JP3243331U - Golf ball - Google Patents

Abstract

A ball having a large bending width and a short rolling distance after landing is provided. A spherical core (4), an intermediate layer (6), and an outermost layer cover (8) provided with a plurality of dimples (10). ) Hs is the hardness, S = Hs - Ho, Hm is the material hardness (Shore D hardness) of the intermediate layer, Tm (mm) is the thickness, Hc is the material hardness (Shore D hardness) of the outermost cover layer, and Hc is the thickness is Tc (mm), and the total lower volume of the plurality of dimples is Vi (mm3), [S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230 is satisfied. and [Selection drawing] Fig. 1

Description

The present invention relates to golf balls, and more particularly to golf balls having a spherical core, an intermediate layer, an outermost cover layer and dimples.

Advanced golfers make draw shots and fade shots to avoid obstacles in the course. Draw shots and fade shots are shots in which the golf ball is intentionally bent left and right to avoid obstacles.

A golfer's shot technique is important for hitting draw shots and fade shots. On the other hand, it is important for a golf ball to easily draw or fade by controlling its spin characteristics and aerodynamic characteristics.

For example, in Patent Document 1, a golf ball having a plurality of dimples and a joining line formed on the outer peripheral edge is provided with a center-of-gravity display point that displays the center of gravity of the golf ball on the outer surface of the golf ball. A balance line passing through the point is formed, and a fade line leading to a fade shot and a draw line leading to a draw shot are formed on both sides of the balance line with a predetermined gap, and the balance line passes through the center of gravity display point. A golf ball is disclosed in which a hitting line for hitting fade shots and draw shots is formed on an arbitrary line perpendicular to the joining line.

U.S. Pat. No. 6,200,400 discloses a golf ball having a particular relationship between ball spin rate, moment of inertia, lift and drag. The golf ball disclosed in U.S. Pat. No. 5,900,004 is a golf ball having a core and a cover, having a moment of inertia of about 0.46 oz/in ² or greater, and a lift coefficient of is greater than about 0.20 and the drag coefficient is less than about 0.22.

Japanese Patent Publication No. 2016-539779 Japanese Unexamined Patent Application Publication No. 2007-190391

When side spin is applied to hit a draw ball, the rolling distance after falling becomes long, and there is a problem in that it stops at the target point. SUMMARY OF THE INVENTION An object of the present invention is to provide a ball that has a large bending width and a short rolling distance after landing.

The golf ball of the present invention, which can solve the above problems,
A golf ball having a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer,
Let the center hardness (Shore C hardness) of the spherical core be Ho, the surface hardness (Shore C hardness) of the spherical core be Hs, the hardness difference S = Hs - Ho,
The material hardness (Shore D hardness) of the intermediate layer is Hm, the thickness is Tm (mm),
Let Hc be the material hardness (Shore D hardness) of the outermost layer cover, and Tc (mm) be the thickness,
When the total lower volume of the plurality of dimples is Vi (mm ³ ),
[S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230 is satisfied.

With the golf ball of the present invention configured as described above, a large amount of side spin can be applied, and the lift force is increased to increase the flight time. The longer the flight time of the shot, the wider the curve. Also, when the flight time increases, the maximum height of the hit ball increases and the angle of fall becomes acute. Since the golf ball falls at an acute angle, the rolling distance of the golf ball after landing can be reduced.

According to the present invention, it is possible to provide a ball that has a large bending width on draw shots and fade shots and a short rolling distance after landing.

1 is a partially cutaway cross-sectional view showing a golf ball according to one embodiment of the present invention; FIG. 4 is a front view of a dimple pattern formed on the outermost layer cover; FIG. FIG. 4 is a plan view of a dimple pattern formed on the outermost layer cover; 4 is an enlarged cross-sectional view of dimples formed in the outermost layer cover; FIG. Explanatory drawing explaining the bending width test of a shot.

The golf ball of the present invention is
A golf ball having a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer,
Let the center hardness (Shore C hardness) of the spherical core be Ho, the surface hardness (Shore C hardness) of the spherical core be Hs, the hardness difference S = Hs - Ho,
The material hardness (Shore D hardness) of the intermediate layer is Hm, the thickness is Tm (mm),
Let Hc be the material hardness (Shore D hardness) of the outermost layer cover, and Tc (mm) be the thickness,
When the total lower volume of the plurality of dimples is Vi (mm ³ ),
[S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230 is satisfied.

