Golf ball

Abstract

To provide a golf ball which improves or maintains a carry of driver shot, to a golfer whose head speed is slow, and stabilizes directional properties of driver shot.SOLUTION: A golf ball comprises: a spherical core; and an outermost layer cover which is provided outside of the spherical core, and on which multiple dimples are provided, When a hardness difference S between center hardness Ho (shore C hardness) of the spherical core and surface hardness Hs of the spherical core is S(=Hs-Ho), material hardness (shore D hardness) of the outermost layer cover is C, and total volume under a virtual spherical surface of the multiple dimples is V(mm3), the S, C and V satisfy: V×(S+C) / 1000≥50.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a golf ball, and more particularly to a golf ball suitable for golfers with a slow head speed. [Background technology]

[0002] In order to score well in golf, not only the distance of the driver shot but also the stability of the flight direction of the golf ball is important. In recent years, the number of senior golfers and female golfers has increased, and these golfers who have a slower head speed have been demanding golf balls with excellent flight distance performance and directional stability.

[0003] Dimples are provided on the surface of a golf ball, and efforts have been made to improve the flight performance of the golf ball by improving the dimples.

[0004] For example, Patent Document 1 discloses a golf ball that has a large number of dimples on its surface and satisfies the following formula (I). 1.320≦L1≦1.420(I) (In this formula, L1 is the Reynolds number, 1.290×10 5 The lift coefficient CL1 measured under the condition of 2820 rpm and a Reynolds number of 1.290×10 5 This represents the ratio to the lift coefficient CL2 measured under the condition of a spin rate of 1740 rpm.) [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-7369 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a golf ball that allows golfers with slow head speed to maintain or improve the flight distance of driver shots while ensuring stable directionality on driver shots. [Means for solving the problem]

[0007] A golf ball with a high spin rate generates lift due to the spin, making the ball's direction unstable. In particular, if the side spin increases due to a mishit with a driver, the ball's direction becomes even more unstable. By reducing the spin rate, the lift generated by the spin can be suppressed. On the other hand, a golf ball with a large total volume of dimples can control the lift generated by the dimples. In other words, a golf ball with a large total volume of dimples also suppresses lateral lift, improving the ball's direction.

[0008] In order to stabilize the directionality of a golf ball, it is believed that a golf ball with a low spin rate and a large total dimple volume is suitable, however, the spin rate and total dimple volume of a golf ball greatly affect the flight distance of a driver shot.

[0009] The inventors of the present application discovered that a golf ball with a low spin rate and a large total volume of dimples will have a short driver shot distance when hit with the average golfer's head speed of 35 m / s to 45 m / s, but that when hit with a slow head speed of less than 35 m / s, the driver shot distance is maintained or even increased, which led to the completion of the present invention.

[0010] That is, the golf ball of the present invention is a golf ball having a spherical core and an outermost cover layer located outside the spherical core and having a plurality of dimples thereon, The difference in hardness between the center hardness Ho (Shore C hardness) of the spherical core and the surface hardness Hs of the spherical core is S (=Hs-Ho), The material hardness (Shore D hardness) of the outermost cover layer is C, The total volume under the virtual sphere of multiple dimples is V (mm3 ), The S, C, and V satisfy V×(S+C) / 1000≧50.

[0011] The golf ball of the present invention, having the above-described construction, can control the lift generated by the dimples while optimizing the amount of spin, achieving an appropriate balance between the lift caused by the spin and the lift caused by the dimples, thereby stabilizing the directionality of driver shots while maintaining or improving the flight distance of the driver shots. Effect of the Invention

[0012] According to the present invention, it is possible to provide a golf ball that allows golfers with slow head speed to maintain or improve the distance of their driver shots while providing stable directionality on driver shots. The golf ball of the present invention has an appropriately controlled spin rate, so that directionality is stable even on mis-shots with a driver. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a golf ball according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged front view of the golf ball of FIG. [Diagram 3] FIG. 3 is a plan view of the golf ball of FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a portion of the golf ball of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The golf ball of the present invention has a spherical core and an outermost cover located outside the spherical core and having a plurality of dimples formed thereon.

[0015] In the golf ball of the present invention, the difference in hardness between the center hardness Ho (Shore C hardness) and the surface hardness Hs of the spherical core is S (=Hs-Ho), the material hardness (Shore D hardness) of the outermost cover is C, and the total volume of the multiple dimples under the virtual spherical surface is V (mm 3 ), The S, C, and V satisfy V×(S+C) / 1000≧50.

[0016] The value of (V×(S+C) / 1000) is preferably 50 or more, more preferably 55 or more, and even more preferably 60 or more, and is preferably 85 or less, more preferably 83 or less, and even more preferably 81 or less. If the value of (V×(S+C) / 1000) is within the above range, a good balance between the flight distance and directionality of driver shots will be achieved.

[0017] The value of (S×C) is preferably 1000 or more, more preferably 1050 or more, and even more preferably 1100 or more, and is preferably 2500 or less, more preferably 2400 or less, and even more preferably 2300 or less. If the value of (S×C) is within the above range, the balance between the flight distance and directionality of the driver shot will be even better.

[0018] The golf ball of the present invention has an outermost cover layer on which a plurality of dimples are formed. The dimples are recesses formed in the outermost cover layer. The dimples formed in the outermost cover layer of the golf ball of the present invention will be described below with reference to the drawings.

[0019] 1 has a spherical core 4 and an outermost cover layer 8 located on the outside of the core 4. The golf ball 2 has a plurality of dimples 10 on its surface. The portion of the surface of the golf ball 2 other than the dimples 10 is land 12. The golf ball 2 has a paint layer and a mark layer on the outside of the outermost cover layer 8, but these layers are omitted from the illustration.

[0020] 2 and 3, a large number of dimples 10 are provided on the surface of the outermost cover of the golf ball 2. The outline of each dimple 10 is a circle.

