JP2018008003A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having excellent flying performance on driver shots.SOLUTION: A golf ball 1 includes a spherical core 2 and a cover 3 of at least one or more layers for covering the spherical core. The spherical core is formed of a rubber composition containing: (a) a base material rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, (d) an unsaturated fatty acid and/or a metal salt thereof (excluding the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or the metal salt thereof), and (e) a saturated fatty acid and/or a metal salt thereof. The rubber composition further contains (f) a metal compound in the case of containing only the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as (b) the co-crosslinking agent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a golf ball excellent in a flight distance on a driver shot, and more particularly, to an improvement in a golf ball core.

  As a method for extending the flight distance of a golf ball on a driver shot, for example, there are a method using a core having high resilience and a method using a core having a hardness distribution in which the hardness increases from the center of the core toward the surface. The former has the effect of increasing the initial velocity of the golf ball, and the latter has the effect of increasing the launch angle and reducing the spin. A golf ball having a high launch angle and a low spin has a large flight distance.

  As a technique for increasing the resilience of the core, there is a method of adding an organic sulfur compound to the rubber composition that is a constituent element of the core. In addition, as a technique for improving the resilience of the core, for example, Patent Document 1 includes, as an essential component, a base rubber, a filler, an organic peroxide, an α, β-unsaturated carboxylic acid and / or a metal salt thereof. In addition, a golf ball characterized in that a crosslinked molded product of a rubber composition in which a copper salt of a saturated or unsaturated fatty acid is blended is used as a constituent element is disclosed (Patent Document 1 (Claim 1, Paragraph 1). 0022, 0023))).

  Further, as a technique for improving the flight distance of a driver shot, Patent Documents 2 and 3 disclose a golf ball having a spherical core and at least one cover that covers the spherical core, wherein the spherical core is ( a) base rubber, (b) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, and (d) 4 carbon atoms. In the case of containing a carboxylic acid having ˜30 or a carboxylic acid salt having 4 to 30 carbon atoms and (b) containing only an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms as a co-crosslinking agent Further, (e) a golf ball formed from a rubber composition containing a metal compound is disclosed (Patent Document 2 (Claim 1, Paragraphs 0035 to 0039) and Patent Document 3 (Claim 1, Paragraph 0036). To 0040)).

JP 2008-212681 A JP 2013-27487 A JP 2013-27488 A

  An object of the present invention is to provide a golf ball excellent in a flight distance on a driver shot.

  The golf ball of the present invention that has solved the above problems has a spherical core and at least one cover that covers the spherical core, and the spherical core comprises (a) a base rubber, and (b). The α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt as a co-crosslinking agent, (c) a crosslinking initiator, (d) an unsaturated fatty acid and / or its metal salt (3 carbon atoms) .Alpha.,. Beta.-unsaturated carboxylic acid and / or a metal salt thereof.-8) and (e) a saturated fatty acid and / or a metal salt thereof, and (b) a carbon number of 3 as a co-crosslinking agent. When it contains only -8 α, β-unsaturated carboxylic acids, it is characterized in that it is further formed from a rubber composition containing (f) a metal compound. By using (d) the unsaturated fatty acid and / or its metal salt in combination with (e) the saturated fatty acid and / or its metal salt in the rubber composition, the flight distance of the obtained golf ball on the driver shot is improved.

  According to the present invention, a golf ball having an excellent flight distance on a driver shot can be obtained.

1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention.

  The golf ball of the present invention has a spherical core and at least one cover that covers the spherical core, and the spherical core has (a) a base rubber and (b) a carbon number of 3 to 3 as a co-crosslinking agent. 8 α, β-unsaturated carboxylic acid and / or metal salt thereof, (c) crosslinking initiator, (d) unsaturated fatty acid and / or metal salt thereof (α, β-unsaturated having 3 to 8 carbon atoms) Carboxylic acid and / or metal salt thereof), and (e) a saturated fatty acid and / or metal salt thereof, and (b) an α, β-non-carbon having 3 to 8 carbon atoms as a co-crosslinking agent. When it contains only saturated carboxylic acid, it is characterized by being formed from a rubber composition further containing (f) a metal compound.

[(A) Base rubber]
As the base rubber (a), natural rubber and / or synthetic rubber can be used. For example, polybutadiene rubber, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (EPDM) and the like. Can be used. These may be used alone or in combination of two or more. Among these, a high cis polybutadiene having 40% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, which is particularly advantageous for repulsion is suitable. The content of the high cis polybutadiene in the (a) base rubber is preferably 50% by mass or more, more preferably 70% by mass or more.

  The high-cis polybutadiene preferably has a 1,2-vinyl bond content of 2.0% by mass or less, more preferably 1.7% by mass or less, and still more preferably 1.5% by mass or less. If the content of 1,2-vinyl bond is too large, the resilience may be lowered.

  The high cis polybutadiene is preferably synthesized with a rare earth element-based catalyst. In particular, the use of a neodymium catalyst using a neodymium compound which is a lanthanum series rare earth element compound has a high content of 1,4-cis bonds. , 1,2-vinyl bond is preferred because a polybutadiene rubber having a low content can be obtained with excellent polymerization activity.

  The high-cis polybutadiene preferably has a molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of 2.0 or more, more preferably 2.2 or more, and still more preferably 2. It is 4 or more, most preferably 2.6 or more, and preferably 6.0 or less, more preferably 5.0 or less, still more preferably 4.0 or less, and most preferably 3.4 or less. If the molecular weight distribution (Mw / Mn) of the high cis polybutadiene is too small, the workability is lowered, and if it is too large, the resilience may be lowered. The molecular weight distribution was determined by gel permeation chromatography (manufactured by Tosoh Corporation, “HLC-8120GPC”), using a differential refractometer as a detector, column: GMHHXL (manufactured by Tosoh Corporation), column temperature: 40 ° C., mobile phase. : Measured under conditions of tetrahydrofuran and calculated as a standard polystyrene equivalent value.

The high-cis polybutadiene preferably has a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 30 or more, more preferably 32 or more, still more preferably 35 or more, and preferably 140 or less, more preferably 120 or less, more preferably 100 or less, and most preferably 80 or less. The Mooney viscosity (ML _{1 + 4} (100 ° C.)) referred to in the present invention is the condition of using an L rotor according to JIS K6300, preheating time 1 minute, rotor rotation time 4 minutes, and 100 ° C. It is the value measured below.

The rubber composition preferably contains at least two high-cis polybutadienes having different Mooney viscosities (ML _{1 + 4} (100 ° C.)) as the base rubber (a), more preferably two. . When the two high-cis polybutadienes are contained, the Mooney viscosity of the first high-cis polybutadiene (ML _{1 + 4} (100 ° C.)) is less than 50, and the Mooney viscosity of the second high-cis polybutadiene (ML _{1 + 4} (100 ° C)) is preferably 50 or more.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the first high cis polybutadiene is preferably 30 or more, more preferably 32 or more, still more preferably 35 or more, and preferably less than 50, more preferably 49 or less. More preferably, it is 48 or less. The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the second high cis polybutadiene is preferably 50 or more, more preferably 52 or more, still more preferably 54 or more, preferably 100 or less, more preferably 90 or less. More preferably, it is 80 or less, and most preferably 70 or less.

  The mass ratio of the first high cis polybutadiene to the second high cis polybutadiene (first high cis polybutadiene / second high cis polybutadiene) in the (a) base rubber is preferably 0.3 or more, more preferably 0. 0.5 or more, more preferably 0.7 or more, preferably 3.0 or less, more preferably 2.0 or less, and still more preferably 1.5 or less.

The rubber composition preferably contains polybutadiene rubber and polyisoprene rubber as the base rubber (a). The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of the polyisoprene rubber is preferably 55 or more, more preferably 60 or more, further preferably 65 or more, preferably 120 or less, more preferably 110 or less, Preferably it is 100 or less.

  The mass ratio (polybutadiene rubber / polyisoprene rubber) between the polybutadiene rubber and the polyisoprene rubber in the base rubber (a) is preferably 1 or more, more preferably 2 or more, still more preferably 4 or more, and 20 or less. Is preferable, more preferably 15 or less, and still more preferably 10 or less.

[(B) Co-crosslinking agent]
The (b) the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof is blended in the rubber composition as a co-crosslinking agent, and is added to the base rubber molecular chain. By graft polymerization, it has a function of crosslinking rubber molecules. 3-8 are preferable, as for carbon number of (alpha), (beta)-unsaturated carboxylic acid used as said (b) co-crosslinking agent, More preferably, it is 3-6, More preferably, it is 3 or 4. The α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof may be used alone or in combination of two or more.

  Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid. When the rubber composition contains only an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms as a co-crosslinking agent, the rubber composition further contains (f) a metal compound as an essential component. . An α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms as a co-crosslinking agent is obtained by neutralizing an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms with a metal compound in the rubber composition. This is because substantially the same effect as that obtained when an acid metal salt is used can be obtained.