(Golf ball structure)
A golf ball of the present invention has a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer.

The structure of the golf ball consists of a three-piece golf ball consisting of a spherical core, an intermediate layer covering the spherical core, and an outermost cover layer covering the intermediate layer; A multi-piece golf ball (four-piece golf ball, five-piece golf ball, etc.) comprising two or more intermediate layers and an outermost cover covering the intermediate layers can be mentioned. The intermediate layer may be called an inner cover layer or an outer core layer depending on the structure of the golf ball.

The structure of the spherical core may be either a single-layer structure or a multi-layer structure, but the single-layer structure is preferred.

The diameter of the spherical core is preferably 34.8 mm or more, more preferably 36.8 mm or more, still more preferably 38.8 mm or more, preferably 42.2 mm or less, more preferably 41.8 mm or less, still more preferably 41.2 mm or less, most preferably 40.8 mm or less. When the diameter of the spherical core is within the above range, the golf ball has good flight performance and feel at impact.

When the spherical core has a diameter of 34.8 mm to 42.2 mm, the amount of compressive deformation (the amount of shrinkage of the spherical core in the direction of compression) from the initial load of 98 N to the final load of 1275 N is 2. It is preferably 0 mm or more, more preferably 2.5 mm or more, still more preferably 3.0 mm or more, and preferably 5.0 mm or less, more preferably 4.5 mm or less, still more preferably 4.0 mm or less. If the amount of compressive deformation is within the above range, the feel at impact will be better.

The surface hardness (Hs) of the spherical core is not particularly limited. More preferably, it is 85 or less. When the surface hardness (Hs) is within the above range, a good feel at impact can be obtained.

The central hardness (Ho) of the spherical core is not particularly limited, but the Shore C hardness is preferably 45 or more, more preferably 47 or more, still more preferably 49 or more, preferably 74 or less, more preferably 72 or less. More preferably, it is 70 or less. When the center hardness (Ho) is within the above range, a good feel at impact can be obtained.

The hardness difference S (=Hs−Ho) between the surface hardness (Hs) and the center hardness (Ho) of the spherical core is preferably 3 or more, more preferably 5 or more in Shore C hardness, and 7. It is more preferably at least 20, preferably less than 20, more preferably 19 or less, even more preferably 18 or less. When the hardness difference S is less than 20, the spin rate is increased and the controllability of each iron shot is improved. If the hardness difference is 3 or more, the flight distance on driver shots increases.

The hardness (H10) at a point 10 mm in the radial direction from the center of the spherical core is not particularly limited, but the Shore C hardness is preferably 60 or more, more preferably 62 or more, and 64 or more. is more preferably 84 or less, more preferably 82 or less, and even more preferably 80 or less. When the hardness (H10) is within the above range, a good feel at impact can be obtained.

In the spherical core of the present invention, the value of (H10-Ho)/S is preferably more than 0.35, preferably 0.38 or more, more preferably 0.40 or more, and 0.40 or more. It is preferably less than 6, more preferably 0.58 or less, even more preferably 0.56 or less. If the value of (H10-Ho)/S is within the above range, it indicates that the hardness of the core varies linearly. When the hardness of the core increases linearly, the core deforms smoothly at the time of hitting, resulting in a good feel at impact on driver shots.

The material hardness Hm of the intermediate layer composition constituting the intermediate layer is preferably 50 or more, more preferably 52 or more, still more preferably 54 or more, and more preferably 73 or less, more preferably 72 in Shore D hardness. 70 or less, more preferably 70 or less. This is because when the material hardness Hm is 50 or more, the resilience performance on driver shots is sufficiently exhibited, resulting in a good flight distance, and when the material hardness Hm is 73 or less, a good feel at impact is obtained. When a plurality of intermediate layers are provided, Hm is the material hardness of the outermost intermediate layer.

The thickness Tm of the intermediate layer is preferably 0.8 mm or more, more preferably 0.9 mm or more, still more preferably 1.0 mm or more, and preferably 3.0 mm or less, more preferably 2.7 mm or less. Preferably, it is 2.5 mm or less. This is because when the thickness Tm is 0.8 mm or more, the durability is good, and when the thickness Tm is 3.0 mm or less, a good feel at impact can be obtained. When a plurality of intermediate layers are provided, the thickness of the outermost intermediate layer is Tm.