[0021] FIG. 4 shows a cross section of the golf ball 2 along a plane passing through the center of the dimple 10 and the center of the golf ball 2. The up-down direction in FIG. 4 is the depth direction of the dimple 10. A phantom sphere is indicated by a two-dot chain line 14 in FIG. 4. The surface of the phantom sphere 14 is the surface of the golf ball 2 when it is assumed that the dimple 10 does not exist. The diameter of the phantom sphere 14 is the same as the diameter of the golf ball 2. The dimple 10 is recessed from the surface of the phantom sphere 14. The land 12 coincides with the surface of the phantom sphere 14. In this embodiment, the cross-sectional shape of the dimple 10 is substantially a circular arc. The radius of curvature of this arc is indicated by the symbol CR in FIG. 4.

[0022] 4 indicates the diameter of the dimple 10. This diameter Dm is the distance between one tangent point Ed and the other tangent point Ed when a tangent line Tg common to both sides of the dimple 10 is drawn. The tangent point Ed is also the edge of the dimple 10. The edge Ed defines the contour of the dimple 10.

[0023] In the present invention, the "volume of a dimple" means the volume of the part surrounded by the imaginary sphere 14 including the contour of the dimple 10 and the surface of the dimple 10. The "dimple volume" is separated by a plane connecting the imaginary sphere 14 and the tangency Ed-Ed of the dimple surface. The "upper volume of a dimple" is the volume of the upper part of the dimple surrounded by the imaginary sphere 14 and the plane connecting the tangency Ed-Ed of the dimple surface. The "lower volume of a dimple" is the volume of the lower part of the dimple surrounded by the plane connecting the tangency Ed-Ed of the dimple surface and the surface of the dimple 10. The volume of a dimple is the sum of the upper volume and the lower volume. The "total volume V of dimples" in the present invention is the sum of the volumes of all dimples. The "total upper volume Vo of dimples" is the sum of the upper volumes of all dimples. The "lower volume Vi of a dimple" is the sum of the lower volumes of all dimples.

[0024] In the present invention, the total volume V of the dimples 10 is 500 mm 3 Above 900mm 3 The total volume V is preferably 500 mm 3 In the golf ball 2 having the above structure, hopping during flight is suppressed. From this viewpoint, the total volume V is 520 mm 3 More than 540mm is preferable. 3 More than 900 mm is particularly preferable. 3 In the golf ball 2, which is equal to or less than 880 mm, the drop during flight is suppressed. 3 Less than 860mm is preferable. 3 The following are particularly preferred:

[0025] If the total volume of the upper part of the dimple is Vo and the total volume of the lower part of the dimple is Vi, then V = Vo + Vi. In the present invention, it is preferable to satisfy Vi - 1.50 x Vo ≥ 0. The value of (Vi - 1.50 x Vo) is preferably 0 or more, more preferably 30 or more, and even more preferably 60 or more, and is preferably 260 or less, more preferably 230 or less, and even more preferably 210 or less. If the value of (Vi-1.50×Vo) is within the above range, the lift generated from the dimples can be controlled, and the flight distance of driver shots will be greater.

[0026] The diameter Dm of each dimple 10 is preferably 2.0 mm or greater and 6.0 mm or less. Dimples 10 with a diameter Dm of 2.0 mm or greater contribute to turbulence. From this viewpoint, the diameter Dm is more preferably 2.5 mm or greater, and particularly preferably 2.8 mm or greater. Dimples 10 with a diameter Dm of 6.0 mm or less do not impair the essence of the golf ball 2 being substantially a sphere. From this viewpoint, the diameter Dm is more preferably 5.5 mm or less, and particularly preferably 5.0 mm or less.

[0027] In Figure 4, a double-headed arrow Dp1 indicates a first depth of the dimple 10. This first depth Dp1 is the distance between the deepest part of the dimple 10 and the surface of the phantom sphere 14. In Figure 4, a double-headed arrow Dp2 indicates a second depth of the dimple 10. This second depth Dp2 is the distance between the deepest part of the dimple 10 and the tangent line Tg.

[0028] From the standpoint of suppressing hopping of the golf ball 2, the first depth Dp1 of the dimple 10 is preferably equal to or greater than 0.10 mm, more preferably equal to or greater than 0.13 mm, and particularly preferably equal to or greater than 0.15 mm. From the standpoint of suppressing dropping of the golf ball 2, the first depth Dp1 is preferably equal to or less than 0.65 mm, more preferably equal to or less than 0.60 mm, and particularly preferably equal to or less than 0.55 mm.

[0029] The area A of the dimple 10 is the area of ​​the region surrounded by the outline of the dimple 10 when viewing the center of the golf ball 2 from infinity. In the case of a circular dimple 10, the area A is calculated by the following formula. A = (Dm / 2) 2 * π

[0030] In the present invention, the ratio of the total area A of all dimples 10 to the surface area of ​​the phantom sphere 14 is referred to as the occupation ratio So. From the viewpoint of obtaining sufficient turbulence, the occupation ratio So is preferably 70% or more, more preferably 75% or more, and particularly preferably 80% or more. The occupation ratio So is preferably 95% or less. In the golf ball 2 shown in Figures 2 and 3, the total area of ​​the dimples 10 is 4707 mm 2 The surface area of ​​the phantom sphere 14 of this golf ball 2 is 5728 mm 2 Therefore, the occupancy rate So is 81.6%.

[0031] From the standpoint of achieving a sufficient occupation ratio So, the total number of dimples 10 is preferably at least 250, more preferably at least 280, and particularly preferably at least 300. From the standpoint of the contribution of each dimple 10 to turbulence, the total number is preferably no more than 450, more preferably no more than 410, and particularly preferably no more than 390.

