JP2003342347A - Golf ball having urethane cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball having a polyurethane cover which can satisfy the requirement for resilience and wear resistance. <P>SOLUTION: The polyurethane cover comprises a cured material obtained by curing an isocyanate-terminated urethane prepolymer with a phenylenediamine derivative represented by general formula (1) (wherein R<SP>1</SP>is a 1-9C alkyl group; R<SP>2</SP>and R<SP>3</SP>are each a methyl group, an ethyl group or a hydrogen atom; and X is a halogen atom), preferably a 4-chloro-3,5- diaminobenzoate. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball having a core covered with a polyurethane cover, and particularly to a polyurethane covered golf ball using a phenylenediamine-based curing agent, which provides durability, resilience and shot feeling. It relates to an excellent golf ball.

[0002]

2. Description of the Related Art In golf balls, a cover made of an ionomer resin is mainly used as a cover for covering a core because it has excellent durability. However, the ionomer resin cover tends to have a larger impact on the golfer at the time of hitting and a poor shot feeling, as compared with the balata rubber cover.

In recent years, polyurethane has attracted attention as an inexpensive cover material that achieves a shot feeling close to that of a balata cover and is more durable than balata. For example, Patent No. 2
No. 662909 discloses a polyurethane cover.

In Japanese Patent No. 2662909, a slow-reacting polyamine curing agent, specifically 3,5-dimethylthio-
2,4-toluenediamine, 3,5-dimethylthio-
2,6-toluenediamine, N, N'-dialkyldiaminodiphenylmethane, trimethylene glycol-di-
By using p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, or a mixture thereof, a rapid increase in viscosity due to the progress of the reaction between the urethane prepolymer and the polyamine curing agent can be suppressed,
Cover molding is possible. However, the obtained urethane cover is not sufficient in resilience and abrasion resistance as compared with the ionomer cover, and further improvement is required.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a golf ball having a polyurethane cover which can satisfy the resilience and abrasion resistance.

[0006]

The golf ball of the present invention has a core and a polyurethane cover for covering the core, wherein the polyurethane cover is an isocyanate group-terminated urethane prepolymer represented by the following general formula. It is characterized in that it is composed of a cured product obtained by curing with a phenylenediamine derivative.

[0007]

[Chemical 2]

(Wherein R ¹ is an alkyl group having 1 to 9 carbon atoms, R ² and R ³ are the same and are selected from the group consisting of a methyl group, an ethyl group, and a hydrogen atom, and X is a halogen atom. is there)

The phenylenediamine compound is preferably 4-chloro-3,5-diaminobenzoate, more preferably isobutyl ester. The isocyanate group-terminated urethane prepolymer is 4,
It is preferably a reaction product of 4'-diphenylmethane diisocyanate and a polyol, and the polyol is preferably polytetramethylene ether glycol. The Shore D hardness of the hardened material forming the cover is preferably 30 to 60.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The golf ball of the present invention is characterized in that a core or wound core composed of one layer or two or more layers of vulcanized rubber is covered with a specific polyurethane cover. .

The polyurethane cover used in the present invention is composed of a cured product obtained by curing an isocyanate group-terminated urethane prepolymer with a phenylenediamine derivative represented by the following general formula. The phenylenediamine derivative having two amino groups at the m position has excellent elastomer physical properties as compared with those having two amino groups at the o position and the p position. Further, when the amino group is located at the m position relative to the carboxylate, a polyurethane having excellent elastomer physical properties can be obtained, which is also preferable from the viewpoint of obtaining raw materials.

[0012]

[Chemical 3]

Where R¹Is an alkyl group having 1 to 9 carbon atoms
is there. It may be a linear alkyl group or a branched alkyl group.
Group, specifically, methyl, ethyl, pro
Pill, iso-propyl, butyl, sec-butyl, t
ert-butyl, pentyl, hexyl, ethylbutyl,
2,3-dimethylpentyl and the like can be mentioned. Where R
²And R³Are the same, methyl group, ethyl group, and hydrogen atom?
It is one species selected from the group consisting of R²And R³Are the same
One phenylenediamine derivative is a monohalo that forms the skeleton.
The molecular structure of diaminobenzoate becomes symmetrical and the final
Of the hard segment of the polyurethane molecule obtained
The symmetry can be enhanced. This is polyureta
It contributes to the linear and planar retention of the molecule,
Urethane bond, urea bond, and benze in urethane
Efficient use of hydrogen bonding and cohesive energies of nuclei
As a result, it has excellent elastomer physical properties and mechanical strength.
Urethane can be obtained, and by extension, the resilience of the ball
The durability can be improved. On the other hand, R²And R³To
When a bulky group is attached, the adjacent amino group is
Compounds become difficult to approach, and reactivity decreases too much
It

