JP7326711B2 - Golf ball - Google Patents

Description

The present invention relates to golf balls. More particularly, the present invention relates to golf ball dimple patterns.

The face of a golf club has a loft angle. When a golf ball is hit with this golf club, backspin is generated in the golf ball due to the loft angle. A golf ball flies with backspin.

A golf ball has a large number of dimples on its surface. The dimples disrupt the flow of air around the golf ball during flight, causing turbulent separation. This phenomenon is called "turbulization". Turbulence shifts the point of air separation from the golf ball rearward, reducing drag. The turbulence promotes the deviation between the upper separation point and the lower separation point of the golf ball caused by backspin, and increases the lift acting on the golf ball. The reduction in drag and increase in lift is referred to as the "dimple effect." Better dimples disrupt airflow better. Good dimples produce great distance.

Japanese Patent Application Laid-Open No. 2010-88640 discloses a golf ball having a random dimple pattern. The contour of each dimple is neither circular nor polygonal. This golf ball has a small land area.

Japanese Patent Application Laid-Open No. 8-276035 discloses a golf ball having multiple dimples and multiple channels. Each channel connects a dimple to another adjacent dimple. This channel contributes to a reduction in land area.

Japanese Patent Application Laid-Open No. 2005-34366 discloses a golf ball having multi-surface dimples. This multi-surface dimple has a recessed portion and a plurality of inclined surfaces surrounding this recessed portion. In this golf ball, the land area is extremely small.

Japanese Patent Application Laid-Open No. 2010-88640 JP-A-8-276035 JP-A-2005-34366

A golf ball with a small land area has excellent aerodynamic characteristics. However, conventional dimple patterns do not provide sufficiently small drag. Golf players desire further improvement in flight distance. From the viewpoint of flight performance, dimples have room for improvement.

SUMMARY OF THE INVENTION An object of the present invention is to provide a golf ball having excellent flight performance.

A golf ball according to the present invention has a plurality of dimples on its surface. Each dimple has a bowl-shaped central portion and a ring-shaped edge that is smoothly continuous with the central portion. The cross-sectional shape of the edge is a curve that is convex radially outwardly of the golf ball. A ratio P1 of the number N1 of dimples having edges adjacent to other edges sharing a boundary line to the total number N of dimples is 50% or more.

Preferably, the land rate PL of the surface of this golf ball is 12% or less.

Preferably, the cross-sectional shape of the edge is an arc with a radius of curvature CR of 1.25 mm or more.

Preferably, the total volume of these dimples is 520 mm ³ or more and 630 mm ³ or less.

The lift and drag coefficients of the golf balls according to the present invention are appropriate in flight. This golf ball has excellent flight performance.

FIG. 1 is a schematic cross-sectional view showing a golf ball according to one embodiment of the invention. 2 is an enlarged front view of the golf ball of FIG. 1; FIG. 3 is an enlarged cross-sectional view showing a portion of the golf ball of FIG. 1; FIG. 4 is an enlarged plan view showing the dimples of the golf ball of FIG. 1. FIG. 5 is an enlarged view showing a portion of the surface of the golf ball of FIG. 1. FIG. FIG. 6 is a front view showing a golf ball according to Example 2 of the present invention. FIG. 7 is a front view showing a golf ball according to Example 3 of the present invention. FIG. 8 is a front view showing a golf ball according to Example 4 of the present invention. FIG. 9 is a front view showing a golf ball according to Example 5 of the present invention. FIG. 10 is a front view showing a golf ball according to Example 6 of the present invention. FIG. 11 is a front view showing a golf ball according to Example 7 of the present invention. FIG. 12 is a front view showing a golf ball according to Example 8 of the present invention. 13 is a front view showing a golf ball according to Example 9 of the present invention. FIG. FIG. 14 is a front view showing a golf ball according to Example 10 of the present invention. FIG. 15 is a front view showing a golf ball according to Example 11 of the present invention. 16 is a front view showing a golf ball according to Comparative Example 1. FIG. 17 is a front view showing a golf ball according to Comparative Example 2. FIG. FIG. 18 is a front view showing a golf ball according to Example 12 of the present invention. FIG. 19 is a front view showing a golf ball according to Example 13 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION 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 intermediate layer 6 located outside the core 4 , and a cover 8 located outside the intermediate layer 6 . This golf ball 2 has a large number of dimples 10 on its surface. A portion of the surface of the golf ball 2 other than the dimples 10 is a land 12 . This golf ball 2 has a paint layer and a mark layer on the outside of the cover 8, but the illustration of these layers is omitted.