[0032] The golf ball 2 of the present invention has a dimple A with a diameter of 4.400 mm, a dimple B with a diameter of 4.285 mm, a dimple C with a diameter of 4.150 mm, a dimple D with a diameter of 3.875 mm, and a dimple E with a diameter of 3.000 mm. The number of types of dimples 10 is five.

[0033] In the golf ball 2 shown in FIGS. 2 and 3, the area of ​​the dimple A is 15.21 mm 2 and the area of ​​dimple B is 14.42 mm 2 and the area of ​​dimple C is 13.53 mm 2 and the area of ​​dimple D is 11.79 mm 2 and the area of ​​dimple E is 7.07 mm 2 It is.

[0034] The structure of the golf ball of the present invention is not particularly limited as long as it has a spherical core and an outermost cover disposed outside the spherical core. Examples of the structure of the golf ball of the present invention include a two-piece golf ball consisting of a single-layered spherical core and a single-layered cover covering the spherical core; a three-piece golf ball consisting of a single-layered spherical core, an inner cover covering the spherical core, and an outermost cover covering the inner cover; and a multi-piece golf ball (four-piece golf ball, five-piece golf ball, etc.) consisting of a single-layered spherical core, two or more inner covers covering the spherical core, and an outermost cover covering the inner cover. The inner cover may be called an outer core or an intermediate layer depending on the structure of the golf ball.

[0035] The spherical core of the golf ball of the present invention is preferably formed from a rubber composition (hereinafter sometimes referred to as the "core rubber composition") containing (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator.

[0036] As the (a) base rubber, natural rubber and / or synthetic rubber can be used, for example, polybutadiene rubber, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (EPDM), etc. These may be used alone or in combination of two or more. Among these, high cis polybutadiene having cis-1,4-bonds, which are advantageous in terms of resilience, in an amount of 40% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more is particularly suitable.

[0037] The high-cis polybutadiene preferably has a 1,2-vinyl bond content of 2% by mass or less, more preferably 1.7% by mass or less, and further preferably 1.5% by mass or less. If the 1,2-vinyl bond content is 2% by mass or less, the resilience is improved.

[0038] The high-cis polybutadiene is preferably one synthesized using a rare earth element catalyst. In particular, the use of a neodymium-based catalyst using a neodymium compound, which is a lanthanum series rare earth element compound, is preferred because it can produce a polybutadiene rubber having a high content of 1,4-cis bonds and a low content of 1,2-vinyl bonds with excellent polymerization activity.

[0039] The high cis polybutadiene has a Mooney viscosity (ML 1+4 (100°C)) is preferably 30 or more, more preferably 32 or more, even more preferably 35 or more, and is preferably 140 or less, more preferably 120 or less, even more preferably 100 or less, and most preferably 80 or less. Note that the Mooney viscosity (ML 1+4 (100°C) is a value measured in accordance with JIS K6300 using an L rotor, with a preheating time of 1 minute, rotor rotation time of 4 minutes, and at 100°C.

[0040] The high cis polybutadiene preferably has a molecular weight distribution Mw / Mn (Mw: weight average molecular weight, Mn: number average molecular weight) of 2.0 or more, more preferably 2.2 or more, even more preferably 2.4 or more, most preferably 2.6 or more, and preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, and most preferably 3.4 or less. If the molecular weight distribution (Mw / Mn) of the high cis polybutadiene is 2.0 or more, the workability is improved, and if it is 6.0 or less, the resilience is high. The molecular weight distribution is measured by gel permeation chromatography (manufactured by Tosoh Corporation, "HLC-8120GPC") using a differential refractometer as a detector under the conditions of column: GMHHXL (manufactured by Tosoh Corporation), column temperature: 40°C, and mobile phase: tetrahydrofuran, and is calculated as a standard polystyrene equivalent value.

[0041] (b) An α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or a metal salt thereof is blended into the rubber composition as a co-crosslinking agent, and has the effect of crosslinking rubber molecules by graft polymerization with the base rubber molecular chains.

[0042] Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and crotonic acid.

[0043] Examples of metals constituting the metal salt of α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include monovalent metal ions such as sodium, potassium, and lithium; divalent metal ions such as magnesium, calcium, zinc, barium, and cadmium; trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The metal components can be used alone or in a mixture of two or more kinds. Among these, divalent metals such as magnesium, calcium, zinc, barium, and cadmium are preferable as the metal components. This is because the use of divalent metal salts of α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms facilitates the formation of metal crosslinks between rubber molecules. In particular, zinc acrylate is preferable as the divalent metal salt because it increases the resilience of the resulting golf ball. The α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt may be used alone or in combination of two or more kinds.

[0044] The content of (b) α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt is preferably 15 parts by weight or more, more preferably 20 parts by weight or more, even more preferably 25 parts by weight or more, and preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less, per 100 parts by weight of (a) base rubber. If the content of (b) α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt is 15 parts by weight or more, the core formed has an appropriate hardness and the resilience of the golf ball is improved. On the other hand, if the content of α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt is 50 parts by weight or less, the core formed is not too hard, and the shot feeling of the golf ball is good.

[0045] The (c) crosslinking initiator is blended to crosslink the (a) base rubber component. As the (c) crosslinking initiator, an organic peroxide is suitable. Specific examples of the organic peroxide include dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and di-t-butyl peroxide. These organic peroxides may be used alone or in combination of two or more. Among these, dicumyl peroxide is preferably used.

[0046] The content of the (c) crosslinking initiator is preferably at least 0.2 parts by weight, more preferably at least 0.4 parts by weight, and even more preferably at least 0.6 parts by weight, and is preferably at most 5.0 parts by weight, more preferably at most 2.5 parts by weight, and even more preferably at most 1.0 part by weight, per 100 parts by weight of the (a) base rubber. If the content of the (c) crosslinking initiator is within the above range, the hardness of the formed core becomes appropriate, and the resilience of the golf ball becomes good.

