JP2002078823A - Yarn wound golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a yarn wound golf ball having a satisfactory hitting feeling as a balata cover and easy to stop with a large spin quantity even in a shot in rain by solving the problem in urethane cover production of a yarn wound golf ball having a urethane cover. SOLUTION: This yarn wound golf ball comprises a core constituted in two layers of an inner layer core and an outer layer core, a yarn rubber layer, and a cover formed of a resin hardened by a complex of a polyamine compound with a metal salt. The cover is formed of a resin consisting of an isocyanate group terminated polymer hardened by the complex of the polyamine compound with the metal salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread-wound golf ball having a good shot feeling, a long flight distance, and a large spin such as a balata cover even on a rough shot or a shot in rainy weather, and easily stopping. It is.

[0002]

2. Description of the Related Art Hitherto, golf balls having a wound layer formed on a liquid center and covered with a balata cover have been widely used by advanced golfers and professional golfers because of their excellent shot feeling and controllability. However, since the manufacturing process of the golf ball covered with the balata cover is complicated and the durability and the cut resistance are inferior, various cover materials replacing the balata cover have been recently proposed.

[0003] For example, as disclosed in Japanese Patent Application Laid-Open No. 1-308577, there is a technique in which a soft ionomer resin is used as a base resin of a cover. The ionomer resin cover is
The balata cover is inexpensive and has excellent durability.

Japanese Patent No. 2662909 discloses a cover made of a urethane resin obtained by curing a urethane prepolymer with a polyamine-based curing agent having low reactivity. A golf ball using a urethane resin cover has higher resilience than a golf ball using an ionomer resin cover, and provides a shot feeling like a balata cover.

[0005]

The manufacturing process of a thread-wound golf ball in which a cover material is formed by curing a urethane prepolymer involves a curing reaction.
Subject to various restrictions.

US Pat. No. 4,123,061 cited in US Pat. No. 2,662,909 discloses a golf ball made from a urethane prepolymer and a diamine-based curing agent. The reaction between the amino group of the diamine-based curing agent and the isocyanate group of the urethane prepolymer is very fast, and the reaction proceeds even at room temperature (25 ° C. or lower). Therefore, when the isocyanate group-terminated urethane prepolymer is cured with a normal polyamine-based curing agent to form a cover, it is not possible to prevent an increase in viscosity or gelation due to a curing reaction during compounding.

Japanese Patent No. 2662909 proposes a golf ball using a polyamine-based curing agent having low reactivity to isocyanate groups in order to solve the above-mentioned problem.

However, when a polyamine-based curing agent having a low reactivity is used, there is a problem that the productivity is reduced due to a long curing time.

Further, when the curing is accelerated at a high temperature in order to shorten the curing time, there is a quality problem that the rubber thread layer is deteriorated. When the thread rubber layer is deteriorated, a thread-wound golf ball having good rebound resilience cannot be obtained, and despite having a polyurethane cover, the feel at impact is reduced, and the spin amount when wet is dry. The spin rate at the time decreases, and as a result, the spin retention decreases.

Another object of the present invention is to provide a thread-wound golf ball which has a large spin rate even when shot from a rough or in the rain and easily stops. The purpose is to do.

[0011]

The thread-wound golf ball of the present invention has an inner layer core having a diameter of 24 to 33 mm and a JIS-A hardness of 5 or more and 50 or less, and a Shore D hardness covering the inner layer core of 10 or more and 60 or more. A center having a diameter of 25 to 35 mm constituted by two layers of the following outer core, a thread rubber layer covering the center, and a shore formed of a resin cured by a complex of a polyamine compound and a metal salt.
A thread wound golf ball including a cover having a D hardness of 40 or more and 65 or less.

The outer layer core is preferably formed of at least one selected from the group consisting of polyurethane elastomers, polyester elastomers, polyolefin elastomers and polystyrene elastomers.