The diameter of the golf ball 2 is preferably 40 mm or more and 45 mm or less. A diameter of 42.67 mm or more is particularly preferable from the viewpoint that the standards of the United States Golf Association (USGA) are satisfied. From the viewpoint of air resistance suppression, the diameter is more preferably 44 mm or less, and particularly preferably 42.80 mm or less.

The weight of the golf ball 2 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, particularly preferably 45.00 g or more. From the viewpoint that the USGA standard is satisfied, the mass is particularly preferably 45.93 g or less.

The core 4 is formed by cross-linking 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 rubbers may be used in combination. From the viewpoint of resilience performance, polybutadiene is preferred, and high-cis polybutadiene is particularly preferred.

The rubber composition of core 4 contains a co-crosslinking agent. Preferred co-crosslinking agents from the viewpoint of resilience performance are zinc acrylate, magnesium acrylate, zinc methacrylate and magnesium methacrylate. It is preferred that the rubber composition contains 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-butylperoxy). oxy)hexane and di-t-butyl peroxide.

The rubber composition of core 4 may contain additives such as fillers, sulfur, vulcanization accelerators, sulfur compounds, anti-aging agents, colorants, plasticizers and dispersants. The rubber composition may contain a carboxylic acid or carboxylate. The rubber composition may comprise synthetic resin powder or crosslinked rubber powder.

The diameter of the core 4 is preferably 30.0 mm or more, particularly preferably 38.0 mm or more. The diameter of the core 4 is preferably 42.0 mm or less, particularly preferably 41.5 mm or less. Core 4 may have more than one layer. The core 4 may have ribs on its surface. Core 4 may be hollow.

The intermediate layer 6 is made of a resin composition. A preferred base polymer for this resin composition is an ionomer resin. Preferred ionomer resins include binary copolymers of α-olefins and α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms. Another preferred ionomer resin is a ternary combination of an α-olefin, an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. polymers. In the bi- and terpolymers, preferred α-olefins are ethylene and propylene, and preferred α,β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. In the bi- and terpolymers, some of the carboxyl groups are neutralized with metal ions. Examples of metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions and neodymium ions.

Instead of the ionomer resin, the resin composition of the intermediate layer 6 may contain other polymers. Other polymers include polystyrene, polyamides, polyesters, polyolefins and polyurethanes. The resin composition may contain two or more polymers.

The resin composition of the intermediate layer 6 contains 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, a fluorescent brightener, and the like. It's okay. For the purpose of specific gravity adjustment, the resin composition may contain powder of high specific gravity metal such as tungsten and molybdenum.

The thickness of the intermediate layer 6 is preferably 0.2 mm or more, particularly preferably 0.3 mm or more. The thickness of the intermediate layer 6 is preferably 2.5 mm or less, particularly preferably 2.2 mm or less. The specific gravity of the intermediate layer 6 is preferably 0.90 or more, particularly preferably 0.95 or more. The specific gravity of the intermediate layer 6 is preferably 1.10 or less, particularly preferably 1.05 or less. Intermediate layer 6 may have two or more layers.

The cover 8 is made of a resin composition. A preferred base polymer for this resin composition is polyurethane. The resin composition may contain thermoplastic polyurethane and may contain thermosetting polyurethane. From the viewpoint of productivity, thermoplastic polyurethane is preferred. Thermoplastic polyurethanes contain polyurethane components as hard segments and polyester or polyether components as soft segments.

Polyurethane has urethane bonds in its molecule. This urethane linkage can be formed by the reaction of a polyol and a polyisocyanate.

A polyol, which is a raw material for urethane bonds, has a plurality of hydroxyl groups. Low molecular weight polyols and high molecular weight polyols can be used.