[0047] When the rubber composition contains only an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms as a co-crosslinking agent, it is preferable that the rubber composition further contains (d) a metal compound. By neutralizing the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms in the rubber composition with a metal compound, substantially the same effect as when a metal salt of an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms is used as a co-crosslinking agent can be obtained. In addition, when an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and a metal salt thereof are used in combination as a co-crosslinking agent, (d) a metal compound may be used.

[0048] The (d) metal compound is not particularly limited as long as it can neutralize the (b) α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms in the rubber composition. Examples of the (d) metal compound include metal hydroxides such as magnesium hydroxide, zinc hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, and copper hydroxide; metal oxides such as magnesium oxide, calcium oxide, zinc oxide, and copper oxide; and metal carbonates such as magnesium carbonate, zinc carbonate, calcium carbonate, sodium carbonate, lithium carbonate, and potassium carbonate. The (d) metal compound is preferably a divalent metal compound, and more preferably a zinc compound. This is because the divalent metal compound reacts with the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms to form a metal bridge. In addition, by using a zinc compound, a golf ball with high resilience can be obtained. These (d) metal compounds may be used alone or in combination of two or more kinds.

[0049] The rubber composition preferably further contains (e) an organic sulfur compound. The (e) organic sulfur compound is not particularly limited as long as it is an organic compound having a sulfur atom in the molecule, and examples thereof include organic compounds having a thiol group (-SH) or a polysulfide bond having 2 to 4 sulfur atoms (-SS-, -SSS-, or -SSSS-), or metal salts thereof (-SM, -SMS-, etc., where M is a metal atom). Examples of the (e) organic sulfur compound include thiophenols, thionaphthols, polysulfides, thiurams, thiocarboxylic acids, dithiocarboxylic acids, sulfenamides, dithiocarbamates, and thiazoles.

[0050] Examples of the thiophenols include thiophenol; thiophenols substituted with a fluoro group, such as 4-fluorothiophenol, 2,4-difluorothiophenol, 2,5-difluorothiophenol, 2,6-difluorothiophenol, 2,4,5-trifluorothiophenol, 2,4,5,6-tetrafluorothiophenol, and pentafluorothiophenol; and chlorothiophenol, such as 2-chlorothiophenol, 4-chlorothiophenol, 2,4-dichlorothiophenol, 2,5-dichlorothiophenol, 2,6-dichlorothiophenol, 2,4,5-trichlorothiophenol, 2,4,5,6-tetrachlorothiophenol, and pentachlorothiophenol. thiophenols substituted with a bromo group, such as 4-bromothiophenol, 2,4-dibromothiophenol, 2,5-dibromothiophenol, 2,6-dibromothiophenol, 2,4,5-tribromothiophenol, 2,4,5,6-tetrabromothiophenol, and pentabromothiophenol; thiophenols substituted with an iodo group, such as 4-iodothiophenol, 2,4-diiodothiophenol, 2,5-diiodothiophenol, 2,6-diiodothiophenol, 2,4,5-triiodothiophenol, 2,4,5,6-tetraiodothiophenol, and pentaiodothiophenol; or metal salts thereof.

[0051] Examples of the thionaphthols (naphthalene thiols) include 2-thionaphthol, 1-thionaphthol, 1-chloro-2-thionaphthol, 2-chloro-1-thionaphthol, 1-bromo-2-thionaphthol, 2-bromo-1-thionaphthol, 1-fluoro-2-thionaphthol, 2-fluoro-1-thionaphthol, 1-cyano-2-thionaphthol, 2-cyano-1-thionaphthol, 1-acetyl-2-thionaphthol, 2-acetyl-1-thionaphthol, and metal salts thereof.

[0052] The polysulfides are organic sulfur compounds having polysulfide bonds, and examples of the polysulfides include disulfides, trisulfides, and tetrasulfides. As the polysulfides, diphenyl polysulfides are preferred.

[0053] Diphenyl polysulfides include, in addition to diphenyl disulfide, bis(4-fluorophenyl) disulfide, bis(2,5-difluorophenyl) disulfide, bis(2,6-difluorophenyl) disulfide, bis(2,4,5-trifluorophenyl) disulfide, bis(2,4,5,6-tetrafluorophenyl) disulfide, bis(pentafluorophenyl) disulfide, bis(4-chlorophenyl) disulfide, Bis(2,5-dichlorophenyl) disulfide, bis(2,6-dichlorophenyl) disulfide, bis(2,4,5-trichlorophenyl) disulfide, bis(2,4,5,6-tetrachlorophenyl) disulfide, bis(pentachlorophenyl) disulfide, bis(4-bromophenyl) disulfide, bis(2,5-dibromophenyl) disulfide, bis(2,6-dibromophenyl) disulfide, bis(2,4,5-tribromophenyl) disulfide phenyl) disulfide, bis(2,4,5,6-tetrabromophenyl) disulfide, bis(pentabromophenyl) disulfide, bis(4-iodophenyl) disulfide, bis(2,5-diiodophenyl) disulfide, bis(2,6-diiodophenyl) disulfide, bis(2,4,5-triiodophenyl) disulfide, bis(2,4,5,6-tetraiodophenyl) disulfide, bis(pentaiodophenyl) disulfide diphenyl disulfides substituted with halogen groups such as 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, bis(penta-t-butylphenyl) disulfide, and the like.

[0054] Examples of thiurams include thiuram monosulfides such as tetramethylthiuram monosulfide, thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetrabutylthiuram disulfide, and thiuram tetrasulfides such as dipentamethylenethiuram tetrasulfide. Examples of thiocarboxylic acids include naphthalene thiocarboxylic acid. Examples of dithiocarboxylic acids include naphthalene dithiocarboxylic acid. Examples of sulfenamides include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and Nt-butyl-2-benzothiazole sulfenamide.