X is a halogen atom, specifically a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. The electron-withdrawing effect of the halogen atom extends to two adjacent amino groups, and the curing reaction between the amino group and the isocyanate group of the urethane prepolymer can be delayed, which in turn ensures a sufficient pot life.

Therefore, the monohalodiaminobenzoate forming the skeleton of the phenylenediamine derivative is 4
Fluorine-substituted compounds such as -fluoro-3,5-diaminobenzoate, 4-fluoro-2,6-dimethyl-3,5-diaminobenzoate and 4-fluoro-2,6-dimethyl-3,5-diaminobenzoate; 4 -Chloro-3,5
-Diaminobenzoate, 4-chloro-2,6-dimethyl-3,5-diaminobenzoate, 4-chloro-2,
Chlorinated compounds such as 6-diethyl-3,5-diaminobenzoate; 4-bromo-3,5-diaminobenzoate,
Bromo-substituted compounds such as 4-bromo-2,6-dimethyl-3,5-diaminobenzoate and 4-bromo-2,6-diethyl-3,5-diaminobenzoate; 4-iodo-
3,5-diaminobenzoate, 4-iodo-2,6-
Examples include iodo-substituted compounds such as dimethyl-3,5-diaminobenzoate and 4-iodo-2,6-diethyl-3,5-diaminobenzoate. Of these, 4-
Chloro-3,5-diaminobenzoate is preferably used, more preferably isobutyl ester, ie isobutyl-4-chloro-3,5-diaminobenzoate. Specifically, Bayer Vitec 1604
(Product name) is preferably used.

Next, the isocyanate group-terminated urethane prepolymer will be described.

The isocyanate group-terminated urethane prepolymer used in the present invention has two or more isocyanate groups in the urethane prepolymer molecular chain, and the position of the isocyanate group may be the main chain terminal or the urethane prepolymer. When the polymer is branched, it may be a side chain terminal. It is obtained by reacting the following polyol compound and the following polyisocyanate compound in a state where the number of moles of the isocyanate group of the isocyanate compound is excessive with respect to the hydroxyl group of the polyol.

The polyisocyanate compound used as a raw material for the isocyanate group-terminated urethane prepolymer is not particularly limited, but 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate and 2,6-toluene diisocyanate are used. (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-bitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI). ), Paraphenylene diisocyanate (P
Aromatic diisocyanates such as PDI); 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MD
I), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and the like alicyclic diisocyanates, aliphatic diisocyanates, and the like, and one or a mixture of two or more thereof. Among these, MDI is preferably used because the obtained polyurethane cover has an appropriate reaction rate, good moldability and productivity, and good resilience and durability.

The polyol used as a raw material for the isocyanate group-terminated urethane prepolymer may be a low molecular weight compound or a high molecular weight compound as long as it has a plurality of hydroxyl groups. Examples of the low molecular weight polyol include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol; glycerin and trimethylol. Triols such as propane and hexanetriol can be mentioned. As the high molecular weight polyol, a polyether polyol that can be obtained by reacting an initiator having active hydrogen with an alkylene oxide; a condensation-type polyester polyol obtained by dehydration condensation of a dibasic acid such as adipic acid and a glycol or triol A lactone-based polyester polyol obtained by ring-opening polymerization of a lactam such as ε-caprolactam;
A polycarbonate diol synthesized by using a cyclic diol; a polymer polyol such as an acrylic polyol obtained by appropriately introducing a hydroxyl group into an acrylic copolymer can be mentioned. Examples of the polyether polyol include polyoxyethylene glycol, polyoxypropylene glycol (PPG) and polyoxytetramethylene glycol (PTMG), and examples of the condensation polyester polyol include polyethylene adipate (PEA) and polybutylene adipate. (PBA), polyhexamethylene adipate (PHMA) and the like, and examples of the lactone polyester polyol include poly-ε-caprolactone (PCL) and the like. From the viewpoint of excellent resilience and water resistance, preferably a polyether polyol, more preferably polyoxytetramethylene glycol (PTMG) is used.

