JP2013247984A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having excellent flying performance and controllability.SOLUTION: A golf ball 2 includes a core 4, an inner cover 6, a mid cover 8, and an outer cover 10. The core 4 includes a center 12 and an envelope layer 14. The center 12 is formed by being crosslinked with a rubber composition. The envelope layer 14 is formed by being crosslinked with a rubber composition. At least one of the rubber composition of the center 12 and the rubber composition of the envelope layer 14 includes (a) base rubber, (b) a co-crosslinking agent, (c) a crosslinking initiator, and (d) an acid and/or a salt. The co-crosslinking agent (b) is (b1) an α, β-unsaturated carboxylic acid having 3-8 carbon atoms; or (b2) a metal salt thereof. The JIS-C hardness Hi of the inner cover 6 is higher than JIS-C hardness Hs at a surface of the core 4, and a difference (Hi-Hs) is 1 or larger. The JIS-C hardness Ho of the outer cover 10 is higher than the hardness Hi.

Description

  The present invention relates to a golf ball. Specifically, the present invention relates to a golf ball having a solid core and a cover.

  A golfer's greatest demand for a golf ball is flight performance. Golfers place particular importance on flight performance on shots with drivers. The flight performance correlates with the resilience performance of the golf ball. When a golf ball excellent in resilience performance is hit, it flies at a high speed and a large flight distance is achieved.

  Golf balls having a core with excellent resilience performance are described in Japanese Patent Application Laid-Open Nos. 61-37178, 2008-212681, 2008-523852, and 2009-119256.

  The core described in JP-A-61-37178 is obtained from a rubber composition containing a co-crosslinking agent and a crosslinking aid. This publication describes palmitic acid, stearic acid and myristic acid as crosslinking aids.

  The core described in JP2008-212681 is obtained from a rubber composition containing an organic peroxide, an α, β-unsaturated carboxylic acid metal salt and a fatty acid copper salt.

  The core described in JP-T-2008-523952 is obtained from a rubber composition containing a metal salt of an unsaturated monocarboxylic acid, a free radical initiator, and a non-conjugated diene monomer.

  The core described in JP-A-2009-119256 has a vinyl content of 2% or less, a cis 1,4-bond content of 80% or more, an active end, and the active end is an alkoxysilane compound. It is obtained from a rubber composition containing a modified polybutadiene.

  In order to achieve a large flight distance, an appropriate ballistic height is required. The ballistic height depends on the spin speed and launch angle. A golf ball that achieves a high trajectory with a high spin rate has insufficient flight distance. A golf ball that achieves a high trajectory with a large launch angle can provide a large flight distance. By adopting the outer-hard / inner-soft structure in the golf ball, a small spin speed and a large launch angle can be achieved. Devices relating to the hardness distribution of the core are described in JP-A-6-154357, JP-A-2008-194471, and JP-A-2008-194473.

  In the core described in JP-A-6-154357, the JIS-C hardness H1 at the center is 58 to 73, and the JIS-C hardness H2 in the region where the distance from the center is 5 mm to 10 mm is 65 to 75. The JIS-C hardness H3 at a point where the distance from the center is 15 mm is 74 or more and 82 or less, and the JIS-C hardness H4 of the surface is 76 or more and 84 or less. The hardness H2 is greater than the hardness H1, the hardness H3 is greater than the hardness H2, and the hardness H4 is equal to or greater than the hardness H3.

  In the core described in Japanese Patent Application Laid-Open No. 2008-194471, the Shore D hardness at the center is 30 or more and 48 or less, and the Shore D hardness at a point where the distance from the center is 4 mm is 34 or more and 52 or less. The Shore D hardness at a point where the distance is 8 mm is 40 to 58, the Shore D hardness at a point where the distance from the center is 12 mm is 43 to 61 and the distance from the surface is 2 mm to 3 mm. The Shore D hardness of the region is 36 or more and 54 or less, and the Shore D hardness of the surface is 41 or more and 59 or less.

  In the core described in Japanese Patent Application Laid-Open No. 2008-194473, the Shore D hardness at the center is 25 or more and 45 or less, and the Shore D hardness in the region where the distance from the center is 5 mm or more and 10 mm or less is 39 or more and 58 or less The Shore D hardness at a point where the distance from the center is 15 mm is 36 or more and 55 or less, and the Shore D hardness of the surface is 55 or more and 75 or less.

  Japanese Patent Application Laid-Open No. 2010-253268 describes a golf ball including a core, an envelope layer, an inner cover, and an outer cover. In this core, the hardness gradually increases from the center toward the surface. The difference between the surface JIS-C hardness and the center JIS-C hardness is 15 or more. The hardness of the outer cover is greater than the hardness of the inner cover, and the hardness of the inner cover is greater than the hardness of the envelope layer.

JP-A-61-37178 JP 2008-212681 A Japanese translation of PCT publication No. 2008-523952 JP 2009-119256 A JP-A-6-154357 JP 2008-194471 A JP 2008-194473 A JP 2010-253268 A

  The golfer wants a great flight distance even on the second shot in the middle hole and long hole. An object of the present invention is to provide a golf ball that exhibits excellent flight performance in a shot with a middle iron.

The golf ball according to the present invention includes a core, an inner cover positioned outside the core, a mid cover positioned outside the inner cover, and an outer cover positioned outside the mid cover. The core has a center and an envelope layer located outside the center. The center is formed by crosslinking the rubber composition. The envelope layer is formed by crosslinking the rubber composition. At least one of the rubber composition of the center and the rubber composition of the envelope layer is
(A) base rubber,
(B) a co-crosslinking agent,
(C) a crosslinking initiator,
And (d) an acid and / or salt. The co-crosslinking agent (b)
(B1) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms or (b2) a metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. The JIS-C hardness Hi of the inner cover is larger than the JIS-C hardness Hs of the surface of the core. The difference (Hi-Hs) between the hardness Hi and the hardness Hs is 1 or more. The outer cover has a JIS-C hardness Ho greater than Hi.

Preferably, the acid and / or salt (d) is
(D1) Carboxylic acid and / or a salt thereof. Preferably, the carboxylic acid component of the carboxylic acid and / or its salt (d1) has 1 to 30 carbon atoms. Preferred carboxylic acids and / or salts thereof (d1) are fatty acids and / or salts thereof.

  Preferably, the carboxylic acid and / or its salt (d1) is a zinc salt of a carboxylic acid. Preferably, one or more carboxylic acids and / or their salts (d1) are selected from the group consisting of zinc octoate, zinc laurate, zinc myristate and zinc stearate.

  Preferably, the rubber composition contains 1.0 part by weight or more and 40 parts by weight or less of the acid and / or salt (d) with respect to 100 parts by weight of the base rubber (a).

  Preferably, this rubber composition contains 15 parts by weight or more and 50 parts by weight or less of the co-crosslinking agent (b) with respect to 100 parts by weight of the base rubber (a). Preferably, the rubber composition includes 0.2 to 5.0 parts by mass of a crosslinking initiator (c) with respect to 100 parts by mass of the base rubber (a).

When the rubber composition contains the α, β-unsaturated carboxylic acid (b1), preferably the rubber composition is
(F) It further contains a metal compound.

  Preferably, the difference between the hardness Ho and the hardness Hi (Ho−Hi) is 2 or more.

  Preferably, the difference (Hs−H (0.0)) between the hardness Hs and the JIS-C hardness H (0.0) of the center point of the core is 15 or more.

  Preferably, the sum of the thickness Ti of the inner cover, the thickness Tm of the mid cover, and the thickness To of the outer cover (Ti + Tm + To) is 4.0 mm or less.

Preferably, the rubber composition is
(E) An organic sulfur compound is further included. Preferred organic sulfur compounds (e) are thiophenols, diphenyl disulfides, thionaphthols and thiuram disulfides and metal salts thereof. Preferably, a rubber composition contains 0.05 mass part or more and 5 mass parts or less of organic sulfur compounds (e) with respect to 100 mass parts base rubber (a).

  Preferably, the JIS-C hardness Hm of the mid cover is larger than the hardness Hi, and the hardness Ho is larger than the hardness Hm. Preferably, the difference (Hm−Hi) between the hardness Hm and the hardness Hi is 2 or more. Preferably, the difference (Hm−Hi) between the hardness Hm and the hardness Hi is 3 or more.

  In the golf ball according to the present invention, the hardness distribution of the core is appropriate. In this golf ball, there is little energy loss in the core when hit with a middle iron. In this golf ball, an outer-hard / inner-soft structure is achieved throughout the ball. This golf ball has a low spin rate when hit with a middle iron. A large flight distance can be obtained with a small amount of spin.

FIG. 1 is a partially cutaway sectional view showing a golf ball according to an embodiment of the present invention. FIG. 2 is a line graph showing the hardness distribution of the envelope layer of the golf ball of FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  A golf ball 2 shown in FIG. 1 includes a spherical core 4, an inner cover 6 located outside the core 4, a mid cover 8 located outside the inner cover 6, and an outside of the mid cover 8. And an outer cover 10 located on the outer side. The core 4 has a spherical center 12 and an envelope layer 14 located outside the center 12. A large number of dimples 16 are formed on the surface of the outer cover 10. A portion of the surface of the golf ball 2 other than the dimples 16 is a land 18. The golf ball 2 includes a paint layer and a mark layer on the outside of the outer cover 10, but these layers are not shown. The golf ball 2 may further include one or more mid covers between the inner cover 6 and the outer cover 10.

  The golf ball 2 preferably has a diameter of 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 golf ball 2 preferably has a mass of 40 g or more and 50 g or less. In light of attainment of great inertia, the mass is more preferably equal to or greater than 44 g, and particularly preferably equal to or greater than 45.00 g. In light of satisfying the USGA standard, the mass is particularly preferably equal to or less than 45.93 g.

In the present invention, the JIS-C hardness at each measurement point is measured according to the distance from the center point of the core 4 to the surface. The distances of these measurement points from the center point of the core 4 are as follows.
First point 0.0mm
Second point 2.5mm
Third point 5.0mm
Fourth point 7.0mm
Fifth point 7.5mm
Sixth point 8.0mm
Seventh point 9.5mm
8th point 10.0mm
9th point 10.5mm
Tenth point 12.5mm
Eleventh point 15.0mm
12th point 17.5mm
Thirteenth surface The hardness from the first point to the twelfth point is measured by pressing a JIS-C type hardness meter against the cut surface of the hemisphere obtained by cutting the core 4. By pressing a JIS-C type hardness meter against the surface of the spherical core 4, the hardness of the thirteenth point is measured. For the measurement, an automatic rubber hardness measuring machine (trade name “P1” by Kobunshi Keiki Co., Ltd.) equipped with this hardness meter is used.

  FIG. 2 is a line graph showing the hardness distribution of the envelope layer 14 of the golf ball 2 of FIG. The horizontal axis of this graph is the distance (mm) from the center point of the core 4. The vertical axis of this graph is JIS-C hardness. In this graph, among the points included in the envelope layer 14, the sixth point, the eighth point, and the tenth to thirteenth points are plotted.

  FIG. 2 also shows a linear approximation curve obtained by the method of least squares based on the distance and hardness of each measurement point. This linear approximation curve is indicated by a dotted line. In FIG. 2, the broken line does not deviate significantly from the linear approximation curve. In other words, the polygonal line has a shape close to a linear approximation curve. In the envelope layer 14, the hardness increases linearly from the inside toward the outside. When the golf ball 2 is hit with a middle iron, there is little energy loss in the envelope layer 14. When the golf ball 2 is hit with a middle iron, the flight distance is large.

R ² of the linear approximation curve obtained by the least square method in the envelope layer 14 is preferably 0.95 or more. R ² is an index representing the linearity of the broken line. The envelope layer 14 having R ² of 0.95 or more has a shape of a broken line of the hardness distribution close to a straight line. The golf ball 2 including the envelope layer 14 having R ² of 0.95 or more has excellent resilience performance. R ² is more preferably 0.97 or more, and particularly preferably 0.99 or more. R ² is calculated by squaring the correlation coefficient R. The correlation coefficient R is obtained by dividing the covariance between the distance (mm) from the center and the hardness (JIS-C) by the standard deviation of the distance (mm) from the center and the standard deviation of the hardness (JIS-C). Is calculated by

  From the viewpoint of spin suppression, the slope α of this linear approximation curve is preferably 1.10 or more, more preferably 1.50 or more, and particularly preferably 1.70 or more.

  In the present invention, the JIS-C hardness of the measurement point whose distance from the center point of the core 4 is x (mm) is represented by H (x). The hardness of the center point of the core 4 is expressed as H (0.0). In the present invention, the JIS-C hardness of the surface of the core 4 is expressed as Hs. The difference (Hs−H (0.0)) between the surface hardness Hs and the center hardness H (0.0) is preferably 15 or more. The core 4 having a difference (Hs−H (0.0)) of 15 or more has an outer-hard / inner-soft structure. When the golf ball 2 is hit with a middle iron, the recoil (twisting back) in the core 4 is large, so that spin is suppressed. The core 4 contributes to the flight performance of the golf ball 2. In light of flight performance, the difference (Hs−H (0.0)) is more preferably 23 or greater and particularly preferably 24 or greater. From the viewpoint that the core 4 can be easily molded, the difference (Hs−H (0.0)) is preferably 50 or less. In the core 4, the hardness gradually increases from the center point toward the surface.