[0055] The (e) organic sulfur compounds can be used alone or in combination of two or more.

[0056] The content of the (e) organic sulfur compound is preferably at least 0.05 parts by mass, more preferably at least 0.1 parts by mass, and even more preferably at least 0.2 parts by mass, and is preferably at most 5.0 parts by mass, more preferably at most 3.0 parts by mass, and even more preferably at most 2.0 parts by mass, per 100 parts by mass of the (a) base rubber. If the content of the (e) organic sulfur compound is within the above range, the resilience is improved.

[0057] The rubber composition may further contain (f) a carboxylic acid and / or a metal salt thereof. As the (f) carboxylic acid and / or a metal salt thereof, a carboxylic acid having 1 to 30 carbon atoms and / or a salt thereof is preferable. As the carboxylic acid, either an aliphatic carboxylic acid (saturated fatty acid, unsaturated fatty acid) or an aromatic carboxylic acid (benzoic acid, etc.) can be used. The compounding amount of the (f) carboxylic acid and / or a metal salt thereof is preferably 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the base rubber.

[0058] The rubber composition may contain additives such as a filler for adjusting the weight, an antioxidant, a peptizer, and a softener, as required.

[0059] The filler used in the rubber composition is mainly blended as a weight adjusting agent for adjusting the weight of the golf ball obtained as the final product, and may be blended as necessary. Examples of the filler include inorganic fillers such as zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder. The content of the filler is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the base rubber. If the content of the filler is 0.5 parts by mass or more, weight adjustment becomes easy, and if it is 30 parts by mass or less, the weight fraction of the rubber component tends to increase and the resilience tends to increase.

[0060] The content of the antioxidant is preferably 0.1 part by mass or more and 1 part by mass or less per 100 parts by mass of the (a) base rubber, and the content of the peptizing agent is preferably 0.1 part by mass or more and 5 parts by mass or less per 100 parts by mass of the (a) base rubber.

[0061] The rubber composition is obtained by kneading (a) base rubber, (b) α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and / or its metal salt, (c) crosslinking initiator, and other components that are mixed as necessary. The kneading method is not particularly limited, and may be performed using a known kneading machine such as a kneading roll, a Banbury mixer, or a kneader.

[0062] The spherical core of the golf ball of the present invention can be molded, for example, by hot pressing the rubber composition for the core. The hot press molding conditions for the rubber composition for the core may be appropriately set depending on the rubber composition, but it is usually preferable to heat the rubber composition for the core at 130°C to 200°C for 10 to 60 minutes, or to heat the rubber composition for the core at 130°C to 150°C for 20 to 40 minutes, and then heat the rubber composition for the core at 160°C to 180°C for 5 to 15 minutes.

[0063] The spherical core may have either a single-layer structure or a multi-layer structure, but is preferably of a single-layer structure.

[0064] The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, even more preferably 38.8 mm or more, and is preferably 42.2 mm or less, more preferably 41.8 mm or less, even more preferably 41.2 mm or less, and most preferably 40.8 mm or less. If the diameter of the spherical core is 34.8 mm or more, the thickness of the cover is not too thick, and the resilience is better. On the other hand, if the diameter of the spherical core is 42.2 mm or less, the cover is not too thin, and the function of the cover is more fully exhibited.

[0065] When the diameter of the spherical core is 34.8 mm to 42.2 mm, the amount of compressive deformation (the amount of shrinkage of the spherical core in the compressive direction) from when an initial load of 98 N is applied to when a final load of 1275 N is applied is preferably 2.0 mm or more, more preferably 2.5 mm or more, even more preferably 3.0 mm or more, and preferably 5.0 mm or less, more preferably 4.5 mm or less, even more preferably 4.0 mm or less. If the amount of compressive deformation is 2.0 mm or more, the hitting feeling becomes better, and if it is 5.0 mm or less, the resilience becomes better.

[0066] The hardness difference S (=Hs-Ho) between the surface hardness (Hs) and the center hardness (Ho) of the spherical core is preferably 5 or more, more preferably 10 or more, and even more preferably 15 or more, and is preferably 45 or less, more preferably 40 or less, and even more preferably 35 or less, in Shore C hardness. A spherical core having a hardness difference S (=Hs-Ho) within the above range has an outer hard / inner soft structure. In a spherical core having an outer hard / inner soft structure, the magnitude of the hardness difference contributes to the increase or decrease of the spin rate.

[0067] The surface hardness (Hs) of the spherical core is not particularly limited, but is preferably 60 or more, more preferably 65 or more, and even more preferably 70 or more in Shore C hardness, and is preferably 95 or less, more preferably 90 or less, and even more preferably 85 or less. If the surface hardness (Hs) is within the above range, a good hitting feel can be obtained upon impact.

[0068] The central hardness (Ho) of the spherical core is not particularly limited, but is preferably 30 or more, more preferably 35 or more, and even more preferably 40 or more, in Shore C hardness, and is preferably 70 or less, more preferably 65 or less, and even more preferably 60 or less. If the central hardness (Ho) of the spherical core is within the above range, a good hitting feel can be obtained upon impact.

[0069] The golf ball of the present invention has an outermost cover layer located outside the core. The outermost cover layer is preferably formed from a cover composition containing a resin component. When the golf ball of the present invention has an inner cover layer, the inner cover layer is preferably formed from a cover composition containing a resin component.

[0070] Examples of resin components forming the outermost cover layer and the inner cover layer include ionomer resins, thermoplastic polyurethane elastomers available from BASF Japan Ltd. under the trade name "Elastollan (registered trademark)", thermoplastic polyamide elastomers available from Arkema K.K. under the trade name "Pebax (registered trademark)", thermoplastic polyester elastomers available from DuPont-Toray Co., Ltd. under the trade name "Hytrel (registered trademark)", and thermoplastic styrene elastomers available from Mitsubishi Chemical Corporation under the trade name "TEFABLOCK".