  Examples of the metal constituting the metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include monovalent metal ions such as sodium, potassium and lithium; magnesium, calcium, zinc, barium, cadmium and the like Bivalent metal ions; trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The said metal component can also be used individually or in mixture of 2 or more types. Among these, as said metal component, bivalent metals, such as magnesium, calcium, zinc, barium, cadmium, are preferable. This is because by using a divalent metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, metal crosslinking is likely to occur between rubber molecules. In particular, the divalent metal salt is preferably a zinc salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, more preferably an acrylic salt because the resilience of the resulting golf ball is high. Zinc acid. In the case where an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and a metal salt thereof are used in combination as the co-crosslinking agent, (f) a metal compound may be used as an optional component.

  (B) The content of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof is preferably 15 parts by mass or more with respect to 100 parts by mass of the base rubber (a), 20 mass parts or more are more preferable, 25 mass parts or more are more preferable, 50 mass parts or less are preferable, 45 mass parts or less are more preferable, and 35 mass parts or less are more preferable. (B) When the content of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof is less than 15 parts by mass, the member formed from the rubber composition has an appropriate hardness. In addition, the amount of the crosslinking initiator (c) described later must be increased, and the resilience of the golf ball tends to decrease. On the other hand, when the content of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof exceeds 50 parts by mass, the member formed from the rubber composition becomes too hard, and golf There is a possibility that the hit feeling of the ball is lowered.

  As the (b) α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof, one whose surface is coated with a saturated fatty acid may be used. In this case, the saturated fatty acid used for the surface treatment is regarded as a saturated fatty acid constituting the component (e) described later.

[(C) Cross-linking initiator]
The (c) crosslinking initiator is blended for crosslinking the (a) base rubber component. (C) As a crosslinking initiator, an organic peroxide is suitable. Specifically, the organic peroxide is dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di Examples thereof include organic peroxides such as (t-butylperoxy) hexane and di-t-butyl peroxide. These organic peroxides may be used alone or in combination of two or more. Of these, dicumyl peroxide is preferably used.

  The content of the (c) crosslinking initiator is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and still more preferably 0.7 parts with respect to 100 parts by mass of the base rubber (a). It is at least 5.0 parts by mass, more preferably at most 2.5 parts by mass, even more preferably at most 2.0 parts by mass, particularly preferably at most 0.9 parts by mass. If the amount is less than 0.2 parts by mass, the member formed from the rubber composition tends to be too soft, and the resilience of the golf ball tends to decrease. If the amount exceeds 5.0 parts by mass, the member is formed from the rubber composition. In order to make the member appropriate hardness, it is necessary to reduce the amount of the (b) co-crosslinking agent described above, and there is a possibility that the resilience of the golf ball is insufficient or the durability is deteriorated.

[(D) Unsaturated fatty acid and / or metal salt thereof]
The (d) unsaturated fatty acid and / or metal salt thereof is an aliphatic carboxylic acid having at least one unsaturated bond in the hydrocarbon chain and / or a metal salt thereof. The (d) unsaturated fatty acid and / or metal salt thereof is preferably a monocarboxylic acid. In addition, (d) unsaturated fatty acids and / or metal salts thereof include (b) α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms and / or metal salts thereof used as a co-crosslinking agent. Shall not.

  The (d) unsaturated fatty acid and / or metal salt thereof preferably has 4 or more carbon atoms, more preferably 5 or more, still more preferably 8 or more, particularly preferably 12 or more, and more preferably 33 or less. Is 30 or less, more preferably 27 or less, and particularly preferably 26 or less. If the component (d) is an unsaturated fatty acid having 33 or less carbon atoms and / or a metal salt thereof, an addition reaction with the component (b) is likely to occur, and the resulting spherical core is highly repulsive.

  In the (d) unsaturated fatty acid and / or metal salt thereof, the number of carbon-carbon double bonds per unit mass is preferably 1.00 mmol / g or more, more preferably 1.50 mmol / g or more, 2.00 mmol / g or more is more preferable, 10.00 mmol / g or less is preferable, 9.00 mmol / g or less is more preferable, and 8.00 mmol / g or less is more preferable. When the component (d) has a carbon-carbon double bond number per unit mass of 1.00 mmol / g or more, an addition reaction with the component (b) is likely to occur, and the resulting spherical core is highly repulsive. become. When the component (d) has a carbon-carbon double bond number per unit mass of 10.00 mmol / g or less, the resulting spherical core has high resilience.

  The (d) unsaturated fatty acid and / or metal salt thereof is preferably an unsaturated fatty acid having at least one carbon-carbon double bond and / or a metal salt thereof, preferably 4 or less, more preferably Two or less, more preferably one. If the component (d) is an unsaturated fatty acid having 4 or less carbon-carbon double bonds and / or a metal salt thereof, an addition reaction with the component (b) is likely to occur, and the resulting spherical core is high. Repel.

  The (d) unsaturated fatty acid and / or metal salt thereof is preferably an unsaturated fatty acid represented by formula (1) and / or a metal salt thereof.

［式（１）中、Ｒ¹は、水素原子または置換基を有していてもよい炭素数１〜３０のアルキル基を表す。Ｒ²は、置換基を有していてもよい炭素数１〜２８のアルキレン基を表す。Ｒ³は、単結合または置換基を有していてもよい炭素数１〜３０のアルキレン基を表す。ｍは、０〜５の自然数を表す。ｍが２〜５の場合、複数あるＲ²はそれぞれ同一でも異なっていてもよい。］

[In Formula (1), R < ¹ > represents the C1-C30 alkyl group which may have a hydrogen atom or a substituent. R ² represents an alkylene group having 1 to 28 carbon atoms which may have a substituent. R ³ represents a single bond or an alkylene group having 1 to 30 carbon atoms which may have a substituent. m represents a natural number of 0 to 5. When m is 2 to 5, a plurality of R ² may be the same or different. ]

The alkyl group having 1 to 30 carbon atoms represented by R ¹ may have a branched structure or a cyclic structure, but a linear alkyl group is preferable. The alkyl group preferably has 1 or more carbon atoms, more preferably 3 or more, still more preferably 5 or more, preferably 25 or less, more preferably 23 or less, and still more preferably 21 or less. The substituent having an alkyl group having 1 to 30 carbon atoms represented by R ^1, include hydroxy group.

The alkylene group having 1 to 28 carbon atoms represented by R ² may have a branched structure or a cyclic structure, but a linear alkylene group is preferable. The alkylene group preferably has 1 or more carbon atoms, more preferably 3 or more, still more preferably 5 or more, and preferably 25 or less, more preferably 23 or less, and still more preferably 21 or less. Examples of the substituent that the alkylene group having 1 to 28 carbon atoms represented by R ² has a hydroxy group.

The alkylene group having 1 to 30 carbon atoms represented by R ³ may have a branched structure or a cyclic structure, but is preferably a linear alkylene group. The alkylene group preferably has 2 or more carbon atoms, more preferably 3 or more, still more preferably 4 or more, preferably 25 or less, more preferably 23 or less, and still more preferably 21 or less. Examples of the substituent that the alkylene group having 1 to 30 carbon atoms represented by R ³ has a hydroxy group.

  The m is preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, and particularly preferably 0.

  As the compound represented by the formula (1), a compound represented by the following formula (2) or (3) is more preferable.

［Ｒ¹¹は、水素原子または置換基を有していてもよい炭素数１〜３０のアルキル基を表す。Ｒ¹²は、単結合または置換基を有していてもよい炭素数１〜３０のアルキレン基を表す。］

[R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 30 carbon atoms which may have a substituent. R ¹² represents a single bond or may have a substituent group alkylene group having 1 to 30 carbon atoms. ]

The alkyl group having 1 to 30 carbon atoms represented by R ¹¹ may have a branched structure or a cyclic structure, but a linear alkyl group is preferable. Examples of the substituent of the alkyl group having 1 to 30 carbon atoms represented by R ¹¹ include a hydroxy group. The alkylene group having 1 to 30 carbon atoms represented by R ¹² may have a branched structure or a cyclic structure, but a linear alkylene group is preferable. Examples of the substituent of the alkylene group having 1 to 30 carbon atoms represented by R ¹² include a hydroxy group.

When R ¹¹ in the formula (2) is an alkyl group, the ratio of carbon atoms to the number of carbon atoms and R ¹² which R ¹¹ has has (R ¹¹ / R ¹²⁾ is preferably 0.1 or more, more preferably 0. 5 or more, more preferably 0.8 or more, preferably 10.0 or less, more preferably 5.0 or less, still more preferably 1.3 or less. When the carbon number ratio (R ¹¹ / R ¹² ) is within the above range, the addition reaction with the component (b) occurs efficiently, and the resulting spherical core is highly repulsive.