  The center 12 is formed by crosslinking a rubber composition. Examples of the base rubber of the rubber composition include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, and natural rubber. Two or more kinds of rubbers may be used in combination. From the viewpoint of resilience performance, polybutadiene is preferred, and high cis polybutadiene is particularly preferred.

  Preferably, the rubber composition of the center 12 includes a co-crosslinking agent. From the viewpoint of resilience performance, preferred co-crosslinking agents are acrylic acid, methacrylic acid, zinc acrylate, magnesium acrylate, zinc methacrylate and magnesium methacrylate. Preferably, the rubber composition further includes a metal compound. Examples of the metal compound include magnesium oxide and zinc oxide. Preferably, the rubber composition includes an organic peroxide together with a co-crosslinking agent. Preferred organic peroxides include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t-butyl). Peroxy) hexane and di-t-butyl peroxide. Preferably, the rubber composition includes a sulfur compound. The rubber composition may contain an acid and / or a salt.

  In the rubber composition of the center 12, various additives such as a filler, sulfur, a vulcanization accelerator, an anti-aging agent, a colorant, a plasticizer, and a dispersant are blended in appropriate amounts as necessary. Synthetic resin powder or crosslinked rubber powder may be blended with the rubber composition.

  In the present embodiment, the center 12 is preferably softer than the envelope layer 14. This center 12 can suppress spin. The center 12 preferably has a diameter of 8 mm or more and 24 mm or less. In the golf ball 2 including the center 12 having a diameter of 8 mm or more, spin can be suppressed. From this viewpoint, the diameter is more preferably 12 mm or more, and particularly preferably 14 mm or more. The golf ball 2 including the center 12 having a diameter of 24 mm or less has excellent resilience performance despite the fact that the center 12 is soft. In this respect, the diameter is more preferably 18 mm or less, and particularly preferably 16 mm or less.

The envelope layer 14 is formed by crosslinking a rubber composition. This rubber composition
(A) base rubber,
(B) a co-crosslinking agent,
(C) contains a crosslinking initiator and (d) an acid and / or salt.

  Examples of the base rubber (a) include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, and natural rubber. From the viewpoint of resilience performance, polybutadiene is preferred. When polybutadiene and other rubber are used in combination, it is preferable that polybutadiene is a main component. Specifically, the ratio of the amount of polybutadiene to the total amount of the base rubber is preferably 50% by mass or more, and more preferably 80% by mass or more. The ratio of cis-1,4 bonds in the polybutadiene is preferably 40% by mass or more, and more preferably 80% by mass or more.

  Polybutadiene having a 1,2-vinyl bond ratio of 2.0% by mass or less is preferred. This polybutadiene can contribute to the resilience performance of the golf ball 2. In this respect, the 1,2-vinyl bond ratio is preferably equal to or less than 1.7% by mass, and particularly preferably equal to or less than 1.5% by mass.

  From the viewpoint that a polybutadiene having a small ratio of 1,2-vinyl bonds and excellent polymerization activity can be obtained, a polybutadiene synthesized with a rare earth element-based catalyst is preferable. In particular, polybutadiene synthesized with a catalyst containing neodymium which is a lanthanum series rare earth element compound is preferable.

The Mooney viscosity (ML _{1 + 4} (100 ° C.)) of polybutadiene is preferably 30 or more, more preferably 32 or more, and particularly preferably 35 or more. The Mooney viscosity (ML _{1 + 4} (100 ° C.)) is preferably 140 or less, more preferably 120 or less, still more preferably 100, and particularly preferably 80 or less. Mooney viscosity (ML _{1 + 4} (100 ° C.)) is measured in accordance with the provisions of “JIS K6300”. The measurement conditions are as follows.
Rotor: L rotor Preheating time: 1 minute Rotor rotation time: 4 minutes Temperature: 100 ° C

  From the viewpoint of workability, the molecular weight distribution (Mw / Mn) of polybutadiene is preferably 2.0 or more, more preferably 2.2 or more, further preferably 2.4 or more, and particularly preferably 2.6 or more. In light of resilience performance, the molecular weight distribution (Mw / Mn) is preferably 6.0 or less, more preferably 5.0 or less, still more preferably 4.0 or less, and particularly preferably 3.4 or less. The molecular weight distribution (Mw / Mn) is calculated by dividing the weight average molecular weight Mw by the number average molecular weight Mn.

The molecular weight distribution is measured by gel permeation chromatography (“HLC-8120GPC” manufactured by Tosoh Corporation). The measurement conditions are as follows.
Detector: differential refractometer Column: GMHHXL (manufactured by Tosoh Corporation)
Column temperature: 40 ° C
Mobile phase: Tetrahydrofuran molecular weight distribution is calculated as a standard polystyrene equivalent value.

As a preferred co-crosslinking agent (b),
(B1) α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and (b2) metal salt of α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms .

  The rubber composition may contain only the α, β-unsaturated carboxylic acid (b1) or only the metal salt (b2) of the α, β-unsaturated carboxylic acid as the co-crosslinking agent (b). The rubber composition may contain both α, β-unsaturated carboxylic acid (b1) and α, β-unsaturated carboxylic acid metal salt (b2) as the co-crosslinking agent (b).

  The metal salt (b2) of α, β-unsaturated carboxylic acid crosslinks the rubber molecule by graft polymerization to the molecular chain of the base rubber. When the rubber composition contains an α, β-unsaturated carboxylic acid (b1), the rubber composition preferably further contains a metal compound (f). This metal compound (f) reacts with the α, β-unsaturated carboxylic acid (b1) in the rubber composition. The salt obtained by this reaction is graft-polymerized to the molecular chain of the base rubber.

  Examples of the metal compound (f) include metal hydroxides such as magnesium hydroxide, zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide and copper hydroxide; magnesium oxide, calcium oxide, Metal oxides such as zinc oxide and copper oxide; and metal carbonates such as magnesium carbonate, zinc carbonate, calcium carbonate, sodium carbonate, lithium carbonate and potassium carbonate. A compound containing a divalent metal is preferred. A compound containing a divalent metal reacts with the co-crosslinking agent (b) to form a metal bridge. A particularly preferred metal compound (f) is a zinc compound. Two or more metal compounds may be used in combination.

  Examples of the α, β-unsaturated carboxylic acid (b1) include acrylic acid, methacrylic acid, fumaric acid, maleic acid and crotonic acid. As a metal component in the metal salt (b2) of α, β-unsaturated carboxylic acid, sodium ion, potassium ion, lithium ion, magnesium ion, calcium ion, zinc ion, barium ion, cadmium ion, aluminum ion, tin ion and zirconium Examples are ions. The metal salt (b2) of α, β-unsaturated carboxylic acid may contain two or more kinds of ions. From the viewpoint that metal crosslinking between rubber molecules is likely to occur, divalent metal ions such as magnesium ion, calcium ion, zinc ion, barium ion and cadmium ion are preferable. A particularly preferred metal salt (b2) of α, β-unsaturated carboxylic acid is zinc acrylate.

  In light of the resilience performance of the golf ball 2, the amount of the co-crosslinking agent (b) is preferably 15 parts by mass or more and particularly preferably 20 parts by mass or more with respect to 100 parts by mass of the base rubber. In light of feel at impact, this amount is preferably equal to or less than 50 parts by weight, more preferably equal to or less than 45 parts by weight, and particularly preferably equal to or less than 40 parts by weight.

  A preferred crosslinking initiator (c) is an organic peroxide. The organic peroxide contributes to the resilience performance of the golf ball 2. Suitable organic peroxides include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t- Butyl peroxy) hexane and di-t-butyl peroxide. From the viewpoint of versatility, dicumyl peroxide is preferable.

  In light of the resilience performance of the golf ball 2, the amount of the crosslinking initiator (c) is preferably 0.2 parts by mass or more and particularly preferably 0.5 parts by mass or more with respect to 100 parts by mass of the base rubber. In light of feel at impact and durability of the golf ball 2, this amount is preferably equal to or less than 5.0 parts by weight, and particularly preferably equal to or less than 2.5 parts by weight.

  The acid component contained in the acid and / or salt (d) has reactivity with the cation component. The acid dissociates when the envelope layer 14 is heated and molded, and reacts with the cation component of the co-crosslinking agent (b). The acid is considered to inhibit metal crosslinking by the co-crosslinking agent (b) inside the envelope layer 14. The acid component contained in the salt exchanges a cation component with the co-crosslinking agent (b). It is presumed that the salt cuts the metal crosslinking by the co-crosslinking agent (b) when the envelope layer 14 is heated and formed.

  Acids and / or salts (d) include oxo acids such as carboxylic acids, sulfonic acids and phosphoric acids and salts thereof; and hydrogen acids such as hydrochloric acid and hydrofluoric acid and salts thereof. Oxo acids and their salts are preferred. From the viewpoint of affinity with the base rubber, preferred acid and / or salt (d) is carboxylic acid and / or salt (d1) thereof. In the present invention, the concept of acid and / or salt (d) does not include the co-crosslinking agent (b).

  From the viewpoint of reactivity with the co-crosslinking agent (b), the carboxylic acid component in the carboxylic acid and / or its salt (d1) preferably has 1 or more carbon atoms, and more preferably 4 or more. 30 or less are preferable and, as for carbon number of the carboxylic acid component in carboxylic acid and / or its salt (d1), 25 or less are especially preferable.

   Preferred carboxylic acids and / or salts (d1) thereof include aliphatic carboxylic acids (fatty acids) and salts thereof, and aromatic carboxylic acids and salts thereof. From the viewpoint of affinity with the base rubber, fatty acids and salts thereof are preferred. The rubber composition may contain a saturated fatty acid and a salt thereof, and may contain an unsaturated fatty acid and a salt thereof. Saturated fatty acids and salts thereof are more preferred.

  As fatty acids, butyric acid (C4), valeric acid (C5), caproic acid (C6), enanthic acid (C7), caprylic acid (octanoic acid) (C8), pelargonic acid (C9), capric acid (decanoic acid) (C10) ), Lauric acid (C12), myristic acid (C14), myristoleic acid (C14), pentadecylic acid (C15), palmitic acid (C16), palmitoleic acid (C16), margaric acid (C17), stearic acid (C18) , Elaidic acid (C18), vaccenic acid (C18), oleic acid (C18), linoleic acid (C18), linolenic acid (C18), 12-hydroxystearic acid (C18), arachidic acid (C20), gadoleic acid (C20) ), Arachidonic acid (C20), eicosenoic acid (C20), behenic acid (C22), erucic acid (C22), Noserin acid (C24), nervonic acid (C24), cerotic acid (C26), montanic acid (C28) and melissic acid (C30) can be mentioned. Two or more fatty acids may be used in combination. Caprylic acid (octanoic acid), lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and behenic acid are preferred.

  The aromatic carboxylic acid has an aromatic ring and a carboxyl group. As aromatic carboxylic acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid (benzene-1,2,3-tricarboxylic acid), trimellitic acid (benzene-1,2,4-tricarboxylic acid), Trimesic acid (benzene-1,3,5-tricarboxylic acid), merophanic acid (benzene-1,2,3,4-tetracarboxylic acid), planitic acid (benzene-1,2,3,5-tetracarboxylic acid) , Pyromellitic acid (benzene-1,2,4,5-tetracarboxylic acid), meritic acid (benzenehexacarboxylic acid), diphenic acid (biphenyl-2,2'-dicarboxylic acid), toluic acid (methylbenzoic acid) , Xylic acid, prenylic acid (2,3,4-trimethylbenzoic acid), γ-isoduric acid (2,3,5-trimethylbenzoic acid), duric acid 2,4,5-trimethylbenzoic acid), β-isoduric acid (2,4,6-trimethylbenzoic acid), α-isoduric acid (3,4,5-trimethylbenzoic acid), cumic acid (4-isopropylbenzoic acid) Acid), ubitoic acid (5-methylisophthalic acid), α-toluic acid (phenylacetic acid), hydroatropic acid (2-phenylpropanoic acid) and hydrocinnamic acid (3-phenylpropanoic acid).

