JP5290742B2 - Golf ball - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf ball 2 excelling in flying performance. <P>SOLUTION: The golf ball 2 includes a first zone 10 and a second zone 12 on the surface. The first zone 10 has a first smooth surface 18 and dimples 20. The first smooth surface 18 coincides with the surface of an imaginary ball of the golf ball 2. The dimples 20 are recessed from the first smooth surface 18. The second zone 12 has a second smooth surface 22 and pimples 24. The second smooth surface 22 is recessed from the surface of the imaginary ball of the golf ball 2. The pimples 24 project from the second smooth surface 22. The total area of the first zone 10 is larger than that of the second zone 12. The second zone 12 does not have dimples 20. An apex of each pimple 24 is located on the surface of the imaginary ball. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a golf ball. Specifically, the present invention relates to an improvement in the surface shape of a golf ball.

  A golf ball in flight receives air resistance. This air resistance causes the golf ball to stall. The air resistance of a small golf ball is small. From the viewpoint of the flight distance, a small golf ball is preferable.

  The United States Golf Association (USGA) has established rules for golf balls. According to this rule, the golf ball has a diameter of 1.68 inches (42.67 mm) or more. The USGA recognizes golf balls that meet this rule. Prior to recognition, the USGA will inspect the golf ball. In this inspection, a metal ring having an inner diameter of 1.68 inches is used. Golf balls that pass this ring more frequently than predetermined are not certified.

  The golf ball has a large number of dimples on its surface. The dimples disturb the air flow around the golf ball during flight and cause turbulent separation. Turbulent separation promotes the deviation between the upper separation point and the lower separation point of the golf ball due to backspin, and increases the lift acting on the golf ball. High lift achieves a high trajectory of the golf ball. With a driver shot, a high flight distance provides a great flight distance. In iron shots, small trajectories (rolls) are achieved by high trajectories. By using a golf ball with a small run, the golfer can easily stop the golf ball at a target point.

  Various proposals for improving the flight performance regarding the surface shape of golf balls have been made.

  Japanese Patent Application Laid-Open No. 10-146403 discloses a golf ball having a sphere having a diameter smaller than 1.68 inches and a convex portion formed on the surface of the sphere. Since the sphere is small, the air resistance of this golf ball is small. In this golf ball diameter inspection, the convex portion prevents the ring from passing. This golf ball conforms to USGA rules. Similar golf balls are also disclosed in JP-A-11-192322 and JP-T2003-515365.

Japanese Patent Application Laid-Open No. 2005-27698 discloses a golf ball having a small spherical surface having a diameter smaller than that of the golf ball. Dimples are formed on the small spherical surface. This publication states that this small spherical surface contributes to the aerodynamic characteristics of the golf ball.
JP 10-146403 A JP 11-192322 A Special Table 2003-515365 JP 2005-27698 A

  The golf ball disclosed in Japanese Patent Laid-Open No. 10-146403 is dropped because the sphere has a small diameter. This golf ball is inferior in control performance on an iron shot. In the golf ball disclosed in Japanese Patent Laid-Open No. 2005-27698, the small spherical surface impairs the essence of the golf ball that is substantially a sphere. When putting, this golf ball is difficult to roll straight. Furthermore, the small sphere invites a drop. An object of the present invention is to provide a golf ball excellent in various performances.

  The golf ball according to the present invention includes a first zone and a second zone on the surface thereof. The first zone has a first smooth surface coinciding with the surface of the phantom sphere of the golf ball and dimples recessed from the first smooth surface. The second zone has a second smooth surface that is recessed from the surface of the phantom sphere of the golf ball and pimples that protrude from the second smooth surface.

  Preferably, the total area of the first zone is greater than the total area of the second zone. Preferably, the second zone does not have dimples. Preferably, the apexes of the pimples are located on the surface of the phantom sphere.

  Preferably, the contour of the first zone and the contour of the second zone are defined by a partition line obtained by projecting a side of a regular polyhedron or a quasi-regular polyhedron inscribed in a virtual sphere onto a spherical surface. Preferably, the first zone is surrounded by a plurality of second zones. Preferably, the second zone is surrounded by a plurality of first zones.

  In the golf ball according to the present invention, the air flow is sufficiently disturbed by the mixture of dimples and pimples. This golf ball is difficult to drop. This golf ball is excellent in flight performance and control performance. In this golf ball, since pimples exist in the second zone, the golf ball rolls straight when putting.