［Ｒ²¹は、水素原子または置換基を有していてもよい炭素数１〜２７のアルキル基を表す。Ｒ²²は、置換基を有していてもよい炭素数１〜２８のアルキレン基を表す。Ｒ²³は、単結合または置換基を有していてもよい炭素数１〜２７のアルキレン基を表す。］

[R ²¹ represents a hydrogen atom or an alkyl group having 1 to 27 carbon atoms which may have a substituent. R ²² represents an alkylene group having 1 to 28 carbon atoms which may have a substituent. R ²³ represents a single bond or an alkylene group having 1 to 27 carbon atoms which may have a substituent. ]

The alkyl group having 1 to 27 carbon atoms represented by R ²¹ may have a branched structure or a cyclic structure, but is preferably a linear alkyl group. Examples of the substituent of the alkyl group having 1 to 27 carbon atoms represented by R ²¹ include a hydroxy group. The alkylene group having 1 to 28 carbon atoms represented by R ²² may have a branched structure or a cyclic structure, but a linear alkylene group is preferable. Examples of the substituent of the alkylene group having 1 to 28 carbon atoms represented by R ²² include a hydroxy group. The alkylene group having 1 to 27 carbon atoms represented by R ²³ may have a branched structure or a cyclic structure, but is preferably a linear alkylene group. Examples of the substituent that the alkylene group having 1 to 27 carbon atoms represented by R ²³ has a hydroxy group.

The alkylene group represented by R ²² preferably has 25 or less carbon atoms, more preferably 20 or less, and still more preferably 15 or less. The alkylene group represented by R ²² is preferably a methylene group or an ethylene group, and more preferably a methylene group.

When R ²¹ in the formula (3) is an alkyl group, the ratio of carbon atoms to the number of carbon atoms and R ²³ which R ²¹ has has (R ²¹ / R ²³⁾ is preferably 0.1 or more, more preferably 0. 5 or more, more preferably 0.8 or more, preferably 10.0 or less, more preferably 5.0 or less, still more preferably 1.3 or less. When the carbon number ratio (R ²¹ / R ²³ ) is within the above range, the addition reaction with the component (b) occurs efficiently, and the resulting spherical core is highly repulsive.

  The (d) unsaturated fatty acid and / or metal salt thereof is preferably a linear unsaturated fatty acid and / or salt thereof. The (d) unsaturated fatty acid and / or metal salt thereof includes an unsaturated fatty acid having a carbon-carbon double bond at the end of the hydrocarbon chain and / or a metal salt thereof, and a carbon-carbon double bond in a trans configuration. Mention may be made of unsaturated fatty acids and / or metal salts thereof having at least one, unsaturated fatty acids and / or metal salts thereof having at least one carbon-carbon double bond in a cis configuration. The (d) unsaturated fatty acid and / or metal salt thereof is more preferably an unsaturated fatty acid having at least one carbon-carbon double bond in a cis configuration and / or a metal salt thereof. When the component (d) has the above structure, the reactivity of the addition reaction with the component (b) is high, and the resulting spherical core is more repulsive.

  When the (d) unsaturated fatty acid and / or metal salt thereof is an unsaturated fatty acid having 5 or more carbon atoms and / or a metal salt thereof, the (d) unsaturated fatty acid and / or metal salt thereof is a carboxy group. It is preferably an unsaturated fatty acid and / or metal salt thereof having the first carbon-carbon double bond in the second and subsequent carbons counted from the side, more preferably the third and subsequent carbons, and the fourth and subsequent carbons. Particularly preferred are unsaturated fatty acids having the first carbon-carbon double bond and / or metal salts thereof. If the unsaturated fatty acid and / or its metal salt having the first carbon-carbon double bond in the carbon within the above range, the addition reaction with the component (b) is likely to occur, and the resulting spherical core is highly repulsive. .

  Specific examples (IUPAC name) of the unsaturated fatty acid and / or the unsaturated fatty acid constituting the metal salt thereof (IUPAC name) include butenoic acid (C4), pentenoic acid (C5), hexenoic acid (C6), heptenoic acid ( C7), octenoic acid (C8), nonenoic acid (C9), decenoic acid (C10), undecenoic acid (C11), dodecenoic acid (C12), tridecenoic acid (C13), tetradecenoic acid (C14), pentadecenoic acid (C15) , Hexadecenoic acid (C16), heptadecenoic acid (C17), octadecenoic acid (C18), nonadecenoic acid (C19), icosenoic acid (C20), henicosenoic acid (C21), docosenoic acid (C22), tricosenoic acid (C23), tetracosene Acid (C24), pentacosenoic acid (C25), hexacosenoic acid (C26), heptacosenoic acid (C27), octa Sen acid (C28), nonacosenoic acid (C29), triacontene acid (C30), hen thoria contency acid (C31), Dotoriakonten acid (C32), and the like tritriacontanoic Ten acid (C33).

  Specific examples (common names) of the unsaturated fatty acid and / or the metal salt thereof (d) are 4-pentenoic acid (C5, monounsaturated fatty acid), 5-hexenoic acid (C6). Monounsaturated fatty acid), 6-heptenoic acid (C7, monounsaturated fatty acid), 7-octenoic acid (C8, monounsaturated fatty acid), 8-nonenoic acid (C9, monounsaturated fatty acid), 9-decenoic acid (C10, monounsaturated fatty acid), unsaturated fatty acid having a double bond at the terminal, such as 10-undecylenic acid (C11, monounsaturated fatty acid); myristoleic acid (C14, cis-9-monounsaturated fatty acid), Palmitoleic acid (C16, cis-9-monounsaturated fatty acid), stearidonic acid (C18, 6,9,12,15-tetraunsaturated fatty acid), vaccenic acid (C18, cis-11-monounsaturated fatty acid), olein Acid (C18, cis-9- Unsaturated fatty acid), elaidic acid (C18, trans-9-monounsaturated fatty acid), linoleic acid (C18, cis-9-cis-12-diunsaturated fatty acid), α-linolenic acid (C18, 9,12) , 15-triunsaturated fatty acid), γ-linolenic acid (C18, 6,9,12-triunsaturated fatty acid), gadoleic acid (C20, cis-9-monounsaturated fatty acid), eicosenoic acid (C20, cis- 11-monounsaturated fatty acid), eicosadienoic acid (C20, cis-11-cis-14-diunsaturated fatty acid), arachidonic acid (C20, 5,8,11,14-tetraunsaturated fatty acid), eicosapentaenoic acid ( C20, 5,8,11,14,17-pentaunsaturated fatty acid), erucic acid (C22, cis-13-monounsaturated fatty acid), docosahexaenoic acid (C22, 4,7,10,13,16,19- Hexaunsaturated fatty acid), nervonic acid (C24, cis-15-monounsaturated fatty acid) and other unsaturated fatty acids having a double bond other than the terminal; Examples thereof include unsaturated fatty acids having a hydroxy group, such as formic acid (C18, cis-9-monounsaturated fatty acid).

  Among these, undecylenic acid (C11, monounsaturated fatty acid), myristoleic acid (C14, monounsaturated fatty acid) are preferable as the unsaturated fatty acid constituting the (d) unsaturated fatty acid and / or metal salt thereof. , Palmitoleic acid (C16, monounsaturated fatty acid), oleic acid (C18, monounsaturated fatty acid), linoleic acid (C18, diunsaturated fatty acid), eicosenoic acid (C20, monounsaturated fatty acid), erucic acid (C22, Monounsaturated fatty acid), nervonic acid (C24, monounsaturated fatty acid), ricinoleic acid (C18, cis-9-monounsaturated fatty acid).

  Examples of the metal constituting the (d) unsaturated fatty acid and / or metal salt thereof include monovalent metal ions such as sodium, potassium and lithium; divalent metal ions such as magnesium, calcium, zinc, barium and cadmium; Trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The said metal component can also be used individually or in mixture of 2 or more types. Among these, as said metal component, bivalent metals, such as magnesium, calcium, zinc, barium, cadmium, are preferable, and zinc is especially preferable. (D) By using a divalent metal salt of an unsaturated fatty acid, the resulting spherical core has high resilience. In addition, (d) unsaturated fatty acids and / or metal salts thereof may be used alone or in combination of two or more.

  The (d) unsaturated fatty acid and / or the metal salt thereof is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the base rubber (a). Preferably, it is 35 parts by mass or less, more preferably 30 parts by mass or less, further preferably 25 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 17 parts by mass or less. If content of (d) component is 1 mass part or more, the effect which added (d) component will fully be exhibited, and the spherical core obtained will become high resilience. If the content of the component (d) is 35 parts by mass or less, the spherical core will not be too soft, and the durability and high resilience of the golf ball will not be impaired.

[(E) Saturated fatty acid and / or metal salt thereof]
The rubber composition further contains (e) a saturated fatty acid and / or a metal salt thereof. By using (d) unsaturated fatty acid and / or metal salt thereof together with (e) saturated fatty acid and / or metal salt thereof, the flight distance on driver shots is further improved. The fatty acid component constituting the (e) saturated fatty acid and / or metal salt thereof is not particularly limited, and may be either a linear saturated fatty acid or a saturated fatty acid having a branched chain. preferable. Said (e) saturated fatty acid and / or its metal salt may be used independently, and may use 2 or more types together.