The material hardness Hc of the cover composition constituting the outermost cover layer is preferably 20 or more, more preferably 22 or more, still more preferably 24 or more, and preferably 40 or less, more preferably 39 in Shore D hardness. 38 or less, more preferably 38 or less. This is because when the material hardness Hc is 20 or more, the spin rate on driver shots does not become too large and flight distance performance is good, and when the material hardness Hc is 40 or less, spin performance on approach shots is good. .

The thickness Tc of the outermost layer cover is preferably 0.4 mm or more, more preferably 0.5 mm or more, still more preferably 0.6 mm or more, and is preferably 1.0 mm or less, more preferably 0.9 mm or less. More preferably, it is 0.8 mm or less. When the thickness Tc is 0.4 mm or more, the spin performance on approach shots is good. Because it becomes

(dimple)
The golf ball of the present invention has an outermost cover layer provided with a plurality of dimples. Dimples are recesses provided in the outermost layer cover. The dimples provided on the outermost cover layer of the golf ball of the present invention will be described below with reference to the drawings.

A golf ball 2 shown in FIG. 1 has a spherical core 4 , an intermediate layer 6 covering the core 4 , and an outermost cover layer 8 located outside the intermediate layer 6 . This golf ball 2 has a plurality 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 outer side of the outermost cover layer 8, but the illustration of these layers is omitted.

As shown in FIGS. 2 and 3, the outermost layer cover of the golf ball 2 is provided with a large number of dimples 10 on its surface. The outline of each dimple 10 is a circle.

FIG. 4 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. 4 is the depth direction of the dimple 10 . A phantom sphere is indicated by a chain double-dashed line 14 in FIG. 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 this embodiment, the cross-sectional shape of the dimple 10 is substantially arcuate. The radius of curvature of this arc is indicated by symbol CR in FIG.

The diameter of the dimple 10 is indicated by an arrow Dm in FIG. This diameter Dm is the distance between one contact point Ed and the other contact point Ed when a tangent line Tg common to both sides of the dimple 10 is drawn. The contact Ed is also the edge of the dimple 10 . Edge Ed defines the contour of dimple 10 .

In the present invention, the “dimple volume” means the volume of the portion surrounded by the phantom spherical surface including the outline of the dimple 10 and the surface of the dimple 10 . The "dimple volume" is separated by a plane connecting the phantom spherical surface 14 and the point of contact Ed-Ed of the dimple surface. The "dimple upper volume" is the upper volume of the dimple surrounded by the phantom spherical surface 14 and the plane connecting the points of contact Ed-Ed of the dimple surface. The “dimple lower volume” is the volume below the dimple surrounded by the surface of the dimple 10 and the plane connecting the points of contact Ed-Ed on the dimple surface. The dimple volume is the sum of the upper and lower volumes. The "total dimple volume V" of the present invention is the sum of the volumes of all dimples. "Total dimple top volume Vo" is the sum of the top volumes of all dimples. "Total dimple lower volume Vi" is the sum of the lower volumes of all dimples. If Vo is the total volume of the upper portion of the dimples and Vi is the total volume of the lower portion of the dimples, then V=Vo+Vi.

In the golf ball, the total lower volume Vi of the plurality of dimples is preferably 190 mm ³ or more, preferably 195 mm ³ or more, and more preferably 200 mm ³ or more. When the total lower volume Vi is 190 mm ³ or more, the lift acting on the golf ball due to backspin is suppressed, and the blow-up on shots is suppressed. The total lower volume Vi is preferably less than 300 mm ³ , more preferably 295 mm ³ or less, even more preferably 290 mm ³ or less. This is because if the total volume Vi of the lower portion is less than 300 mm ³ , the lift acting on shots will be greater, and the flight time will be longer.

The diameter Dm of the dimple 10 is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 2.8 mm or more, and preferably 6.0 mm or less, more preferably 5.5 mm or less, still more preferably. is 5.0 mm or less. This is because when the diameter Dm is 2.0 mm or more, the dimples tend to contribute to turbulence, and when the diameter Dm is 6.0 mm or less, the golf ball can maintain its substantially spherical nature.