  The rubber composition may include an aromatic carboxylic acid substituted with a hydroxyl group, an alkoxy group, or an oxo group. Examples of the carboxylic acid include salicylic acid (2-hydroxybenzoic acid), anisic acid (methoxybenzoic acid), cresotic acid (hydroxy (methyl) benzoic acid), o-homosalicylic acid (2-hydroxy-3-methylbenzoic acid), m-homosalicylic acid (2-hydroxy-4-methylbenzoic acid), p-homosalicylic acid (2-hydroxy-5-methylbenzoic acid), o-pyrocatechuic acid (2,3-dihydroxybenzoic acid), β-resorcylic acid (2,4-dihydroxybenzoic acid), γ-resorcylic acid (2,6-dihydroxybenzoic acid), protocatechuic acid (3,4-dihydroxybenzoic acid), α-resorcylic acid (3,5-dihydroxybenzoic acid), Vanillic acid (4-hydroxy-3-methoxybenzoic acid), isovanillic acid (3-hydroxy-4-methoxybenzoic acid), Ratrumic acid (3,4-dimethoxybenzoic acid), o-veratormic acid (2,3-dimethoxybenzoic acid), orthoric acid (2,4-dihydroxy-6-methylbenzoic acid), m-hemipic acid (4,5 -Dimethoxyphthalic acid), gallic acid (3,4,5-trihydroxybenzoic acid), syringic acid (4-hydroxy-3,5-dimethoxybenzoic acid), asaronic acid (2,4,5-trimethoxybenzoic acid) , Mandelic acid (hydroxy (phenyl) acetic acid), vanylmandelic acid (hydroxy (4-hydroxy-3-methoxyphenyl) acetic acid), homoanisic acid ((4-methoxyphenyl) acetic acid), homogentisic acid ((2,5-dihydroxyphenyl) ) Acetic acid), homoprotocatechuic acid ((3,4-dihydroxyphenyl) acetic acid), homovanillic acid ((4-hydroxy- -Methoxyphenyl) acetic acid), homoisovanillic acid ((3-hydroxy-4-methoxyphenyl) acetic acid), homoveratrumic acid ((3,4-dimethoxyphenyl) acetic acid), o-homoveratric acid ((2,3-dimethoxy) Phenyl) acetic acid), homophthalic acid (2- (carboxymethyl) benzoic acid), homoisophthalic acid (3- (carboxymethyl) benzoic acid), homoterephthalic acid (4- (carboxymethyl) benzoic acid), phthalonic acid (2 -(Carboxycarbonyl) benzoic acid), isophthalonic acid (3- (carboxycarbonyl) benzoic acid), terephthalonic acid (4- (carboxycarbonyl) benzoic acid), benzylic acid (hydroxydiphenylacetic acid), atrolactic acid (2-hydroxy) -2-phenylpropanoic acid), tropic acid (3-hydroxy-2-phenyl) Phenylpropanoic acid), mellilotic acid (3- (2-hydroxyphenyl) propanoic acid), furoleto acid (3- (4-hydroxyphenyl) propanoic acid), hydrocaffeic acid (3- (3,4-dihydroxyphenyl) propane Acid), hydroferulic acid (3- (4-hydroxy-3-methoxyphenyl) propanoic acid), hydroisoferulic acid (3- (3-hydroxy-4-methoxyphenyl) propanoic acid), p-coumaric acid (3 -(4-hydroxyphenyl) acrylic acid), umbelic acid (3- (2,4-dihydroxyphenyl) acrylic acid), caffeic acid (3- (3,4-dihydroxyphenyl) acrylic acid), ferulic acid (3- (4-hydroxy-3-methoxyphenyl) acrylic acid), isoferulic acid (3- (3-hydroxy-4-methoxypheny) ) Acrylic acid) and sinapinic acid (3- (4-hydroxy-3,5-dimethoxyphenyl) acrylic acid) may be exemplified.

  The cation component contained in the acid and / or salt (d) is a metal ion or an organic cation. As metal ions, sodium ion, potassium ion, lithium ion, silver ion, magnesium ion, calcium ion, zinc ion, barium ion, cadmium ion, copper ion, cobalt ion, nickel ion, manganese ion, aluminum ion, iron ion, tin Examples include ions, zirconium ions, and titanium ions. Two or more ions may be used in combination. Zinc ions and magnesium ions are preferred.

  The organic cation has a carbon chain. An organic ammonium ion is mentioned as an organic cation. As organic ammonium ions, primary ammonium ions such as stearyl ammonium ion, hexyl ammonium ion, octyl ammonium ion and 2-ethylhexyl ammonium ion; secondary ammonium ions such as dodecyl (lauryl) ammonium ion and octadecyl (stearyl) ammonium ion A tertiary ammonium ion such as trioctylammonium ion; and a quaternary ammonium ion such as dioctyldimethylammonium ion and distearyldimethylammonium ion. Two or more organic cations may be used in combination.

  In view of the ease of the cation exchange reaction, fatty acid salts are particularly preferred. Fatty acids and fatty acid salts may be used in combination, or two or more fatty acid salts may be used in combination.

  Preferred carboxylic acids and / or salts thereof (d1) include octanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and behenic acid potassium salt, magnesium salt, aluminum salt, zinc salt, iron salt, copper Salts, nickel salts and cobalt salts are exemplified. A zinc salt of a carboxylic acid is particularly preferred. Specific examples of preferred carboxylic acids and / or salts thereof (d1) include zinc octoate, zinc laurate, zinc myristate and zinc stearate.

  From the viewpoint of the linearity of the hardness distribution of the envelope layer 14, the amount of the acid and / or salt (d) is preferably 0.5 parts by mass or more, and 1.0 part by mass or more with respect to 100 parts by mass of the base rubber. More preferred is 2.0 parts by mass or more. In light of resilience performance, this amount is preferably equal to or less than 40 parts by weight, more preferably equal to or less than 30 parts by weight, and particularly preferably equal to or less than 20 parts by weight.

  The mass ratio between the co-crosslinking agent (b) and the acid and / or salt (d) in the rubber composition is preferably 3/7 or more and 9/1 or less, particularly preferably 4/6 or more and 8/2 or less. With the rubber composition having a mass ratio within the above range, the core 4 having an appropriate hardness distribution can be obtained.

  As the co-crosslinking agent (b), zinc acrylate is preferably used. For the purpose of improving dispersibility in rubber, there is zinc acrylate whose surface is coated with stearic acid or zinc stearate. When this zinc acrylate is contained in the rubber composition, stearic acid or zinc stearate coated on zinc acrylate is not included in the concept of acid and / or salt (d).

  Preferably, the rubber composition further includes an organic sulfur compound (e). The organic sulfur compound (e) can contribute to control of the linearity of the hardness distribution of the envelope layer 14 and the degree of the outer-hard / inner-soft structure. Examples of the organic sulfur compound (e) include organic compounds having a thiol group or a polysulfide bond having 2 to 4 sulfur atoms. The metal salt of this organic compound is also included in the organic sulfur compound (e). As the organic sulfur compound (e), aliphatic compounds such as aliphatic thiols, aliphatic thiocarboxylic acids, aliphatic dithiocarboxylic acids and aliphatic polysulfides; heterocyclic compounds; alicyclic thiols, alicyclic thiocarboxylic acids, fats Illustrative are alicyclic compounds such as cyclic dithiocarboxylic acids and alicyclic polysulfides; and aromatic compounds. Specific examples of the organic sulfur compound (e) include thiophenols, thionaphthols, polysulfides, thiocarboxylic acids, dithiocarboxylic acids, sulfenamides, thiurams, dithiocarbamates and thiazoles. Preferred organic sulfur compounds (e) are thiophenols, diphenyl disulfides, thionaphthols and thiuram disulfides and metal salts thereof.

  Specific examples of the organic sulfur compound (e) are represented by the following chemical formulas (1) to (4).

  In the chemical formula (1), R1 to R5 each represent H or a substituent.

  In the chemical formula (2), R1 to R10 each represent H or a substituent.

  In the chemical formula (3), R1 to R5 each represent H or a substituent, and M1 represents a monovalent metal atom.

  In the chemical formula (4), R1 to R10 each represent H or a substituent, and M2 represents a divalent metal atom.

In the above formulas (1) to (4), the substituent is a halogen group (F, Cl, Br, I), an alkyl group, a carboxyl group (—COOH), an ester of a carboxyl group (—COOR), a formyl group (— CHO), acyl group (—COR), halogenated carbonyl group (—COX), sulfo group (—SO ₃ H), ester of sulfo group (—SO ₃ R), halogenated sulfonyl group (—SO ₂ X), Selected from the group consisting of a sulfino group (—SO ₂ H), an alkylsulfinyl group (—SOR), a carbamoyl group (—CONH ₂ ), a halogenated alkyl group, a cyano group (—CN) and an alkoxy group (—OR). At least one kind.

  Examples of the organic sulfur compound represented by the chemical formula (1) include thiophenol; 4-fluorothiophenol, 2,5-difluorothiophenol, 2,4,5-trifluorothiophenol, 2,4,5. , 6-tetrafluorothiophenol, pentafluorothiophenol, 2-chlorothiophenol, 4-chlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 2,6-dichlorothiophenol, 2 , 4,5-trichlorothiophenol, 2,4,5,6-tetrachlorothiophenol, pentachlorothiophenol, 4-bromothiophenol, 2,5-dibromothiophenol, 2,4,5-tribromothio Phenol, 2,4,5,6-tetrabromothiophenol, pentabromothiol Halogen groups such as diol, 4-iodothiophenol, 2,5-diiodothiophenol, 2,4,5-triiodothiophenol, 2,4,5,6-tetraiodothiophenol and pentaiodothiophenol 4-methylthiophenol, 2,4,5-trimethylthiophenol, pentamethylthiophenol, 4-t-butylthiophenol, 2,4,5-tri-t-butylthiophenol and penta Thiophenols substituted with alkyl groups such as t-butylthiophenol; Thio substituted with carboxyl groups such as 4-carboxythiophenol, 2,4,6-tricarboxythiophenol and pentacarboxythiophenol Phenols; 4-methoxycarbonylthiophenol Thiophenols substituted with alkoxycarbonyl groups such as 2,4,6-trimethoxycarbonylthiophenol and pentamethoxycarbonylthiophenol; 4-formylthiophenol, 2,4,6-triformylthiophenol and pentaformyl Thiophenols substituted with formyl groups such as thiophenol; Thiophenols substituted with acyl groups such as 4-acetylthiophenol, 2,4,6-triacetylthiophenol and pentaacetylthiophenol; 4 Thiophenols substituted with carbonyl halide groups such as chlorocarbonylthiophenol, 2,4,6-tri (chlorocarbonyl) thiophenol and penta (chlorocarbonyl) thiophenol; 4-sulfothiophenol, 2, 4,6 -Thiophenols substituted with sulfo groups such as trisulfothiophenol and pentasulfothiophenol; such as 4-methoxysulfonylthiophenol, 2,4,6-trimethoxysulfonylthiophenol and pentamethoxysulfonylthiophenol Thiophenols substituted with alkoxysulfonyl groups; substituted with halogenated sulfonyl groups such as 4-chlorosulfonylthiophenol, 2,4,6-tri (chlorosulfonyl) thiophenol and penta (chlorosulfonyl) thiophenol Thiophenols; thiophenols substituted with sulfino groups such as 4-sulfinothiophenol, 2,4,6-trisulfinothiophenol and pentasulfinothiophenol; 4-methylsulfinylthiopheno Thiophenols substituted with alkylsulfinyl groups such as 2,4,6-tri (methylsulfinyl) thiophenol and penta (methylsulfinyl) thiophenol; 4-carbamoylthiophenol, 2,4,6-tri Thiophenols substituted with carbamoyl groups such as carbamoylthiophenol and pentacarbamoylthiophenol; such as 4-trichloromethylthiophenol, 2,4,6-tri (trichloromethyl) thiophenol and penta (trichloromethyl) thiophenol Thiophenols substituted with various halogenated alkyl groups; thiophenols substituted with cyano groups such as 4-cyanothiophenol, 2,4,6-tricyanothiophenol and pentacyanothiophenol; and 4-meth Shi thiophenol, thiophenols substituted with an alkoxy group such as 2,4,6-methoxythiophenol and penta-methoxy thiophenol and the like. These thiophenols are substituted with one type of substituent.

As another example of the organic sulfur compound represented by the chemical formula (1), a compound substituted with at least one kind of the above substituent and another substituent can be given. Examples of other substituents include a nitro group (—NO ₂ ), an amino group (—NH ₂ ), a hydroxyl group (—OH), and a phenylthio group (—SPh). Specific examples of this compound include 4-chloro-2-nitrothiophenol, 4-chloro-2-aminothiophenol, 4-chloro-2-hydroxythiophenol, 4-chloro-2-phenylthiothiophenol, 4 -Methyl-2-nitrothiophenol, 4-methyl-2-aminothiophenol, 4-methyl-2-hydroxythiophenol, 4-methyl-2-phenylthiothiophenol, 4-carboxy-2-nitrothiophenol, 4-carboxy-2-aminothiophenol, 4-carboxy-2-hydroxythiophenol, 4-carboxy-2-phenylthiothiophenol, 4-methoxycarbonyl-2-nitrothiophenol, 4-methoxycarbonyl-2-amino Thiophenol, 4-methoxycarbonyl-2-hydroxy Thiophenol, 4-methoxycarbonyl-2-phenylthiothiophenol, 4-formyl-2-nitrothiophenol, 4-formyl-2-aminothiophenol, 4-formyl-2-hydroxythiophenol, 4-formyl-2 -Phenylthiothiophenol, 4-acetyl-2-nitrothiophenol, 4-acetyl-2-aminothiophenol, 4-acetyl-2-hydroxythiophenol, 4-acetyl-2-phenylthiothiophenol, 4-chloro Carbonyl-2-nitrothiophenol, 4-chlorocarbonyl-2-aminothiophenol, 4-chlorocarbonyl-2-hydroxythiophenol, 4-chlorocarbonyl-2-phenylthiothiophenol, 4-sulfo-2-nitrothio Phenol, 4-sulfo- -Aminothiophenol, 4-sulfo-2-hydroxythiophenol, 4-sulfo-2-phenylthiothiophenol, 4-methoxysulfonyl-2-nitrothiophenol, 4-methoxysulfonyl-2-aminothiophenol, 4- Methoxysulfonyl-2-hydroxythiophenol, 4-methoxysulfonyl-2-phenylthiothiophenol, 4-chlorosulfonyl-2-nitrothiophenol, 4-chlorosulfonyl-2-aminothiophenol, 4-chlorosulfonyl-2- Hydroxythiophenol, 4-chlorosulfonyl-2-phenylthiothiophenol, 4-sulfino-2-nitrothiophenol, 4-sulfino-2-aminothiophenol, 4-sulfino-2-hydroxythiophenol, 4-sulfino 2-phenylthiothiophenol, 4-methylsulfinyl-2-nitrothiophenol, 4-methyl-2-aminosulfinylthiophenol, 4-methylsulfinyl-2-hydroxythiophenol, 4-methylsulfinyl-2-phenylthio Thiophenol, 4-carbamoyl-2-nitrothiophenol, 4-carbamoyl-2-aminothiophenol, 4-carbamoyl-2-hydroxythiophenol, 4-carbamoyl-2-phenylthiothiophenol, 4-trichloromethyl-2 -Nitrothiophenol, 4-trichloromethyl-2-aminothiophenol, 4-trichloromethyl-2-hydroxythiophenol, 4-trichloromethyl-2-phenylthiothiophenol, 4-cyano-2-nitrothiopheno 4-cyano-2-aminothiophenol, 4-cyano-2-hydroxythiophenol, 4-cyano-2-phenylthiothiophenol, 4-methoxy-2-nitrothiophenol, 4-methoxy-2-aminothio Examples include phenol, 4-methoxy-2-hydroxythiophenol and 4-methoxy-2-phenylthiothiophenol.