The resin forming the cover is preferably a resin obtained by curing an isocyanate group-terminated prepolymer with a complex of a polyamine compound and a metal salt. More preferably, the resin forming the cover is a polyamine compound and a metal salt. Is a resin cured by a complex with

The complex of the polyamine compound and the metal salt is not more than 60 ° C., and the amino group is inactive because the polyamine compound and the metal salt form a complex. It is preferable that the elimination activates the amino group. The polyamine compound in the complex of the polyamine compound and the metal salt is preferably methylene dianiline and / or a derivative thereof, and the metal salt is preferably sodium chloride or lithium chloride. The complex of the polyamine compound and the metal salt is preferably used by being dispersed in a plasticizer.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a thread wound golf ball according to the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view showing one embodiment of the thread wound golf ball of the present invention. As shown in FIG. 1, the thread wound golf ball of the present invention has an inner core 1
A thread rubber layer 2 is provided on a center 1 having an outer layer core 1b formed on the thread rubber layer a, and a cover 3 is formed on the thread rubber layer 2.

Inner layer core 1 of thread wound golf ball of the present invention
The diameter of a is 24 mm or more, preferably 25 mm or more, 33 mm or less, preferably 32 mm or less, more preferably 31 mm or less. If the diameter of the inner core 1a is smaller than 24 mm, the center does not have a flexible characteristic, and the spin rate at the time of hitting increases, so that not only the flight distance decreases, but also the shot feeling deteriorates. If the diameter is larger than 33 mm, the outer layer core 1b becomes too thin to obtain a hardness when formed into a ball, and does not have an appropriate hardness.

Inner core 1 of thread wound golf ball of the present invention
The hardness of a is JIS-A hardness 50 or less, preferably 45 or less. If the hardness of the inner layer core 1a is larger than 50, the center becomes too hard, and the spin rate at the time of hitting ball increases,
Not only the flight distance decreases, but also the shot feeling deteriorates. Further, if the inner core 1a is too soft, not only the molding of the outer core 1b becomes difficult, but also the center is easily deformed when the rubber thread is wound, so that the hardness of the inner core 1a is JIS-A hardness 5 or more, Preferably it is 10 or more, more preferably 15 or more, even more preferably 20 or more.

The composition of the inner layer core 1a is as follows.
The hardness of the rubber composition is not particularly limited as long as it has a JIS-A hardness of 5 or more and 50 or less, and preferably comprises a vulcanized molded product of a rubber composition containing an oily substance. For example, butadiene rubber (BR), natural rubber (NR), ethylene-propylene-
Diene terpolymer (EPDM), polynorbornene and the like can be suitably used. The base rubber has excellent compatibility with oily substances, can be highly filled with oily substances, and has a suitable rebound resilience when a crosslinked structure is formed in a state where the oily substances are uniformly dispersed in the rubber. It is desirable that

Examples of the oily substance include petroleum compound oil, plasticizer, sub- (factis), alkylbenzene,
Liquid rubber and the like can be mentioned. As petroleum compound oils, those used as rubber extender oils include paraffinic oils (containing 50% or more of paraffin chains), naphthenic oils (containing 30 to 45% of naphthenic ring carbon), aromatics (aromatics) ) -Based oils (containing 30% or more of aromatic carbon). Examples of the plasticizer include phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipates such as dioctyl adipate (DOA), sebacates such as dioctyl sebacate (DOS), and tricresyl phosphate (TCP). And adipic acid-based polyesters. The sub (factice) is obtained by vulcanizing vegetable oil or the like with sulfur or sulfur chloride, and includes candy sub, black sub, brown sub and the like. Examples of the alkylbenzene include 1-dodecyl-4-hexylbenzene, 1-dodecyl-3-hexylbenzene, and 1,2,3-hemimelitene. Examples of the liquid rubber include liquid polybutadiene and liquid polyisoprene. These oils may be used alone or as a mixture of two or more.

The combination of the oily substance and the base rubber is determined in consideration of the compatibility of the oily substance with the rubber. Suitable combinations include, for example, polybutadiene rubber, naphthenic oil or aromatic oil for natural rubber, paraffin oil for EPDM, naphthenic oil, aromatic oil, plasticizer for polynorbornene rubber. Alkylbenzene and paraffin-based oils, and urethane rubbers include a plasticizer and a sub-agent. The amount of the oily substance is as follows:
About 30 to 500 parts by mass, preferably 50 to 400 parts by mass, per 100 parts by mass. If the amount is less than 30 parts by mass, no improvement effect can be expected, and if it exceeds 500 parts by mass, the oily substance may not be mixed into the rubber depending on the combination.