Therefore, as the isocyanate group-terminated urethane prepolymer, MDI type urethane prepolymer is preferably used. Here, the MDI urethane prepolymer is an isocyanate group-terminated urethane prepolymer obtained by reacting MDI or a polyisocyanate compound containing MDI as a main component with a polyol (preferably polyoxytetramethylene glycol). Say.

The urethane cover of the golf ball of the present invention is obtained by curing the isocyanate group-terminated urethane prepolymer obtained by reacting the above-mentioned isocyanate compound and polyol with the above-mentioned phenylenediamine-based curing agent. Here, the equivalent ratio (NH ₂ / NCO) of the amino group in the amine curing agent to the isocyanate group in the urethane prepolymer is preferably 0.70 or more, more preferably 0.80 or more, and further preferably It is 0.85 or more, preferably 1.20 or less, more preferably 1.05 or less, and further preferably 1.00 or less. If it is less than 0.70, the amount of the isocyanate group-terminated urethane prepolymer with respect to the amine curing agent (that is, the phenylenediamine derivative) becomes excessive, the reaction of forming allophanate or burette is likely to occur, and the flexibility of the finally obtained polyurethane becomes insufficient. . On the other hand, if it exceeds 1.20, allophanate or burette cross-linking reaction is less likely to occur because of insufficient isocyanate groups. As a result, the number of three-dimensional crosslinking points becomes too small, and the strength of the polyurethane finally obtained is lowered.

The polyurethane cover composition according to the present invention may contain a conventionally known catalyst used in the urethane reaction, in addition to the isocyanate group-terminated urethane prepolymer and the phenylenediamine derivative. Examples of the catalyst include monoamines such as triethylamine and N, N-dimethylcyclohexylamine; N, N, N ′,
N'-tetramethylethylenediamine, N, N, N ',
Polyamines such as N ″, N ″ -pentamethyldiethylenetriamine; 1,8-diazabicyclo [5,4,0] -7-
Cyclic diamines such as undecene (DBU) and triethylenediamine; tin-based catalysts such as dibutyltin dilaurylate and dibutyltin diacetate. Also,
If necessary, a filler such as barium sulfate; a coloring agent such as titanium dioxide; a dispersant, an antiaging agent, an ultraviolet absorber, a light stabilizer, a fluorescent material, an additive such as an optical brightener, and the like may be added to the golf ball cover. It may be contained in a range that does not impair the desired properties of.

The curing reaction of polyurethane must be carried out in a state where the isocyanate group-terminated urethane prepolymer and the curing agent are homogeneously mixed. The phenylenediamine derivative used in the present invention is usually a solid at room temperature, and the isocyanate group-terminated urethane prepolymer is a viscous liquid. Therefore, after the isocyanate group-terminated urethane prepolymer and the phenylenediamine derivative are each heated to a molten state, they are mixed, and the mixture may be poured into a mold heated to a temperature close to the mixing temperature. Depending on the type of curing agent and isocyanate group-terminated urethane prepolymer used, it is generally at room temperature to 140 ° C.
It can be cured in about 60 minutes. By curing under these conditions, the rubber vulcanizate during cover molding,
The wound core has little effect on the thread rubber, and the productivity and workability are good.

The preferred urethane cover has a Shore D hardness of 30 or more, more preferably 35 or more, preferably 60 or less, and more preferably 55 or less as a urethane cured product formed by the above composition. Is. This is because if it exceeds 60, it is too hard and the impact at the time of hitting the ball becomes too large, and the spin amount decreases and the controllability deteriorates. On the other hand, when it is less than 30, it becomes too soft and the rebound becomes too low.

The thickness of the urethane cover made of the above materials is 0.2 mm or more, preferably 0.5 mm.
It is above, and is 1.5 mm or less, preferably 1.3 mm or less. By making the cover thickness thinner than the conventional cover thickness such as 1.5 mm or less, the reduction of the resilience due to the soft urethane cover is prevented.
However, if it is less than 0.2 mm, it is too thin and difficult to mold. Even if molding is possible, the tear strength is lowered, so that the core is easily damaged by hitting and the core may be exposed due to friction with the club face. Because there is.