  Still another example of the organic sulfur compound represented by the chemical formula (1) includes a compound substituted with two or more kinds of substituents. Specific examples of this compound include 4-acetyl-2-chlorothiophenol, 4-acetyl-2-methylthiophenol, 4-acetyl-2-carboxythiophenol, 4-acetyl-2-methoxycarbonylthiophenol, 4-acetyl 2-formylthiophenol, 4-acetyl-2-chlorocarbonylthiophenol, 4-acetyl-2-sulfothiophenol, 4-acetyl-2-methoxysulfonylthiophenol, 4-acetyl-2-chlorosulfonylthiophenol, 4-acetyl-2-sulfinothiophenol, 4-acetyl-2-methylsulfinylthiophenol, 4-acetyl-2-carbamoylthiophenol, 4-acetyl-2-trichloromethylthiophenol, 4-acetyl-2-cyanothio Phenol Beauty 4-acetyl-2-methoxy-thiophenol and the like.

  Examples of the organic sulfur compound represented by the chemical formula (2) include diphenyl disulfide; bis (4-fluorophenyl) disulfide, bis (2,5-difluorophenyl) disulfide, bis (2,4,5-trifluoro). Phenyl) disulfide, bis (2,4,5,6-tetrafluorophenyl) disulfide, bis (pentafluorophenyl) disulfide, bis (4-chlorophenyl) disulfide, bis (2,5-dichlorophenyl) disulfide, bis (2, 4,5-trichlorophenyl) disulfide, bis (2,4,5,6-tetrachlorophenyl) disulfide, bis (pentachlorophenyl) disulfide, bis (4-bromophenyl) disulfide, bis (2,5-dibromophenyl) disulfide , Screws (2, 4, -Tribromophenyl) disulfide, bis (2,4,5,6-tetrabromophenyl) disulfide, bis (pentabromophenyl) disulfide, bis (4-iodophenyl) disulfide, bis (2,5-diiodophenyl) Diphenyl disulfides substituted with halogen groups such as disulfide, bis (2,4,5-triiodophenyl) disulfide, bis (2,4,5,6-tetraiodophenyl) disulfide and bis (pentaiodophenyl) disulfide Bis (4-methylphenyl) disulfide, bis (2,4,5-trimethylphenyl) disulfide, bis (pentamethylphenyl) disulfide, bis (4-t-butylphenyl) disulfide, bis (2,4,5) -Tri-t-butylphenyl) disulfide Diphenyl disulfides substituted with alkyl groups such as bis (penta-t-butylphenyl) disulfide; bis (4-carboxyphenyl) disulfide, bis (2,4,6-tricarboxyphenyl) disulfide and bis (penta Diphenyl disulfides substituted with carboxyl groups such as carboxyphenyl) disulfide; bis (4-methoxycarbonylphenyl) disulfide, bis (2,4,6-trimethoxycarbonylphenyl) disulfide and bis (pentamethoxycarbonylphenyl) disulfide Diphenyl disulfides substituted with alkoxycarbonyl groups such as: bis (4-formylphenyl) disulfide, bis (2,4,6-triformylphenyl) disulfide and bis (pentaformyl) Diphenyl disulfides substituted with formyl groups such as phenyl) disulfide; acyls such as bis (4-acetylphenyl) disulfide, bis (2,4,6-triacetylphenyl) disulfide and bis (pentaacetylphenyl) disulfide Group substituted diphenyl disulfides; halogens such as bis (4-chlorocarbonylphenyl) disulfide, bis (2,4,6-tri (chlorocarbonyl) phenyl) disulfide and bis (penta (chlorocarbonyl) phenyl) disulfide Diphenyl disulfides substituted with a carbonyl group; substituted with sulfo groups such as bis (4-sulfophenyl) disulfide, bis (2,4,6-trisulfophenyl) disulfide and bis (pentasulfophenyl) disulfide Diphenyl disulfides; diphenyls substituted with alkoxysulfonyl groups such as bis (4-methoxysulfonylphenyl) disulfide, bis (2,4,6-trimethoxysulfonylphenyl) disulfide and bis (pentamethoxysulfonylphenyl) disulfide Disulfides; substituted with sulfonyl halides such as bis (4-chlorosulfonylphenyl) disulfide, bis (2,4,6-tri (chlorosulfonyl) phenyl) disulfide and bis (penta (chlorosulfonyl) phenyl) disulfide Diphenyl disulfides; such as bis (4-sulfinophenyl) disulfide, bis (2,4,6-trisulfinophenyl) disulfide and bis (pentasulfinophenyl) disulfide Diphenyl disulfides substituted with a rufino group; such as bis (4-methylsulfinylphenyl) disulfide, bis (2,4,6-tri (methylsulfinyl) phenyl) disulfide and bis (penta (methylsulfinyl) phenyl) disulfide Diphenyl disulfides substituted with alkylsulfinyl groups; substituted with carbamoyl groups such as bis (4-carbamoylphenyl) disulfide, bis (2,4,6-tricarbamoylphenyl) disulfide and bis (pentacarbamoylphenyl) disulfide Diphenyl disulfides; bis (4-trichloromethylphenyl) disulfide, bis (2,4,6-tri (trichloromethyl) phenyl) disulfide and bis (penta (trichloromethyl) phenyl) Diphenyl disulfides substituted with halogenated alkyl groups such as disulfides; cyano such as bis (4-cyanophenyl) disulfide, bis (2,4,6-tricyanophenyl) disulfide and bis (pentacyanophenyl) disulfide Substituted diphenyl disulfides; and diphenyl substituted with alkoxy groups such as bis (4-methoxyphenyl) disulfide, bis (2,4,6-trimethoxyphenyl) disulfide and bis (pentamethoxyphenyl) disulfide Disulfides are exemplified. These diphenyl disulfides are substituted with one type of substituent.

As another example of the organic sulfur compound represented by the chemical formula (2), a compound substituted with at least one kind of the substituent and another substituent can be given. Examples of other substituents include a nitro group (—NO ₂ ), an amino group (—NH ₂ ), a hydroxyl group (—OH), and a phenylthio group (—SPh). Specific examples of this compound include bis (4-chloro-2-nitrophenyl) disulfide, bis (4-chloro-2-aminophenyl) disulfide, bis (4-chloro-2-hydroxyphenyl) disulfide, bis (4 -Chloro-2-phenylthiophenyl) disulfide, bis (4-methyl-2-nitrophenyl) disulfide, bis (4-methyl-2-aminophenyl) disulfide, bis (4-methyl-2-hydroxyphenyl) disulfide, Bis (4-methyl-2-phenylthiophenyl) disulfide, bis (4-carboxy-2-nitrophenyl) disulfide, bis (4-carboxy-2-aminophenyl) disulfide, bis (4-carboxy-2-hydroxyphenyl) ) Disulfide, bis (4-carboxy-2-fe) Ruthiophenyl) disulfide, bis (4-methoxycarbonyl-2-nitrophenyl) disulfide, bis (4-methoxycarbonyl-2-aminophenyl) disulfide, bis (4-methoxycarbonyl-2-hydroxyphenyl) disulfide, bis (4 -Methoxycarbonyl-2-phenylthiophenyl) disulfide, bis (4-formyl-2-nitrophenyl) disulfide, bis (4-formyl-2-aminophenyl) disulfide, bis (4-formyl-2-hydroxyphenyl) disulfide Bis (4-formyl-2-phenylthiophenyl) disulfide, bis (4-acetyl-2-nitrophenyl) disulfide, bis (4-acetyl-2-aminophenyl) disulfide, bis (4-acetyl-2-hydroxy) Enyl) disulfide, bis (4-acetyl-2-phenylthiophenyl) disulfide, bis (4-chlorocarbonyl-2-nitrophenyl) disulfide, bis (4-chlorocarbonyl-2-aminophenyl) disulfide, bis (4- Chlorocarbonyl-2-hydroxyphenyl) disulfide, bis (4-chlorocarbonyl-2-phenylthiophenyl) disulfide, bis (4-sulfo-2-nitrophenyl) disulfide, bis (4-sulfo-2-aminophenyl) disulfide Bis (4-sulfo-2-hydroxyphenyl) disulfide, bis (4-sulfo-2-phenylthiophenyl) disulfide, bis (4-methoxysulfonyl-2-nitrophenyl) disulfide, bis (4-methoxysulfonyl-2) -Aminofe Nyl) disulfide, bis (4-methoxysulfonyl-2-hydroxyphenyl) disulfide, bis (4-methoxysulfonyl-2-phenylthiophenyl) disulfide, bis (4-chlorosulfonyl-2-nitrophenyl) disulfide, bis (4 -Chlorosulfonyl-2-aminophenyl) disulfide, bis (4-chlorosulfonyl-2-hydroxyphenyl) disulfide, bis (4-chlorosulfonyl-2-phenylthiophenyl) disulfide, bis (4-sulfino-2-nitrophenyl) ) Disulfide, bis (4-sulfino-2-aminophenyl) disulfide, bis (4-sulfino-2-hydroxyphenyl) disulfide, bis (4-sulfino-2-phenylthiophenyl) disulfide, bis (4-methyl) Rufinyl-2-nitrophenyl) disulfide, bis (4-methylsulfinyl-2-aminophenyl) disulfide, bis (4-methylsulfinyl-2-hydroxyphenyl) disulfide, bis (4-methylsulfinyl-2-phenylthiophenyl) Disulfide, bis (4-carbamoyl-2-nitrophenyl) disulfide, bis (4-carbamoyl-2-aminophenyl) disulfide, bis (4-carbamoyl-2-hydroxyphenyl) disulfide, bis (4-carbamoyl-2-phenyl) Thiophenyl) disulfide, bis (4-trichloromethyl-2-nitrophenyl) disulfide, bis (4-trichloromethyl-2-aminophenyl) disulfide, bis (4-trichloromethyl-2-hydroxyphenyl) Disulfide, bis (4-trichloromethyl-2-phenylthiophenyl) disulfide, bis (4-cyano-2-nitrophenyl) disulfide, bis (4-cyano-2-aminophenyl) disulfide, bis (4-cyano-2) -Hydroxyphenyl) disulfide, bis (4-cyano-2-phenylthiophenyl) disulfide, bis (4-methoxy-2-nitrophenyl) disulfide, bis (4-methoxy-2-aminophenyl) disulfide, bis (4- Methoxy-2-hydroxyphenyl) disulfide and bis (4-methoxy-2-phenylthiophenyl) disulfide.

  Still another example of the organic sulfur compound represented by the chemical formula (2) includes a compound substituted with two or more kinds of substituents. Specific examples of this compound include bis (4-acetyl-2-chlorophenyl) disulfide, bis (4-acetyl-2-methylphenyl) disulfide, bis (4-acetyl-2-carboxyphenyl) disulfide, and bis (4-acetyl). -2-methoxycarbonylphenyl) disulfide, bis (4-acetyl-2-formylphenyl) disulfide, bis (4-acetyl-2-chlorocarbonylphenyl) disulfide, bis (4-acetyl-2-sulfophenyl) disulfide, bis (4-acetyl-2-methoxysulfonylphenyl) disulfide, bis (4-acetyl-2-chlorosulfonylphenyl) disulfide, bis (4-acetyl-2-sulfinophenyl) disulfide, bis (4-acetyl-2-methyl) Sulfinylfe Di) disulfide, bis (4-acetyl-2-carbamoylphenyl) disulfide, bis (4-acetyl-2-trichloromethylphenyl) disulfide, bis (4-acetyl-2-cyanophenyl) disulfide and bis (4-acetyl-) 2-methoxyphenyl) disulfide.