The rubber composition for the inner layer core 1a includes a filler (for example, barium sulfate) and a reinforcing agent (for example, hydrous silicic acid, carbon black, etc.) in addition to the base rubber and the oily substance. ), A processing aid as a tackifier, an antioxidant, and the like can be added. further,
A styrene-based elastomer, an ethylene-based elastomer, a urethane-based elastomer, and the like described below may be mixed. The inner layer core 1a can be obtained by kneading the above-mentioned rubber composition and vulcanizing and molding in a mold at, for example, 150 to 170 ° C. for 10 to 20 minutes.

Outer layer core 1 of thread wound golf ball of the present invention
The hardness b is a hardness in a state where the inner core 1a is covered, and the Shore D hardness is 60 or less, preferably 55 or less. When the Shore D hardness is more than 60, the center becomes too hard, and the spin rate at the time of hitting increases, so that not only the flight distance decreases, but also the shot feeling deteriorates. If the core is too soft, it tends to have low resilience.
-A hardness of 55 or more, Shore D hardness of 10 or more, preferably Shore D hardness of 15 or more. Further, regarding the relationship between the hardness of the inner core 1a and the hardness of the outer core 1b, the outer core 1b may be softer than the inner core 1a within the above-mentioned respective hardness ranges. It is preferable that the following relational expression be satisfied, whereby both high rebound and good shot feeling can be achieved. (Outer layer core hardness−Inner layer core hardness) ≧ 10

Specific materials used for the outer layer core are as follows:
There is no particular limitation as long as the hardness is within the above range, and a thermoplastic resin such as a polyurethane resin, an ionomer resin, nylon, or a polyethylene and a thermoplastic elastomer containing a soft segment and a hard segment in a molecule and exhibiting rubber elasticity. And the like. It is preferable to use a thermoplastic elastomer for the outer layer core because the spin rate at the time of wet increases. As the thermoplastic elastomer, for example, at least one selected from the group consisting of a polystyrene elastomer, a polyolefin elastomer, a polyurethane elastomer, and a polyester elastomer can be used. Inner layer core 1
In order to prevent bleeding of the oily substance contained in a, it is particularly preferable to use a polyester elastomer.

Here, a specific example of the polystyrene-based elastomer is given by a trade name.
SBS A1010, Kuraray's Septon HG-2
There are 52. In addition, specific examples of the polyolefin-based elastomer are exemplified by trade names such as Mirastomer M4800NW of Mitsui Chemicals, Inc. and Sumitomo TP of Sumitomo Chemical.
E3682, 9455. Specific examples of urethane elastomers are given by trade names, such as Kuramyon Co., Ltd. 9195 and 9180, and Takeda Birdish Urethane Industry Co., Ltd. Elastollan ET880. Further, specific examples of polyester-based elastomers are given by trade names, such as Hytrel 4047, 47 of Toray Dupont.
67,5557.

The outer layer core 1b used in the present invention may contain a specific gravity adjuster such as barium sulfate and tungsten in addition to the thermoplastic resin and the thermoplastic elastomer.

The blending amount of the thermoplastic resin and / or the thermoplastic elastomer is based on the total mass of the outer layer core 1b.
It is 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more.

The outer layer core 1b can be manufactured by using a general method used for forming a cover of a golf ball. The composition for the outer layer core is previously formed into a hemispherical shell half shell, and the two layers are used to wrap the inner layer core and press-mold, or the outer layer composition is directly injection-molded on the inner layer core. Alternatively, a method of wrapping the inner layer core may be used. As described above, the thickness of 0.5 to
A center 1 is obtained by forming a 9 mm outer core. The diameter of the center is 25 mm or more, preferably 26 mm or more, and 35 mm or less, preferably 32 mm or less.
If the diameter is smaller than 25 mm, the spin rate at the time of hitting increases and the flight distance decreases, while if the diameter is larger than 35 mm, the rubber thread layer becomes thin and the hardness when forming a ball can not be obtained, The hardness is not appropriate.

Next, a thread rubber for a golf ball is wound around the obtained center 1 to form a thread-wound core composed of the center 1 and the thread rubber layer 2. As the rubber thread wound on the center 1, materials conventionally used as thread rubber for thread-wound golf balls, such as natural rubber or natural rubber and synthetic isoprene, sulfur, vulcanization aid, vulcanization accelerator, aging prevention Those obtained by vulcanizing a rubber composition containing an agent and the like can be used. The thread rubber layer 2 can be formed by a method of manufacturing a thread wound core of a conventional thread wound golf ball. The thickness of the rubber thread layer 2 is 1.5 mm or more, preferably 2.0 mm or more, and 7.5 mm or less, preferably 7.
0 mm or less. If the thickness is smaller than 1.5 mm, the resilience of the thread rubber cannot be utilized, and if the thickness is larger than 7.5 mm, the spin rate at the time of hitting becomes large and the trajectory rises and the flight distance decreases.

