JP2019110986A - Golf ball - Google Patents

Abstract

To provide a golf ball capable of reducing furthermore a spin amount in a driver shot, and improving furthermore carry, while maintaining high durability.SOLUTION: A golf ball 1 includes a core 10 positioned on the center, a cover 20 positioned on the outside of the core, and having a plurality of dimples 22 on the surface, and a metal mesh layer 30 positioned between the core and the cover, in which the metal mesh layer 30 has a wire size in the range of 0.01-0.5 mm, and has a mesh number of 16-1,000.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a golf ball, and more particularly to a golf ball with improved flight distance at the time of driver shots while maintaining durability.

  In order to improve the flight distance of the golf ball in the driver shot, it is advantageous to reduce the spin amount of the golf ball in the driver shot. As a golf ball structure for reducing the spin amount, for example, in JP 2013-220353 A, by using a predetermined ionomer resin as one material of the cover of the golf ball and the intermediate layer between the core and the cover, It is described that the resilience of the cover and the intermediate layer is improved, and therefore the spin amount of the golf ball in driver shots can be suppressed.

  On the other hand, in JP-A-11-76458, the weight is 0.2 to 4.0 g at a position 17 mm or more away from the center of the core of the golf ball and between the core and the cover or between the plurality of cover layers. It is described that by providing the metal layer of the above, it is possible to increase the moment of inertia of the golf ball and to reduce the spin on driver shots.

JP, 2013-220353, A Japanese Patent Application Laid-Open No. 11-76458

  Although a predetermined ionomer resin currently used for golf balls, as described in JP 2013-220353 A, is a material excellent in resilience and durability, it is desired to further reduce the spin rate. When a higher resilience ionomer resin is used, there is a problem that the durability is greatly deteriorated and it is difficult to put it into practical use. On the other hand, when a metal layer is provided as in JP-A-11-76458, the spin amount certainly decreases from the viewpoint of the moment of inertia, but the strength against bending at the time of shot of the golf ball also increases. It is too hard to obtain a large decrease in spin amount, and there is a problem that the feel at impact is also poor.

  Therefore, in view of the above problems, it is an object of the present invention to provide a golf ball capable of further reducing the spin amount on driver shots while maintaining high durability and further improving the flight distance. I assume.

  In order to achieve the above object, a golf ball according to the present invention comprises a core located at the center of the golf ball, a cover located outside the core and having a plurality of dimples on the surface, the core and the cover And a metal mesh layer positioned between them, wherein the metal mesh layer has a wire diameter of 0.01 to 0.5 mm and a mesh number of 16 to 1000.

  The metal mesh layer preferably has a relationship of d × M where the wire diameter is d and the number of meshes is M is in the range of 5 to 12.

  The golf ball according to the present invention may further comprise an intermediate layer located between the core and the cover, in which case the metal mesh layer is located between the intermediate layer and the cover. Is preferred.

  The hardness of the cover is preferably 56 or less in Shore D.

  The μ hardness of the golf ball is preferably 2.0 mm or more.

  As described above, according to the present invention, by providing a metal mesh layer having a predetermined wire diameter and mesh number between the core and the cover, the golf ball is appropriately flexed and the elastic force in the bending direction necessary for the golf ball is obtained. And the rigidity in the pulling direction, it is possible to achieve a further reduction in the amount of spin in the driver shot and to maintain high durability.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a golf ball according to the present invention. It is an enlarged view which shows an example of the metal mesh layer used for the golf ball of FIG. It is a photograph which shows the state which covered the intermediate | middle layer by the metal mesh layer in the preparation process of the golf ball concerning this invention.

  Hereinafter, an embodiment of a golf ball according to the present invention will be described with reference to the attached drawings.

  As shown in FIG. 1, the golf ball 1 of the present embodiment is located between the core 10 located at the center of the ball, the cover 20 surrounding the outer periphery of the core 10, and the core 10 and the cover 20. The metal mesh layer 30 is mainly provided. A plurality of dimples 22 are formed on the surface of the cover 20. Also, the golf ball 1 of the present embodiment includes an intermediate layer 40 between the core 10 and the metal mesh layer 30. In the present embodiment, a three-piece golf ball having a core 10, an intermediate layer 40, and a cover 20 will be described. However, the present invention is not limited thereto, and a two-piece structure of the core 10 and the cover 20 may be used. The layer 40 may further have a multi-layer structure having a core and / or cover function, or the core 10 may have a multi-layer structure.