The core used in the golf ball of the present invention is not particularly limited, but it should be a hot press molded product of a rubber composition containing a diene rubber as a base rubber, a co-crosslinking agent, and a crosslinking initiator. Is preferred. As the diene rubber, it is particularly preferable to use high cis polybutadiene having a cis bond advantageous for repulsion of 40% or more, preferably 70% or more, more preferably 90% or more. As the co-crosslinking agent, an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms or a metal salt thereof, preferably a metal salt of acrylic acid or methacrylic acid is used. Examples of the metal include zinc, magnesium, calcium, and aluminum. , Sodium is preferably used, and zinc is more preferably used. Such a co-crosslinking agent is preferably 20 to 50 parts by mass per 100 parts by mass of the base rubber. An organic peroxide is preferably used as the crosslinking initiator. Specifically, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,5-
Trimethylcyclohexane, 2,5-dimethyl-2,5
Examples thereof include organic peroxides such as -di (t-butylperoxy) hexane and di-t-butylperoxide. Of these, dicumyl peroxide is preferably used.
The amount of the organic peroxide compounded is preferably 0.2 to 1.5 parts by mass, more preferably 0.3 to 1.0 part by mass, relative to 100 parts by mass of the base rubber.

In addition to the base rubber, the co-crosslinking agent, and the crosslinking initiator, the core rubber composition further contains a disulfide compound such as diphenyl disulfide or dipentachlorodiphenyl disulfide for enhancing the resilience. It is preferable to keep. The rubber composition for core further includes
Specific gravity adjusting agents such as zinc oxide and barium sulfate, antiaging agents,
Colored powder or the like can be appropriately mixed.

The above core composition is hot press molded to form a spherical core. The heating condition may be appropriately set according to the rubber composition, but is usually 130 to 200.
Heat at ℃ 10 ~ 60 minutes, or 130 ~ 15
After heating at 0 ° C. for 20 to 40 minutes, it is preferable to perform two-stage heating at 160 to 180 ° C. for 5 to 15 minutes.

It is preferable to use a solid core whose deformation amount is 2.50 to 3.50 mm when an initial load of 98 N (10 kgf) to a final load of 1275 N (130 kgf) is applied to the core, more preferably 2 .60 ~
It is 3.30 mm. In the golf ball of the present invention, since the urethane cover is thin, the hardness of the core has a great influence on the shot feeling. If it is less than 2.50 mm, it is hard, and the impact on the golfer at the time of hitting the ball becomes too large, and if it exceeds 3.50 mm, it is too soft and the resilience decreases
Also, the ball feels heavier when hit.

The core diameter is 39.8 to 41.8 mm,
It is preferably 40.2 to 41.4 mm.

The solid golf ball of the present invention is obtained by coating the above core with the above urethane cover. It is preferable that dimples be formed during molding of the urethane cover.

The cover may be manufactured by a conventionally known method. Specifically, the cover is cured by holding the solid core in a hemispherical mold into which the composition for the cover is injected, and hardening the cover. The cover may be produced, then inverted and the composition for a cover injected into another hemispherical mold is cured to produce a ball.

The golf ball of the present invention produced as described above has an initial load of 98 N (10 kgf) to a final load of 1
The amount of deformation of the ball when loaded with 275 N (130 kgf) is preferably 2.50 to 3.50 mm, and more preferably 2.60 to 3.30 mm. 2.50
If it is less than mm, the shot feeling is too hard, and if it exceeds 3.50 mm, it is too soft and the resilience is lowered, and the ball feels heavy at the time of hitting. The golf ball of the present invention is put on the market by further applying paint, printing a marking stamp or the like on the cover surface in order to enhance the appearance and commercial value of the golf ball.

[0034]

[Examples] [Measurement and evaluation methods] A core is coated with a moldable cover composition to mold a cover. At this time, if the cover composition cures too quickly, it will cure before the entire core is coated, and the entire core cannot be coated, resulting in a defective product in which the core portion is exposed. When the occurrence of this defective product was 50% or more, "x" was given, and when the unmoldable rate was 10% or less, "o" was given.