  The number of carbon atoms of the fatty acid component constituting the (e) saturated fatty acid and / or metal salt thereof is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and preferably 30 or less, more preferably 28 Hereinafter, it is more preferably 26 or less, particularly preferably 17 or less.

  Examples of the saturated fatty acid include butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid Nonadecanoic acid, icosanoic acid, henicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid, pentacosanoic acid, hexacosanoic acid, heptacosanoic acid, octacosanoic acid, nonacosanoic acid, triacontanoic acid and the like.

  Examples of the cation component of the saturated fatty acid metal salt include monovalent metal ions such as sodium, potassium, lithium, and silver; divalent metals such as magnesium, calcium, zinc, barium, cadmium, copper, cobalt, nickel, and manganese. Metal ions; trivalent metal ions such as aluminum and iron; and other ions such as tin, zirconium and titanium. The said cation component can also be used individually or in mixture of 2 or more types.

  The amount of the (e) saturated fatty acid and / or metal salt thereof is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass with respect to 100 parts by mass of the base rubber (a). Part or more, preferably 35 parts by weight or less, more preferably 30 parts by weight or less, still more preferably 25 parts by weight or less, and particularly preferably 10 parts by weight or less. (E) If the blending amount of saturated fatty acid and / or metal salt thereof is 1 part by mass or more, the dispersibility of each material in the rubber composition becomes better, and if it is 35 parts by mass or less, (e) saturated fatty acid And / or the change of the physical-property value of the rubber composition by containing the metal salt can be suppressed.

  When the saturated fatty acid and / or metal salt thereof having 4 to 17 carbon atoms is used as the (e) saturated fatty acid and / or metal salt thereof, the blending amount thereof is (a) 100 parts by mass of the base rubber. It is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 3 parts by mass or more, preferably 14 parts by mass or less, more preferably 12 parts by mass or less, still more preferably 10 parts by mass or less. .

  When the saturated fatty acid and / or metal salt thereof having 18 to 30 carbon atoms is used as the (e) saturated fatty acid and / or metal salt thereof, the compounding amount thereof is (a) 100 parts by mass of the base rubber. It is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, further preferably 6 parts by mass or more, preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 25 parts by mass or less. .

  Note that (b) the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof may be treated with zinc stearate or the like in order to improve dispersibility in rubber. is there. When such a co-crosslinking agent surface-treated with zinc stearate or the like is used, the cationic component and anionic component such as zinc stearate which is the surface treating agent are also the cationic component and anionic component of component (e). To include.

[(F) Metal compound]
When the rubber composition used in the present invention contains only an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms as a co-crosslinking agent, the rubber composition contains (f) a metal compound as an essential component. Furthermore, it contains. The (f) metal compound is not particularly limited as long as (b) the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms can be neutralized in the rubber composition. Examples of the metal compound (f) include metal hydroxides such as magnesium hydroxide, zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, copper hydroxide; magnesium oxide, calcium oxide Metal oxides such as zinc oxide and copper oxide; metal carbonates such as magnesium carbonate, zinc carbonate, calcium carbonate, sodium carbonate, lithium carbonate and potassium carbonate. The metal compound (f) is preferably a divalent metal compound, more preferably a zinc compound. This is because the divalent metal compound reacts with the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms to form a metal bridge. Moreover, a golf ball with high resilience can be obtained by using a zinc compound. (F) A metal compound may be used independently and may use 2 or more types together. (F) The content of the metal compound is appropriately adjusted according to the desired degree of neutralization of (b) the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and (d) the unsaturated fatty acid. That's fine.

[(G) Organic sulfur compound]
The rubber composition used in the present invention preferably further contains (g) an organic sulfur compound. When the rubber composition contains (g) an organic sulfur compound, the resilience of the spherical core is further improved.

  As said (g) organic sulfur compound, if it is an organic compound which has a sulfur atom in a molecule | numerator, it will not specifically limit, For example, a thiol group (-SH) or a polysulfide bond (2-4) with a sulfur number of 2-4. An organic compound having S—S—, —S—S—S— or —S—S—S—S—, or a metal salt thereof (—SM, —SMS—, —S—) M-S-S-, -S-S-MS-S-, -S-MSS-SS-, etc., where M is a metal atom). Examples of the metal salt include monovalent metal salts such as sodium, lithium, potassium, copper (I), silver (I), zinc, magnesium, calcium, strontium, barium, titanium (II), manganese (II), Examples thereof include divalent metal salts such as iron (II), cobalt (II), nickel (II), zirconium (II), tin (II) and the like. In addition, (g) organic sulfur compounds include aliphatic compounds (aliphatic thiols, aliphatic thiocarboxylic acids, aliphatic dithiocarboxylic acids, aliphatic polysulfides, etc.), heterocyclic compounds, alicyclic compounds (alicyclic thiols, Any of alicyclic thiocarboxylic acid, alicyclic dithiocarboxylic acid, alicyclic polysulfide, and the like) and aromatic compounds may be used.

  Examples of the organic sulfur compound (g) include thiols (thiophenols, thionaphthols), polysulfides, thiurams, thiocarboxylic acids, dithiocarboxylic acids, sulfenamides, dithiocarbamates, and thiazoles. There may be mentioned at least one selected from the group.

  Examples of thiols include thiophenols and thionaphthols. Examples of the thiophenols include thiophenol; 4-fluorothiophenol, 2,5-difluorothiophenol, 2,6-difluorothiophenol, 2,4,5-trifluorothiophenol, 2,4,5. Thiophenols substituted with fluoro groups such as 1,6-tetrafluorothiophenol and pentafluorothiophenol; 2-chlorothiophenol, 4-chlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothio Thiophenols substituted with a chloro group such as phenol, 2,6-dichlorothiophenol, 2,4,5-trichlorothiophenol, 2,4,5,6-tetrachlorothiophenol, pentachlorothiophenol; 4 -Bromothiophenol, 2,5-dibromothiophenol Thiophenols substituted with a bromo group such as 2,6-dibromothiophenol, 2,4,5-tribromothiophenol, 2,4,5,6-tetrabromothiophenol, pentabromothiophenol; Iodothiophenol, 2,5-diiodothiophenol, 2,6-diiodothiophenol, 2,4,5-triiodothiophenol, 2,4,5,6-tetraiodothiophenol, pentaiodothiophenol Thiophenols substituted with an iodo group such as; or a metal salt thereof. As the metal salt, a zinc salt is preferable.

  Examples of the thionaphthols (naphthalenethiols) include 2-thionaphthol, 1-thionaphthol, 1-chloro-2-thionaphthol, 2-chloro-1-thionaphthol, 1-bromo-2-thionaphthol, 2 -Bromo-1-thionaphthol, 1-fluoro-2-thionaphthol, 2-fluoro-1-thionaphthol, 1-cyano-2-thionaphthol, 2-cyano-1-thionaphthol, 1-acetyl-2- Mention may be made of thionaphthol, 2-acetyl-1-thionaphthol, or a metal salt thereof, and 2-thionaphthol, 1-thionaphthol, or a metal salt thereof is preferred. The metal salt is preferably a divalent metal salt, more preferably a zinc salt. Specific examples of the metal salt include 1-thionaphthol zinc salt and 2-thionaphthol zinc salt.

  Polysulfides are organic sulfur compounds having a polysulfide bond, and examples thereof include disulfides, trisulfides, and tetrasulfides. As the polysulfides, diphenyl polysulfides are preferable.

  Diphenyl polysulfides include diphenyl disulfide; bis (4-fluorophenyl) disulfide, bis (2,5-difluorophenyl) disulfide, bis (2,6-difluorophenyl) disulfide, bis (2,4,5- Trifluorophenyl) disulfide, bis (2,4,5,6-tetrafluorophenyl) disulfide, bis (pentafluorophenyl) disulfide, bis (4-chlorophenyl) disulfide, bis (2,5-dichlorophenyl) disulfide, bis ( 2,6-dichlorophenyl) disulfide, bis (2,4,5-trichlorophenyl) disulfide, bis (2,4,5,6-tetrachlorophenyl) disulfide, bis (pentachlorophenyl) disulfide, bis (4-bromophenyl) Disulfide, (2,5-dibromophenyl) disulfide, bis (2,6-dibromophenyl) disulfide, bis (2,4,5-tribromophenyl) disulfide, bis (2,4,5,6-tetrabromophenyl) Disulfide, bis (pentabromophenyl) disulfide, bis (4-iodophenyl) disulfide, bis (2,5-diiodophenyl) disulfide, bis (2,6-diiodophenyl) disulfide, bis (2,4,5) -Diphenyl disulfides substituted with halogen groups such as triiodophenyl) disulfide, bis (2,4,5,6-tetraiodophenyl) disulfide, bis (pentaiodophenyl) disulfide; bis (4-methylphenyl) disulfide Bis (2,4,5-trimethylphenyl) disulfide, bis (pentamethyl) Substituted with an alkyl group such as benzyl) disulfide, bis (4-t-butylphenyl) disulfide, bis (2,4,5-tri-t-butylphenyl) disulfide, bis (penta-t-butylphenyl) disulfide Diphenyl disulfides; and the like.