  Examples of the organic sulfur compound represented by the chemical formula (3) include thiophenol sodium salt; 4-fluorothiophenol sodium salt, 2,5-difluorothiophenol sodium salt, 2,4,5-trifluorothiophenol. Sodium salt, 2,4,5,6-tetrafluorothiophenol sodium salt, pentafluorothiophenol sodium salt, 4-chlorothiophenol sodium salt, 2,5-dichlorothiophenol sodium salt, 2,4,5-trichloro Thiophenol sodium salt, 2,4,5,6-tetrachlorothiophenol sodium salt, pentachlorothiophenol sodium salt, 4-bromothiophenol sodium salt, 2,5-dibromothiophenol sodium salt, 2,4,5 -Tribromothiophene Sodium salt, 2,4,5,6-tetrabromothiophenol sodium salt, pentabromothiophenol sodium salt, 4-iodothiophenol sodium salt, 2,5-diiodothiophenol sodium salt, 2,4,5- Thiophenol sodium salts substituted with halogen groups such as triiodothiophenol sodium salt, 2,4,5,6-tetraiodothiophenol sodium salt and pentaiodothiophenol sodium salt; 4-methylthiophenol sodium salt, 2 , 4,5-trimethylthiophenol sodium salt, pentamethylthiophenol sodium salt, 4-t-butylthiophenol sodium salt, 2,4,5-tri-t-butylthiophenol sodium salt and penta (t-butyl) thio Phenol nato Thiophenol sodium salts substituted with alkyl groups such as um salt; substituted with carboxyl groups such as 4-carboxythiophenol sodium salt, 2,4,6-tricarboxythiophenol sodium salt and pentacarboxythiophenol sodium salt Thiophenol sodium salts; sodium thiophenol substituted with alkoxycarbonyl groups such as 4-methoxycarbonylthiophenol sodium salt, 2,4,6-trimethoxycarbonylthiophenol sodium salt and pentamethoxycarbonylthiophenol sodium salt Salts; substituted with formyl groups such as 4-formylthiophenol sodium salt, 2,4,6-triformylthiophenol sodium salt and pentaformylthiophenol sodium salt Thiophenol sodium salts; thiophenol sodium salts substituted with acyl groups such as 4-acetylthiophenol sodium salt, 2,4,6-triacetylthiophenol sodium salt and pentaacetylthiophenol sodium salt; Thiophenol sodium salts substituted with halogenated carbonyl groups such as chlorocarbonylthiophenol sodium salt, 2,4,6-tri (chlorocarbonyl) thiophenol sodium salt and penta (chlorocarbonyl) thiophenol sodium salt; Thiophenol sodium salts substituted with a sulfo group such as sulfothiophenol sodium salt, 2,4,6-trisulfothiophenol sodium salt and pentasulfothiophenol sodium salt; Thiophenol sodium salts substituted with alkoxysulfonyl groups such as sodium nylthiophenol, sodium salt of 2,4,6-trimethoxysulfonylthiophenol and sodium salt of pentamethoxysulfonylthiophenol; sodium salt of 4-chlorosulfonylthiophenol 1,4,6-tri (chlorosulfonyl) thiophenol sodium salt and thiophenol sodium salts substituted with a sulfonyl halide group such as penta (chlorosulfonyl) thiophenol sodium salt; 4-sulfinothiophenol sodium salt Thiophenol sodium salts substituted with sulfino groups such as 2,4,6-trisulfinothiophenol sodium salt and pentasulfinothiophenol sodium salt; Thiophenol sodium salts substituted with alkylsulfinyl groups such as sulfinylthiophenol sodium salt, 2,4,6-tri (methylsulfinyl) thiophenol sodium salt and penta (methylsulfinyl) thiophenol sodium salt; 4-carbamoyl Thiophenol sodium salts substituted with carbamoyl groups such as thiophenol sodium salt, 2,4,6-tricarbamoylthiophenol sodium salt and pentacarbamoyl thiophenol sodium salt; 4-trichloromethylthiophenol sodium salt, 2,4,4 Thiophenols substituted with alkyl halide groups such as 6-tri (trichloromethyl) thiophenol sodium salt and penta (trichloromethyl) thiophenol sodium salt Sodium salts; thiophenol sodium salts substituted with cyano groups such as 4-cyanothiophenol sodium salt, 2,4,6-tricyanothiophenol sodium salt and pentacyanothiophenol sodium salt; and 4-methoxythiophenol sodium Illustrative are thiophenol sodium salts substituted with alkoxy groups such as salts, 2,4,6-trimethoxythiophenol sodium salt and pentamethoxythiophenol sodium salt. These thiophenol sodium salts are substituted with one kind of substituent.

As another example of the organic sulfur compound represented by the chemical formula (3), a compound substituted with at least one kind of the above substituent and another substituent can be given. Examples of other substituents include a nitro group (—NO ₂ ), an amino group (—NH ₂ ), a hydroxyl group (—OH), and a phenylthio group (—SPh). Specific examples of this compound include 4-chloro-2-nitrothiophenol sodium salt, 4-chloro-2-aminothiophenol sodium salt, 4-chloro-2-hydroxythiophenol sodium salt, 4-chloro-2- Phenylthiothiophenol sodium salt, 4-methyl-2-nitrothiophenol sodium salt, 4-methyl-2-aminothiophenol sodium salt, 4-methyl-2-hydroxythiophenol sodium salt, 4-methyl-2-phenyl Thiothiophenol sodium salt, 4-carboxy-2-nitrothiophenol sodium salt, 4-carboxy-2-aminothiophenol sodium salt, 4-carboxy-2-hydroxythiophenol sodium salt, 4-carboxy-2-phenylthio Thiophenol natri Salt, 4-methoxycarbonyl-2-nitrothiophenol sodium salt, 4-methoxycarbonyl-2-aminothiophenol sodium salt, 4-methoxycarbonyl-2-hydroxythiophenol sodium salt, 4-methoxycarbonyl-2-phenyl Thiothiophenol sodium salt, 4-formyl-2-nitrothiophenol sodium salt, 4-formyl-2-aminothiophenol sodium salt, 4-formyl-2-hydroxythiophenol sodium salt, 4-formyl-2-phenylthio Thiophenol sodium salt, 4-acetyl-2-nitrothiophenol sodium salt, 4-acetyl-2-aminothiophenol sodium salt, 4-acetyl-2-hydroxythiophenol sodium salt, 4-acetyl-2-phenol Ruthiothiophenol sodium salt, 4-chlorocarbonyl-2-nitrothiophenol sodium salt, 4-chlorocarbonyl-2-aminothiophenol sodium salt, 4-chlorocarbonyl-2-hydroxythiophenol sodium salt, 4-chlorocarbonyl- 2-phenylthiothiophenol sodium salt, 4-sulfo-2-nitrothiophenol sodium salt, 4-sulfo-2-aminothiophenol sodium salt, 4-sulfo-2-hydroxythiophenol sodium salt, 4-sulfo-2 -Phenylthiothiophenol sodium salt, 4-methoxysulfonyl-2-nitrothiophenol sodium salt, 4-methoxysulfonyl-2-aminothiophenol sodium salt, 4-methoxysulfonyl-2-hydroxythiopheno Sodium salt, 4-methoxysulfonyl-2-phenylthiothiophenol sodium salt, 4-chlorosulfonyl-2-nitrothiophenol sodium salt, 4-chlorosulfonyl-2-aminothiophenol sodium salt, 4-chlorosulfonyl-2- Hydroxythiophenol sodium salt, 4-chlorosulfonyl-2-phenylthiothiophenol sodium salt, 4-sulfino-2-nitrothiophenol sodium salt, 4-sulfino-2-aminothiophenol sodium salt, 4-sulfino-2- Hydroxythiophenol sodium salt, 4-sulfino-2-phenylthiothiophenol sodium salt, 4-methylsulfinyl-2-nitrothiophenol sodium salt, 4-methylsulfinyl-2-aminothiophene Sodium salt, 4-methylsulfinyl-2-hydroxythiophenol sodium salt, 4-methylsulfinyl-2-phenylthiothiophenol sodium salt, 4-carbamoyl-2-nitrothiophenol sodium salt, 4-carbamoyl-2-aminothio Phenol sodium salt, 4-carbamoyl-2-hydroxythiophenol sodium salt, 4-carbamoyl-2-phenylthiothiophenol sodium salt, 4-trichloromethyl-2-nitrothiophenol sodium salt, 4-trichloromethyl-2-amino Thiophenol sodium salt, 4-trichloromethyl-2-hydroxythiophenol sodium salt, 4-trichloromethyl-2-phenylthiothiophenol sodium salt, 4-cyano-2-nitrothiooff Nord sodium salt, 4-cyano-2-aminothiophenol sodium salt, 4-cyano-2-hydroxythiophenol sodium salt, 4-cyano-2-phenylthiothiophenol sodium salt, 4-methoxy-2-nitrothiophenol Examples include sodium salt, 4-methoxy-2-aminothiophenol sodium salt, 4-methoxy-2-hydroxythiophenol sodium salt and 4-methoxy-2-phenylthiothiophenol sodium salt.

  Still another example of the organic sulfur compound represented by the chemical formula (3) includes a compound substituted with two or more substituents. Specific examples of this compound include 4-acetyl-2-chlorothiophenol sodium salt, 4-acetyl-2-methylthiophenol sodium salt, 4-acetyl-2-carboxythiophenol sodium salt, 4-acetyl-2-methoxycarbonyl Thiophenol sodium salt, 4-acetyl-2-formylthiophenol sodium salt, 4-acetyl-2-chlorocarbonylthiophenol sodium salt, 4-acetyl-2-sulfothiophenol sodium salt, 4-acetyl-2-methoxysulfonyl Thiophenol sodium salt, 4-acetyl-2-chlorosulfonylthiophenol sodium salt, 4-acetyl-2-sulfinothiophenol sodium salt, 4-acetyl-2-methylsulfinylthiophenol sodium salt, 4 Acetyl-2-carbamoylthiophenol phenol sodium salt, 4-acetyl-2-trichloromethyl-thiophenol sodium salt, 4-acetyl-2-cyano thiophenol sodium salt and 4-acetyl-2-methoxy thiophenol sodium salt. In the chemical formula (3), examples of the monovalent metal represented by M1 include sodium, lithium, potassium, copper (I), and silver (I).

  As the organic sulfur compound represented by the chemical formula (4), thiophenol zinc salt; 4-fluorothiophenol zinc salt, 2,5-difluorothiophenol zinc salt, 2,4,5-trifluorothiophenol zinc salt, 2,4,5,6-tetrafluorothiophenol zinc salt, pentafluorothiophenol zinc salt, 4-chlorothiophenol zinc salt, 2,5-dichlorothiophenol zinc salt, 2,4,5-trichlorothiophenol zinc Salt, 2,4,5,6-tetrachlorothiophenol zinc salt, pentachlorothiophenol zinc salt, 4-bromothiophenol zinc salt, 2,5-dibromothiophenol zinc salt, 2,4,5-tribromo Thiophenol zinc salt, 2,4,5,6-tetrabromothiophenol zinc salt, pentabromothiophenol Lead salt, 4-iodothiophenol zinc salt, 2,5-diiodothiophenol zinc salt, 2,4,5-triiodothiophenol zinc salt, 2,4,5,6-tetraiodothiophenol zinc salt and Thiophenol zinc salts substituted with halogen groups such as pentaiodothiophenol zinc salt; 4-methylthiophenol zinc salt, 2,4,5-trimethylthiophenol zinc salt, pentamethylthiophenol zinc salt, 4-t-butyl Thiophenol zinc salts substituted with alkyl groups such as thiophenol zinc salt, 2,4,5-tri-t-butylthiophenol zinc salt and penta-t-butylthiophenol zinc salt; 4-carboxythiophenol zinc Salt, 2,4,6-tricarboxythiophenol zinc salt and pentacarboxythiophenol Thiophenol zinc salts substituted with carboxyl groups such as lead salts; alkoxy such as 4-methoxycarbonylthiophenol zinc salts, 2,4,6-trimethoxycarbonylthiophenol zinc salts and pentamethoxycarbonylthiophenol zinc salts Thiophenol zinc salts substituted with a carbonyl group; thiophenol zinc substituted with a formyl group such as 4-formylthiophenol zinc salt, 2,4,6-triformylthiophenol zinc salt and pentaformylthiophenol zinc salt Salts; 4-acetylthiophenol zinc salts, thiophenol zinc salts substituted with acyl groups such as 2,4,6-triacetylthiophenol zinc salts and pentaacetylthiophenol zinc salts; 4-chlorocarbonylthiophenol zinc Salt, 2,4,6- Thiophenol zinc salts substituted with a carbonyl halide group such as tri (chlorocarbonyl) thiophenol zinc salt and penta (chlorocarbonyl) thiophenol zinc salt; 4-sulfothiophenol zinc salt, 2,4,6-tri Thiophenol zinc salts substituted with sulfo groups such as sulfothiophenol zinc salt and pentasulfothiophenol zinc salt; 4-methoxysulfonylthiophenol zinc salt, 2,4,6-trimethoxysulfonylthiophenol zinc salt and penta Thiophenol zinc salts substituted with alkoxysulfonyl groups such as methoxysulfonylthiophenol zinc salt; 4-chlorosulfonylthiophenol zinc salt, 2,4,6-tri (chlorosulfonyl) thiophenol zinc salt and penta (chlorosulfonyl) Thio Thiophenol zinc salts substituted with a sulfonyl halide group such as enol zinc salt; such as 4-sulfinothiophenol zinc salt, 2,4,6-trisulfinothiophenol zinc salt and pentasulfinothiophenol zinc salt Thiophenol zinc salts substituted with sulfino groups; alkylsulfinyls such as 4-methylsulfinylthiophenol zinc salt, 2,4,6-tri (methylsulfinyl) thiophenol zinc salt and penta (methylsulfinyl) thiophenol zinc salt Group substituted thiophenol zinc salts; 4-carbamoylthiophenol zinc salts, thiophenol zinc salts substituted with carbamoyl groups such as 2,4,6-tricarbamoylthiophenol zinc salts and pentacarbamoylthiophenol zinc salts ; -Thiophenol zinc salts substituted with halogenated alkyl groups such as trichloromethylthiophenol zinc salt, 2,4,6-tri (trichloromethyl) thiophenol zinc salt and penta (trichloromethyl) thiophenol zinc salt; Thiophenol zinc salts substituted with a cyano group such as cyanothiophenol zinc salt, 2,4,6-tricyanothiophenol zinc salt and pentacyanothiophenol zinc salt; and 4-methoxythiophenol zinc salt, 2,4 Examples thereof include thiophenol zinc salts substituted with an alkoxy group such as 1,6-trimethoxythiophenol zinc salt and pentamethoxythiophenol zinc salt. These thiophenol zinc salts are substituted with one type of substituent.