Examples of isocyanates for polyurethane components include alicyclic diisocyanates, aromatic diisocyanates and aliphatic diisocyanates. Alicyclic diisocyanates are particularly preferred. Since the alicyclic diisocyanate does not have a double bond in its main chain, yellowing of the cover 8 is suppressed. 4,4′-dicyclohexylmethane diisocyanate (H ₁₂ MDI), 1,3-bis(isocyanatomethyl)cyclohexane (H ₆ XDI), isophorone diisocyanate (IPDI) and trans-1,4-cyclohexane as cycloaliphatic diisocyanates Diisocyanate (CHDI) is exemplified. From the viewpoint of versatility and workability, H ₁₂ MDI is preferred.

Instead of polyurethane, the resin composition of cover 8 may contain other polymers. Other polymers include ionomer resins, polystyrene, polyamides, polyesters and polyolefins. The resin composition may contain two or more polymers.

The resin composition of the cover 8 may contain 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, a fluorescent whitening agent, and the like. good.

The thickness of the cover 8 is preferably 0.2 mm or more, particularly preferably 0.3 mm or more. The thickness of the cover 8 is preferably 2.5 mm or less, particularly preferably 2.2 mm or less. The specific gravity of the cover 8 is preferably 0.90 or more, particularly preferably 0.95 or more. The specific gravity of the cover 8 is preferably 1.10 or less, particularly preferably 1.05 or less. The cover 8 may have two or more layers.

Golf ball 2 may include a reinforcing layer between intermediate layer 6 and cover 8 . The reinforcing layer firmly adheres to the intermediate layer 6 and also to the cover 8 . The reinforcing layer suppresses peeling of the cover 8 from the intermediate layer 6 . The reinforcing layer consists of a polymer composition. Examples of the base polymer of the reinforcing layer include a two-component curing type epoxy resin and a two-component curing type urethane resin.

As shown in FIG. 2, golf ball 2 has dimples AE. Dimple A is larger than dimple B. Dimple B is larger than dimple C. Dimple C is larger than dimple D. Dimple D is larger than dimple E. The number of dimples A is 60, the number of dimples B is 158, the number of dimples C is 72, the number of dimples D is 36, and the number of dimples E is 12. The total number of dimples 10 is 338. These dimples 10 and lands 12 form a dimple pattern.

FIG. 3 shows a cross-section of golf ball 2 along a plane passing through the center of dimple 10 and the center of golf ball 2 . The vertical direction in FIG. 3 is the depth direction of the dimple 10 . A two-dot chain line 14 in FIG. 3 represents a phantom sphere. The surface of phantom sphere 14 is the surface of golf ball 2 when it is assumed that dimples 10 do not exist. The phantom sphere 14 has the same diameter as the golf ball 2 . Dimple 10 is recessed from the surface of phantom sphere 14 . Land 12 coincides with the surface of phantom sphere 14 . In FIG. 3, the reference EP denotes edge points of the dimple 10, and the reference JP denotes joint points (detailed later).

FIG. 4 is an enlarged plan view showing dimples 10 of golf ball 2 of FIG. Reference character EL in FIG. 4 represents the edge line of the dimple 10 . An edge line EL is a set of many edge points EP (see FIG. 3). A portion of the surface of the golf ball 2 surrounded by the edge line EL is the dimple 10 . The surface of the golf ball 2 outside the edge line EL is a land 12 (see FIG. 2).

The dimple 10 has a central portion 16 and edge portions 18 . Reference character JL in FIG. 4 represents a joint line. A joint line JL is a set of many joint points JP (see FIG. 3). A central portion 16 of the dimple 10 is surrounded by the joint line JL. A portion of the dimple 10 sandwiched between the edge line EL and the joint line JL is an edge portion 18 .

As shown in FIGS. 3 and 4, central portion 16 is bowl-shaped. The cross-sectional shape of the central portion 16 is an inwardly convex curve in the radial direction of the golf ball 2 . In this embodiment, the cross-sectional shape of the central portion 16 is an arc. The cross-sectional shape of the central portion 16 may be a combination of arcs. The cross-sectional shape of the central portion 16 may be a curved line other than an arc. The cross-sectional shape of the central portion 16 may be partially outwardly convex. In this embodiment, the contour of the central portion 16 (that is, the joint line JL) is a circle.

