably from 5 to 400 .mu.m. As used
herein, the average particle size (also called, for example, the
"characteristic diameter") refers to the value determined by
sampling 30 large particles from an enlarged image of the
water-soluble powder obtained under, for example, an optical
microscope, measuring the vertical and horizontal dimensions and
determining their average for each particle, summing these
particle-specific average values and dividing the total by n=30
("n" being the number of measured particles).
[0045] The water-soluble fine powder has a melting point of
preferably at least 100.degree. C., more preferably at least
200.degree. C., and even more preferably at least 300.degree. C. In
order to keep the polymer material from melting at the molding
temperature, it is preferable for this melting point to be higher
than the molding temperature of the polymer material. The molding
temperature of golf balls is from 150 to 270.degree. C. Examples of
fine powders having a melting point higher than this temperature
include sodium chloride (800.degree. C.), potassium chloride
(776.degree. C.) and magnesium chloride (714.degree. C.).
[0046] In order for the water-soluble fine powder used to be easily
leached out and removed, it should have a solubility per 100 g of
water at 20.degree. C. of preferably at least 1 g, more preferably
at least 10 g, and even more preferably at least 30 g.
[0047] A water-soluble compound such as salt or sugar may typically
be used as the water-soluble fine powder. A compound that is easily
rendered into a fine powder, does not dissolve at the molding and
processing temperatures of the thermoplastic resin, and moreover
can easily be extracted with water after molding is preferred.
[0048] The water-soluble fine powder may be selected from the group
consisting of sodium chloride, calcium chloride, potassium
chloride, magnesium chloride, sodium sulfate, potassium sulfate,
magnesium sulfate, sodium nitrate, calcium nitrate, potassium
nitrate, sodium tetraborate, potassium tetraborate, calcium
tetraborate, soluble starch, monosaccharides, disaccharides,
trisaccharides, oligosaccharides, polysaccharides, and to hydrates
thereof. These may be used singly or two or more may be used in
admixture. The use of sodium chloride, sodium sulfate, sodium
nitrate, calcium chloride and magnesium chloride is especially
preferred.
[0049] The amount of water-soluble fine powder included in the foam
composition is suitably selected according to the foam
morphology--such as expansion ratio and foam cell size--desired in
the foam member, but is typically from 1 to 600 parts by weight,
and preferably from 1 to 400 parts by weight, per 100 parts by
weight of the above polymer material used in the invention. For
example, in cases where a golf ball cover material is to be
rendered into a foam member, from the standpoint of the desired
feel of the ball at impact and its controllability on approach
shots, the content per 100 parts by weight of polyurethane resin is
typically from 1 to 600 parts by weight, preferably from 1 to 400
parts by weight, more preferably from 1 to 200 parts by weight, and
even more preferably from 1 to 100 parts by weight. In cases where
a golf ball cover material is to be rendered into a visually
recognizable foam member, from the standpoint of the desired feel
at impact, sense of softness obtained from the appearance and
controllability on approach shots, the content per 100 parts by
weight of the polyurethane resin is preferably from 100 to 500
parts by weight, and more preferably from 200 to 400 parts by
weight.
[0050] In addition, various additives other than the above
ingredients may be optionally included in the inventive
composition. For example, pigments, dispersants, antioxidants,
light stabilizers, ultraviolet absorbers and internal mold
lubricants may be suitably included. Various blowing agents such as
chemical blowing agents are not included in this invention.
[0051] The foam composition can be obtained by mixing together and
incorporating the above ingredients using any of various types of
mixers, such as a kneading-type single-screw or twin-screw
extruder, a Banbury mixer or a kneader.
[0052] In this invention, the foam composition is molded to form a
solid molded body and the water-soluble fine powder contained
within the solid molded body is subsequently leached out and
removed, thereby obtaining an open-cell or closed-cell porous body
(foam body) in which the particle shapes of the water-soluble fine
powder have become pores.