As another example of the organic sulfur compound represented by the chemical formula (4), a compound substituted with at least one kind of the above substituent and another substituent can be given. Examples of other substituents include a nitro group (—NO ₂ ), an amino group (—NH ₂ ), a hydroxyl group (—OH), and a phenylthio group (—SPh). Specific examples of this compound include 4-chloro-2-nitrothiophenol zinc salt, 4-chloro-2-aminothiophenol zinc salt, 4-chloro-2-hydroxythiophenol zinc salt, 4-chloro-2- Phenylthiothiophenol zinc salt, 4-methyl-2-nitrothiophenol zinc salt, 4-methyl-2-aminothiophenol zinc salt, 4-methyl-2-hydroxythiophenol zinc salt, 4-methyl-2-phenyl Thiothiophenol zinc salt, 4-carboxy-2-nitrothiophenol zinc salt, 4-carboxy-2-aminothiophenol zinc salt, 4-carboxy-2-hydroxythiophenol zinc salt, 4-carboxy-2-phenylthio Thiophenol zinc salt, 4-methoxycarbonyl-2-nitrothiophenol zinc salt, 4-meth Sicarbonyl-2-aminothiophenol zinc salt, 4-methoxycarbonyl-2-hydroxythiophenol zinc salt, 4-methoxycarbonyl-2-phenylthiothiophenol zinc salt, 4-formyl-2-nitrothiophenol zinc salt, 4-formyl-2-aminothiophenol zinc salt, 4-formyl-2-hydroxythiophenol zinc salt, 4-formyl-2-phenylthiothiophenol zinc salt, 4-acetyl-2-nitrothiophenol zinc salt, 4 -Acetyl-2-aminothiophenol zinc salt, 4-acetyl-2-hydroxythiophenol zinc salt, 4-acetyl-2-phenylthiothiophenol zinc salt, 4-chlorocarbonyl-2-nitrothiophenol zinc salt, 4 -Chlorocarbonyl-2-aminothiophenol zinc salt, -Chlorocarbonyl-2-hydroxythiophenol zinc salt, 4-chlorocarbonyl-2-phenylthiothiophenol zinc salt, 4-sulfo-2-nitrothiophenol zinc salt, 4-sulfo-2-aminothiophenol zinc salt, 4-sulfo-2-hydroxythiophenol zinc salt, 4-sulfo-2-phenylthiothiophenol zinc salt, 4-methoxysulfonyl-2-nitrothiophenol zinc salt, 4-methoxysulfonyl-2-aminothiophenol zinc salt 4-methoxysulfonyl-2-hydroxythiophenol zinc salt, 4-methoxysulfonyl-2-phenylthiothiophenol zinc salt, 4-chlorosulfonyl-2-nitrothiophenol zinc salt, 4-chlorosulfonyl-2-aminothio Phenol zinc salt, 4-chlorosulfonyl- 2-hydroxythiophenol zinc salt, 4-chlorosulfonyl-2-phenylthiothiophenol zinc salt, 4-sulfino-2-nitrothiophenol zinc salt, 4-sulfino-2-aminothiophenol zinc salt, 4-sulfino- 2-hydroxythiophenol zinc salt, 4-sulfino-2-phenylthiothiophenol zinc salt, 4-methylsulfinyl-2-nitrothiophenol zinc salt, 4-methylsulfinyl-2-aminothiophenol zinc salt, 4-methyl Sulfinyl-2-hydroxythiophenol zinc salt, 4-methylsulfinyl-2-phenylthiothiophenol zinc salt, 4-carbamoyl-2-nitrothiophenol zinc salt, 4-carbamoyl-2-aminothiophenol zinc salt, 4- Carbamoyl-2-hydroxythi Phenol zinc salt, 4-carbamoyl-2-phenylthiothiophenol zinc salt, 4-trichloromethyl-2-nitrothiophenol zinc salt, 4-trichloromethyl-2-aminothiophenol zinc salt, 4-trichloromethyl-2- Hydroxythiophenol zinc salt, 4-trichloromethyl-2-phenylthiothiophenol zinc salt, 4-cyano-2-nitrothiophenol zinc salt, 4-cyano-2-aminothiophenol zinc salt, 4-cyano-2- Hydroxythiophenol zinc salt, 4-cyano-2-phenylthiothiophenol zinc salt, 4-methoxy-2-nitrothiophenol zinc salt, 4-methoxy-2-aminothiophenol zinc salt, 4-methoxy-2-hydroxy Thiophenol zinc salt and 4-methoxy-2-phenylthiothio Phenol zinc salts.

  Still another example of the organic sulfur compound represented by the chemical formula (4) includes a compound substituted with two or more kinds of substituents. Specific examples of this compound include 4-acetyl-2-chlorothiophenol zinc salt, 4-acetyl-2-methylthiophenol zinc salt, 4-acetyl-2-carboxythiophenol zinc salt, 4-acetyl-2-methoxycarbonyl Thiophenol zinc salt, 4-acetyl-2-formylthiophenol zinc salt, 4-acetyl-2-chlorocarbonylthiophenol zinc salt, 4-acetyl-2-sulfothiophenol zinc salt, 4-acetyl-2-methoxysulfonyl Thiophenol zinc salt, 4-acetyl-2-chlorosulfonylthiophenol zinc salt, 4-acetyl-2-sulfinothiophenol zinc salt, 4-acetyl-2-methylsulfinylthiophenol zinc salt, 4-acetyl-2- Carbamoylthiophenol zinc salt, 4-acetyl-2 Trichloromethylthiophenol zinc salt, 4-acetyl-2-cyano thiophenol zinc salt and 4-acetyl-2-methoxy thiophenol zinc salt. Examples of the divalent metal represented by M2 in the chemical formula (4) include zinc, magnesium, calcium, strontium, barium, titanium (II), manganese (II), iron (II), cobalt (II), nickel ( Illustrative are II), zirconium (II) and tin (II).

  As thionaphthols, 2-thionaphthol, 1-thionaphthol, 2-chloro-1-thionaphthol, 2-bromo-1-thionaphthol, 2-fluoro-1-thionaphthol, 2-cyano-1-thionaphthol 2-acetyl-1-thionaphthol, 1-chloro-2-thionaphthol, 1-bromo-2-thionaphthol, 1-fluoro-2-thionaphthol, 1-cyano-2-thionaphthol and 1-acetyl- Examples include 2-thionaphthol and metal salts thereof. 1-thionaphthol and 2-thionaphthol and their zinc salts are preferred.

  Examples of the sulfenamide-based organic sulfur compound include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and Nt-butyl-2-benzothiazole sulfenamide. Illustrated. Examples of the thiuram-based organic sulfur compound include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, and dipentamethylenethiuram tetrasulfide. Dithiocarbamates include zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, copper (II) dimethyldithiocarbamate, iron dimethyldithiocarbamate (III ), Selenium diethyldithiocarbamate and tellurium diethyldithiocarbamate. As the thiazole-based organic sulfur compound, 2-mercaptobenzothiazole (MBT); dibenzothiazyl disulfide (MBTS); sodium salt, zinc salt, copper salt and cyclohexylamine salt of 2-mercaptobenzothiazole; 2- (2,4- Examples include dinitrophenyl) mercaptobenzothiazole; and 2- (2,6-diethyl-4-morpholinothio) benzothiazole.

  Particularly preferred organic sulfur compounds (e) are 2-thionaphthol, bis (pentabromophenyl) disulfide, and 2,6-dichlorothiophenol from the viewpoint that an outer-hard / inner-soft structure is easily obtained.

  From the viewpoint that an outer-hard / inner-soft structure is easily obtained, the content of the organic sulfur compound (e) is preferably 0.05 parts by mass or more, and 0.1 parts by mass or more with respect to 100 parts by mass of the base rubber. More preferred is 0.2 part by mass or more. In light of resilience performance, this amount is preferably equal to or less than 5.0 parts by weight, more preferably equal to or less than 3.0 parts by weight, and particularly preferably equal to or less than 1.0 part by weight.

  A filler may be added to the envelope layer 14 for the purpose of adjusting specific gravity and the like. Suitable fillers include zinc oxide, barium sulfate, calcium carbonate and magnesium carbonate. The amount of the filler is appropriately determined so that the intended specific gravity of the core 4 is achieved. A particularly preferred filler is zinc oxide. Zinc oxide functions not only as a specific gravity adjusting role but also as a crosslinking aid.

  An anti-aging agent, a colorant, a plasticizer, a dispersant, sulfur, a vulcanization accelerator, and the like are added to the rubber composition of the envelope layer 14 as necessary. Crosslinked rubber powder or synthetic resin powder may be dispersed in the rubber composition.

  When the core 4 is heated, the reaction heat of the crosslinking reaction of the base rubber is accumulated near the center of the core 4. Therefore, when the core 4 is heated, the temperature at the center is high. The temperature gradually decreases from the center toward the surface. The acid and / or salt (d) reacts with the metal salt of the co-crosslinking agent (b) to inhibit or cleave the metal bridge. This reaction is promoted in the high temperature region. That is, the inhibition and cutting of the metal cross-linking is likely to occur near the innermost part of the envelope layer 14 having a high temperature, and is difficult to occur near the surface. As a result, the crosslink density of the envelope layer 14 increases from the inside toward the outside. In the envelope layer 14, the hardness increases linearly from the inside toward the outside. Furthermore, when the rubber composition contains the organic sulfur compound (e) together with the acid and / or salt (d), the gradient of the hardness distribution can be controlled, and the degree of the outer-hard / inner-soft structure of the core 4 is increased. Can do. In order to control the hardness distribution of the core 4, the golf ball 2 may include a plurality of envelope layers.

  The hardness H (0.0) of the center point of the core 4 is preferably 40.0 or more and 68.0 or less. The golf ball 2 having a hardness H (0.0) of 40.0 or more is excellent in resilience performance. In this respect, the hardness H (0.0) is more preferably equal to or greater than 45.0, and particularly preferably equal to or greater than 47.0. In the core 4 having a hardness H (0.0) of 68.0 or less, an outer-hard / inner-soft structure can be achieved. In the golf ball 2 having the core 4, spin can be suppressed. In this respect, the hardness H (0.0) is more preferably equal to or less than 65.0, and particularly preferably equal to or less than 63.0.

  The hardness Hs of the surface of the core 4 is preferably 70.0 or more and 95.0 or less. In the core 4 having the hardness Hs of 70.0 or more, an outer-hard / inner-soft structure can be achieved. In the golf ball 2 having the core 4, spin can be suppressed. In this respect, the hardness Hs is more preferably equal to or greater than 80.0, and particularly preferably equal to or greater than 82.0. The golf ball 2 having a hardness Hs of 95.0 or less is excellent in durability. In this respect, the hardness Hs is more preferably equal to or less than 94.0, and particularly preferably equal to or less than 92.0.

  The diameter of the core 4 is preferably 34.0 mm or more and 39.0 mm or less. The excellent resilience performance of the golf ball 2 can be achieved by the core 4 having a diameter of 34.0 mm or more. In this respect, the diameter is more preferably 35.0 mm or more, and particularly preferably 35.5 mm or more. In the golf ball 2 having the core 4 having a diameter of 39.0 mm or less, the inner cover 6 and the outer cover 10 can have a sufficient thickness. The golf ball 2 having a large thickness of the inner cover 6 and the outer cover 10 is excellent in durability. In this respect, the diameter is more preferably 38.0 mm or less, and particularly preferably 37.5 mm or less.