As shown in Figures 3 and 4, the edge 18 is ring-shaped. The cross-sectional shape of the edge portion 18 is an outwardly convex curve in the radial direction of the golf ball 2 . In this embodiment, the cross-sectional shape of the edge 18 is an arc. The cross-sectional shape of the edge 18 may be a combination of arcs. The cross-sectional shape of the edge portion 18 may be a curved line other than an arc.

In this embodiment, the curve of edge 18 touches the curve of phantom sphere 14 . In other words, the edge 18 continues smoothly with the phantom sphere 14 . Therefore, in the actual golf ball 2, the edge line EL is not clearly recognized as an edge.

The cross-sectional curve of the central portion 16 and the cross-sectional curve of the edge portion 18 meet at a joint point JP. In other words, the edge 18 continues smoothly with the central portion 16 . Therefore, in the actual golf ball 2, the joint line JL is not clearly visible as an edge.

FIG. 5 is an enlarged view showing a portion of the surface of golf ball 2 of FIG. Three dimples 10a-10c are shown in FIG. In the present invention, when a straight line connecting the centers of two dimples 10 does not intersect another dimple 10, these two dimples 10 are called adjacent dimples 10 to each other. A straight line connecting the center of the dimple 10a and the center of the dimple 10b does not cross another dimple 10. - 特許庁Therefore, dimple 10b is a neighboring dimple of dimple 10a. A straight line connecting the center of the dimple 10a and the center of the dimple 10c does not cross another dimple 10. - 特許庁Therefore, dimple 10c is a neighboring dimple of dimple 10a.

Edge 18a of dimple 10a is not spaced from edge 18b of dimple 10b. Edge 18a shares boundary line 20 and is adjacent to edge 18b. For purposes of the present invention, a dimple 10 whose edge 18 shares a boundary line 20 and is adjacent to the edge 18 of another dimple 10 is said to be "adjacent" to that other dimple 10 . Dimple 10b is adjacent to dimple 10a. In this embodiment, the boundary line 20 is a curve that is convex radially outward of the golf ball 2 . Edge 18a of dimple 10a is spaced apart from edge 18c of dimple 10c. Dimple 10c is not adjacent to dimple 10a.

Dimple 10b is a neighboring dimple of dimple 10a and an adjacent dimple of dimple 10a. Dimple 10c is a neighboring dimple of dimple 10a, but not an adjacent dimple of dimple 10a.

A dimple 10 having edges 18 is larger than a dimple having only a central portion 16 . In the golf ball 2 having this dimple 10, the area of the land 12 is small. With this golf ball 2, a small drag coefficient can be achieved. In this golf ball 2 , the central portion 16 does not interfere with other dimples 10 . Therefore, the shape of the central portion 16 is not affected by the other dimples 10 . This central portion 16 may contribute to a small drag coefficient. This golf ball 2 has excellent flight performance.

The effect of the dimples 10 is exhibited particularly on shots with a driver. A small drag coefficient is obtained in the trajectory after the peak when the golf ball 2 is hit with a driver.

In the present invention, the ratio P1 is calculated by the following formula.
P1 = (N1/N)*100
In this formula, N1 is the number of dimples 10 adjacent to one or more dimples 10, and N is the total number of dimples 10.

The ratio P1 is preferably 50% or more. A golf ball 2 having a ratio P1 of 50% or more has excellent flight performance. From this point of view, the ratio P1 is more preferably 70% or more, and particularly preferably 90% or more. Ideally, the ratio P1 is 100%.

In the present invention, the ratio P2 is calculated by the following formula.
P2 = (N2/N)*100
In this formula, N2 is the number of dimples 10 whose central portion 16 interferes with other dimples 10, and N is the total number of dimples 10.

The ratio P2 is preferably 20% or less. A golf ball 2 having a ratio P2 of 20% or less has a small drag. From this point of view, the ratio P2 is more preferably 10% or less, and particularly preferably 5% or less. Ideally, the ratio P2 is 0%.

The average number of dimples 10 adjacent to one dimple 10 is preferably 2 or more, more preferably 3 or more, and particularly preferably 4 or more. This number is preferably 8 or less.