The thread-wound golf ball cover 3 of the present invention.
Is formed from a resin cured by a complex of a polyamine compound and a metal salt. The resin is not particularly limited as long as it is a resin cured by a complex of a polyamine compound and a metal salt used in the present invention.For example, an isocyanate group-terminated prepolymer, an epoxy group-terminated prepolymer, or the like may be used. Examples of the resin include a resin obtained by curing with a complex.

The isocyanate group-terminated prepolymer is not particularly limited as long as it has at least two isocyanate groups in the molecular chain of the prepolymer.
The position of the isocyanate group in the prepolymer molecular chain is not particularly limited either, and may be at the main chain terminal of the prepolymer molecular chain or at the side chain terminal. Isocyanate group-terminated prepolymers include, for example, isocyanate group-terminated urethane prepolymers obtained by reacting a polyisocyanate compound and a polyol, and resins modified by introducing an isocyanate group into an acrylic resin or an epoxy resin. Can be In particular, it is particularly desirable to use the above-mentioned isocyanate group-terminated urethane prepolymer in terms of excellent resilience, cut resistance and spin retention of a golf ball. The isocyanate group-terminated urethane prepolymer can be obtained by performing a reaction such that the molar ratio of the isocyanate groups of the polyisocyanate compound to the hydroxyl groups of the polyol is excessive.

As the polyisocyanate compound,
Although not particularly limited, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate ( MDI), hexamethylene diisocyanate (H
DI), 1,5-naphthylene diisocyanate (NDI),
3,3'-vitrilen-4,4'-diisocyanate (TOD
I), isophorone diisocyanate (IPDI), paraphenylene diisocyanate (PPDI), xylylene diisocyanate (XDI) and the like.

The polyol is not particularly limited, but is a polyether polyol obtainable by reacting an initiator having active hydrogen with an alkylene oxide; a dehydration condensation of a dibasic acid such as adipic acid with glycol or triol. A condensed polyester polyol obtained; a lactone polyester polyol obtained by ring-opening polymerization of a lactam such as ε-caprolactam;
Polycarbonate diols synthesized using cyclic diols; polymer polyols such as acrylic polyols obtained by appropriately introducing a hydroxyl group into an acrylic copolymer, and the like. Examples of the polyether polyol include polyoxyethylene glycol, polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (P
TMG) and the like. Polycondensed polyester polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (P
HMA), and the lactone-based polyester polyol includes poly-ε-caprolactone (PCL). From the viewpoint of excellent resilience and water resistance, a polyether polyol is preferably used, and more preferably polyoxytetramethylene glycol is used.

Examples of the epoxy group-terminated prepolymer include a bisphenol A epoxy resin, a phenol novolak epoxy resin, and an orthocresol novolak epoxy resin. The epoxy group-terminated prepolymer can be used together with the isocyanate group-terminated urethane prepolymer to such an extent that the resilience of the urethane cover is not impaired.

In the complex of the polyamine compound and the metal salt used in the present invention, the amino group is inactive at a certain temperature or lower because the polyamine forms a complex with the metal salt. At a high temperature, the metal salt is eliminated from the polyamine, and the amino group becomes active.
Therefore, according to the present invention, there is a problem when a conventional urethane prepolymer is blended by blending a complex of a polyamine compound and a metal salt with the isocyanate group-terminated prepolymer at a temperature at which the metal salt is not eliminated. In addition, viscosity increase and gelation due to a curing reaction during compounding can be prevented.