[0053] The method used to mold the foam composition may be suitably
selected according to the shape and nature of the manufactured
article, which is a molded product. For example, the method used to
mold a golf ball cover may entail feeding the above-described foam
composition to an injection molding machine and injecting the
molten foamable composition over the core so as to mold a cover. In
this case, the molding temperature varies with the foam composition
that is used; for polyurethane or polyurea, the molding temperature
is typically in the range of 150 to 270.degree. C. Another method
that may be used is one in which the molten foam composition is
shaped by pressing within a mold so as to obtain foam-molded bodies
in the shape of half-cups, following which the core is enveloped by
two such foam-molded half-cups and heat and pressure are applied in
a press or the like, thereby molding a golf ball cover.
[0054] The water-soluble fine powder included in the molded
material thus obtained from the foam composition is leached out and
removed. The specific method for doing so, although not
particularly limited, involves leaching out the water-soluble fine
powder with water having a temperature of between about 5.degree.
C. and about 100.degree. C., preferably between about 10.degree. C.
and about 80.degree. C., and more preferably between about
20.degree. C. and about 60.degree. C. From the standpoint of the
efficiency of the operation, it is preferable for the water-soluble
powder to be capable of being leached out and removed in a short
time at a high temperature, such as by immersion for a length of
time during which the water-soluble fine powder can be fully
leached out and removed with water at the above temperature, the
length of time being typically from 10 minutes to 12 hours,
preferably from 30 minutes to 8 hours, and more preferably from 1
to 6 hours. Methods for accelerating such leaching and removal may
also be suitably selected and added. Examples include, but are not
limited to, physical methods of removal such as shaking, stirring,
rocking, aeration, microbubbles, ultrasound, high-pressure spraying
and brushing. After the water-soluble fine powder has been leached
out and removed, the foam-molded body can be obtained by thorough
drying. The specific drying method used is not particularly
limited, although the desired foam-molded body can be obtained
after adhering water is thoroughly removed by using a dryer or a
dehumidifying dryer to carry out drying at a temperature of, for
example, up to 120.degree. C. preferably up to 80.degree. C., and
more preferably up to 60.degree. C.
[0055] The morphology of the foam cells in the molded material
obtained from the foam composition is suitably selected according
to the particle size and content of the water-soluble fine powder
to be included in the polymer material. For example, in cases where
sodium chloride is mixed as the water-soluble fine powder into
polyurethane, the to resulting composition is molded as a golf ball
cover material and the sodium chloride is subsequently leached out
with cold or hot water, at a low sodium chloride content, only the
sodium chloride present at the surface of the golf ball cover
leaches out and pore formation occurs only at the surface, with
sodium chloride remaining behind at the interior. On the other
hand, at a high sodium chloride content, mutually adjoining sodium
chloride particles contiguously leach out, forming an open-cell
foam body, with substantially all of the sodium chloride leaching
out and being removed. It should be noted, however, that the sodium
chloride, which has become even finer due to shear stresses, etc.
that are applied when incorporating the sodium chloride into the
polyurethane and when molding golf ball covers (as the foam-molded
material) from the polyurethane and sodium chloride-containing foam
composition, is taken up within the urethane. Some of this sodium
chloride that has been taken up within the urethane does not come
into contact with water and thus remains behind.
[0056] The molded material (foam body) obtained from the foam
composition has a specific gravity of preferably from 0.2 to 1.2.
In cases where the molded material is used as a cover member in
golf balls, from the standpoint of both maintaining a good scuff
resistance and keeping the initial velocity on approach shots low,
it is generally preferable for the specific gravity to be from 1.0
to 1.2. In cases where the desired properties include a softer feel
at impact and greater softness of appearance, the specific gravity
is more preferably 1.0 or less.
[0057] When used in manufactured golf balls, from the standpoint of
the flight performance, spin performance, etc. of the ball, this
foam body has a rebound resilience, as measured in accordance with
MS-K 6255, which is preferably from 9 to 62%, and more preferably
from 20 to 60%.