The land rate PL of the surface of the golf ball 2 is preferably 12% or less. The land ratio PL is the ratio of the area of the land 12 to the surface area of the phantom sphere 14 . A golf ball 2 having a land ratio PL of 12% or less has excellent flight performance. From this point of view, the land ratio PL is more preferably 10% or less, and particularly preferably 8% or less.

Arrow CR in FIG. 3 is the radius of curvature of the arc of edge 18 . The radius of curvature CR is preferably 1.25 mm or more. A rim 18 with a radius of curvature CR greater than or equal to 1.25 mm contributes to a small drag coefficient. From this point of view, the radius of curvature CR is preferably 1.50 mm or more, particularly preferably 1.75 mm or more. From the viewpoint that the central portion 16 can have a sufficient volume, the radius of curvature CR is preferably 4.0 mm or less.

It is preferable that all the dimples 10 have a radius of curvature CR within the above range. Only some of the dimples 10 may have the radius of curvature CR within the above range. The ratio of the number of dimples 10 having a radius of curvature CR within the above range to the total number N of dimples 10 is preferably 50% or more, more preferably 70% or more, and particularly preferably 90% or more.

A double-headed arrow Dp1 in FIG. 3 represents the depth of the dimple 10 . This depth Dp1 is the distance between the deepest part of the dimple 10 and the surface of the phantom sphere 14 . A double arrow Dp2 in FIG. 3 represents the depth of the central portion 16 . This depth Dp2 is the distance between the deepest part of the dimple 10 and the plane including the joint line JL. From the viewpoint that both the central portion 16 and the edge portion 18 contribute to aerodynamic characteristics, the ratio of the depth Dp2 to the depth Dp1 is preferably 20% or more and 80% or less, more preferably 30% or more and 70% or less. % or more and 65% or less is particularly preferable.

From the viewpoint of suppressing hopping of golf ball 2, depth Dp1 of dimple 10 is preferably 0.10 mm or more, more preferably 0.13 mm or more, and particularly preferably 0.15 mm or more. From the viewpoint of preventing the golf ball 2 from dropping, the depth Dp1 is preferably 0.65 mm or less, more preferably 0.60 mm or less, and particularly preferably 0.55 mm or less.

From the viewpoint of achieving a sufficiently small land ratio PL, the total number of dimples 10 is preferably 250 or more, more preferably 280 or more, and particularly preferably 300 or more. From the viewpoint that the individual dimples 10 can contribute to turbulence, the total number is preferably 450 or less, more preferably 410 or less, and particularly preferably 390 or less.

In the present invention, the “dimple volume V” means the volume of the portion surrounded by the surface of the phantom sphere 14 and the surface of the dimple 10 . The total volume TV of the dimples 10 is preferably 520 mm ³ or more and 630 mm ³ or less. A golf ball 2 having a total volume TV of 520 mm ³ or more suppresses hopping during flight. From this point of view, the total volume TV is more preferably 530 mm ³ or more, particularly preferably 535 mm ³ or more. A golf ball 2 having a total volume TV of 630 mm ³ or less is less likely to drop during flight. From this point of view, the total volume TV is more preferably 620 mm ³ or less, and particularly preferably 615 mm ³ or less.

The effects of the present invention will be clarified by examples below, but the present invention should not be construed in a limited manner based on the description of these examples.

[Example 1]
100 parts by mass of high-cis polybutadiene (JSR's trade name "BR-730"), 22.5 parts by mass of zinc acrylate, 5 parts by mass of zinc oxide, 5 parts by mass of barium sulfate, 0.5 parts by mass of Diphenyl disulfide and 0.6 parts by mass of dicumyl peroxide were kneaded to obtain a rubber composition. This rubber composition was put into a mold consisting of an upper mold and a lower mold having a hemispherical cavity and heated at 170° C. for 18 minutes to obtain a core with a diameter of 38.5 mm.

50 parts by mass of ionomer resin ("Himilan 1605", trade name of Mitsui DuPont Polychemical Co., Ltd.), 50 parts by mass of other ionomer resin ("Himilan AM7329", trade name of DuPont Mitsui Polychemical Co., Ltd.) and 4 parts by mass of titanium dioxide were kneaded with a twin-screw kneading extruder to obtain a resin composition. This resin composition was coated around the core by an injection molding method to form an intermediate layer. The thickness of this intermediate layer was 1.6 mm.