[0071] Examples of the ionomer resin include a binary copolymer of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, in which at least a part of the carboxyl groups is neutralized with a metal ion, a ternary copolymer of an olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester, in which at least a part of the carboxyl groups is neutralized with a metal ion, or a mixture thereof. The olefin is preferably an olefin having 2 to 8 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, etc., and ethylene is particularly preferred. Examples of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms include acrylic acid, methacrylic acid, fumaric acid, maleic acid, crotonic acid, etc., and acrylic acid or methacrylic acid is particularly preferred. Examples of the α,β-unsaturated carboxylic acid ester include methyl, ethyl, propyl, n-butyl, and isobutyl esters of acrylic acid, methacrylic acid, fumaric acid, and maleic acid, and acrylic acid esters and methacrylic acid esters are particularly preferred. Among these, the ionomer resin is preferably a metal ion neutralized product of an ethylene-(meth)acrylic acid binary copolymer or a metal ion neutralized product of an ethylene-(meth)acrylic acid-(meth)acrylic acid ester ternary copolymer.

[0072] Specific examples of the ionomer resins by trade name include "Himilan (registered trademark)" available from Mitsui DuPont Polychemicals Co., Ltd. (e.g., Himilan 1555 (Na), Himilan 1557 (Zn), Himilan 1605 (Na), Himilan 1706 (Zn), Himilan 1707 (Na), Himilan AM3711 (Mg), Himilan AM7329 (Zn), etc.; examples of terpolymer ionomer resins include Himilan 1856 (Na), Himilan 1855 (Zn), etc.).

[0073] Further, examples of ionomer resins commercially available from DuPont include "Surlyn (registered trademark) (e.g., Surlyn 8945 (Na), Surlyn 9945 (Zn), Surlyn 8140 (Na), Surlyn 8150 (Na), Surlyn 9120 (Zn), Surlyn 9150 (Zn), Surlyn 6910 (Mg), Surlyn 6120 (Mg), Surlyn 7930 (Li), Surlyn 7940 (Li), Surlyn AD8546 (Li), and the like; examples of terpolymer ionomer resins include Surlyn 8120 (Na), Surlyn 8320 (Na), Surlyn 9320 (Zn), Surlyn 6320 (Mg), HPF1000 (Mg), HPF2000 (Mg), and the like)."

[0074] Furthermore, examples of ionomer resins commercially available from ExxonMobil Chemical Co. include "Iotek (registered trademark) (e.g., Iotek 8000(Na), Iotek 8030(Na), Iotek 7010(Zn), Iotek 7030(Zn), etc., and examples of terpolymer ionomer resins include Iotek 7510(Zn), Iotek 7520(Zn), etc.)."

[0075] The names of the ionomer resins in parentheses after their trade names, such as Na, Zn, Li, and Mg, indicate the metal species of these neutralizing metal ions. The ionomer resins may be used alone or in combination of two or more kinds.

[0076] The cover composition preferably contains a thermoplastic polyurethane elastomer or an ionomer resin as a resin component. The content of the thermoplastic polyurethane elastomer or the ionomer resin in the resin component of the cover composition is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The cover composition may contain only a thermoplastic polyurethane elastomer or an ionomer resin as a resin component.

[0077] In addition to the resin components described above, the cover composition may contain pigment components such as white pigments (e.g., titanium oxide), blue pigments, and red pigments, weight adjusters such as zinc oxide, calcium carbonate, and barium sulfate, dispersants, antioxidants, ultraviolet absorbing agents, light stabilizers, fluorescent materials, or fluorescent brighteners, to the extent that the performance of the cover is not impaired.

[0078] The content of the white pigment (e.g., titanium oxide) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, based on 100 parts by mass of the resin component constituting the cover. By making the content of the white pigment 0.5 parts by mass or more, it is possible to impart hiding properties to the cover. In addition, if the content of the white pigment is 10 parts by mass or less, the durability of the obtained cover is not impaired.

[0079] Methods for molding the cover include, for example, a method in which a hollow shell is molded from the cover composition, the core is coated with multiple shells, and the resulting mixture is compression molded (preferably, a method in which a hollow half shell is molded from the cover composition, the core is coated with two half shells, and the resulting mixture is compression molded), or a method in which the cover composition is directly injection molded onto the core.

[0080] When the cover is molded by the compression molding method, the molding of the half shell can be performed by either the compression molding method or the injection molding method, but the compression molding method is preferable. The conditions for compressing and molding the resin composition into the half shell include, for example, a pressure of 1 MPa or more and 20 MPa or less, and a molding temperature of -20°C or more and 70°C or less with respect to the flow start temperature of the resin composition. By using the above molding conditions, a half shell having a uniform thickness can be molded. For example, a method for molding the cover using the half shell includes a method of compressing and molding the core with two half shells. The conditions for compressing and molding the half shell into the cover include, for example, a molding pressure of 0.5 MPa or more and 25 MPa or less, and a molding temperature of -20°C or more and 70°C or less with respect to the flow start temperature of the resin composition. By using the above molding conditions, a cover having a uniform thickness can be molded.

[0081] When the cover composition is injection molded to form the cover, the cover composition in pellet form obtained by extrusion may be used for injection molding, or the cover material such as the base resin component and the pigment may be dry blended and directly injection molded. As the upper and lower molds for molding the cover, it is preferable to use those having a hemispherical cavity, with pimples, and a part of the pimples also serving as a hold pin that can move forward and backward. The cover can be molded by injection molding by protruding the hold pin, inserting the core and holding it, injecting the cover composition, and cooling it. For example, the resin composition heated to 200°C to 250°C is injected for 0.5 to 5 seconds into a mold clamped at a pressure of 9 MPa to 15 MPa, and cooled for 10 to 60 seconds, and then opening the mold.