Compressive Deformation Amount of Core or Ball (mm) The amount of compressive deformation of the core or the ball when the initial load of 98 N (10 kgf) to the final load of 1275 N (130 kgf) was applied was measured.

Shore D hardness A urethane cured body sheet having a thickness of 2 mm was prepared and its hardness was measured using a Shore D hardness meter.

Repulsion Index 198.4 g of an aluminum cylinder was made to collide with each golf ball at a speed of 45 m / sec, and the speeds of the cylinder and the golf ball before and after the collision were measured. The coefficient of restitution of the golf ball was calculated. The measurement was performed 5 times for each golf ball, and the average was calculated.

A golf ball (No. 5) using polytetramethylene oxide-di-p-aminobenzoate as an amine curing agent was indexed with a coefficient of restitution of 100. The larger the repulsion index, the higher the resilience.

Fly Distance Golf Laboratory Swing Robot Wood 1
A No. club (titanium driver W # 1) was attached, the head speed was set to 45 m / sec, each golf ball was hit, and the distance (carry: m) from the hit point to the point where the ball dropped was measured.

Chunking (Scratch resistance) A commercially available pitching wedge is attached to a robot machine,
The ball was hit once at two locations at a head speed of 36 m / sec, the hit portion was visually observed, and the result was evaluated in four levels based on the following criteria, and the worse result was used as the evaluation. ⊚: Almost no scratches ○: Slight scratches on the ball surface, but hardly noticeable Δ: Scratches remain on the ball surface, and some fluffing is observed. X: The surface of the ball was considerably scraped, and fuzz was noticeable.

[Production of Golf Ball] (1) Production of Solid Core A rubber composition having the compounding composition shown in Table 1 was subjected to heat compression molding at 160 ° C. for 20 minutes to give a diameter of 41.2 mm, 4
0.9 g of a spherical solid core was obtained. The amount of compressive deformation of the obtained core was 2.83 mm.

[0042]

[Table 1]

In Table 1, as butadiene rubber, J
SR-made "BR18" (cis content of 96% or more) is used, and as zinc acrylate, "ZNDA9" manufactured by Nihon Distillery
0S ”was used as the zinc oxide,“ Ginrei R ”made by Toho Zinc,“ Pumkil D ”made by NOF Corporation as dicumyl peroxide, and Sumitomo Seika made as diphenyl disulfide. .

(2) Production of Golf Ball The urethane prepolymer shown in Table 2 is heated to 80 ° C., and the temperature at which each curing agent is in a molten state (curing agent a: 120)
C., curing agents b and d: normal temperature, curing agent c: 60.degree. C.), and both were mixed, and titanium oxide was further added to obtain a viscous liquid cover composition.

The core obtained in (1) was held in a hemispherical mold having a dimple-forming protrusion, and the prepared cover composition was poured into the mold and then inverted. ,
It was combined with another hemispherical mold (comprising convex portions for forming dimples) into which the composition for a cover was injected, and was heat-press molded at 90 ° C. for 20 minutes to be cured.

After curing, the balls were taken out of the mold, the surface was deburred, and then white paint and then clear paint were applied to the surface to give a diameter of 42.8 mm and a mass of 45.2-4.
5.7 g of golf ball No. 1-5 were obtained.

With respect to the manufactured golf ball, the amount of compressive deformation, the coefficient of restitution, the flight distance, and the
Chunking property was evaluated. The results are combined and shown in Table 2.

The following were used as the urethane prepolymer and the curing agent. -Urethane prepolymer A: MDI-PTMG-based prepolymer "Vibrasen B-6" manufactured by Uniroyal Co., Ltd.
25 ", NCO content = 6.3 mass% -Urethane prepolymer B: MDI-PTMG prepolymer" Vibrasen B-6 "manufactured by Uniroyal Co., Ltd.
35 ", NCO content = 7.8 mass% -Urethane prepolymer C: TDI-PTMG prepolymer" Adiprene LF95 "manufactured by Uniroyal Co., Ltd.
0A ", NCO content = 6.1% by mass-Curing agent a:" Vitec 1604 "manufactured by Bayer, isobutyl-3,5-diamino-4-chlorobenzoate, amine value = 480 mgKOH / g-Curing agent b: Albemare "Etacure 300" made by
Mixture of 3,5-dimethylthio-2,6-toluenediamine and 3,5-dimethylthio-2,4-toluenediamine, amine value = 530 mgKOH / g-Curing agent c: "Versalink P-" manufactured by Air Products
250 ", polytetramethylene oxide-di-paraaminobenzoate, amine value = 249 mg KOH / g-Curing agent d:" Etacure 100 "manufactured by Albemare,
A mixture of 3,5-diethyltoluene-2,4-diamine (content rate about 76%) and 3,5-diethyltoluene-2,4-diamine (content rate about 18%), amine value = 630
mgKOH / g