  In light of feel at impact, the core 4 has an amount of compressive deformation Dc of preferably 3.5 mm or greater and particularly preferably 3.8 mm or greater. In light of the resilience performance of the core 4, the amount of compressive deformation Dc is preferably equal to or less than 4.5 mm, and particularly preferably equal to or less than 4.0 mm.

  A resin composition is suitably used for the inner cover 6. Examples of the base polymer of this resin composition include ionomer resin, polystyrene, polyester, polyamide and polyolefin.

  A particularly preferred base polymer is an ionomer resin. The golf ball 2 having the inner cover 6 containing an ionomer resin is excellent in resilience performance. The inner cover 6 may be used in combination with an ionomer resin and another resin. When used in combination, the main component of the base polymer is preferably an ionomer resin. Specifically, the ratio of the ionomer resin to the total amount of the base polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

  A preferable ionomer resin includes a binary copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. A preferable binary copolymer contains 80% by mass or more and 90% by mass or less α-olefin and 10% by mass or more and 20% by mass or less α, β-unsaturated carboxylic acid. This binary copolymer is excellent in resilience performance. Other preferable ionomer resins include ternary α-olefin, α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α, β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. A copolymer is mentioned. Preferred terpolymers are 70% to 85% by weight α-olefin, 5% to 30% by weight α, β-unsaturated carboxylic acid, and 1% to 25% by weight. α, β-unsaturated carboxylic acid ester. This ternary copolymer is excellent in resilience performance. In the binary copolymer and ternary copolymer, preferred α-olefins are ethylene and propylene, and preferred α, β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. Particularly preferred ionomer resins are a copolymer of ethylene and acrylic acid and a copolymer of ethylene and methacrylic acid.

  In the binary copolymer and ternary copolymer, some of the carboxyl groups are neutralized with metal ions. Examples of the metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions, and neodymium ions. Neutralization may be performed with two or more metal ions. Particularly suitable metal ions from the viewpoint of resilience performance and durability of the golf ball 2 are sodium ion, zinc ion, lithium ion and magnesium ion.

  As specific examples of the ionomer resin, trade names “Hi-Milan 1555”, “Hi-Milan 1557”, “Hi-Milan 1605”, “Hi-Milan 1706”, “Hi-Milan 1856”, “Hi-Milan 1856”, “Hi-Milan 1855” “High Milan AM7337”, “High Milan AM7311”, “High Milan AM7315”, “High Milan AM7317”, “High Milan AM7318”, “High Milan AM7329”, “High Milan MK7320” and “High Milan MK7329”; “Surling 6910”, “Surling 7930”, “Surling 7940”, “Surling 8140”, “Surling 8150”, “Surling 8940”, “Surling 8945”, “Surling 9” 20 ”,“ Surlin 9150 ”,“ Surlin 9910 ”,“ Surlin 9945 ”,“ Surlin AD8546 ”,“ HPF1000 ”and“ HPF2000 ”; and trade names“ IOTEK7010 ”,“ IOTEK7030 ”,“ IOTEK7510 ”of ExxonMobil Chemical , “IOTEK7520”, “IOTEK8000”, and “IOTEK8030”.

  Two or more ionomer resins may be used in combination with the inner cover 6. An ionomer resin neutralized with a monovalent metal ion and an ionomer resin neutralized with a divalent metal ion may be used in combination.

  A preferred resin that can be used in combination with an ionomer resin is a styrene block-containing thermoplastic elastomer. The styrene block-containing thermoplastic elastomer is excellent in compatibility with the ionomer resin. A resin composition containing a styrene block-containing thermoplastic elastomer is excellent in fluidity.

  The styrene block-containing thermoplastic elastomer includes a polystyrene block as a hard segment and a soft segment. A typical soft segment is a diene block. Examples of the diene block compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene. Butadiene and isoprene are preferred. Two or more compounds may be used in combination.

  The styrene block-containing thermoplastic elastomer includes styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS), SBS hydrogenated, SIS hydrogenated and SIBS hydrogenated are included. Examples of the hydrogenated product of SBS include styrene-ethylene-butylene-styrene block copolymer (SEBS). As a hydrogenated product of SIS, styrene-ethylene-propylene-styrene block copolymer (SEPS) can be mentioned. Examples of the hydrogenated product of SIBS include styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS).

  In light of flight performance of the golf ball 2, the content of the styrene component in the styrene block-containing thermoplastic elastomer is preferably 10% by mass or more, more preferably 12% by mass or more, and particularly preferably 15% by mass or more. In light of resilience performance of the golf ball 2, the content is preferably equal to or less than 50% by weight, more preferably equal to or less than 47% by weight, and particularly preferably equal to or less than 45% by weight.

  In the present invention, the styrene block-containing thermoplastic elastomer includes a polymer alloy of one or more selected from the group consisting of SBS, SIS and SIBS, and hydrogenated products thereof, and an olefin. The olefin component in the polymer alloy is presumed to contribute to the improvement of compatibility with the ionomer resin. By using this polymer alloy, the resilience performance of the golf ball 2 is improved. Preferably, an olefin having 2 to 10 carbon atoms is used. Suitable olefins include ethylene, propylene, butene and pentene. Ethylene and propylene are particularly preferred.

  Specific examples of polymer alloys include Mitsubishi Chemical's trade names “Lavalon T3221C”, “Lavalon T3339C”, “Lavalon SJ4400N”, “Lavalon SJ5400N”, “Lavalon SJ6400N”, “Lavalon SJ7400N”, “Lavalon SJ8400N”, “ And “Lavalon SJ9400N” and “Lavalon SR04”. Other specific examples of the styrene block-containing thermoplastic elastomer include Daicel Chemical Industries' trade name “Epofriend A1010” and Kuraray's trade name “Septon HG-252”.

  If necessary, the resin composition of the inner cover 6 may include a colorant such as titanium dioxide, a filler such as barium sulfate, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent agent, and a fluorescent enhancer. An appropriate amount of whitening agent is blended.

  In light of the resilience performance of the golf ball 2, the JIS-C hardness Hi of the inner cover 6 is preferably equal to or greater than 70, more preferably equal to or greater than 72, and particularly preferably equal to or greater than 74. In light of the feel at impact of the golf ball 2, the hardness Hi is preferably equal to or less than 94, more preferably equal to or less than 93, and particularly preferably equal to or less than 92.

  The hardness Hi is measured by a JIS-C type hardness meter attached to an automatic rubber hardness measuring device (trade name “P1” of Kobunshi Keiki Co., Ltd.). For the measurement, a slab having a thickness of about 2 mm formed by hot pressing is used. A slab stored for 2 weeks at a temperature of 23 ° C. is used for the measurement. At the time of measurement, three slabs are overlaid. A slab made of the same resin composition as that of the inner cover 6 is used for measurement.

  The JIS-C hardness Hi of the inner cover 6 is larger than the surface hardness Hs of the core 4. Preferably, the difference (Hi-Hs) between the hardness Hi and the hardness Hs is 1 or more. When the difference (Hi−Hs) is 1 or more, an outer-hard / inner-soft structure is achieved in the sphere composed of the core 4 and the inner cover 6. When the golf ball 2 including the core 4 and the inner cover 6 is hit, the spin speed is small. When the golf ball 2 is hit with a middle iron, particularly excellent flight performance is exhibited. In this respect, the difference (Hi-Hs) is more preferably equal to or greater than 3, and particularly preferably equal to or greater than 5.

  The thickness Ti of the inner cover 6 is preferably 0.5 mm or greater and 1.6 mm or less. In the sphere provided with the inner cover 6 having a thickness Ti of 0.5 mm or more, the spin suppression effect by the outer-hard / inner-soft structure is great. In this respect, the thickness Ti is particularly preferably equal to or greater than 0.7 mm. The golf ball 2 including the inner cover 6 having a thickness Ti that is 1.6 mm or less can include a large core 4. The large core 4 can contribute to the resilience performance of the golf ball 2. In this respect, the thickness Ti is particularly preferably equal to or less than 1.2 mm.

  A resin composition is suitably used for the mid cover 8. Examples of the base polymer of this resin composition include ionomer resin, polystyrene, polyester, polyamide and polyolefin.

  A particularly preferred base polymer is an ionomer resin. The ionomer resin described above with respect to the inner cover 6 can be used. The golf ball 2 having the mid cover 8 containing an ionomer resin has excellent resilience performance. An ionomer resin and another resin may be used in combination with the mid cover 8. When used in combination, the main component of the base polymer is preferably an ionomer resin. Specifically, the ratio of the ionomer resin to the total amount of the base polymer is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more. The mid cover 8 may include other resins described above with respect to the inner cover 6.

  As will be described later, the JIS-C hardness Hm of the mid cover 8 is preferably larger than the hardness Hi of the inner cover 6. A large hardness Hm can be achieved by reducing the amount of the styrene block-containing thermoplastic elastomer compounded in the resin composition of the mid cover 8. Large hardness Hm may be achieved by blending a highly elastic resin with the resin composition. Specific examples of the highly elastic resin include polyamide.

  The resin composition of the mid cover 8 includes a colorant such as titanium dioxide, a filler such as barium sulfate, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent agent, and a fluorescent enhancer as necessary. An appropriate amount of whitening agent is blended.

  From the viewpoint of spin suppression, the hardness Hm is preferably 70 or higher, more preferably 72 or higher, and particularly preferably 74 or higher. In light of feel at impact, the hardness Hm is preferably 94 or less, more preferably 93 or less, and particularly preferably 92 or less. The hardness Hm is measured by the same method as the method for measuring the hardness Hi.

  From the viewpoint of resilience performance in a sphere composed of the core 4, the inner cover 6 and the mid cover 8, the JIS-C hardness Hm of the mid cover 8 is greater than the surface hardness Hs of the core 4. The golf ball 2 including this sphere exhibits excellent flight performance.

  Preferably, the hardness Hm is larger than the hardness Hi of the inner cover 6. When the hardness Hm is larger than the hardness Hi, an outer-hard / inner-soft structure is achieved in the sphere composed of the core 4, the inner cover 6, and the mid cover 8.

  From the viewpoint of flight performance, the difference (Hm-Hi) between the hardness Hm and the hardness Hi is preferably 2 or more, and more preferably 4 or more. From the viewpoint of durability, the difference (Hm-Hi) is preferably 20 or less.

  The thickness Tm of the mid cover 8 is preferably 0.5 mm or greater and 1.6 mm or less. In the sphere provided with the mid cover 8 having a thickness Tm of 0.5 mm or more, the spin suppression effect by the outer-hard / inner-soft structure is great. In this respect, the thickness Tm is particularly preferably equal to or greater than 0.7 mm. The golf ball 2 including the mid cover 8 having a thickness Tm of 1.6 mm or less can include a large core 4. The large core 4 can contribute to the resilience performance of the golf ball 2. In this respect, the thickness Tm is particularly preferably equal to or less than 1.2 mm.

  A resin composition is suitably used for the outer cover 10. Examples of the base polymer of this resin composition include ionomer resin, polystyrene, polyester, polyamide and polyolefin.

  A particularly preferred base polymer is an ionomer resin. The ionomer resin described above for the inner cover 6 can be used. The golf ball 2 having the outer cover 10 containing an ionomer resin is excellent in resilience performance. The outer cover 10 may be used in combination with an ionomer resin and another resin. When used in combination, the main component of the base polymer is preferably an ionomer resin. Specifically, the ratio of the ionomer resin to the total amount of the base polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. The outer cover 10 can include other resins described above with respect to the inner cover 6.

  Another resin that can be used in combination with the ionomer resin is an ethylene- (meth) acrylic acid copolymer. This copolymer is obtained by a copolymerization reaction of a monomer composition containing ethylene and (meth) acrylic acid. In this copolymer, some of the carboxyl groups are neutralized with metal ions. This copolymer contains 3% by weight or more and 25% by weight or less (meth) acrylic acid component. An ethylene-methacrylic acid copolymer having a polar functional group is particularly preferred. Specific examples of the ethylene-methacrylic acid copolymer include “Nucrel N1050H”, a trade name of Mitsui DuPont Polychemical Co., Ltd.

  As will be described later, the JIS-C hardness Ho of the outer cover 10 is preferably larger than the hardness Hm of the mid cover 8. From this viewpoint, the resin composition of the outer cover 10 may be blended with a highly elastic resin. Specific examples of the highly elastic resin include polyamide.

  If necessary, the resin composition of the outer cover 10 may include a colorant such as titanium dioxide, a filler such as barium sulfate, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent agent, and a fluorescent enhancer. An appropriate amount of whitening agent is blended.

  From the viewpoint that an outer-hard / inner-soft structure is achieved in a sphere composed of the core 4, the inner cover 6, the mid cover 8, and the outer cover 10, the hardness Ho of the outer cover 10 is preferably 80 or more, more preferably 82 or more. 84 or more is particularly preferable. In light of feel at impact, the hardness Ho is preferably 96 or less, more preferably 95 or less, and particularly preferably 93 or less. The hardness Ho is measured by the same method as the method for measuring the hardness Hi.

  The hardness Ho of the outer cover 10 is greater than the hardness Hi of the inner cover 6. When the golf ball 2 is hit with a middle iron, the spin speed is low. The golf ball 2 has a large flight distance.