[0082] The outermost cover layer has dimples formed thereon that are the inverse of the pimples formed on the cavity surface of the mold.

[0083] The golf ball body with the cover molded thereon is preferably removed from the mold and, if necessary, subjected to surface treatment such as deburring, cleaning, and sandblasting. A coating film or marking can also be formed as desired. The thickness of the coating film is not particularly limited, but is preferably 5 μm or more, more preferably 6 μm or more, even more preferably 7 μm or more, preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. If the thickness is 5 μm or more, the coating film is less likely to wear away even with continuous use, and if the thickness is 50 μm or less, the effect of the dimples is sufficiently obtained, improving the flight performance of the golf ball.

[0084] The material hardness C of the outermost cover layer of the golf ball of the present invention (i.e., the slab hardness of the cover composition constituting the cover) is preferably 20 or more, more preferably 25 or more, even more preferably 30 or more, and is preferably 65 or less, more preferably 64 or less, and even more preferably 63 or less, in Shore D hardness. By making the material hardness of the cover 20 or more, the abrasion resistance of the outermost cover layer is improved. Furthermore, by making the material hardness of the outermost cover layer 65 or less, the durability of the cover is improved.

[0085] The thickness of the outermost cover layer is preferably 4.0 mm or less, more preferably 3.0 mm or less, and even more preferably 2.0 mm or less, and is preferably 0.3 mm or more, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more, because the resilience and shot feel of the resulting golf ball are improved if the thickness of the outermost cover layer is within the above range.

[0086] The golf ball of the present invention preferably has an inner cover between the spherical core and the outermost cover. The slab hardness of the inner cover is preferably 30 or more, more preferably 35 or more, and even more preferably 40 or more, and is preferably 70 or less, more preferably 69 or less, and even more preferably 68 or less, in Shore D hardness. If the slab hardness of the inner cover is within the above range, the hitting feel is soft.

[0087] The thickness of the inner cover is preferably 0.2 mm or more, more preferably 0.4 mm or more, and even more preferably 0.6 mm or more, and is preferably 3.0 mm or less, more preferably 2.5 mm or less, and even more preferably 2.0 mm or less, because the thickness of the inner cover within the above range provides good durability and a soft and good feel on impact.

[0088] The inner cover may be made of one layer, or two or more layers.

[0089] The diameter of the golf ball of the present invention is preferably 40 mm to 45 mm. From the viewpoint of satisfying the standards of the United States Golf Association (USGA), the diameter is particularly preferably 42.67 mm or more. From the viewpoint of suppressing air resistance, the diameter is more preferably 44 mm or less, and particularly preferably 42.80 mm or less. The mass of the golf ball of the present invention is preferably 40 g or more and 50 g or less. From the viewpoint of obtaining a large inertia, the mass is more preferably 44 g or more, and particularly preferably 45.00 g or more. From the viewpoint of satisfying the standards of the USGA, the mass is particularly preferably 45.93 g or less.

[0090] In the golf ball of the present invention, when the diameter is 40mm to 45mm, the compressive deformation amount (the amount of shrinkage of the golf ball in the compressive direction) when a final load of 1275N is applied from an initial load of 98N is preferably 3.4mm or more, more preferably 3.6mm or more, even more preferably 3.8mm or more, and is preferably 5.4mm or less, more preferably 5.2mm or less, even more preferably 5.0mm or less. A golf ball with the compressive deformation amount of 3.4mm or more is not too hard and has a good shot feeling. On the other hand, by making the compressive deformation amount 5.4mm or less, durability is increased. EXAMPLES

[0091] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and all modifications and embodiments that do not deviate from the spirit of the present invention are included within the scope of the present invention.

[0092] [Evaluation method] (1) Compressive deformation amount (mm) A Yamada compression tester "SCH" was used to measure the amount of compressive deformation. In this tester, a golf ball or core is placed on a metal hard plate. A metal cylinder is gradually lowered towards the golf ball or core. The golf ball or core is deformed when sandwiched between the bottom of the cylinder and the hard plate. The travel distance of the cylinder was measured from when an initial load of 98N was applied to the golf ball or core until a final load of 1275N was applied. The amount of compressive deformation (mm) is this travel distance. The travel speed of the cylinder until the initial load was applied was 0.83mm / s. The travel speed of the cylinder from when the initial load was applied to when the final load was applied was 1.67mm / s.

[0093] (2) Material (slab) hardness (Shore D hardness) A sheet with a thickness of about 2 mm was prepared by injection molding using the intermediate layer composition or the cover composition, and stored at 23° C. for two weeks. The hardness was measured using an automatic hardness tester (Digitest II, manufactured by H. Burleith Co.) in a state where three or more sheets were stacked so as not to be affected by the measurement substrate, etc. The detector used was "Shore D."

[0094] (3) Core hardness distribution (Shore C hardness) The Shore C hardness of the core surface was measured on the surface of the core using an automatic rubber hardness tester, Model P1, manufactured by Kobunshi Keiki Co., Ltd., equipped with a spring-type Shore C hardness tester. The core was cut into a hemisphere, and the hardness of the center of the cut surface was measured.

[0095] (4) Driver distance and lateral deviation (m) A driver (Sumitomo Rubber Industries' product name "XXIO PRIME (manufactured in 2021)", shaft hardness: R2, loft angle: 11.5 degrees) was attached to Golf Laboratory's swing machine, and a golf ball was hit with a head speed of 30 m / sec under conditions that reproduced the mis-shot described below, and the flight distance and deviation distance (m) from the launch point to the resting point were measured. The deviation distance is the horizontal distance from the resting point of the golf ball to the imaginary flight line if the golf ball flies straight from the impact point. Each golf ball was measured 12 times, and the average value of the data obtained was used as the measured value of that golf ball. Conditions for replicating a missed shot Set the swing trajectory to 5 degrees outside-in - Hit the ball at a point 20mm away from the center of the face toward the heel. Adjust the face direction (angle) so that golf ball No. 1 is hit in a slice with a launch angle of 15 degrees, swing angle of 0 degrees, backspin of 2500 rpm, and side spin of 1250 rpm.