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

  FIG. 1 is a schematic cross-sectional view showing a golf ball 2 according to an embodiment of the present invention. The golf ball 2 includes a spherical core 4 and a cover 6. The golf ball 2 includes a paint layer and a mark layer outside the cover 6, but these layers are not shown. An intermediate layer may be provided between the core 4 and the cover 6.

  The golf ball 2 has a diameter of 40 mm or greater and 45 mm or less. From the viewpoint of satisfying the standards of the US Golf Association (USGA), the diameter is more preferably 42.67 mm or more. In light of suppression of air resistance, the diameter is more preferably equal to or less than 44 mm, and particularly preferably equal to or less than 42.80 mm. The golf ball 2 has a mass of 40 g or more and 50 g or less. In light of attainment of great inertia, the mass is more preferably equal to or greater than 44 g, and particularly preferably equal to or greater than 45.00 g. From the viewpoint that the USGA standard is satisfied, the mass is more preferably 45.93 g or less.

  The core 4 is formed by crosslinking a rubber composition. Examples of the base rubber of the rubber composition include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-propylene-diene copolymer, and natural rubber. Two or more kinds of rubbers may be used in combination. From the viewpoint of resilience performance, polybutadiene is preferred, and high cis polybutadiene is particularly preferred.

  For crosslinking of the core 4, a co-crosslinking agent is preferably used. From the viewpoint of resilience performance, preferred co-crosslinking agents are zinc acrylate, magnesium acrylate, zinc methacrylate and magnesium methacrylate. It is preferable that an organic peroxide is blended with the co-crosslinking agent in the rubber composition. Suitable organic peroxides include dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di (t- Butyl peroxy) hexane and di-t-butyl peroxide.

  Various additives such as sulfur compounds, fillers, anti-aging agents, colorants, plasticizers, and dispersants are blended in the rubber composition of the core 4 as necessary. Crosslinked rubber powder or synthetic resin powder may be blended with the rubber composition.

  The diameter of the core 4 is 30.0 mm or more, particularly 38.0 mm or more. The diameter of the core 4 is 42.0 mm or less, particularly 41.5 mm or less. The core 4 may be composed of two or more layers. The core 4 may be hollow. The core 4 may include a rib on the surface thereof.

  A suitable polymer for the cover 6 is an ionomer resin. A preferable ionomer resin includes a binary copolymer of an α-olefin and an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. Other preferable ionomer resins include ternary α-olefin, α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α, β-unsaturated carboxylic acid ester having 2 to 22 carbon atoms. A copolymer is mentioned. In the binary copolymer and ternary copolymer, preferred α-olefins are ethylene and propylene, and preferred α, β-unsaturated carboxylic acids are acrylic acid and methacrylic acid. In the binary copolymer and ternary copolymer, some of the carboxyl groups are neutralized with metal ions. Examples of the metal ions for neutralization include sodium ions, potassium ions, lithium ions, zinc ions, calcium ions, magnesium ions, aluminum ions, and neodymium ions.

  Other polymers may be used in place of or in conjunction with the ionomer resin. Examples of other polymers include thermoplastic styrene elastomers, thermoplastic polyurethane elastomers, thermoplastic polyamide elastomers, thermoplastic polyester elastomers, and thermoplastic polyolefin elastomers.

  If necessary, the cover 6 may contain an appropriate amount of a colorant such as titanium dioxide, a filler such as barium sulfate, a dispersant, an antioxidant, an ultraviolet absorber, a light stabilizer, a fluorescent agent, and a fluorescent brightening agent. Blended. For the purpose of adjusting the specific gravity, the cover 6 may be mixed with powder of a high specific gravity metal such as tungsten or molybdenum.

  The cover 6 has a thickness of 0.3 mm or more, particularly 0.5 mm or more. The cover 6 has a thickness of 2.5 mm or less, particularly 2.2 mm or less. The specific gravity of the cover 6 is 0.90 or more, particularly 0.95 or more. The specific gravity of the cover 6 is 1.10 or less, particularly 1.05 or less. The cover 6 may be composed of two or more layers.

  FIG. 2 is an enlarged front view showing the golf ball 2 of FIG. In FIG. 2, a plurality of lane markings 8 are drawn. Each partition line 8 is a virtual line and does not appear as an edge on the surface of the golf ball 2. With these lane markings 8, the surface of the golf ball 2 is partitioned into a first zone 10 and a second zone 12. The shape of the first zone 10 is a spherical regular pentagon. The shape of the second zone 12 is a spherical regular triangle. The number N1 of the first zones 10 is twelve. The number N2 of the second zones 12 is 20.

  FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. 4 is an enlarged cross-sectional view showing a part of the golf ball 2 of FIG. What is indicated by reference numeral 14 in FIG. 4 is a virtual sphere. The radius R1 of the phantom sphere 14 matches the radius of the golf ball 2. The surface of the phantom sphere 14 coincides with the surface of the golf ball 2 when it is assumed to be smooth. What is indicated by reference numeral 16 in FIG. 4 is a virtual small sphere. The center of the virtual sphere 16 coincides with the center of the virtual sphere 14. The radius R2 of the virtual sphere 16 is smaller than the radius R1 of the virtual sphere 14.

  As shown in FIGS. 3 and 4, the first zone 10 has a first smooth surface 18 and dimples 20. The first smooth surface 18 coincides with the surface of the phantom sphere 14. The first smooth surface 18 is a part of the surface of the phantom sphere 14. The dimple 20 is recessed from the first smooth surface 18. In FIG. 2, the dimple 20 is indicated by reference characters C and D. In FIG. 2, the reference numerals of the dimples 20 are shown for one first zone 10. The dimple pattern of the first zone 10 is developed in all the first zones 10.

  The second zone 12 has a second smooth surface 22 and pimples 24. The second smooth surface 22 coincides with the surface of the virtual sphere 16. In other words, the second smooth surface 22 is recessed from the surface of the phantom sphere 14. The second smooth surface 22 is a part of the surface of the virtual sphere 16. The pimple 24 protrudes from the second smooth surface 22. In FIG. 2, the pimples 24 are indicated by symbols A and B. In FIG. 2, reference numerals of the pimples 24 are shown for one second zone 12. The pimple pattern in the second zone 12 is developed in all the second zones 12.

  As shown in FIG. 4, a slope 26 exists at the boundary between the first zone 10 and the second zone 12. In FIG. 4, what is indicated by a symbol Pm is the midpoint of the slope 26. In FIG. 4, a reference numeral 28 indicates a straight line passing through the center of the phantom sphere 14 and the midpoint Pm. The first zone 10 and the second zone 12 are partitioned by the straight line 28.

  When this golf ball 2 is hit with a golf club, it flies with backspin. Due to the backspin, the first zone 10 and the second zone 12 appear. Since the second smooth surface 22 is recessed more than the first smooth surface 18, the air flow is disturbed by the first zone 10 and the second zone 12. Since the dimple 20 is recessed from the first smooth surface 18, the air flow is also disturbed by the dimple 20. Since the pimple 24 protrudes from the second smooth surface 22, the air flow is also disturbed by the pimple 24. This golf ball 2 is excellent in flight performance.

  In this golf ball 2, the radius R1 of the first smooth surface 18 is sufficiently large. Therefore, the drop is difficult to occur. This golf ball 2 is excellent in control performance in an iron shot.

  The difference (R1-R2) between the radius R1 of the phantom sphere 14 and the radius R2 of the phantom sphere 16 is preferably 0.05 mm or more. In the golf ball 2 in which the difference (R1-R2) is 0.05 mm or more, the air flow is sufficiently disturbed. In this respect, the difference (R1−R2) is particularly preferably equal to or greater than 0.10 mm. In light of suppression of drop, the difference (R1−R2) is preferably equal to or less than 0.50 mm, and particularly preferably equal to or less than 0.25 mm.

  The area s <b> 1 of each first zone 10 is an area of a spherical regular pentagon formed on the surface of the phantom sphere 14. As described above, the golf ball 2 includes 12 first zones 10. Therefore, the total area S1 of these first zones 10 is 12 times the area s1.

  The area s <b> 2 of each second zone 12 is an area of a spherical regular triangle formed on the surface of the phantom sphere 14. As described above, the golf ball 2 includes 20 second zones 12. Therefore, the total area S2 of these second zones 12 is 20 times the area s2.

  From the viewpoint of aerodynamic characteristics, the ratio (S1 / S2) is preferably 1/9 or more and 9/1 or less, and particularly preferably 2/8 or more and 8/2 or less. From the viewpoint of control performance, the total area S1 is preferably larger than the total area S2. From the viewpoint of control performance, the ratio (S1 / S2) is preferably 6/4 or more, and particularly preferably 7/3 or more. In the golf ball 2 shown in FIG. 2, the ratio (S1 / S2) is 71/29.