A coating composition ("Porin 750LE", a trade name of Shinto Toryo Co., Ltd.) was prepared using a two-component curing type epoxy resin as a base polymer. and 70 parts by mass of a solvent.The curing agent liquid of this coating composition comprises 40 parts by mass of modified polyamidoamine, 55 parts by mass of a solvent, and 5 parts by mass of titanium dioxide. The mass ratio to the curing agent liquid is 1/1.This coating composition was applied to the surface of the intermediate layer with a spray gun and held in an atmosphere of 23° C. for 6 hours to obtain a reinforcing layer. The thickness of the reinforcing layer was 10 μm.

100 parts by mass of a thermoplastic polyurethane elastomer (trade name “Elastollan XNY85A” manufactured by BASF Japan) and 4 parts by mass of titanium dioxide were kneaded with a twin-screw kneading extruder to obtain a resin composition. Half shells were obtained from this resin composition by compression molding. Two half-shells covered a sphere consisting of a core, an intermediate layer and a reinforcing layer. These half-shells and spheres were put into a final mold consisting of an upper mold and a lower mold each having a hemispherical cavity and numerous pimples on the cavity surface, and a cover was obtained by compression molding. The thickness of the cover was 0.5 mm. The cover was formed with dimples having a shape that was the inverse of the shape of the pimples. A clear paint based on a two-component curing type polyurethane was applied around the cover to obtain a golf ball of Example 1 having a diameter of about 42.7 mm and a weight of about 45.6 g. The dimple pattern of this golf ball is shown in FIG. The dimple specifications of this golf ball are shown in Table 1 below. Each dimple has a central portion and an edge portion. The edge radius of curvature CR is 2.0 mm. In this dimple pattern, the ratio P1 is 100% and the land ratio PL is 7.7%. The total dimple volume TV is 569 mm ³ .

[Examples 2-13 and Comparative Example 2]
Golf balls of Examples 2-13 and Comparative Example 2 were obtained in the same manner as in Example 1, except that the final mold was changed and the dimple specifications were as shown in Table 1-4 below.

[Comparative Example 1]
A golf ball of Comparative Example 1 was obtained in the same manner as in Example 1, except that the final mold was changed and the dimple specifications were as shown in Table 4 below. The dimples of this golf ball are generally bowl-shaped.

[Flight test]
A golf laboratory swing machine was equipped with a driver having a titanium alloy head (trade name “XXIO-10” manufactured by Sumitomo Rubber Industries, shaft hardness: R, loft angle: 10.5°). This golf ball was hit under conditions of a head speed of 40 m/sec, a launch angle of about 11°, and a backspin speed of about 2200 rpm, and the distance from the launch point to the stationary point was measured. There was almost no wind during the test. The average values of data obtained from 20 measurements are shown in Tables 1-4 below.

As shown in Tables 1-4, the golf balls of each example have excellent flight performance. From this evaluation result, the superiority of the present invention is clear.

The aforementioned dimple pattern is applicable not only to three-piece golf balls, but also to golf balls having various structures, such as one-piece golf balls, two-piece golf balls, four-piece golf balls, five-piece golf balls, six-piece golf balls, and wound golf balls. can be

2 Golf ball 4 Core 6 Intermediate layer 8 Cover 10 Dimple 12 Land 14 Virtual sphere 16 Center 18 Edge 20 Boundary

Claims (4)

A golf ball having 250 or more dimples on its surface,
each dimple having a bowl-shaped central portion and a ring-shaped edge smoothly continuous with the central portion;
The contour of the central portion in plan view is a circle,
a cross-sectional shape of the edge portion is a curved line convex radially outward of the golf ball;
A golf ball, wherein a ratio P1 of the number N1 of dimples having edges adjacent to other edges sharing a boundary line to the total number N of dimples is 50% or more. 2. The golf ball according to claim 1, wherein the surface land rate PL is 12% or less. 3. The golf ball according to claim 1, wherein the cross-sectional shape of the edge portion is an arc having a curvature radius CR of 1.25 mm or more. 4. The golf ball according to any one of claims 1 to 3, wherein the dimples have a total volume of 520 mm ^<3> or more and 630 mm ^<3> or less.

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