The plurality of dimples may be a plurality of dimples having a single diameter, or a combination of dimples having a plurality of types of diameters. The golf ball 2 shown in FIGS. 2 and 3 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, and a dimple C with a diameter of 3.4 mm. It has five types of dimples, a dimple D having a diameter of 875 mm and a dimple E having a diameter of 3.000 mm.

A first depth of the dimple 10 is indicated by a double arrow Dp1 in FIG. This first depth Dp1 is the distance between the deepest part of the dimple 10 and the surface of the phantom sphere 14 .
The first depth Dp1 is preferably 0.15 mm or more, more preferably 0.17 mm or more, still more preferably 0.20 mm or more, and preferably 0.45 mm or less, more preferably 0.43 mm or less, still more preferably 0.40 mm or less. This is because if the first depth Dp1 is 0.15 mm or more, a sufficient lift can be generated by the dimples, and if the first depth Dp1 is 0.45 mm or less, the substantially spherical golf ball can be maintained.

The second depth of the dimple 10 is indicated by a double arrow Dp2 in FIG. This second depth Dp2 is the distance between the deepest portion of the dimple 10 and the tangent line Tg.
The second depth Dp2 is preferably 0.08 mm or more, more preferably 0.10 mm or more, still more preferably 0.12 mm or more, and preferably 0.30 mm or less, more preferably 0.28 mm or less, still more preferably is 0.26 mm or less. When the second depth Dp2 is 0.08 mm or more, the dimples tend to contribute to turbulence. Because it becomes

The area A of the dimple 10 is the area surrounded by the outline of the dimple 10 when the center of the golf ball 2 is viewed from infinity. In the case of the circular dimple 10, the area A is calculated by the following formula.
A=π×(Dm/2) ²

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

The ratio of the total area A of all the dimples 10 to the surface area of the phantom sphere 14 (total area of dimples/virtual surface area) is called occupation ratio So. The occupancy rate So is preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, preferably 95% or less, more preferably 92% or less, and even more preferably 90% or less. If the occupancy rate So is within the above range, the effect of turbulence by the dimples becomes greater.

The number of dimples may be appropriately adjusted according to the dimple diameter and occupation ratio. Considering the occupancy rate and the effects of individual dimples, the total number of dimples 10 is preferably 250 or more, more preferably 280 or more, still more preferably 300 or more, and preferably 450 or less, more preferably 450 or less. 410 or less, more preferably 390 or less.

The golf ball of the present invention satisfies [S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230. Here, S is the hardness difference between the surface hardness Hs (Shore C) and the center hardness Ho (Shore C) of the spherical core, Hm is the material hardness (Shore D) of the intermediate layer, and Tm is the intermediate layer hardness. is the thickness of the layer (mm), Hc is the material hardness (Shore D) of the outermost layer cover, Tc is the thickness of the outermost layer cover (mm), and Vi is the total lower volume of the dimple (mm ³ ). The value of {[S × (Hm × Tm + Hc × Tc)] / (Tm + Tc) × Vi / 1000} is preferably 110 or more, more preferably 120 or more, more preferably 130 or more, preferably less than 230, and 225 or less. More preferably, 220 or less is even more preferable.

If the value of {[S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000} is less than 230, side spin tends to occur, and the bending width increases. When the value of {[S×(Hm×Tm)+(Hc×Tc)]/(Tm+Tc)×Vi/1000} is 110 or more, the flight distance on driver shots increases.

The product (Hm×Tm) of the thickness Tm (mm) of the intermediate layer and the material hardness Hm (Shore D hardness) is preferably 50 or more, more preferably 55 or more, still more preferably 60 or more, and 140 The following is preferable, more preferably 130 or less, and still more preferably 120 or less. This is because when the ratio (Hm×Tm) is 50 or more, the spin rate on driver shots is reduced, resulting in good flight distance performance, and when the ratio is 140 or less, a good feel at impact is obtained.

The product (Hc×Tc) of the thickness Tc (mm) of the outermost layer cover and the material hardness Hc (Shore D hardness) is preferably 10 or more, more preferably 12 or more, still more preferably 14 or more, It is preferably 45 or less, more preferably 42 or less, and even more preferably 40 or less. This is because when the ratio (Hc×Tc) is 10 or more, the deformation amount of the cover is stabilized on approach shots, thereby stabilizing the spin rate, and when the ratio is 45 or less, the rebound performance of the ball is improved. .