  The second smooth surface 22 is recessed from the surface of the phantom sphere 14, but the pimple 24 protrudes from the second smooth surface 22. When putting, the pimple 24 comes into contact with the ground. Therefore, the golf ball 2 rolls straight. The pimple 24 can further abut the inner surface of a 1.68 inch ring. This golf ball 2 is easy to conform to USGA rules.

  The first zone 10 may include the pimples 24 together with the dimples 20. Mixing the dimples 20 and the pimples 24 in the first zone 10 promotes air turbulence.

  It is preferable that the second zone 12 does not include the dimple 20. Since the second smooth surface 22 is recessed from the surface of the phantom sphere 14, if the second zone 12 includes the dimple 20, the bottom of the dimple 20 is located away from the surface of the phantom sphere 14. Such dimples 20 invite a drop of the golf ball 2. The golf ball 2 in which the second zone 12 does not include the dimple 20 is difficult to drop.

  The lane marking 8 shown in FIG. 2 is obtained by a 20-12 plane. A 20-12 plane that is inscribed in the phantom sphere 14 is assumed, and the sides of the 20-12 plane are projected onto the surface of the phantom sphere 14 to obtain the partition line 8. In the golf ball 2, the first zone 10 and the second zone 12 are adjacent to each other with the lane marking 8 interposed therebetween. In all lane markings 8, the first zone 10 and the second zone 12 are adjacent to each other. One first zone 10 is surrounded by five second zones 12. One second zone 12 is surrounded by three first zones 10. When the golf ball 2 is hit with a golf club, the first zone 10 and the second zone 12 appear alternately by backspin. In the golf ball 2, the air flow is sufficiently disturbed. The spherical regular triangle may be the first zone, and the spherical regular pentagon may be the second zone.

  The dividing line 8 may be obtained by another polyhedron. From the viewpoint of aerodynamic symmetry, it is preferable that the demarcation line 8 is obtained by a regular polyhedron or a quasi-regular polyhedron. Preferred regular polyhedrons include regular hexahedrons, regular octahedrons, regular dodecahedrons, and regular icosahedrons. As a preferable quasi-regular polyhedron, a cubic octahedron is exemplified in addition to the above-mentioned 20-12 polyhedron. From the viewpoint that the first zone and the second zone can be adjacent to each other in all lane markings, a regular octahedron, a cubic octahedron, and a 20-12 plane are preferable.

  As described above, the number N1 of the first zones 10 is 12. From the viewpoint of flight performance, the number N1 is preferably 4 or more, more preferably 6 or more, and particularly preferably 12 or more. The number N1 is preferably 30 or less. As described above, the number N2 of the second zones 12 is 20. From the viewpoint of flight performance, the number N2 is preferably 4 or more, more preferably 6 or more, and particularly preferably 12 or more. The number N2 is preferably 30 or less. From the viewpoint of flight performance, the ratio (N1 / N2) is preferably 3/5 or more and 5/3 or less, and particularly preferably 3/4 or more and 4/3 or less.

  From the viewpoint of flight performance, the number of dimples 20 in one first zone 10 is preferably 3 or more, and more preferably 6 or more. From the viewpoint of flight performance, the number of pimples 24 in one second zone 12 is preferably 3 or more, and particularly preferably 6 or more.

  From the viewpoint of flight performance, the sum (Nd + Np) of the total number Nd of dimples 20 and the total number Np of pimples 24 is preferably 300 or more, more preferably 400 or more, and particularly preferably 500 or more. From the viewpoint of flight performance, the sum (Nd + Np) is preferably 2000 or less, more preferably 1800 or less, and particularly preferably 1600 or less. In the golf ball 2 shown in FIG. 2, each first zone 10 includes 51 dimples 20, and the second zone 12 does not include dimples 20. Therefore, the total number Nd is 612. In the golf ball 2, the first zone 10 does not include the pimples 24, and each second zone 12 includes ten pimples 24. Therefore, the total number Np is 200. The sum (Nd + Np) of this golf ball 2 is 812.

  From the viewpoint of flight performance, the ratio (Nd / Np) is preferably 20/80 or more and 80/20 or less, and particularly preferably 25/75 or more and 75/25 or less. In the golf ball 2 shown in FIG. 2, the ratio (Nd / Np) is 75/25.