  Examples of thiurams include thiuram monosulfides such as tetramethylthiuram monosulfide, thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabutylthiuram disulfide, and thiuram tetrasulfides such as dipentamethylenethiuram tetrasulfide. Is mentioned. Examples of thiocarboxylic acids include naphthalene thiocarboxylic acid. Examples of dithiocarboxylic acids include naphthalene dithiocarboxylic acid. Examples of the sulfenamides include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and Nt-butyl-2-benzothiazole sulfenamide. Can be mentioned.

  As the organic sulfur compound (g), thiophenols and / or metal salts thereof, thionaphthols and / or metal salts thereof, diphenyl disulfides and thiuram disulfides are preferable, and 2,4-dichlorothiophenol is more preferable. 2,6-difluorothiophenol, 2,6-dichlorothiophenol, 2,6-dibromothiophenol, 2,6-diiodothiophenol, 2,4,5-trichlorothiophenol, pentachlorothiophenol, 1 -Thionaphthol, 2-thionaphthol, diphenyl disulfide, bis (2,6-difluorophenyl) disulfide, bis (2,6-dichlorophenyl) disulfide, bis (2,6-dibromophenyl) disulfide, bis (2,6- Diiodophenyl) disulfi , Bis (pentabromophenyl) disulfide.

  Said (g) organic sulfur compound can be used individually or in mixture of 2 or more types.

  The content of the organic sulfur compound (g) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0.2 parts with respect to 100 parts by mass of the base rubber (a). It is not less than 5.0 parts by mass, more preferably not more than 3.0 parts by mass, still more preferably not more than 2.0 parts by mass. If it is less than 0.05 part by mass, the effect of adding (g) an organic sulfur compound cannot be obtained, and the resilience of the golf ball may not be improved. On the other hand, if the amount exceeds 5.0 parts by mass, the amount of compressive deformation of the resulting golf ball increases, and the resilience may be reduced.

[Rubber composition]
(B) the (d) unsaturated fatty acid and / or its relative to the total number of moles of carbon-carbon double bonds of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof; The ratio of the total number of moles of carbon-carbon double bonds of the metal salt (component (d) / component (b)) is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.06 or more. 0.20 or less, more preferably 0.18 or less, and still more preferably 0.16 or less. When the ratio (component (d) / component (b)) is 0.01 or more, an addition reaction with the component (b) is likely to occur, and the resulting spherical core is highly repulsive. On the other hand, when the ratio ((d) component / (b) component) is 0.20 or less, the durability of the golf ball can be maintained without changing the amount of compressive deformation of the spherical core.

The total number of moles of the carboxyl group (—COOH) and carboxylate group (—COO ⁻ ) of the component (b) and the total number of moles of the carboxyl group and carboxylate group of the component (d) and the component (e) The ratio ((d) component + (e) component) / (b) component) is preferably 0.01 or more, more preferably 0.02 or more, further preferably 0.03 or more, and preferably 0.25 or less, 0.23 or less is more preferable, and 0.21 or less is more preferable.

  The ratio of the total number of carboxy groups and carboxylate groups of component (d) and the total number of moles of carboxy groups and carboxylate groups of component (e) (component (d) / component (e)) 0.10 or more is preferable, 0.20 or more is more preferable, 0.30 or more is further preferable, 2.4 or less is preferable, 2.2 or less is more preferable, and 2.0 or less is further more preferable. When the ratio (component (d) / component (e)) is 0.10 or more, the resilience of the spherical core is good, and when it is 2.4 or less, a spherical core having moderate flexibility can be obtained.

  The total number of moles of carboxy groups and carboxylate groups contained in the component (d) in the rubber composition is preferably 0.001 or more, more preferably 0.010, relative to 100 parts by weight of the base rubber (a). More preferably, it is 0.020 or more, preferably 0.065 or less, more preferably 0.060 or less, more preferably 0.050 or less. When the total number of moles of the carboxy group and the carboxylate group contained in the component (d) is within the above range, the resilience of the resulting spherical core is further improved.

  The total number of carboxy groups and carboxylate groups of the component (e) in the rubber composition is preferably 0.010 or more, more preferably 0.020, relative to 100 parts by weight of the base rubber (a). As described above, it is more preferably 0.030 or more, preferably 0.090 or less, more preferably 0.080 or less, more preferably 0.070 or less. When the total number of moles of the carboxyl group and carboxylate group contained in the component (e) is within the above range, the resilience of the resulting spherical core is further improved.

  In the rubber composition, the total number of moles of the carboxyl group and carboxylate group (d) component and the carboxyl group and carboxylate group (e) component has in the rubber composition is (a) 100 parts by mass of the base rubber. 0.020 or more is preferable, More preferably, it is 0.030 or more, More preferably, it is 0.040 or more, 0.10 or less is preferable, More preferably, it is 0.090 or less, More preferably, it is 0.080 or less. When the total number of moles of carboxy groups and carboxylate groups is within the above range, the resilience of the resulting spherical core is further improved.

  The total blending amount of the (d) unsaturated fatty acid and / or metal salt thereof and the (e) saturated fatty acid and / or metal salt thereof in the rubber composition is based on (a) 100 parts by mass of the base rubber. 5 parts by mass or more, preferably 6 parts by mass or more, more preferably 7 parts by mass or more, preferably 20 parts by mass or less, more preferably 18 parts by mass or less, still more preferably 16 parts by mass or less. is there. When the total content of the component (d) and the component (e) is within the above range, the resilience of the obtained spherical core is further improved.

  The rubber composition preferably has a degree of neutralization (alkali equivalent of metal ions when the acid equivalent of the carboxyl group and carboxylate group in the rubber composition is 100 mol%) of 100 mol% or more, preferably 105 mol%. The above is more preferable, 108 mol% or more is more preferable, 110 mol% or more is particularly preferable, 300 mol% or less is preferable, 270 mol% or less is more preferable, 250 mol% or less is further preferable, and 200 mol% or less is particularly preferable. preferable. If the degree of neutralization is 100 mol% or more, the durability of the golf ball can be maintained without changing the amount of compressive deformation of the core. On the other hand, if the degree of neutralization is 300 mol% or less, the resulting spherical core will not be too soft, and the high resilience of the golf ball will not be impaired. The degree of neutralization of the spherical core is defined by the following formula.

［式中、Σ（陽イオン成分のモル数×陽イオン成分の価数）は、（ｂ）成分の各金属イオンのモル数と各金属イオンの価数との積、（ｄ）成分の各金属イオンのモル数と各金属イオンの価数との積、（ｅ）成分の各金属イオンのモル数と各金属イオンの価数との積、（ｆ）成分の各金属イオンのモル数と各金属イオンの価数との積の合計である。Σ（陰イオン成分のモル数×陰イオン成分の価数）は、（ｂ）成分のカルボキシ基およびカルボキシレート基の総モル数、（ｄ）成分のカルボキシ基およびカルボキシレート基の総モル数、（ｅ）成分のカルボキシ基およびカルボキシレート基の総モル数の合計である。］

[In the formula, Σ (number of moles of cation component × valence of cation component) is the product of the number of moles of each metal ion of component (b) and the valence of each metal ion; The product of the number of moles of metal ions and the valence of each metal ion, (e) the product of the number of moles of each metal ion in the component and the valence of each metal ion, (f) the number of moles of each metal ion in the component It is the sum of products with the valence of each metal ion. Σ (number of moles of anion component × valence of anion component) is the total number of moles of carboxy group and carboxylate group of component (b), (d) the total number of moles of carboxyl group and carboxylate group of component, (E) The total number of moles of the carboxyl group and carboxylate group of the component. ]

  The rubber composition used in the present invention may contain additives such as pigments, fillers for weight adjustment, anti-aging agents, peptizers, softeners and the like, if necessary. Moreover, the rubber composition for a core may contain a rubber powder obtained by pulverizing a core of a golf ball or an end material generated at the time of producing the core.

  Examples of the pigment blended in the rubber composition include a white pigment, a blue pigment, and a purple pigment. As the white pigment, titanium oxide is preferably used. The type of titanium oxide is not particularly limited, but it is preferable to use a rutile type because it has good concealability. Further, the content of titanium oxide is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and preferably 8 parts by mass or less, relative to 100 parts by mass of (a) the base rubber. Preferably it is 5 mass parts or less.