(Tm+Tc) is preferably 1.2 or more, more preferably 1.3 or more, further preferably 1.4 or more, and preferably 3.5 or less; It is more preferably 3 or less, and even more preferably 3.1 or less. This is because, when the value of (Tm+Tc) is within the above range, a good feel at impact can be obtained.

The golf ball of the present invention preferably satisfies spherical core surface hardness Hs (Shore C hardness)<intermediate layer surface hardness Hms (Shore C hardness)>golf ball surface hardness Hcs (Shore C hardness). When the intermediate layer surface hardness Hms is higher than the spherical core surface hardness Hs, the outer-hardness and inner-softness are increased, the spin rate on driver shots is suppressed, and the flight distance is increased. When the surface hardness Hcs of the golf ball is lower than the intermediate layer surface hardness Hms, the spin rate on approach shots increases and the controllability increases.

In the golf ball, the difference (Hms−Hcs) between the surface hardness Hcs of the golf ball and the surface hardness Hms of the intermediate layer (Hms−Hcs) in terms of Shore C hardness is preferably greater than 0, more preferably 2 or more, and further Preferably it is 4 or more. This is because if the difference (Hms−Hcs) is more than 0, the deformation of the cover at the time of hitting becomes greater, thereby improving the spin performance on approach shots. Although the upper limit of the difference (Hms−Hcs) is not particularly limited, it is about 20.

In the golf ball, the difference (Hms−Hs) between the surface hardness Hs of the spherical core and the surface hardness Hms of the intermediate layer (Hms−Hs) is preferably greater than 0, more preferably 2 or more, in terms of Shore C hardness. More preferably, it is 4 or more. This is because if the difference (Hms−Hs) is greater than 0, the outer-hardness and inner-softness of the intermediate-layer-covered sphere as a whole, in which the intermediate layer is formed on the surface of the spherical core, increases, and the spin rate on driver shots can be suppressed. be.

The golf ball of the present invention preferably has a diameter of 40 mm to 45 mm. 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. Further, the weight 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, 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.

When the golf ball has a diameter of 40 mm to 45 mm, the amount of compressive deformation (the amount of shrinkage in the compression direction) when the initial load of 98 N is applied and the final load of 1275 N is applied is preferably 2.0 mm or more. It is more preferably 2.1 mm or more, still more preferably 2.2 mm or more, and preferably 3.0 mm or less, more preferably 2.9 mm or less, still more preferably 2.8 mm or less. If the amount of compressive deformation is within the above range, the feel at impact of the golf ball will be good.

Next, materials for forming the constituent members of the golf ball of the present invention will be described.

(Composition for core)
The spherical core of the golf ball of the present invention comprises (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 ) is preferably formed from a rubber composition containing a cross-linking initiator (hereinafter sometimes referred to as “core rubber composition”).

(a) As the 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. can. These may be used alone or in combination of two or more.

(b) An α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof is added as a co-crosslinking agent to the rubber composition and grafted onto the molecular chain of the base rubber. By polymerizing, it has the effect of cross-linking rubber molecules.

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

Metals constituting metal salts of α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms include monovalent metal ions such as sodium, potassium and lithium; divalent metal ions; trivalent metal ions such as aluminum; and other ions such as tin and zirconium. The metal components may be used singly or as a mixture of two or more. Among these, divalent metals such as magnesium, calcium, zinc, barium, and cadmium are preferable as the metal component. This is because the use of a divalent metal salt of an 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 suitable as the divalent metal salt because the resulting golf ball has a high resilience. The α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms and/or metal salts thereof may be used alone or in combination of two or more.

(b) The content of the α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or the metal salt thereof may be appropriately adjusted according to the desired hardness of the spherical core. The content of component (b) is, for example, preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and still more preferably 25 parts by mass or more, relative to 100 parts by mass of the base rubber (a). , is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

(c) The cross-linking initiator is added to cross-link the (a) base rubber component. (c) As the cross-linking 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 Examples include organic peroxides such as (t-butylperoxy)hexane and di-t-butylperoxide. These organic peroxides may be used alone or in combination of two or more. Among these, dicumyl peroxide is preferably used.

(c) The content of the cross-linking initiator may be appropriately adjusted according to the desired hardness of the spherical core. (c) The content of the cross-linking initiator is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, and still more preferably 100 parts by mass of the base rubber (a) It is 0.6 parts by mass or more, preferably 5.0 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 1.0 parts by mass or less.