  FIG. 5 is an enlarged cross-sectional view showing a part of the golf ball 2 of FIG. FIG. 5 shows a cross section along a plane passing through the center Pd of the dimple 20 and the center of the golf ball 2. The vertical direction in FIG. 5 is the depth direction of the dimple 20.

  In FIG. 5, the diameter of the dimple 20 is indicated by an arrow Dd. The diameter Dd is a distance between one contact 30 and the other contact 30 when a common tangent line 28 is drawn on both sides of the dimple 20. The contact 30 is also an edge of the dimple 20. The edge 30 defines the contour of the dimple 20. The diameter Dd is preferably 1.0 mm or greater and 6.0 mm or less. By setting the diameter Dd to be 1.0 mm or more, the air flow is well disturbed. In this respect, the diameter Dd is more preferably equal to or greater than 1.5 mm, and particularly preferably equal to or greater than 2.0 mm. By setting the diameter Dd to 6.0 mm or less, the original characteristic of the golf ball 2 that is substantially a sphere is maintained. In this respect, the diameter Dd is more preferably equal to or less than 5.0 mm, and particularly preferably equal to or less than 4.5 mm.

The area sd of the dimple 20 is an area of a region surrounded by a contour line when the center of the golf ball 2 is viewed from infinity. In the case of the circular dimple 20, the area sd is calculated by the following mathematical formula.
sd = (Dd / 2) ² * π
In the golf ball 2 shown in FIG. 2, the dimple C has a diameter Dd of 2.643 mm, and the dimple D has a diameter Dd of 2.237 mm. Therefore, the area sd of the dimple C is 5.488 mm ² and the area sd of the dimple D is 3.929 mm ² . The number of dimples C is 540, and the number of dimples D is 72. The total area Sd of the dimples 20 of this golf ball 2 is 3246.3 mm ² .

  In FIG. 5, what is indicated by an arrow De is the depth of the dimple 20. The depth De is the distance between the tangent line 28 and the deepest part of the dimple 20. In light of suppression of hops of the golf ball 2, the depth De is preferably 0.05 mm or more, more preferably 0.08 mm or more, and particularly preferably 0.10 mm or more. In light of suppression of dropping of the golf ball 2, the depth De is preferably 0.60 mm or less, more preferably 0.50 mm or less, and particularly preferably 0.40 mm or less.

In the present invention, the “dimple volume vd” is a volume of a portion surrounded by a plane including the outline of the dimple 20 and the surface of the dimple 20. In the golf ball 2 shown in FIG. 2, the volume vd of the dimple C is 0.413 mm ³ and the volume vd of the dimple D is 0.296 mm ³ . The total volume Vd of the dimples 20 of this golf ball 2 is 244.6 mm ³ .

  The planar shape of the dimple 20 is a circle. The golf ball 2 may include dimples whose planar shape is non-circular. Specific examples of non-circular shapes include polygons, ellipses, and ellipses. The cross-sectional shape of the dimple 20 is generally an arc. The golf ball 2 may include dimples having other cross-sectional shapes. Specific examples of other cross-sectional shapes include a double radius shape.

  FIG. 6 is an enlarged cross-sectional view showing a part of the golf ball 2 of FIG. FIG. 6 shows a cross section along a plane passing through the apex Pp of the pimple 24 and the center of the golf ball 2. The vertical direction in FIG. 6 is the height direction of the pimple 24.

  In FIG. 6, the diameter of the pimple 24 is indicated by the arrow Dp. The diameter Dp is preferably 1.0 mm or greater and 6.0 mm or less. By setting the diameter Dp to be 1.0 mm or more, the air flow is well disturbed. In this respect, the diameter Dp is more preferably equal to or greater than 1.5 mm, and particularly preferably equal to or greater than 2.0 mm. By setting the diameter Dp to 6.0 mm or less, the air flow is well disturbed. In this respect, the diameter Dp is more preferably equal to or less than 5.0 mm, and particularly preferably equal to or less than 4.5 mm.