  The core 10 can be formed of a rubber composition containing rubber as a main component. As the main component rubber (base rubber), synthetic rubber and natural rubber can be used widely, without being limited thereto, polybutadiene rubber (BR), styrene butadiene rubber (SBR), natural rubber (NR) Polyisoprene rubber (IR), polyurethane rubber (PU), butyl rubber (IIR), vinyl polybutadiene rubber (VBR), ethylene propylene rubber (EPDM), nitrile rubber (NBR), and silicone rubber can be used. As polybutadiene rubber (BR), for example, 1,2-polybutadiene, cis 1,4-polybutadiene and the like can be used.

  In the core 10, in addition to such base rubber, optionally, for example, a co-crosslinking agent, a crosslinking initiator, a filler, an antiaging agent, an isomerizing agent, a peptizer, sulfur, and an organic sulfur compound It can be added. Also, as the main component, instead of rubber, a resin may be used, and for example, a thermoplastic elastomer, an ionomer resin, or a mixture thereof can also be used.

  As a co-crosslinking agent, although not limited thereto, for example, it is preferable to use an α, β-unsaturated carboxylic acid or a metal salt thereof. Examples of the α, β-unsaturated carboxylic acid or metal salt thereof include acrylic acid, methacrylic acid, and zinc salts, magnesium salts, calcium salts thereof and the like. The composition of the co-crosslinking material is not limited to this, but for example, about 5 parts by weight or more is preferable, and about 10 parts by weight or more is more preferable based on 100 parts by weight of the base rubber. In addition, about 70 parts by weight or less is preferable, and about 50 parts by weight or less is more preferable.

  The crosslinking initiator is not limited to this, but it is preferable to use an organic peroxide, for example, dicumyl peroxide, t-butylperoxybenzoate, di-t-butyl peroxide, 1,1-bis ( t-Butylperoxy) 3, 3, 5 trimethylcyclohexane and the like. Although the composition of the crosslinking initiator is not limited to this, for example, about 0.10 parts by weight or more is preferable, and about 0.15 parts by weight or more is more preferable, and about 0.30 parts by weight with respect to 100 parts by weight of the base rubber. More than part is more preferable. Also, about 8 parts by weight or less is preferable, and about 6 parts by weight or less is more preferable.

  Examples of fillers include, but are not limited to, silver, gold, cobalt, chromium, copper, iron, germanium, manganese, molybdenum, nickel, lead, platinum, tin, titanium, tungsten, zinc, zirconium, barium sulfate, etc. Zinc oxide, manganese oxide or the like can be used. The filler is preferably in powder form. The composition of the filler is not limited to this, but for example, about 1 part by weight or more is preferable, about 2 parts by weight or more is more preferable, and about 3 parts by weight or more is more preferable. Also, about 100 parts by weight or less is preferable, about 80 parts by weight or less is more preferable, and about 70 parts by weight or less is more preferable.

  As an anti-aging agent, although it is not limited to this, for example, a commercial product such as Nokrac NS-6 (manufactured by Ouchi Emerging Chemical Industry Co., Ltd.) can be used. The composition of the antiaging agent is not limited thereto, but is preferably about 0.1 parts by weight or more, and more preferably about 0.15 parts by weight or more, based on 100 parts by weight of the base rubber. In addition, about 1.0 parts by mass or less is preferable, and about 0.7 parts by mass or less is more preferable.

  The resilience of the core 30 can be improved by the addition of the organic sulfur compound (shearing material). The organic sulfur compound is selected from thiophenols, thiocarboxylic acids and metal salts thereof. Thiophenols and thiocarboxylic acids include thiophenols such as pentachlorothiophenol, 4-t-butyl-o-thiophenol, 4-t-butylthiophenol, 2-benzamidothiophenol, and thiocarboxylic acids such as thiobenzoic acid There are acids. Moreover, as these metal salts, a zinc salt etc. are preferable. The content of the organic sulfur compound is not limited to this, but is preferably about 0.05 parts by weight or more, and more preferably about 0.1 parts by weight or more, based on 100 parts by weight of the base rubber. Moreover, about 2 parts by weight or less is preferable, and about 1 part by weight or less is more preferable.