The polyamine component of the complex of the polyamine compound and the metal salt is not particularly restricted but includes, for example, an alkylamine having an amino group bonded to an alkyl group; an aromatic amine having an amino group bonded to an aromatic ring; Or heterocyclic amines; hydrazine and derivatives thereof; amino alcohols and the like. Examples of the alkylamine include ethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenedimine, hexamethylenediamine, diethylenetriamine and the like, and aromatic amines include tolylenediamine, methylenedianiline,
Xylylenediamine and the like. As the alicyclic or heterocyclic amine, isophorone diamine,
Piperazine; and the amino alcohols include ethanolamine and diethanolamine. From the viewpoint of the stability of the complex, methylene dianiline and / or a derivative thereof are preferable. Derivatives of methylene dianiline include 3,3′-dichloro-
4,4′-diaminodiphenylmethane, 2,2 ′, 3
Halogenated diaminodiphenylmethane such as 3'-tetrachloro-4,4'-diaminodiphenylmethane; 2,2 '
-Dimethyl-4,4'-diaminodiphenylmethane,
Dialkyldiaminodiphenylmethane such as 2,2'-diethyl-4,4'-diaminodiphenylmethane;
2 ′, 3,3′-tetramethyl-4,4′-diaminodiphenylmethane, 2,2 ′, 3,3′-tetraethyl-4,
And tetraalkyldiaminodiphenylmethane such as 4'-diaminodiphenylmethane.

The metal salt in the complex of the polyamine compound and the metal salt used in the present invention is not particularly limited.
Alkali metal salts such as lithium, sodium and potassium;
Alkaline earth metal salts such as magnesium, calcium, and strontium; transition metal salts such as chromium, iron, cobalt, copper, and zinc; and the like, preferably alkali metal salts. Examples of the alkali metal salt include sodium chloride, sodium bromide, sodium iodide, sodium nitrite, lithium chloride, lithium bromide, lithium iodide,
Examples thereof include lithium nitrite and sodium cyanide, and particularly preferably sodium chloride or lithium chloride. The ratio of the polyamine compound to the metal salt in the complex of the polyamine compound and the metal salt is desirably 1 mol of the metal salt to 3 mol of the polyamine compound from the viewpoint of the stability of the complex.

The complex of the polyamine compound and the metal salt is preferably used by dispersing it in a dispersion medium. By dispersing and using the dispersion medium, the complex of the polyamine compound and the metal salt can be uniformly dispersed in the isocyanate group-terminated prepolymer, and the compounding temperature can be lowered. The dispersion medium is not particularly limited, and can be appropriately selected in consideration of the compatibility with the material in which the complex of the polyamine and the metal salt is compounded. Examples of the dispersion medium include ethyl acetate, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, toluene, xylene,
Solvents such as N-methylpyrrolidone, phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipates such as dioctyl adipate (DOA), sebacates such as dioctyl sebacate (DOS), tricresyl phosphate ( A plasticizer such as a phosphate-based polyester such as TCP) or an adipic acid-based polyester can be used.

When the material cured by the complex of the polyamine compound and the metal salt is an isocyanate group-terminated urethane prepolymer, a plasticizer is used as a dispersion medium in view of dispersibility in the urethane prepolymer. It is more preferable to use dioctyl phthalate as a dispersion medium.

The complex of the polyamine compound and the metal salt forms a complex at a temperature of 60 ° C. or lower in the combination of the polyamine compound and the metal salt, and the metal salt is eliminated at a temperature higher than 60 ° C. Are preferred. Examples of such a combination include a combination of methylene dianiline and sodium chloride, and specific examples include Caycher 21 which is a complex of methylene dianiline and sodium chloride (methylene dianiline: sodium chloride = 3: 1 molar ratio). And commercially available as a 50% dispersion of dioctyl phthalate.

In the present invention, in addition to the complex type curing agent of the polyamine compound and the metal salt, ethylene glycol,
You may use together low molecular weight polyols, such as diethylene glycol and glycerin. By using the low-molecular-weight polyol in combination, the temperature at which the metal salt desorbs from the polyamine compound can be reduced.

The composition for the cover 3 of the present invention may further contain a filler such as barium sulfate, a coloring agent such as titanium dioxide, and other additives, if necessary, in addition to the resin as a main component. A dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent material or an optical brightener, and the like may be contained as long as the desired properties of the golf ball cover are not impaired. The colorant is added in an amount of 1.0 to 100 parts by mass of the isocyanate group-terminated urethane prepolymer.
It is preferred to be blended in an amount of up to 6.0 parts by mass.