The area sp of the pimple 24 is an area of a region surrounded by the outline of the pimple 24 when the center of the golf ball 2 is viewed from infinity. In the case of the circular pimple 24, the area sp is calculated by the following mathematical formula.
sp = (Dp / 2) ² * π
In the golf ball 2 shown in FIG. 2, the diameter Dp of the pimple A is 2.776 mm, and the diameter Dp of the pimple B is also 2.776 mm. Therefore, the area sp of the pimple A is 6.052 mm ² and the area sp of the pimple B is 6.052 mm ² . The number of pimples A is 80, and the number of pimples B is 120. The total area Sp of the pimples 24 of this golf ball 2 is 1210.5 mm ² .

  In FIG. 6, what is indicated by an arrow H is the height of the pimple 24. The height H is the distance between the vertex Pp and the virtual sphere 16. In light of suppression of hops in the golf ball 2, the height H is preferably 0.05 mm or more, more preferably 0.08 mm or more, and particularly preferably 0.10 mm or more. In light of suppression of dropping of the golf ball 2, the height H is preferably 0.60 mm or less, more preferably 0.50 mm or less, and particularly preferably 0.40 mm or less.

In the present invention, the “pimple volume vp” is the volume of the portion surrounded by the surface of the pimple 24 and the virtual sphere 16. In the golf ball 2 shown in FIG. 2, the volume vp of the pimple A is 0.458 mm ³ and the volume vp of the pimple B is also 0.458 mm ³ . The total volume Vp of the pimples 24 of this golf ball 2 is 91.6 mm ³ .

  In FIG. 6, an arrow L indicates the distance between the center of the phantom sphere 14 and the apex Pp of the pimple 24. When the distance L is smaller than the radius R1, the vertex Pp is located between the surface of the virtual sphere 16 and the surface of the phantom sphere 14. When the distance L is the same as the radius R1, the vertex Pp is located on the surface of the phantom sphere 14. When the distance L is larger than the radius R1, the vertex Pp is located outside the surface of the phantom sphere 14. In light of suppression of wear of the pimple 24, the difference (R1-L) is preferably equal to or greater than -0.15 mm, and particularly preferably equal to or greater than -0.10 mm. From the viewpoint of flight performance, the difference (R1-L) is preferably 0.15 mm or less, and particularly preferably 0.10 mm or less. The difference (R1−L) is preferably zero from the viewpoint that it easily conforms to USGA rules. In other words, the vertex Pp is preferably located on the surface of the phantom sphere 14. The height H of the pimple 24 where the vertex Pp is located on the surface of the phantom sphere 14 coincides with the difference (R1-R2).

In the present invention, the occupation ratio Y (%) is calculated by the following mathematical formula.
Y = ((Sd + Sp) / (4 * π * R1 ² )) * 100
Sd: Total area of the dimple 20 (mm ² )
Sp: Total area of pimple 24 (mm ² )
R1: Radius of phantom sphere 14 (mm)
As described above, the total area Sd of the dimples 20 is 3246.3 mm ² and the total area Sp of the pimples 24 is 1210.5 mm ² . Since the radius R1 is 42.70 mm, the occupation ratio Y is 77.8%.

  From the viewpoint of flight performance, the occupation ratio Y is preferably 65% or more, more preferably 70% or more, and particularly preferably 75% or more. The occupation ratio Y is preferably 95% or less.

As described above, the total volume Vd of the dimple 20 is 244.6 mm ³ , and the total volume Vp of the pimple 24 is 91.6 mm ³ . Therefore, the sum (Vd + Vp) is 336.1 mm ³ . From the viewpoint of rising of the golf ball 2 is suppressed, the sum (Vd + Vp) is 200 mm ³ or more, more preferably 220 mm ³ or more, 250 mm ³ or more is particularly preferable. In view of dropping of the golf ball 2 is suppressed, the sum (Vd + Vp) is preferably 500 mm ³ or less, 450 mm ^3, more preferably less, particularly preferably 400 mm ³ or less.

  The shape of the pimple 24 is a part of a sphere. The golf ball 2 may include pimples having shapes such as a cylinder, a truncated cone, a cone, a prism, a truncated pyramid, a truncated pyramid, and a muscle mountain. The planar shape of the pimple is preferably circular.