  From the viewpoint of flight performance, the difference (Ho−Hi) between the hardness Ho of the outer cover 10 and the hardness Hi of the inner cover 6 is preferably 2 or more, more preferably 4 or more, and particularly preferably 6 or more. From the viewpoint of durability, the difference (Ho−Hi) is preferably 20 or less.

  The hardness Ho of the outer cover 10 is preferably larger than the hardness Hm of the mid cover 8. When the hardness Ho is larger than the hardness Hi, in the golf ball 2 including the core 4, the inner cover 6, the mid cover 8, and the outer cover 10, the outer-hard / inner-soft structure of the entire ball is achieved. When the golf ball 2 is hit with a middle iron, a great flight distance is achieved.

  From the viewpoint of flight performance, the difference (Ho−Hm) between the hardness Ho of the outer cover 10 and the hardness Hm of the mid cover 8 is preferably 3 or more, and particularly preferably 6 or more. From the viewpoint of durability, the difference (Ho−Hm) is preferably 20 or less.

  From the viewpoint of durability, the thickness To of the outer cover 10 is preferably 0.1 mm or more, particularly preferably 0.2 mm or more. From the viewpoint of flight performance, the thickness To is preferably 1.4 mm or less, and particularly preferably 1.2 mm or less.

  For forming the outer cover 10, known methods such as an injection molding method and a compression molding method can be employed. When the outer cover 10 is molded, dimples 16 are formed by pimples formed on the cavity surface of the mold.

  In light of feel at impact, the sum of thickness Ti, thickness Tm, and thickness To (Ti + Tm + To) is preferably 4.0 mm or less, more preferably 3.9 mm or less, and particularly preferably 3.5 mm or less. From the viewpoint of durability and wear resistance of the golf ball 2, the sum (Ti + Tm + To) is more preferably 0.3 mm or more, more preferably 0.5 mm or more, and particularly preferably 0.8 mm or more.

  In light of feel at impact, the golf ball 2 has an amount of compressive deformation Db of preferably 2.2 mm or greater, more preferably 2.5 mm or greater, and particularly preferably 2.8 mm or greater. In light of resilience performance, the amount of compressive deformation Db is preferably equal to or less than 4.0 mm, more preferably equal to or less than 3.7 mm, and particularly preferably equal to or less than 3.4 mm.

  A YAMADA compression tester is used to measure the amount of compressive deformation. In this tester, spheres such as the core 4 and the golf ball 2 are placed on a metal rigid plate. A metal cylinder gradually descends toward the sphere. The sphere sandwiched between the bottom surface of the cylinder and the rigid plate is deformed. The moving distance of the cylinder from the state where the initial load of 98 N is applied to the sphere to the state where the final load of 1274 N is applied is measured.

  The golf ball may include a center molded from a rubber composition containing an acid and / or salt (d), and an envelope layer molded from a rubber composition not containing an acid and / or salt (d). . The rubber composition of this center is equivalent to the rubber composition of the envelope layer 14 shown in FIG. The hardness distribution at this center is appropriate.

  The golf ball may include a center molded from a rubber composition containing an acid and / or salt (d), and an envelope layer molded from a rubber composition containing an acid and / or salt (d). The rubber composition of this center is equivalent to the rubber composition of the envelope layer 14 shown in FIG. The rubber composition of the envelope layer is equivalent to the rubber composition of the envelope layer 14 shown in FIG. The hardness distribution at this center is appropriate. The hardness distribution of the envelope layer is appropriate.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
100 parts by weight of high-cis polybutadiene (trade name “BR-730” from JSR), 34 parts by weight of magnesium oxide (trade name “Magsarat 150ST” from Kyowa Chemical Industry Co., Ltd.), 28 parts by weight of methacrylic acid and 0.75 A rubber composition was obtained by kneading part by mass of dicumyl peroxide. This rubber composition was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at a temperature of 170 ° C. for 25 minutes to obtain a center having a diameter of 15 mm.

  100 parts by mass of high-cis polybutadiene (previously referred to as “BR-730”), 26.0 parts by mass of zinc acrylate (trade name “Sunceller SR” from Sanshin Chemical Industry Co., Ltd.), 5 parts by mass of zinc oxide, an appropriate amount Barium sulfate, 0.2 parts by mass of 2-thionaphthol, 10 parts by mass of zinc stearate and 0.75 parts by mass of dicumyl peroxide were kneaded to obtain a rubber composition. A half shell was molded from this rubber composition. The center was covered with two half shells. The center and the half shell were both put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at a temperature of 150 ° C. for 20 minutes to obtain a core having a diameter of 37.1 mm. . An envelope layer was formed from the rubber composition. The amount of barium sulfate was adjusted so that the specific gravity of the envelope layer coincided with the specific gravity of the center and the ball mass was 45.4 g.

  40 parts by weight of ionomer resin (previously referred to as “Himiran AM7337”), 40 parts by weight of other ionomer resins (previously referred to as “Himiran AM7329”), and 20 parts by weight of a styrene block-containing thermoplastic elastomer (previously referred to as “Lavalon T3221C”) And 6 mass parts titanium dioxide was knead | mixed with the biaxial kneading extruder, and the resin composition was obtained. The core was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity. The resin composition was injected around the core by an injection molding method to form an inner cover. The inner cover had a thickness of 1.0 mm.

  51 parts by weight of ionomer resin (previously referred to as “HIMILAN AM7337”), 40 parts by weight of other ionomer resin (previously described as “HIMILAN AM7329”), 9 parts by weight of a styrene block-containing thermoplastic elastomer (previously described “Lavalon T3221C”) And 6 mass parts titanium dioxide was knead | mixed with the biaxial kneading extruder, and the resin composition was obtained. A sphere composed of a core and an inner cover was introduced into a mold composed of an upper mold and a lower mold each having a hemispherical cavity. The resin composition was injected around the core by an injection molding method to form a mid cover. The thickness of this mid cover was 1.0 mm.

  5 parts by weight of ionomer resin (previously referred to as “Himiran AM7337”), 10 parts by weight of other ionomer resins (previously referred to as “Himiran 1555”), 55 parts by weight of other ionomer resins (previously referred to as “Himiran AM7329”), 30 Two parts by mass of ethylene-methacrylic acid copolymer (the above-mentioned “Nucleel N1050H”), 3 parts by mass of titanium dioxide and 0.2 parts by mass of an ultraviolet absorber (trade name “Tinuvin 770” from Ciba Japan Co., Ltd.) The resin composition was obtained by kneading with a shaft kneading extruder. A sphere composed of a core, an inner cover, and a mid cover was placed in a final mold having a large number of pimples on the cavity surface. The resin composition was injected around the sphere by an injection molding method to form an outer cover. The thickness of this outer cover was 0.8 mm. A dimple having a shape obtained by inverting the shape of the pimple was formed on the outer cover. A clear paint based on a two-component curable polyurethane was applied around the outer cover to obtain a golf ball of Example 1 having a diameter of 42.7 mm.

[Example 2-15 and Comparative Example 1-7]
The golf balls of Example 2-15 and Comparative Example 1-7 were manufactured in the same manner as in Example 1 except that the specifications of the center, envelope layer, inner cover, and outer cover were as shown in Table 10-14 below. Obtained. Details of the composition of the center are shown in Table 1 below. Details of the composition of the envelope layer are shown in Tables 2 and 3 below. Details of the composition of the inner cover, mid cover and outer cover are shown in Tables 4 and 5 below. The hardness distribution of the core is shown in Tables 6-9 below.

[Blow by Middle Iron (I # 5)]
A middle iron (Dunlop Sports brand name “XXIO”, shaft hardness: R, loft angle: 24.0 °) was attached to a swing machine manufactured by Tsurtemper. A golf ball was hit under the condition that the head speed was 35 m / sec. The spin speed immediately after hitting was measured. In addition, the distance from the launch point to the stationary point was measured. The average value of data obtained by 10 measurements is shown in Table 10-14 below.

Details of the compounds described in Table 1-3 are as follows.
BR730: High cis polybutadiene (cis-1,4-bond content: 96 mass%, 1,2-vinyl bond content: 1.3 mass%, Mooney viscosity (ML _{1 + 4} (100 ° C.)) from JSR: 55, molecular weight distribution (Mw / Mn): 3)
Magsarat 150ST: Magnesium oxide from Kyowa Chemical Industry Co., Ltd.
Methacrylic acid: Mitsubishi Rayon Suncellor SR: Sanshin Chemical Co., Ltd. zinc acrylate (10% by weight stearic acid coating)
Zinc oxide: Toho Zinc Co., Ltd. trade name “Ginbao R”
Barium sulfate: The trade name “Barium sulfate BD” by Sakai Chemical
2-thionaphthol: Tokyo Chemical Industry Co., Ltd. Zinc octoate: Mitsuwa Chemicals Co., Ltd. (purity: 99% or more)
Zinc stearate: Wako Pure Chemical Industries, Ltd. (Purity: 99% or more)
Zinc laurate: Mitsuwa Chemicals (Purity: 99% or more)
Zinc myristate: NOF Corporation (purity: 90% or more)
Dicumyl peroxide: NOF Corporation

  As shown in Tables 10-14, the golf balls according to the examples have excellent flight performance. From this evaluation result, the superiority of the present invention is clear.

  The golf ball according to the present invention can be used for golf play and practice in a driving range.

2 ... Golf ball 4 ... Core 6 ... Inner cover 8 ... Mid cover 10 ... Outer cover 12 ... Center 14 ... Enveloping layer 16 ... Dimple 18 ... Land

Claims (19)

A core, an inner cover located outside the core, a mid cover located outside the inner cover, and an outer cover located outside the mid cover;
The core has a center and an envelope layer located outside the center;
The center is formed by crosslinking the rubber composition,
The envelope layer is formed by crosslinking the rubber composition,
At least one of the rubber composition of the center and the rubber composition of the envelope layer is
(A) base rubber,
(B) a co-crosslinking agent,
(C) a crosslinking initiator,
And (d) an acid and / or salt,
The co-crosslinking agent (b) is
(B1) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms, or (b2) a metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms,
The JIS-C hardness Hi of the inner cover is larger than the JIS-C hardness Hs of the surface of the core,
The difference (Hi−Hs) between the hardness Hi and the hardness Hs is 1 or more,
A golf ball having a JIS-C hardness Ho of the outer cover larger than the Hi. The acid and / or salt (d) is
(D1) The golf ball according to claim 1, which is a carboxylic acid and / or a salt thereof.   The golf ball according to claim 2, wherein the carboxylic acid component of the carboxylic acid and / or salt thereof (d1) has 1 to 30 carbon atoms.   4. The golf ball according to claim 2, wherein the carboxylic acid and / or salt (d1) thereof is a fatty acid and / or a salt thereof.   The golf ball according to claim 2, wherein the carboxylic acid and / or salt (d1) thereof is a zinc salt of carboxylic acid.   6. The carboxylic acid and / or salt thereof (d1) is one or more selected from the group consisting of zinc octoate, zinc laurate, zinc myristate and zinc stearate. The golf ball described.   7. The rubber composition according to claim 1, wherein the rubber composition contains 1.0 part by weight or more and 40 parts by weight or less of the acid and / or salt (d) with respect to 100 parts by weight of the base rubber (a). The golf ball described.   The golf ball according to claim 1, wherein the rubber composition contains 15 to 50 parts by mass of the co-crosslinking agent (b) with respect to 100 parts by mass of the base rubber (a). .   9. The rubber composition according to claim 1, wherein the rubber composition contains 0.2 to 5.0 parts by mass of the crosslinking initiator (c) with respect to 100 parts by mass of the base rubber (a). The golf ball described. The rubber composition contains the α, β-unsaturated carboxylic acid (b1),
Furthermore, this rubber composition
(F) The golf ball according to any one of claims 1 to 9, comprising a metal compound.   The golf ball according to claim 1, wherein a difference (Ho−Hi) between the hardness Ho and the hardness Hi is 2 or more.   The difference (Hs-H (0.0)) between the hardness Hs and the JIS-C hardness H (0.0) of the center point of the core is 15 or more. Golf ball.   The golf ball according to claim 1, wherein a sum (Ti + Tm + To) of a thickness Ti of the inner cover, a thickness Tm of the mid cover, and a thickness To of the outer cover is 4.0 mm or less. The rubber composition is
The golf ball according to claim 1, further comprising (e) an organic sulfur compound.   The golf ball according to claim 14, wherein the organic sulfur compound (e) is a thiophenol, diphenyl disulfide, thionaphthol, thiuram disulfide, or a metal salt thereof.   The golf ball according to claim 14 or 15, wherein the rubber composition contains 0.05 to 5 parts by mass of the organic sulfur compound (e) with respect to 100 parts by mass of the base rubber (a).   The golf ball according to claim 1, wherein a JIS-C hardness Hm of the mid cover is larger than the hardness Hi, and the hardness Ho is larger than the hardness Hm.   The golf ball according to claim 17, wherein a difference (Hm−Hi) between the hardness Hm and the hardness Hi is 2 or more.   The golf ball according to claim 17 or 18, wherein a difference (Ho-Hm) between the hardness Ho and the hardness Hm is 3 or more.

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