  It is also a preferred embodiment that the rubber composition contains a white pigment and a blue pigment. The blue pigment is blended to make white appear vivid, and examples thereof include ultramarine blue, cobalt blue, and phthalocyanine blue. Examples of the purple pigment include anthraquinone violet, dioxazine violet, and methyl violet.

  The filler used in the rubber composition is mainly blended as a weight regulator for adjusting the weight of the golf ball obtained as a final product, and may be blended as necessary. Examples of the filler include inorganic fillers such as zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder.

  The content of the antioxidant is preferably 0.1 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the base rubber (a). Moreover, it is preferable that content of a peptizer is 0.1 to 5 mass parts with respect to 100 mass parts of (a) base rubber.

  The rubber composition used in the present invention comprises (a) a base rubber, (b) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof, (c) a crosslinking initiator, (D) Unsaturated aliphatic carboxylic acid and / or metal salt thereof, (e) Saturated fatty acid and / or metal salt thereof, and other additives as necessary are mixed and kneaded. . The method of kneading is not particularly limited, and for example, a kneading roll, a Banbury mixer, a kneader or the like may be used.

  The spherical core can be obtained by molding the kneaded rubber composition in a mold. The temperature at which the spherical core is molded is preferably 120 ° C. or higher, more preferably 150 ° C. or higher, and preferably 170 ° C. or lower. The pressure during molding is preferably 2.9 MPa to 11.8 MPa. The molding time is preferably 10 minutes to 60 minutes.

[Spherical core]
The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, further preferably 38.8 mm or more, preferably 42.2 mm or less, more preferably 41.8 mm or less, and still more preferably. 41.2 mm or less, and most preferably 40.8 mm or less. If the diameter of the spherical core is 34.8 mm or more, the cover will not be too thick and the resilience will be better. On the other hand, if the diameter of the spherical core is 42.2 mm or less, the cover is not too thin, and the function of the cover is more exhibited.

  When the spherical core has a diameter of 34.8 mm to 42.2 mm, the amount of compressive deformation (the amount by which the center contracts in the compression direction) from when the initial load 98 N is applied to when the final load 1275 N is applied is 1.90 mm. The above is preferable, More preferably, it is 2.00 mm or more, More preferably, it is 2.10 mm or more, 5.00 mm or less is preferable, More preferably, it is 4.80 mm or less, More preferably, it is 4.60 mm or less. When the amount of compressive deformation is 1.90 mm or more, the feel at impact is better, and when the amount is 5.00 mm or less, the resilience is better.

  The hardness difference (Hs−Ho) between the surface hardness Hs and the center hardness Ho of the spherical core is preferably 1 or more, more preferably 5 or more, further preferably 7 or more, particularly preferably 10 or more in Shore C hardness. Yes, preferably 90 or less, more preferably 80 or less, and even more preferably 70 or less. If the hardness difference is large, a golf ball having a high launch angle and a low spin distance can be obtained.

  The spherical core has a center hardness Ho of Shore C hardness of preferably 10 or more, more preferably 15 or more, and still more preferably 20 or more. If the center hardness Ho of the spherical core is 10 or more in Shore C hardness, it will not be too soft and the resilience will be good. Further, the central hardness Ho of the spherical core is preferably 90 or less, more preferably 80 or less, and even more preferably 70 or less in Shore C hardness. If the center hardness Ho is a Shore C hardness of 90 or less, it will not be too hard and the feel at impact will be good.

  The surface hardness Hs of the spherical core is preferably Shore C hardness of 30 or more, more preferably 40 or more, further preferably 50 or more, preferably 100 or less, more preferably 90 or less, and still more preferably 80 or less. is there. By setting the surface hardness of the spherical core to 30 or more in Shore C hardness, the spherical core does not become too soft and good resilience can be obtained. Further, when the spherical core has a surface hardness of 100 or less in Shore C hardness, the spherical core does not become too hard, and a good shot feeling can be obtained.

[cover]
The cover of the golf ball of the present invention is formed from a cover composition containing a resin component. Examples of the resin component include an ionomer resin, a thermoplastic polyurethane elastomer marketed by BASF Japan Co., Ltd. under the trade name “Elastollan (registered trademark)”, and a trade name “Pebax (registered trademark)” from Arkema Co., Ltd. , Thermoplastic polyester elastomer marketed by Toray DuPont Co., Ltd. under the trade name “Hytrel®”, and trade name “Lavalon” from Mitsubishi Chemical Co., Ltd. ) "And the like are commercially available.

  Examples of the ionomer resin include those obtained by neutralizing at least a part of a carboxy group in a binary copolymer of an olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms with a metal ion, olefin And a ternary copolymer of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and an α, β-unsaturated carboxylic acid ester, wherein at least part of the carboxy group is neutralized with a metal ion, or And mixtures thereof. The olefin is preferably an olefin having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, butene, pentene, hexene, heptene, octene and the like, and ethylene is particularly preferable. Examples of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid. Acrylic acid or methacrylic acid is particularly preferable. Examples of the α, β-unsaturated carboxylic acid ester include methyl, ethyl, propyl, n-butyl, isobutyl ester and the like such as acrylic acid, methacrylic acid, fumaric acid and maleic acid, and particularly acrylic acid ester. Or a methacrylic acid ester is preferable. Among these, as the ionomer resin, a metal ion neutralized product of an ethylene- (meth) acrylic acid binary copolymer, an ethylene- (meth) acrylic acid- (meth) acrylic acid ester terpolymer, A metal ion neutralized product is preferred.

  Specific examples of the ionomer resin are exemplified by trade names, such as “Himilan (registered trademark)” (for example, Himilan 1555 (Na), 1557 (Zn), commercially available from Mitsui DuPont Polychemical Co., Ltd. 1605 (Na), 1706 (Zn), 1707 (Na), AM3711 (Mg) and the like, and the terpolymer ionomer resin includes Himiran 1856 (Na) and 1855 (Zn)). .

  Further, ionomer resins commercially available from DuPont include “Surlyn (registered trademark)” (for example, Surlyn 8945 (Na), 9945 (Zn), 8140 (Na), 8150 (Na), 9120 (Zn)). 9150 (Zn), 6910 (Mg), 6120 (Mg), 7930 (Li), 7940 (Li), AD8546 (Li), and the like. As the terpolymer ionomer resin, Surlyn 8120 (Na) 8320 (Na), 9320 (Zn), 6320 (Mg), HPF1000 (Mg), HPF2000 (Mg), etc.).

  Examples of ionomer resins commercially available from ExxonMobil Chemical Co., Ltd. include “Iotek” (registered trademark) (for example, Iotech 8000 (Na), 8030 (Na), 7010 (Zn), 7030 (Zn), etc.). Examples of the terpolymer ionomer resin include Iotech 7510 (Zn) and 7520 (Zn)).

  Note that Na, Zn, Li, Mg, and the like described in parentheses after the trade name of the ionomer resin indicate the metal species of these neutralized metal ions. The ionomer resins may be used alone or in admixture of two or more.

  The cover composition constituting the golf ball cover of the present invention preferably contains a thermoplastic polyurethane elastomer or an ionomer resin as a resin component. When an ionomer resin is used, it is also preferable to use a thermoplastic styrene elastomer in combination. The content of the polyurethane or ionomer resin in the resin component of the cover composition is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more.

  In addition to the resin component described above, the cover composition includes a pigment component such as a white pigment (for example, titanium oxide), a blue pigment, and a red pigment, a weight adjusting agent such as zinc oxide, calcium carbonate, and barium sulfate, a dispersant, You may contain anti-aging agent, a ultraviolet absorber, a light stabilizer, a fluorescent material, or a fluorescent brightening agent in the range which does not impair the performance of a cover.

  The content of the white pigment (for example, titanium oxide) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and 10 parts by mass with respect to 100 parts by mass of the resin component constituting the cover. The following is preferable, and more preferably 8 parts by mass or less. By setting the content of the white pigment to 0.5 parts by mass or more, the cover can be concealed. Moreover, it is because durability of the cover obtained may fall when content of a white pigment exceeds 10 mass parts.

  The slab hardness of the cover composition is preferably set as appropriate according to the desired performance of the golf ball. For example, in the case of a distance-based golf ball that places importance on the flight distance, the slab hardness of the cover composition is preferably Shore D hardness of 50 or more, more preferably 55 or more, further preferably 60 or more, and preferably 80 or less, 70 or less is more preferable, and 68 or less is more preferable. By setting the slab hardness of the cover composition to 50 or more, a golf ball having a high launch angle and a low spin can be obtained on driver shots and iron shots, and the flight distance is improved. Further, by setting the slab hardness of the cover composition to 80 or less, a golf ball having excellent durability can be obtained. In the case of a spin-type golf ball that places importance on controllability, the slab hardness of the cover composition is preferably a Shore D hardness of less than 50, preferably 20 or more, more preferably 25 or more, and even more preferably 30 or more. . If the slab hardness of the cover composition is less than 50 in Shore D hardness, on the driver shot, the core of the present invention increases the flying distance and increases the spin rate of the approach shot, which tends to stop on the green. A golf ball is obtained. Moreover, by setting the slab hardness to 20 or more, the scratch resistance is improved. In the case of a plurality of cover layers, the slab hardness of the cover composition constituting each layer may be the same or different as long as it is within the above range.