[0096] [Manufacturing of golf balls] (1) Core preparation The rubber composition having the composition shown in Table 1 was kneaded with a kneading roll and molded in upper and lower molds having hemispherical cavities under the vulcanization conditions shown in Table 1 to obtain a spherical core having a diameter of 39.8 mm. The amount of barium sulfate was adjusted so that the mass of the golf ball was 45.6 g.

[0097] [Table 1]

[0098] Polybutadiene: JSR Corporation, "BR730 (high cis polybutadiene)" Zinc acrylate: Nisshoku Techno Fine Chemical Co., Ltd., "ZN-DA90S" Zinc oxide: "Ginrei R" manufactured by Toho Zinc Co., Ltd. Barium sulfate: Sakai Chemical Industry Co., Ltd., "Barium Sulfate BD" Benzoic acid: Tokyo Chemical Industry Co., Ltd. (purity 98% or more) Pentachlorothiophenol zinc salt: Tokyo Chemical Industry Co., Ltd. Dicumyl peroxide: NOF Corporation, "Percumyl (registered trademark) D"

[0099] (2) Preparation of cover composition A pellet-shaped cover composition was prepared by mixing the materials shown in Table 2 using a twin-screw kneading extruder. The extrusion conditions were a screw diameter of 45 mm, a screw rotation speed of 200 rpm, and a screw L / D of 35, and the compound was heated to 160 to 240° C. at the die of the extruder.

[0100] [Table 2]

[0101] Himilan (registered trademark) AM7337: Sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui Dow Polychemicals Himilan (registered trademark) AM7329: Zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin manufactured by Mitsui DuPont Polychemicals Tefablock (registered trademark) T3221C: Thermoplastic styrene-based elastomer manufactured by Mitsubishi Chemical Corporation Titanium dioxide: Ishihara Sangyo Kaisha, Ltd., "A-220"

[0102] A predetermined shape of pimples was made on the cavity surface of the mold. The spherical core was put into a final mold with pimples on the cavity surface, and the holding pin was pushed out to fix the spherical core. The cover composition heated to 260°C was poured into the mold clamped under a pressure of 80 tons in 0.3 seconds, cooled for 30 seconds, and the mold was opened to remove the golf ball. A large number of dimples were formed on the cover, which were the inverse shape of the pimples on the cavity surface. The surface of the obtained golf ball body was sandblasted and marked, and then clear paint was applied, and the paint was dried in an oven at 40°C to obtain a golf ball with a diameter of 42.7 mm and a mass of 45.6 g. The specifications of the dimples formed on the outermost cover are shown in Tables 3 to 6. The properties and evaluation results of the resulting golf balls are shown in Tables 7 and 8.

[0103] [Table 3]

[0104] [Table 4]

[0105] [Table 5]

[0106] [Table 6]

[0107] [Table 7]

[0108] From the results of Tables 7 and 8, it can be seen that a golf ball having a spherical core and an outermost cover layer having a plurality of dimples and positioned outside the spherical core, The central hardness H0 (Shore C hardness) of the spherical core and the surface hardness H sThe difference in hardness between the The material hardness (Shore D hardness) of the outermost cover layer is C, The total volume under the virtual sphere of multiple dimples is V (mm 3 ), A golf ball in which S, C, and V satisfy V×(S+C) / 1000≧50 maintains or improves the flight distance of driver shots while providing stable directionality for golfers with slow head speed. [Industrial Applicability]

[0109] The golf ball of the present invention is a golf ball that maintains or improves the flight distance of driver shots while providing stable directionality for golfers with slow head speed.

[0110] A preferred embodiment (1) of the present invention is a golf ball having a spherical core and an outermost cover layer located outside the spherical core and having a plurality of dimples thereon, The difference in hardness between the center hardness Ho (Shore C hardness) of the spherical core and the surface hardness Hs of the spherical core is S (=Hs-Ho), The material hardness (Shore D hardness) of the outermost cover layer is C, The total volume under the virtual sphere of multiple dimples is V (mm 3 ), The S, C, and V are The golf ball is characterized by satisfying V×(S+C) / 1000≧50.

[0111] A preferred embodiment (2) of the present invention is a golf ball according to embodiment (1), in which when the total upper volume of the dimples is Vo and the total lower volume is Vi, and V=Vo+Vi, Vi-1.50×Vo≧0 is satisfied.

[0112] A preferred embodiment (3) of the present invention is a golf ball according to embodiment (1) or (2) which satisfies S×C≧1000.

[0113] A preferred embodiment (4) of the present invention is a golf ball according to any one of the embodiments (1) to (3), in which the cover contains an ionomer resin.

Claims

1. A golf ball having a spherical core and an outermost cover layer located outside the spherical core and having a plurality of dimples thereon, The difference in hardness between the center hardness Ho (Shore C hardness) of the spherical core and the surface hardness Hs of the spherical core is S (=Hs-Ho), The material hardness (Shore D hardness) of the outermost cover layer is C, The total volume of the dimples under the virtual spherical surface is V (mm ３ ) and The S, C, and V are A golf ball satisfying V×(S+C) / 1000≧50.

2. 2. The golf ball according to claim 1, wherein when a total volume of the upper portions of the dimples is Vo and a total volume of the lower portions is Vi, and V=Vo+Vi, Vi-1.50×Vo≧0 is satisfied.

3. 2. The golf ball according to claim 1, which satisfies S×C≧1000.

4. 2. The golf ball according to claim 1, wherein the cover comprises an ionomer resin.

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