  The deflection hardness of the core 10 is defined as the amount of deformation (mm) of the core in the load direction from the initial load of 10 kgf (about 98 N) to the final load of 130 kgf (about 1275 N). Point to The higher the value of the deflection hardness of the core 10, the softer the core. The deflection hardness of the core 10 is preferably in the range of 2.5 to 4.5, and more preferably in the range of 3.0 to 4.0.

  The core 10 has a substantially spherical shape. The upper limit of the outer diameter of the core 10 is preferably 42 mm or less, more preferably 41 mm or less, and still more preferably 40 mm or less. The outer diameter of the core 10 is preferably 5 mm or more, more preferably 15 mm or more, and most preferably 25 mm or more, as the lower limit. The core 10 is shown as a solid core in FIG. 1, but is not limited to this and may be a hollow core. In addition, although the core 10 is shown as a single layer in FIG. 1, the present invention is not limited thereto. For example, the core 10 may be a core composed of a plurality of layers such as a center core and its surrounding layer.

  As a method of molding the core 10, a known method of molding a core of a golf ball can be adopted. For example, although not limited to this, after kneading the material containing the base rubber with a kneader, the kneaded product can be obtained by pressure vulcanization molding with a round mold. In addition, as a method of forming a core having a plurality of layers, a known method of forming a solid core having a multilayer structure can be employed. For example, after the center core is obtained by kneading the material in a kneader and subjecting this kneaded material to pressure vulcanization molding using a round mold, the material is kneaded in a kneader as an envelope layer, and this kneaded material is A multi-layered core can be obtained by molding into a sheet and covering the center core with this sheet by pressure vulcanization molding using a round mold.

  As shown in FIG. 2, the metal mesh layer 30 is a layer in which the metal wires 32 are formed in a net shape, and has a mesh structure in which a plurality of vertical lines 32 a and a plurality of horizontal lines 32 b are orthogonal to each other. The mesh structure is represented by a wire diameter d of the metal wire 32 and a mesh number M which is the number of meshes per 1 inch (25.4 mm) as a general standard. The wire diameter d of the metal mesh layer 30 is in the range of 0.01 to 0.5 mm, and the mesh number M is in the range of 16 to 1000. By setting the wire diameter d and the mesh number M in this range, it is possible to give the golf ball 1 a required elastic force in the bending direction and rigidity in the pulling direction. The range of 0.02-0.40 mm is preferable, and the range of 0.04-0.20 mm is more preferable for the wire diameter d. The range of 20-250 is preferable and, as for the mesh number M, the range of 50-200 is more preferable.

  The metal mesh layer 30 preferably has a d × M relationship in the range of 5 to 12 when the wire diameter is d and the number of meshes is M. By setting the relationship of d × M to 5 or more, the golf ball 1 can be sufficiently provided with the required rigidity in the pulling direction. Further, by setting the d × M relationship to 12 or less, the golf ball 1 can be sufficiently provided with elasticity required in the bending direction. The d × M relationship is more preferably in the range of 8 to 12.

Further, an aperture A which is a distance between the metal wires 32 can be expressed by the following equation, where d is a wire diameter and M is the number of meshes. A range of 0.05 to 1.10 mm is preferable, a range of 0.07 to 0.60 mm is more preferable, and a range of 0.10 to 0.20 mm is still more preferable.

  As a metal material of the metal wire 32, stainless steel, steel, a nickel alloy, aluminum, an aluminum alloy, copper, a copper alloy etc. can be used, Among them, stainless steel is particularly preferable because of its resistance to rusting.

  As a method of forming the metal mesh layer 30 on the surface of the core 10 or the intermediate layer, for example, two metal mesh materials having a gourd shape in a plane are formed, and the other metal mesh is formed in the constriction portion of one metal mesh material. The spherical metal mesh layer 30 can be formed by combining two metal mesh materials so as to connect the two end portions of the material. The metal mesh material is preferably crimped to the surface of the core 10 or the intermediate layer while heating.