  As a method for molding the cover of the golf ball of the present invention, for example, a hollow shell-like shell is molded from the cover composition, and the core is covered with a plurality of shells and compression molded (preferably, the cover composition And a method in which a hollow shell-shaped half shell is molded from a product and the core is covered with two half shells and compression molded), or a cover composition is directly injection molded on the core.

  When the cover is molded by the compression molding method, the half shell can be molded by either the compression molding method or the injection molding method, but the compression molding method is preferred. The conditions for compression molding the cover composition into a half shell include, for example, a pressure of 1 MPa or more and 20 MPa or less and a flow start temperature of the cover composition of −20 ° C. or more and 70 ° C. or less. A molding temperature can be mentioned. By setting the molding conditions, a half shell having a uniform thickness can be molded. As a method for forming a cover using a half shell, for example, a method in which a core is covered with two half shells and compression-molded can be mentioned. As a condition for compression-molding the half shell into a cover, for example, at a molding pressure of 0.5 MPa or more and 25 MPa or less, a flow start temperature of the cover composition is −20 ° C. or more and 70 ° C. or less. A molding temperature can be mentioned. By setting the molding conditions, a golf ball cover having a uniform cover thickness can be molded.

  When a cover composition is injection molded to form a cover, it may be injection molded using a pellet-shaped cover composition obtained by extrusion, or it may be used for a cover such as a base resin component or a pigment. The materials may be dry blended and directly injection molded. As the upper and lower molds for forming the cover, it is preferable to use a cover mold having a hemispherical cavity and having a pimple and also serving as a hold pin in which a part of the pimple can advance and retreat. The cover can be formed by injection molding by protruding a hold pin, inserting a core and holding it, and then injecting the cover composition and cooling the cover. For example, a cover of 9 MPa to 15 MPa can be formed. A cover composition heated to 200 ° C. to 250 ° C. is poured into a mold clamped with pressure in 0.5 seconds to 5 seconds, cooled for 10 seconds to 60 seconds, and then opened.

  When molding a cover, a depression called a dimple is usually formed on the surface. The total number of dimples formed on the cover is preferably 200 or more and 500 or less. If the total number of dimples is less than 200, the dimple effect is difficult to obtain. Further, when the total number of dimples exceeds 500, the size of each dimple becomes small and it is difficult to obtain the dimple effect. The shape (plan view shape) of the dimple formed is not particularly limited, and a circular shape; a polygon such as a substantially triangular shape, a substantially square shape, a substantially pentagonal shape, or a substantially hexagonal shape; Alternatively, two or more kinds may be used in combination.

  The thickness of the cover is preferably 4.0 mm or less, more preferably 3.0 mm or less, and still more preferably 2.0 mm or less. If the cover has a thickness of 4.0 mm or less, the resulting golf ball will have better resilience and feel at impact. The thickness of the cover is preferably 0.3 mm or more, more preferably 0.5 mm or more, further preferably 0.8 mm or more, and particularly preferably 1.0 mm or more. If the thickness of the cover is less than 0.3 mm, the durability and wear resistance of the cover may decrease. In the case of a plurality of cover layers, the total thickness of the plurality of cover layers is preferably in the above range.

  The golf ball body formed with the cover is preferably removed from the mold and subjected to surface treatment such as deburring, washing, and sandblasting as necessary. Moreover, a coating film and a mark can also be formed if desired. The film thickness of the coating film is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, preferably 50 μm or less, more preferably 40 μm or less, and further preferably 30 μm or less. This is because when the film thickness is less than 5 μm, the coating tends to be worn away by continuous use, and when the film thickness exceeds 50 μm, the dimple effect is reduced and the flight performance of the golf ball is reduced.

[Golf ball]
The structure of the golf ball of the present invention is not particularly limited as long as it has a spherical core and one or more covers that cover the spherical core. The spherical core preferably has a single layer structure. This is because the single-layer spherical core has no energy loss at the time of impact at the interface of the multilayer structure, and the resilience is improved. Further, the cover may have a structure of one or more layers, and may have a single layer structure or a multilayer structure of at least two layers. As the golf ball of the present invention, for example, a two-piece golf ball comprising a spherical core and a single-layer cover disposed so as to cover the spherical core; disposed so as to cover the spherical core and the spherical core A multi-piece golf ball having two or more layers (including a three-piece golf ball); a spherical core, a thread rubber layer provided around the spherical core, and a coating covering the thread rubber layer And a wound golf ball having a cover. The present invention can be suitably used for golf balls having any of the above structures.

  The diameter of the golf ball of the present invention is preferably 40 mm to 45 mm. The diameter is particularly preferably equal to or greater than 42.67 mm from the viewpoint that US Golf Association (USGA) standards are satisfied. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm, and particularly preferably equal to or less than 42.80 mm. The mass of the golf ball of the present invention is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining a large inertia, the mass is more preferably 44 g or more, and particularly preferably 45.00 g or more. In light of satisfying the USGA standard, the mass is particularly preferably equal to or less than 45.93 g.

  When the golf ball of the present invention has a diameter of 40 mm to 45 mm, the amount of compressive deformation (the amount of contraction in the compression direction) when the final load 1275N is applied from the state where the initial load 98N is applied may be 2.0 mm or more. More preferably, it is 2.2 mm or more, more preferably 2.4 mm or more, and preferably 4.0 mm or less, more preferably 3.5 mm or less, and still more preferably 3.4 mm or less. A golf ball having a compression deformation amount of 2.0 mm or more does not become too hard and has a good shot feeling. On the other hand, when the amount of compressive deformation is 4.0 mm or less, the resilience is increased.

  FIG. 1 is a partially cutaway sectional view showing a golf ball 1 according to an embodiment of the present invention. The golf ball 1 has a spherical core 2 and a cover 3 that covers the spherical core 2. A large number of dimples 31 are formed on the surface of the cover. Of the surface of the golf ball 3, a portion other than the dimple 31 is a land 32. The golf ball 1 includes a paint layer and a mark layer on the outside of the cover 3, but these layers are not shown.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range.

[Evaluation method]
(1) Compression deformation (mm)
The amount of deformation in the compression direction (the amount by which the core or golf ball shrinks in the compression direction) from when the initial load 98N was applied to the core or golf ball to when the final load 1275N was applied was measured.

(2) Coefficient of restitution 198.4 g of a metal cylinder collides with each core or golf ball at a speed of 40 m / sec, and measures the speed of the cylinder and core or golf ball before and after the collision. The restitution coefficient of each core or golf ball was calculated from the mass. The measurement was performed 12 pieces for each core or golf ball, and the average value was used as the coefficient of restitution of the core or golf ball. The coefficient of restitution is the golf ball no. The difference from 13 is shown.

(3) Core hardness (Shore C hardness)
The hardness measured on the surface of the core was defined as the core surface hardness. Further, the core was cut into a hemisphere, and the hardness was measured at the center of the cut surface. The hardness was measured using an automatic hardness tester (manufactured by H. Burleys, Digitest II). The detector used was “Shore C”.

(4) Slab hardness (Shore D hardness)
Using the cover composition, a sheet having a thickness of about 2 mm was produced by injection molding and stored at 23 ° C. for 2 weeks. The hardness was measured using an automatic hardness tester (Higgle Burleys, Digitest II) in a state where three or more sheets were stacked so that the measurement substrate and the like were not affected. The detector used was “Shore D”.

(5) Driver flying distance A metal head W # 1 driver (Dunlop Sports, XXIO S Loft 11 °) is attached to a swing robot M / C manufactured by Golf Laboratory, and a golf ball is hit at a head speed of 40 m / sec. The flight distance (distance from the launching point to the stationary point) was measured. The measurement was performed 12 times for each golf ball, and the average value was used as the measured value of the golf ball. In addition, the flying distance of each golf ball is the golf ball No. 13 (flight distance difference = flight distance of each golf ball−flight distance of golf ball golf ball No. 13).

(6) Durability A golf head swing robot M / C is mounted with a metal head W # 1 driver (Dunlop Sports, XXIO S Loft 11 °), and repeatedly hits a golf ball at a head speed of 45 m / sec. The number of hits until cracking occurred was measured. In addition, 12 measurements were performed for each golf ball, and the average value was defined as the number of hits of the golf ball. The number of hits of each golf ball is the golf ball no. 13 (difference in the number of hits = number of hits of each golf ball−number of hits of golf ball golf ball No. 13) was calculated and evaluated according to the following criteria.
Evaluation criteria ○: The difference in the number of hits is 0 or more.
X: The difference in the number of hits is less than zero.