In the cover composition, the above-mentioned components are blended and mixed at a temperature at which the metal salt does not desorb from the complex. By blending at such a temperature or less, it becomes possible to suppress the start of a curing reaction due to amino groups during blending. Further, when the isocyanate group-terminated prepolymer is used, the compounding temperature is preferably as low as possible because of the high toxicity of the isocyanate. Specifically, the combination of the complex in which the amino group becomes active at a temperature higher than 60 ° C. and the isocyanate group-terminated prepolymer is 60 ° C. or less, preferably 5 ° C. or less.
The reaction is performed at a temperature of 0 ° C. or less, more preferably 40 ° C. or less.

The cover 3 is formed by press molding using the cover composition prepared as described above. In the press molding, in a state where the above-mentioned wound core is held in a hemispherical mold, the composition is injected, and then inverted, the composition injected into another hemispherical mold is used. It may be cured together. The curing reaction is carried out at a temperature higher than
Preferably 70 ° C. or higher and 120 ° C. or lower, preferably 10 ° C.
It is preferably performed at 0 ° C. or lower. At a temperature of 60 ° C. or lower, the curing reaction does not take place because the amino group is inactive.
When cured at a temperature of not less than ℃, the thread rubber layer is deteriorated, so that the resilience is reduced. When the resilience of the thread rubber layer is reduced, the spin retention becomes low even in a thread wound golf ball having a polyurethane cover.

The curing time of the complex of the polyamine compound and the metal salt is appropriately set depending on the curing temperature.
It can be performed in a short time at a temperature of 20 ° C. or less,
The reaction can be performed for 30 minutes or less, preferably 10 minutes or less.

The cover 3 of the present invention has a hardness of 40 or more, preferably 4
It is 3 or more, more preferably 45 or more, 65 or less, preferably 63 or less, more preferably 60 or less. If the Shore D hardness is less than 40, the ball becomes too soft and the ball initial velocity is low. If the Shore D hardness exceeds 60, conversely, the spin rate when hit with a short iron or the like becomes small.

Further, when forming the cover, a large number of dimples are formed on the surface as required. Further, the golf ball of the present invention is usually put on the market with a paint finish, a marking stamp, etc., in order to enhance aesthetics and commercial value.

In the present invention, the cover may be formed as a single layer, but may be formed as a plurality of covers.

[0048]

EXAMPLES [Evaluation Method] (1) Measurement of Hardness The hardness of the inner layer core is measured by contacting the hardness meter from the outside of the ball in the state of the ball using a spring type hardness meter A specified in JIS-K6301. did.

The outer layer core and the cover hardness are ASTM-
Using a spring type hardness tester D type defined in D2240,
Each was measured by contacting a hardness meter with the inner core and the wound core covered.

The slab hardness was determined by heating a hot-pressed sheet having a thickness of about 2 mm made from the cover composition at 23 ° C.
ASTM-D2240 after storing for 3 weeks
It measured according to.

(2) Flight Performance of Golf Ball Wood No. 1 (W
# 1) A club and a sand wedge club (SW) are attached, and a golf ball is set at a head speed of 55 m /
It was hit at 20 m / sec. In the case of wood, hitting was performed only under dry conditions, and in the case of sand wedges, hitting was performed under dry conditions and wet conditions in which a ball and a club face were wetted with water.

Spin Amount The spin amount was determined by continuously photographing the hit golf ball. The spin holding ratio is defined as a value of spin amount in wet / spin amount in dry × 100. As the value of the spin holding ratio is larger, the spin amount is larger even on a shot in rainy weather, and a thread-wound golf ball that is easy to stop. It means there is. Measurement of flight distance The flight distance to the drop point was measured. Initial velocity of ball The initial velocity of the ball at the time of hitting was measured.

(3) Shot feeling The evaluation was made by an actual hit test by 10 top professionals. The criteria were as follows. Judgment criteria ８: Eight or more out of ten responded that soft feeling was enough. ×: Eight or more players out of ten answered that the shot feeling was hard / heavy and the repelling was poor.

(4) The criteria for workability during the production of a golf ball were as follows. Judgment criteria ：: The compounding temperature is 60 ° C. or less, the compounding is easy, and there is no increase in viscosity due to the curing reaction during compounding. Further, the curing reaction can be performed in a short time. X: There are problems such as that the compounding temperature is higher than 60 ° C., the compounding is difficult, compounding causes a significant increase in viscosity due to a curing reaction, or the curing time is long.

[Manufacture of Golf Ball] (1) Production of Inner Layer Core The rubber composition for the inner layer core having the composition shown in Table 1 was kneaded and pressed in a mold at 160 ° C. for 15 minutes to form the inner layer core 1a. Produced.