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

[Example 1]
100 parts by weight of polybutadiene (trade name “BR-730” from JSR), 30 parts by weight of zinc acrylate, 6 parts by weight of zinc oxide, 10 parts by weight of barium sulfate, 0.5 parts by weight of diphenyl disulfide and 0.5 parts by mass of dicumyl peroxide was kneaded to obtain a rubber composition. This rubber composition was put into a mold composed of an upper mold and a lower mold each having a hemispherical cavity and heated at 170 ° C. for 18 minutes to obtain a core having a diameter of 39.7 mm. On the other hand, 50 parts by mass of ionomer resin (trade name “HIMILAN 1605” from Mitsui DuPont Polychemical Co.), 50 parts by mass of other ionomer resins (trade name “HIMILAN 1706” from Mitsui DuPont Polychemical Co., Ltd.) and 3 parts by mass Part of titanium dioxide was kneaded to obtain a resin composition. The core is put into a final mold having a large number of pimples and dimples on the inner peripheral surface, and the resin composition is injected around the sphere by an injection molding method to form a cover having a thickness of 1.5 mm. did. A dimple having a shape in which the shape of the pimple is inverted and a pimple having a shape in which the shape of the dimple is inverted are formed on the cover. A clear paint based on a two-component curable polyurethane was applied to this cover to obtain a golf ball of Example 1 having a diameter of 42.70 mm and a mass of about 45.4 g. The golf ball has a PGA compression of about 85. This golf ball has the pattern shown in FIG. Details of the dimple and pimple specifications are shown in Table 1 below.

[Examples 2 to 5 and Comparative Examples 1 to 3]
Golf balls of Examples 2 to 5 and Comparative Examples 1 to 3 were obtained in the same manner as Example 1 except that the final mold was changed and the dimples or dimples whose specifications are shown in Tables 1 and 2 below were formed. It was.

[Flight distance test]
A driver equipped with a titanium head (trade name “XXIO” of SRI Sports, shaft hardness: X, loft angle: 9 °) equipped with a titanium head was mounted on a golf laboratory swing machine. A golf ball was hit under the conditions that the head speed was 49 m / sec, the launch angle was about 11 °, and the spin rate of back spin was about 3000 rpm, and the distance from the launch point to the rest point was measured. During the test, there was almost no wind. The average value of 20 measurements is shown in Table 3 below.

[Evaluation of control performance]
A golfer hit a golf ball with a short iron. The control performance was rated according to the following criteria.
A: Control performance is very good B: Control performance is good C: Control performance is not good The results are shown in Table 3 below.

  As shown in Table 3, the golf balls of the examples are excellent in flight performance and control performance. From this evaluation result, the superiority of the present invention is clear.

  The dimple pattern according to the present invention can be applied not only to a two-piece golf ball but also to a one-piece golf ball, a multi-piece golf ball and a thread wound golf ball.

FIG. 1 is a schematic cross-sectional view showing a golf ball according to an embodiment of the present invention. FIG. 2 is an enlarged front view showing the golf ball of FIG. FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. FIG. 4 is an enlarged cross-sectional view showing a part of the golf ball of FIG. FIG. 5 is an enlarged cross-sectional view showing a part of the golf ball of FIG. FIG. 6 is an enlarged cross-sectional view showing a part of the golf ball of FIG.

Explanation of symbols

2 ... Golf ball 4 ... Core 6 ... Cover 8 ... Dividing line 10 ... First zone 12 ... Second zone 14 ... Virtual sphere 16 ... Virtual sphere 18 ... First smooth surface 20 ... Dimple 22 ... Second smooth surface 24 ... Pimple

Claims (5)

It has a first zone and a second zone on its surface,
The first zone has a plurality of first smooth surfaces coinciding with the surface of the phantom sphere of the golf ball, and a plurality of circular dimples recessed from each of the first smooth surfaces,
The second zone has a plurality of second smooth surface to recessed from the surface of the phantom sphere of the golf ball, and a plurality of circular pimples projecting from the second smooth surface of each
The contour of the first zone and the contour of the second zone are defined by the division lines obtained by projecting the sides of the regular polyhedron or quasi-regular polyhedron inscribed in the phantom sphere onto a spherical surface,
The first zone is surrounded by a plurality of second zones, the second zone is surrounded by a plurality of first zones ,
Golf ball sum Ru der 300 to 2,000 of the total number of the total number and the pimple of the dimple.   The golf ball according to claim 1, wherein a total area of the first zone is larger than a total area of the second zone.   The golf ball according to claim 1, wherein the second zone does not have dimples.   The golf ball according to claim 1, wherein a top of the pimple is located on a surface of the phantom sphere. 5. The golf ball according to claim 1 , wherein a ratio of a total area of the dimples and a total area of the pimples to a surface area of the phantom sphere is 65% or more.

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