(1) Production of core A rubber composition having the composition shown in Tables 1 to 4 was kneaded with a kneading roll, and heated and pressed in an upper and lower mold having hemispherical cavities at 170 ° C. for 20 minutes to have a diameter of 39.8 mm. A spherical core was obtained. It should be noted that an appropriate amount of barium sulfate was added so that the mass of the obtained golf ball was 45.4 g.

The materials used in Tables 1 to 4 are as follows.
BR730: High cis polybutadiene rubber (cis-1,4-bond content = 96 mass%, 1,2-vinyl bond content = 1.3 mass%, Mooney viscosity (ML _{1 + 4} (100 ° C. )) = 55, molecular weight distribution (Mw / Mn) = 3)
ZN-DA90S: Zinc acrylate (containing 10% by mass of zinc stearate), manufactured by Nippon Touche Techno Fine Chemical Co., Ltd.
Dicumyl peroxide: manufactured by Tokyo Chemical Industry Co., Ltd. Oleic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C18, in formula (2), R ¹¹ has 8 carbon atoms, R ¹² has 7 carbon atoms, R ¹¹ Carbon number / carbon number of R ¹² = 1.1)
Myristoleic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C14, in formula (2), R ¹¹ has 4 carbon atoms, R ¹² has 7 carbon atoms, R ¹¹ carbon atoms / R ¹² carbon atoms = 0.6)
Palmitoleic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C16, in formula (2), R ¹¹ has 6 carbon atoms, R ¹² has 7 carbon atoms, R ¹¹ carbon atoms / R ¹² carbon atoms = 0 .9)
Eicosenoic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C20, in formula (2), R ¹¹ has 8 carbon atoms, R ¹² has 9 carbon atoms, R ¹¹ carbon atoms / R ¹² carbon atoms = 0 .9)
Erucic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C22, in formula (2), R ¹¹ has 8 carbon atoms, R ¹² has 11 carbon atoms, R ¹¹ carbon atoms / R ¹² carbon atoms = 0 .7)
Nervonic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (unsaturated fatty acid, C24, in formula (2), R ¹¹ has 8 carbon atoms, R ¹² has 13 carbon atoms, R ¹¹ carbon atoms / R ¹² carbon atoms = 0 .6)
Ricinoleic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (purity 80% by mass) (unsaturated fatty acid, C18, in formula (2), R ¹¹ has 8 carbon atoms, R ¹² has 7 carbon atoms, R ¹¹ carbon atoms / R ¹² Carbon number of 1.1, R ¹¹ has one hydroxy group as a substituent)
Octanoic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (saturated fatty acid, C8)
Decanoic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (saturated fatty acid, C10)
Lauric acid: Tokyo Chemical Industry Co., Ltd. (saturated fatty acid, C12)
Myristic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (saturated fatty acid, C14)
Stearic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (saturated fatty acid, C18)
Zinc octoate: Mitsuwa Chemical Co., Ltd. Zinc decanoate: Mitsuwa Chemical Co., Ltd. Zinc laurate: Mitsuwa Chemical Co., Ltd. Zinc myristate: NOF Co., Ltd. Zinc stearate: Nippon Distillation Co., Ltd. Zinc oxide: Toho Zinc Co., Ltd. “Ginren R”
PBDS: manufactured by Kawaguchi Chemical Industry Co., Ltd., bis (pentabromophenyl) disulfide barium sulfate: manufactured by Sakai Chemical Co., Ltd., “barium sulfate BD”

(2) Production of Cover and Production of Golf Ball The cover material having the composition shown in Table 5 was extruded by a biaxial kneading extruder to prepare a pellet-like cover composition. The extrusion conditions for the cover composition were: screw diameter 45 mm, screw rotation speed 200 rpm, screw L / D = 35, and the formulation was heated to 160-230 ° C. at the die position of the extruder. The obtained cover composition was injection molded on the spherical core obtained as described above to produce a golf ball having a spherical core and a cover covering the core. The cover thickness was 1.5 mm.

The materials used in Table 5 are as follows.
High Milan (registered trademark) 1605: Mitsui DuPont Polychemical Co., Ltd., sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himiran 1706: Mitsui DuPont Polychemical Co., Ltd., zinc ion neutralized ethylene-methacrylic acid co Polymeric ionomer resin Titanium oxide: A220 manufactured by Ishihara Sangyo Co., Ltd.

  The evaluation results of the golf ball are shown in Tables 1-4. Golf ball no. 1-5, 8-12, 15-19, 21-24, 26-28, 30-33, the spherical core is (a) base rubber, (b) co-crosslinking agent, (c) crosslinking initiator, It is formed from the rubber composition containing (d) unsaturated fatty acid and / or its metal salt, and (e) saturated fatty acid and / or its metal salt. These golf balls are all golf ball Nos. Rebound is better than 13 and flying distance on driver shots. Golf ball No. In 6, 7, 20 and 29, since the component (d) or the component (e) was excessive, the resilience was not improved.

  Golf ball no. 14 is a case where (d) component is not contained. This golf ball No. 14 is a golf ball No. 14; Although the flight distance of the driver shot is improved compared to 13, the effect was very small. Golf ball no. 25 is a case where there is little content of (e) component. This golf ball No. 25 is a golf ball No. 25. Compared to 13, the rebound is improved and the flight distance of the driver shot is improved. However, the effect of improving the flight distance of driver shots was small.

1: Golf ball, 2: Spherical core, 3: Cover, 31: Dimple, 32: Land

Claims (15)

A golf ball having a spherical core and at least one cover that covers the spherical core,
The spherical core comprises (a) a base rubber, (b) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, (d) ) Unsaturated fatty acids and / or metal salts thereof (excluding α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms and / or metal salts thereof), and (e) saturated fatty acids and / or metal salts thereof. Containing
(B) In the case where only the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms is contained as a co-crosslinking agent, it is further formed from a rubber composition containing (f) a metal compound. A featured golf ball.   The ratio of the total number of moles of the carboxy group and carboxylate group of the component (d) and the total number of moles of the carboxyl group and carboxylate group of the component (e) (component (d) / component (e)) The golf ball according to claim 1, wherein the golf ball is 0.10 to 2.4.   The number of carbon-carbon double bonds per unit mass of the (d) unsaturated fatty acid and / or metal salt thereof is 1.00 mmol / g to 10.00 mmol / g. Golf ball.   (B) the (d) unsaturated fatty acid and / or its relative to the total number of moles of carbon-carbon double bonds of the α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or the metal salt thereof; 4. The ratio of the total number of moles of carbon-carbon double bonds of the metal salt (component (d) / component (b)) is 0.01 to 0.20. 5. Golf ball.   The golf ball according to claim 1, wherein the (d) unsaturated fatty acid and / or metal salt thereof is an unsaturated fatty acid having 4 to 33 carbon atoms and / or a metal salt thereof.   The (d) unsaturated fatty acid and / or metal salt thereof is an unsaturated fatty acid having one or two carbon-carbon double bonds and / or a metal salt thereof. The golf ball described. The golf ball according to claim 1, wherein the (d) unsaturated fatty acid and / or metal salt thereof is an unsaturated fatty acid represented by formula (1) and / or a metal salt thereof.

[In Formula (1), R < ¹ > represents the C1-C30 alkyl group which may have a hydrogen atom or a substituent. R ² represents an alkylene group having 1 to 28 carbon atoms which may have a substituent. R ³ represents a single bond or an alkylene group having 1 to 30 carbon atoms which may have a substituent. m represents a natural number of 0 to 5. When m is 2 to 5, a plurality of R ² may be the same or different. ]   The golf ball according to claim 1, wherein the (d) unsaturated fatty acid and / or metal salt thereof is a linear unsaturated fatty acid and / or metal salt thereof.   The rubber composition according to any one of claims 1 to 8, wherein the rubber composition contains 1 part by mass to 35 parts by mass of the (d) unsaturated fatty acid and / or a metal salt thereof with respect to 100 parts by mass of the base rubber (a). The golf ball according to claim 1.   The golf ball according to any one of claims 1 to 9, wherein the rubber composition contains a metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms as the (b) co-crosslinking agent. .   The golf ball according to claim 1, wherein the rubber composition has a neutralization degree of 100 mol% or more and 300 mol% or less.   The golf ball according to claim 1, wherein the rubber composition further contains (g) an organic sulfur compound.   The golf ball according to claim 12, wherein (g) the organic sulfur compound is at least one selected from the group consisting of thiophenols, diphenyl disulfides, thionaphthols, thiuram disulfides, and metal salts thereof. .   14. The rubber composition according to claim 12, wherein the rubber composition contains (g) 0.05 to 5.0 parts by mass of an organic sulfur compound with respect to 100 parts by mass of the base rubber. Golf ball.   The rubber composition contains 15 parts by mass to 50 parts by mass of (b) α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof per 100 parts by mass of the base rubber. The golf ball according to claim 1, comprising a mass part.

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