[0056]

[Table 1]

* 1) Polynorbornene rubber manufactured by Nippon Zeon Co., Ltd. * 2) Alkyl benzene oil manufactured by Zeon Co., Ltd. * 3) High cis polybutadiene manufactured by JSR Co., Ltd. * 4) Ouchi Shinko Chemical Industry Co., Ltd. ) Vulcanization accelerator, zinc dibenzyldithiocarbamate * 5) Ouchi Shinko Chemical Co., Ltd. vulcanization accelerator, dibenzothiazyl disulfide * 6) Ouchi Shinko Chemical Co., Ltd. vulcanization Accelerator, N-cyclohexyl-2-benzothiazylsulfenamide * 7) Ouchi Shinko Chemical Co., Ltd. vulcanization accelerator, tetramethylthiuram disulfide

(2) Preparation of Center A center 1 was obtained by injection-molding the composition for the outer layer core having the composition shown in Table 2 directly on the inner layer core.

[0059]

[Table 2]

* 8) Polyester thermoplastic elastomer manufactured by Toray DuPont * 9) Polyurethane thermoplastic elastomer manufactured by Takeda Birdish Urethane Industry * 10) Zinc ion-neutralized ethylene manufactured by DuPont Methacrylic acid-butyl acrylate ionomer resin

(3) Preparation of a wound core Around the center, the base rubber is natural rubber / low cis-isoprene rubber (Shell IR-309 manufactured by Shell Chemical Company).
= 50/50 (mass ratio) of a blended rubber was wound to produce a wound core having an outer diameter of about 39.0 mm.

(4) Preparation of Cover Based on the blending conditions shown in Table 3, the isocyanate group-terminated urethane prepolymer and the curing agent were brought to a predetermined temperature and blended. The composition was injected into a hemispherical mold holding a wound core, then inverted, pressed together with the composition injected into another hemispherical mold, and cured. The curing conditions are shown in Table 3.

[0063]

[Table 3]

Adiprene LF650D: TDI / PTMG-based isocyanate group-terminated urethane prepolymer NCO content: 7.56%, manufactured by Uniroyal Corp. Coronate 4095: TD, manufactured by Nippon Polyurethane Industry Co., Ltd.
I / PTMG urethane prepolymer NCO content 6.1% Coronate 4099: TD manufactured by Nippon Polyurethane Industry Co., Ltd.
I / PTMG urethane prepolymer NCO content 8.3% Coronate 4362: MDI manufactured by Nippon Polyurethane Industry Co., Ltd.
/ PTMG-based urethane prepolymer Kaychar 21: Mole ratio M of methylene dianiline (MDA) and sodium chloride (NaCl) manufactured by Uniroyal
DA: NaCl = 3: 1 complex 50% dioctyl phthalate dispersion Iharacuamine MT: 3,3 ′ manufactured by Ihara Chemical Industry Co., Ltd.
-Dichloro-4,4'-diaminodiphenylmethane

In Cover Formulation Examples II and IV, the curing agent, iharacuamine MT, has a melting point of 98 ° C. or more, and has a melting point of 120 ° C. for uniform dispersion in the prepolymer.
And blended into the prepolymer kept at 80 ° C.

The ionomer resin cover of Cover Formulation Example III was prepared by the following method.

Himilan 1855 (a zinc ion-neutralized ethylene-methacrylic acid-butyl acrylate ionomer resin manufactured by Mitsui Dupont Polychemical Co., Ltd.) and Himilan 1555 (a zinc ion-neutralized ethylene-methacrylic acid ionomer manufactured by Mitsui Dupont Polychemical Co., Ltd.) resin),
Surlyn 6320 (a magnesium ion neutralized ethylene-methacrylic acid-butyl acrylate ionomer resin manufactured by DuPont) was mixed by a twin-screw kneading extruder,
A pellet-shaped cover composition was obtained. The extrusion conditions were as follows: screw diameter: 45 mm screw rotation: 200 rpm screw L / D: 35, and the compound was placed at 200 ° C. to 26 ° C. at the position of the die of the extruder.
Heated to 0 ° C.

Using the obtained cover composition, a hemispherical half-shell was formed. Using two of the half-shells, the wound core was wrapped and press-compressed at 150 ° C.