  The material forming the cover 20 can be formed using, but not limited to, thermoplastic polyurethane, ionomer resin, or a mixture thereof. In addition to the above main components, other thermoplastic elastomers, polyisocyanate compounds, fatty acids or derivatives thereof, basic inorganic metal compounds, fillers and the like can be added to the cover 20.

  The structure of the thermoplastic polyurethane material is composed of a soft segment consisting of a polymeric polyol (polymeric glycol), a chain extender constituting the hard segment and a polyisocyanate. Here, the high molecular weight polyol serving as the raw material is not particularly limited, but in the present invention, polyester based polyols and polyether based polyols are preferable. Specific examples of polyester-based polyols include adipate-based polyols such as polyethylene adipate glycol, polypropylene adipate glycol, polybutadiene adipate glycol and polyhexamethylene adipate glycol, and lactone polyols such as polycaprolactone polyol. Examples of polyether polyols include poly (ethylene glycol), poly (propylene glycol) and poly (tetramethylene glycol).

  The chain extender is not particularly limited, but in the present invention, a low molecular weight compound having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule and having a molecular weight of 2,000 or less Among them, aliphatic diols having 2 to 12 carbon atoms are preferred. Specifically, 1,4-butylene glycol, 1,2-ethylene glycol, 1,3-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, etc. may be mentioned. Among these, 1,4-butylene glycol is particularly preferable.

  The polyisocyanate compound is not particularly limited, but in the present invention, for example, 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate From the group consisting of isocyanate, naphthylene 1,5-diisocyanate, tetramethylxylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate One or more selected species can be used. However, depending on the type of isocyanate, it is difficult to control the crosslinking reaction during injection molding. Therefore, in the present invention, from the viewpoint of the balance between the stability during production and the physical properties to be expressed, aromatic diisocyanate Preferred is 4,4'-diphenylmethane diisocyanate which is

  As ionomer resin, although it is not limited to this, what uses the following (a) ingredient and / or (b) ingredient as base resin can be used. Moreover, the following (c) components can be optionally added to this base resin. Component (a) is an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer and / or a metal salt thereof, and component (b) is an olefin-unsaturated carboxylic acid binary random copolymer and And / or a metal salt thereof, component (c) is a thermoplastic block copolymer having a polyolefin crystal block and a polyethylene / butylene random copolymer.

  In addition to the main component of the thermoplastic polyurethane or the ionomer resin described above, the cover 20 can be blended with a thermoplastic resin or an elastomer other than the thermoplastic polyurethane. Specifically, polyester elastomer, polyamide elastomer, ionomer resin, styrene block elastomer, hydrogenated styrene butadiene rubber, styrene-ethylene.butylene-ethylene block copolymer or modified product thereof, ethylene-ethylene.butylene-ethylene block copolymer It is selected from a combination or a modified product thereof, a styrene-ethylene.butylene-styrene block copolymer or a modified product thereof, an ABS resin, a polyacetal, a polyethylene and a nylon resin, and one or more selected from them can be used. In particular, it is preferable to use polyester elastomers, polyamide elastomers and polyacetals for the reason that the resilience and scratch resistance are improved by the reaction with isocyanate groups while maintaining good productivity. When the above components are blended, the blending amount thereof is appropriately selected according to the adjustment of the hardness of the cover material, the improvement of the resilience, the improvement of the flowability, the improvement of the adhesiveness, etc. It can be preferably 5 parts by mass or more based on 100 parts by mass of the thermoplastic polyurethane component. Further, the upper limit of the compounding amount is also not particularly limited, but it may be preferably 100 parts by mass or less, more preferably 75 parts by mass or less, still more preferably 50 parts by mass or less based on 100 parts by mass of the thermoplastic polyurethane component. . In addition, polyisocyanate compounds, fatty acids or derivatives thereof, basic inorganic metal compounds, fillers and the like can be added.

  The hardness of the cover 20 is preferably 56 or less in Shore D in order to ensure the approach spin and the effect of the metal mesh. The upper limit of the hardness of the cover 20 is preferably 53 or less, and more preferably 48 or less. Further, the hardness of the cover 20 is preferably 30 or more, and more preferably 40 or more in Shore D as the lower limit.