[0049]

[Table 2]

No. Nos. 1 to 3 are golf balls molded by using the phenylenediamine-based curing agent according to the present invention, and are more repulsive than the conventionally used amine-based curing agent (polytetramethylene oxide-di-paraaminobenzoate). It was high and had excellent chunking properties.
In addition, No. From the comparison of Nos. 1 and 3, it can be seen that the resilience and the chunking property are different depending on the type of the isocyanate component constituting the urethane prepolymer, and the MDI-PTMG prepolymer is superior in the resilience and the chunking property. No. 4, No. No. 6 is a case where a mixture of a phenylenediamine compound having an asymmetrical molecular structure and a symmetric phenylenediamine compound is used. In all cases, the reaction was very fast and the moldability was poor, probably because the electron-withdrawing group, which is thought to slow the curing reaction, was not bonded to the benzene skeleton. Also, because it is mixed with asymmetric compounds, or because it does not have a carboxylate,
It was inferior in chunking. No. For No. 4, the flight distance was also inferior. No. Reference numeral 5 is a diaminodiphenyl-based curing agent, which is considered to have delayed the curing reaction by interposing a long spacer group between the two phenyl groups. The pot life was secured and the moldability was good. Although the molecular structure has symmetry, N of the examples of the present invention in which the type of urethane prepolymer is the same
o. Compared with No. 1, the resilience and the chunking property were inferior. It is considered that it was difficult to maintain the planarity of polyurethane due to the long spacer group, and as a result, hydrogen bonds between molecules and cohesive energy were not efficiently utilized.

[0051]

INDUSTRIAL APPLICABILITY The golf ball of the present invention is a phenylenediamine-based curing agent, and by using a phenylenediamine-based curing agent with excellent symmetry, a cover is formed with polyurethane having excellent elastomeric properties and mechanical strength. Therefore, it has excellent resilience and durability.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4J034 BA08 CA04 CA15 CB03 CB04                       CB07 CC01 CC11 CC12 CC52                       CC61 CC65 CD11 CD13 DA01                       DB04 DB05 DB07 DC50 DF01                       DF02 DF12 DG03 DG04 DG06                       HA01 HA07 HC03 HC12 HC13                       HC17 HC22 HC46 HC52 HC61                       HC64 HC67 HC71 HC73 JA01                       JA41 JA42 KA01 KB02 KC17                       KD12 KE02 QA03 QC08 QD03                       RA03

Claims (6)

[Claims] 1. A golf ball having a core and a polyurethane cover covering the core, wherein the polyurethane cover is a cured product obtained by curing an isocyanate group-terminated urethane prepolymer with a phenylenediamine derivative represented by the following general formula. A golf ball, which is characterized in that [Chemical 1] (In the formula, R ¹ is an alkyl group having 1 to 9 carbon atoms, R ² and R ³
Are the same and are selected from the group consisting of a methyl group, an ethyl group and a hydrogen atom, and X is a halogen atom.) 2. The phenylenediamine derivative is 4-
Chloro-3,5-diaminobenzoate.
The golf ball described in. 3. The golf ball according to claim 2, wherein the phenylenediamine derivative is isobutyl ester. 4. The golf ball according to claim 1, wherein the isocyanate group-terminated urethane prepolymer is a reaction product of 4,4′-diphenylmethane diisocyanate and a polyol. 5. The golf ball according to claim 1, wherein the polyol is polyoxytetramethylene glycol. 6. A Shore D of a cured body which constitutes the cover.
The golf ball according to any one of claims 1 to 5, which has a hardness of 30 to 60.