As shown in Table 3, in the urethane cover I used in the present invention, the composition for the cover could be blended at a temperature of 60 ° C. or less, and there was no increase in viscosity at the time of blending. In the curing reaction, 70 ° C which does not cause deterioration of the rubber thread layer
In a short time of 5 minutes.

(5) Production of Ball The molded ball was taken out of the mold, deburred, and then subjected to white paint and clear paint on the surface to obtain a thread-wound golf ball having a diameter of 42.8 mm and a mass of 45.4 g. Obtained.

Table 4 shows the results of the measurements of the hardness and diameter of the inner core and the outer core, the cover hardness, and the physical properties of the thread-wound golf ball obtained based on the above measurement and evaluation methods.

[0072]

[Table 4]

As can be seen from Table 4, the thread wound golf ball of the present invention is superior to the golf ball of the comparative example in flight distance, ball initial speed, spin rate, and shot feeling. In particular, when the outer layer core 1b is a thermoplastic elastomer (Examples 1 to 6), it can be seen that the spin retention is extremely high.

Since the ball of Comparative Example 1 was an ionomer resin cover, when wet, it easily slipped on the club face, the spin amount was reduced, and the spin retention was reduced. Further, in Comparative Example 7, the inner layer core was hard and the dry spin amount was high, and the wet spin amount was reduced due to the use of the ionomer resin cover which easily slips on the club face during wet, and the retention was further reduced. did.

As can be seen from Comparative Examples 2 and 3, even a thread wound golf ball having a urethane cover has a poor shot feeling when the cover hardness is too hard (cover IV) or too soft (cover V).

The thread-wound golf ball of Comparative Example 4 uses the urethane cover II, but since the curing temperature is as high as 120 ° C., it is considered that the thread rubber layer has deteriorated and the resilience and the spin rate have decreased. .

In Comparative Examples 5 and 6, the urethane cover I using the curing agent of the present invention is used, but the inner core is hard and the dry spin amount is large as a whole, but the wet spin amount is not increased. As a result, the spin retention decreased.

[0078]

According to the present invention, it is possible to solve the problem of controlling the curing reaction during the production of the urethane cover and the problem of deterioration of the thread rubber layer due to high temperature curing, which could not be solved conventionally. Furthermore, by preventing the thread rubber layer from deteriorating during curing, the thread-wound golf ball of the present invention has a good shot feeling, and has a spin rate even when shot from a rough or a shot in the rain like a balata cover. Large, easy to stop.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a golf ball of the present invention.

[Explanation of symbols]

 1a: Inner layer core 1b: Outer layer core 1: Center 2: Thread rubber layer 3: Cover

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Moriyama 3-6-9, Wakihama-cho, Chuo-ku, Kobe City, Hyogo Prefecture Within Sumitomo Rubber Industries, Ltd. (72) Inventor Kazuhiko Isagawa 3 Wakihama-cho, Chuo-ku, Kobe City, Hyogo Prefecture 6-9, Sumitomo Rubber Industries, Ltd.

Claims (7)

[Claims] 1. An inner core having a diameter of 24-33 mm and a JIS-A hardness of 5 or more and 50 or less, and an outer core having a Shore D hardness of 10 or more and 60 or less covering the inner core. A spool including a center having a diameter of 25 to 35 mm; a thread rubber layer covering the center; and a cover having a Shore D hardness of 40 or more and 65 or less formed by a resin cured by a complex of a polyamine compound and a metal salt. Golf ball. 2. The thread-wound golf ball according to claim 1, wherein the outer layer core is formed of at least one selected from the group consisting of a polyurethane elastomer, a polyester elastomer, a polyolefin elastomer, and a polystyrene elastomer. 3. The thread-wound golf ball according to claim 1, wherein the resin forming the cover is a resin obtained by curing an isocyanate group-terminated prepolymer with a complex of a polyamine compound and a metal salt. 4. The thread-wound golf according to claim 1, wherein the amino group of the complex of the polyamine compound and the metal salt is inactive below 60 ° C. and activated at a temperature higher than 60 ° C. ball. 5. The thread-wound golf ball according to claim 1, wherein the polyamine compound is methylene dianiline and / or a derivative thereof. 6. The thread-wound golf ball according to claim 1, wherein the metal salt is sodium chloride or lithium chloride. 7. The thread-wound golf ball according to claim 1, wherein the complex of the polyamine compound and the metal salt is dispersed in a plasticizer.