[0058] In this invention, the foam member (foam-molded body)
obtained as described above is preferably used in particular as an
encasing member that is formed at a surface or periphery of a
member serving as a core material. Exemplary applications include,
aside from golf balls, various other types of balls such as
baseballs, billiard balls and bowling balls, as well as grips,
electrical cable, fabric articles such as gloves and shoes, and
also tires and rollers. In the case of golf balls, the core
material is a single-layer or multilayer core made of rubber or the
like, and the foam member corresponds to an encasing layer (also
referred to as, for example, an intermediate layer, envelope layer
or cover layer) which directly or indirectly encases this core.
EXAMPLES
[0059] The following Examples and Comparative Examples are provided
to illustrate the invention, and are not intended to limit the
scope thereof.
Examples 1 to 10, Comparative Example 1
[0060] A golf ball core-forming rubber composition formulated as
shown in Table 1 and common to all of the Examples was prepared and
then molded and vulcanized to produce a 38.6 mm diameter core.
TABLE-US-00001 TABLE 1 Rubber composition parts by weight
cis-1,4-Polybutadiene 100 Zinc acrylate 27 Zinc oxide 4.0 Barium
sulfate 16.5 Antioxidant 0.2 Organic peroxide (1) 0.6 Organic
peroxide (2) 1.2 Zinc salt of pentachlorothiophenol 0.3 Zinc
stearate 1.0
[0061] Details on the above core material are given below. [0062]
Cis-1,4-Polybutadiene: Available under the trade name "BR 01" from
JSR Corporation [0063] Zinc acrylate: From Nippon Shokuhai Co.,
Ltd. [0064] Zinc oxide: From Sakai Chemical Co., Ltd. [0065] Barium
sulfate: From Sakai Chemical Co., Ltd. [0066] Antioxidant:
Available under the trade name "Nocrac NS6" from Ouchi Shinko
Chemical Industry Co., Ltd. [0067] Organic peroxide (1): Dicumyl
peroxide, available under the trade name "Percumyl D" from NOF
Corporation [0068] Organic peroxid A mixture of
1,1-di(tert-butylperoxy)cyclohexane and silica, available under the
trade name "Perhexa C-40" from NOF Corporation [0069] Zinc
stearate: Available from NOF Corporation
[0070] Next, an intermediate layer-forming resin material common to
all of the Examples was formulated. This intermediate layer resin
material was a blend of 50 parts by weight of a sodium-neutralized
ethylene-unsaturated carboxylic acid copolymer having an acid
content of 18 wt % and 50 parts by weight of a zinc-neutralized
ethylene-unsaturated carboxylic acid copolymer having an acid
content of 15 wt % (for a combined amount of 100 parts by weight).
This resin material was injection molded over a core having a
diameter of 38.6 mm, thereby producing an intermediate
layer-encased sphere having an intermediate layer with a thickness
of 1.25 mm.
Preparation of Cover-Forming Resin Composition
[0071] In all of the Examples, an ether-type thermoplastic
polyurethane (Shore D hardness, 40) available under the trade name
Pandex from DIC Covestro Polymer, Ltd. was used as the
thermoplastic polyurethane elastomer, and sodium chloride (average
particle size, 350 .mu.m; melting point, 800.degree. C.; solubility
in water, 36 g/100 g (20.degree. C.)) was added thereto as the
water-soluble fine powder. As shown in Table 2 below, cover-forming
resin compositions for the respective Examples were prepared by
suitably varying the amount of water-soluble fine powder added.