  Although the thickness of the cover 20 is not limited to this, 0.2 mm or more is preferable as a lower limit, and 0.4 mm or more is more preferable. Moreover, 4 mm or less is preferable as an upper limit, as for the thickness of the cover 20, 3 mm or less is more preferable, and 2 mm or less is still more preferable. A plurality of dimples 22 are formed on the surface of the cover 20. The size, shape, number and the like of the dimples 22 can be designed as appropriate according to the desired aerodynamic characteristics of the golf ball 1.

  As a method of forming the cover 20, a known method of molding a golf ball cover can be adopted. For example, but not limited to, the cover 20 is formed by injection molding a material for the cover in a mold. The mold for molding the cover has a cavity for molding the cover, and the wall surface of the cavity has a plurality of projections for forming dimples. By arranging the core 10 at the center of the cavity, the cover 20 is formed to cover the core 10.

  The material of the intermediate layer 40 can be formed using the same material as that of the cover 20 described above, that is, a thermoplastic polyurethane, an ionomer resin, or a mixture thereof. In addition to the above main components, other thermoplastic elastomers, polyisocyanate compounds, fatty acids or derivatives thereof, basic inorganic metal compounds, fillers and the like can be added to the intermediate layer 40.

  The material hardness of the intermediate layer 40 is not limited to this, but the lower limit is preferably 50 or more, and more preferably 55 or more in Shore D. The hardness of the intermediate layer 40 is preferably 70 or less, and more preferably 65 or less, in Shore D as an upper limit.

  Although the thickness of the intermediate layer 40 is not limited to this, 0.5 mm or more is preferable, and 1 mm or more is more preferable. Moreover, 10 mm or less is preferable, as for the thickness of the intermediate | middle layer 40, 5 mm or less is more preferable, and 3 mm or less is still more preferable.

  The golf ball 1 obtained by the above configuration preferably has a μ hardness of 2.0 mm or more. The μ hardness of a golf ball refers to the amount of compressive deformation (deflection) when the golf ball is loaded to an initial load of 98 N (10 kgf) to 1275 N (130 kgf). The unit of μ hardness is expressed in mm. The lower the hardness of the μ hardness, the higher the hardness. The lower limit of the μ hardness is more preferably 1.5 mm or more, and still more preferably 2.3 mm or more. The upper limit of the μ hardness is preferably 5.0 mm or less, more preferably 4.0 mm or less, and still more preferably 3.2 mm or less.

  The golf balls of the example and the comparative example of the configuration shown in Table 1 were respectively manufactured, and tests were performed to measure each performance of the golf ball. The contents of the core material shown in Table 1 are shown in Table 2, and the contents of the intermediate layer and the cover material are shown in Table 3. In addition, the compounding quantity of each component in Table 2 and Table 3 was represented by the mass part. In the metal mesh layers of the examples, stainless steel was used as the same metal. Moreover, the cover which has the same dimple arrangement also in any Example and the comparative example was formed. The core composition was adjusted so that the deflection hardness was 2.5 mm, the outer diameter was 42.7 mm, the weight was 45.4 g, and the USGA initial velocity was 77 m / s.

The following were used for each component in Table 2 which shows the mixing | blending of the material of a core.
Peroxide (1) is dicumyl peroxide manufactured by Nippon Oil and Fats Co., Ltd. under the trade name of Park Mill D.
The peroxide (2) is a mixture of 1,1-di (t-butylperoxy) cyclohexane and silica manufactured by Nippon Oil and Fats Co., Ltd. under the trade name Perhexa C-40.
The anti-aging agent is a product name Nocrac NS-6 manufactured by Ouchi Emerging Chemical Industry Co., Ltd.