TABLE-US-00002 TABLE 2 Content (pbw) No. 1 No. 2 No. 3 No. 4 No. 5
No. 6 No. 7 No. 8 No. 9 No. 10 No. 11 Thermoplastic polyurethane
100 100 100 100 100 100 100 100 100 100 100 elastomer (TPU)
Water-soluble fine powder 0 5 10 20 30 40 50 100 200 400 600 Sheet
Specific gravity 1.12 1.12 1.12 1.11 1.09 1.06 1.05 1.03 0.31 0.26
0.24 properties Rebound resilience (%) 55 50 50 43 40 40 37 28 9 9
9 .DELTA. value 0 -5 -5 -12 -15 -15 -18 -27 -46 -46 -46 (difference
with No. 1)
Fabrication of Sheet Samples for Evaluation
[0072] The blend in Table 1 was kneaded in a mixer, following which
it was formed into a 2 mm thick sheet by pressing with a heated
press. The sheet was then immersed for four hours in hot water
having a temperature of 55.degree. C., after which it was dried for
12 hours at 55.degree. C., thereby obtaining the desired foam sheet
sample.
Production of Golf Balls
[0073] Next, the above intermediate layer-encased sphere (diameter,
41.1 mm; weight, 40.8 g) was peripherally encased by the
cover-forming resin composition. The resulting sphere encased by a
cover (outermost layer) having a thickness after molding of 0.8 mm
was subsequently immersed for four hours in hot water having a
temperature of 55.degree. C. and then dried at 55.degree. C. for 12
hours. The cover-encased sphere thus obtained was then painted,
thereby producing a three-piece golf ball having a diameter of 42.7
mm.
[0074] The golf balls produced as described above in the Examples
and Comparative Example 1 were evaluated by the following methods
for feel at impact, scuff resistance, and ball initial velocity and
controllability on approach shots. The results are shown in Table
3.
Initial Velocity of Ball on Approach Shots
[0075] A sand wedge (SW) was mounted on a golf swing robot, and the
initial velocity of the ball immediately after being struck at a
head speed (HS) of 20 m/s was measured with an apparatus for
measuring the initial conditions. The amount of decrease in the
ball initial velocity (.DELTA.V) in each Example was computed
relative to, as the standard, the initial velocity to of the ball
in Comparative Example 1.
Evaluation of Controllability on Approach Shots
[0076] Sensory evaluations of the ball controllability on approach
shots were carried out as follows. The club used was a sand wedge
(SW).
[0077] Excellent (Exc): Controllability was very good.
[0078] Good: Controllability was good.
[0079] No Good (NG): Controllability was somewhat poor.
Evaluation of Feel on Approach Shots
[0080] Sensory evaluations of the ball feel at impact on approach
shots were carried out. The club used was a sand wedge (SW).
[0081] Excellent (Exc): Very soft feel at impact; easy to feel
sweet spot.
[0082] Good: Soft feel at impact; easy to feel sweet spot.
[0083] No Good (NG): Rapid ball separation from club; cannot feel
sweet spot.
Evaluation of Scuff Resistance
[0084] The golf balls were held isothermally at 23.degree. C. and
five balls of each type were hit at a head speed of 33 m/s using as
the club a pitching wedge mounted on a swing robot machine. The
damage to the ball from the impact was visually rated according to
the following criteria.
[0085] Excellent (Exc): Slight scuffing or substantially no
apparent scuffing.
[0086] Good: Slight fraying of surface or slight dimple damage.
[0087] No Good (NG): Dimples completely obliterated in places.
TABLE-US-00003 TABLE 3 Comp. Ex. Example 1 1 2 3 4 5 6 7 8 9 10
Cover formulation No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8
No. 9 No. 10 No. 11 Ball Approach Initial velocity 19.08 18.99
18.70 18.70 18.70 17.99 17.94 17.94 17.61 17.29 16.91 performance
shots (m/s) .DELTA.V 0 -0.09 -0.38 -0.38 -0.38 -1.09 -1.14 -1.14
-1.47 -1.79 -2.17 Controllability NG good good good good good good
good Exc Exc Exc Feel NG good good good good good good good Exc Exc
Exc Scuff resistance Exc Exc Exc Exc Exc Exc Exc Exc good good good
.DELTA.V: Initial velocity difference with Comparative Example
1.
[0088] Japanese Patent Application No. 2018-239788 is incorporated
herein by reference.
[0089] 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.
* * * * *