The following were used for each component in Table 3 which shows compounding of the material of a cover and an intermediate | middle layer.
Surlyn S8150 is an ionomer resin manufactured by DuPont.
HIMIRAN 1706, HIMIRAN 1557, HIMIRAN 1605, HIMIRAN 1601 are ionomer resins made of Mitsui Du Pont Polychemical Co., a binary copolymer.
T-8290 and T-8283 are trade name Pandex manufactured by DIC Bayer Polymer, MDI-PTMG type thermoplastic polyurethane.
Hytrel 4001 is a thermoplastic polyether ester elastomer manufactured by Toray DuPont Co., Ltd.
Polyethylene wax is trade name Sanwax 161P manufactured by Sanyo Chemical Industries, Ltd.
The isocyanate compound is 4,4'-diphenylmethane diisocyanate.
Titanium oxide is Typek R-550 manufactured by Ishihara Sangyo Co., Ltd.
Trimethylolpropane TMP is a low molecular weight polyol manufactured by Toyo Chemicals.

  The USGA initial speed is measured using an initial speed measuring device of the same type as the USGA drum rotation type initial speedometer approved by R & A. The golf ball was temperature-controlled for at least 3 hours in a 23.9 ± 1 ° C. environment, and then tested in a room at a room temperature of 23 ± 2 ° C. Use a 250 lb (113.4 kg) head to strike the ball at an impact speed of 143.8 ft / s (43.83 m / s) and strike 30 balls of each sample twice each to 6.28 ft ( The time to pass between 1.91 m) was measured, and the initial velocity (m / s) was calculated.

  The amount of spin shown in Table 1 is the amount of spin (rpm) by shooting the ball immediately after hitting the driver (W # 1) attached to a swing robot (manufactured by Miyamae) using a high-speed camera. The The driver hit at a head speed of 45 m / s using BridgeStage Sports' TourStage X-Drive Type 455 9.5 °.

  The durability in Table 1 is an evaluation of golf ball durability using an ADC Ball COR Durability Tester machine manufactured by Automated Design Corporation in the United States. This tester has a function of causing a golf ball to be pneumatically fired and then to continuously collide with two metal plates installed in parallel. The incident speed to the metal plate was 43 m / s. Then, the average value of the number of shots required to break the golf ball was determined. The average value is a value obtained by preparing ten balls for each sample, and firing the balls to average the number of shots required to break the golf ball. As for evaluation, ◎ is an average value of 200 times or more, ○ is 100 times or more, and x is less than that.

  As shown in Table 1, Examples 1 to 3 in which the metal mesh layer having a predetermined wire diameter and the number of meshes is provided on the inner side of the cover have a driver shot compared to Comparative Example 1 having no such metal mesh layer. Was able to significantly reduce the amount of spin at. Further, the durability of the golf balls of Examples 1 to 3 was as excellent as that of Comparative Example 1. On the other hand, in Comparative Example 4 in which the hardness of the intermediate layer was increased by changing the material of the intermediate layer as compared with Comparative Example 1, although the spin amount in the driver shot could be significantly reduced by such an intermediate layer, The durability was not able to withstand practical use.

  Further, in Example 4 in which a metal mesh layer having a predetermined wire diameter and mesh number was provided between the core and the cover without providing the intermediate layer, the spin amount in the driver shot was significantly increased as in Examples 1 to 3. Could be reduced to There was no problem with durability. On the other hand, in the structure where a solid metal layer which is not a mesh is provided instead of the metal mesh layer, it can not be manufactured with a predetermined μ hardness and can not be measured due to deformation due to impact. Also in Comparative Examples 2 and 3 in which the wire diameter and the number of meshes of the metal mesh layer were not within the predetermined range, the spin amount in the driver shot could not be significantly reduced.

1 golf ball 10 core 20 cover 22 dimple 30 metal mesh layer 32 metal wire 40 middle layer

Claims (5)

  A golf ball comprising a core located at the center of a golf ball, a cover located outside the core and having a plurality of dimples on the surface, and a metal mesh layer located between the core and the cover. In the golf ball, the metal mesh layer has a wire diameter of 0.01 to 0.5 mm and a mesh number of 16 to 1000.   2. The golf ball according to claim 1, wherein the metal mesh layer has a relationship of d × M where d is the wire diameter and M is the number of meshes.   The golf ball according to claim 1, further comprising an intermediate layer positioned between the core and the cover, wherein the metal mesh layer is positioned between the intermediate layer and the cover.   The golf ball according to any one of claims 1 to 3, wherein the hardness of the cover is 56 or less at Shore D.   The golf ball according to any one of claims 1 to 4, wherein the μ hardness of the golf ball is 2.0 mm or more.