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

The metal compound (d) 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; magnesium oxide and 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, more preferably a zinc compound. This is because the divalent metal compound reacts with an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms to form a metal bridge. These (d) metal compounds may be used alone or in combination of two or more.

The rubber composition may further contain (e) an organic sulfur compound. (e) The organic sulfur compound improves the resilience of the spherical core. (e) The organic sulfur compound is not particularly limited as long as it is an organic compound having a sulfur atom in the molecule. -S-, -SSS-, or -S-S-S-S-), or metal salts thereof (-SM, -SMS-, etc., where M is a metal atom) can be mentioned. The (e) organic sulfur compound can be used alone or in combination of two or more.

Examples of the (e) organic sulfur compounds include thiophenols, thionaphthols, polysulfides, thiurams, thiocarboxylic acids, dithiocarboxylic acids, sulfenamides, dithiocarbamates, and thiazoles. . Diphenyl disulfides (eg, diphenyl disulfide, bis(pentabromophenyl) disulfide), thiophenols, and thionaphthols (eg, 2-thionaphthol) can be preferably used as the organic sulfur compound.

The content of the (e) organic sulfur compound may be appropriately adjusted according to the desired resilience performance of the spherical core. The content of the (e) organic sulfur compound is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably, for 100 parts by mass of the (a) base rubber. is 0.2 parts by mass or more, preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, and still more preferably 1.0 parts by mass or less.

The rubber composition may further contain (f) a carboxylic acid and/or a metal salt thereof. As the (f) carboxylic acid and/or metal salt thereof, a carboxylic acid having 1 to 30 carbon atoms and/or a salt thereof is preferable. As the carboxylic acid, either aliphatic carboxylic acid (saturated fatty acid, unsaturated fatty acid) or aromatic carboxylic acid (benzoic acid, etc.) can be used. The amount of the (f) carboxylic acid and/or 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.

The rubber composition may contain additives such as fillers for weight adjustment, antioxidants, peptizers, and softeners, if necessary.

The filler used in the rubber composition is mainly used as a weight modifier for adjusting the weight of the golf ball obtained as the final product, and may be added as necessary. Examples of the filler include inorganic fillers such as barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder.

The rubber composition comprises (a) a base rubber, (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof, (c) a crosslinking initiator, and, if necessary, It can be obtained by kneading other ingredients to be blended accordingly. The kneading method is not particularly limited, and for example, a known kneader such as a kneading roll, a Banbury mixer, or a kneader may be used.

The spherical core can be molded, for example, by hot-pressing the core rubber composition. The heat press molding conditions for the core rubber composition may be appropriately set according to the rubber composition. After heating for 10 minutes to 40 minutes, it is preferable to heat at 160° C. to 180° C. for 5 minutes to 15 minutes in two stages.

(Cover Composition, Intermediate Layer Composition)
The golf ball of the present invention has an intermediate layer covering the spherical core. The intermediate layer is preferably formed from an intermediate layer composition containing a resin component.

The golf ball of the present invention has an outermost cover layer positioned outside the intermediate layer. The outermost cover layer is preferably formed from a cover composition containing a resin component.

Resin components used in the resin composition forming the outermost cover layer and the intermediate layer include, for example, ionomer resins, urethane resins (thermoplastic polyurethane elastomers, thermosetting polyurethane elastomers), thermoplastic styrene elastomers, thermoplastic polyamide elastomers, heat Examples include plastic polyester elastomers.

As the ionomer resin, for example, a binary system obtained by neutralizing at least part of the carboxyl groups in a binary copolymer of an olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms with a metal ion Neutralization of at least part of the carboxyl groups of ionomer resins, terpolymers of olefins, α,β-unsaturated carboxylic acids having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid esters with metal ions ternary ionomer resins, or mixtures thereof.

As the binary ionomer resin, Himilan (registered trademark) 1555 (Na), 1557 (Zn), 1605 (Na), 1706 (Zn), 1707 (Na), AM7311 (Mg), AM7329 (Zn), AM7337 (manufactured by Mitsui Dow Polychemicals); Surlyn (registered trademark) 8945 (Na), 9945 (Zn), 8140 (Na), 8150 (Na), 9120 (Zn), 9150 (Zn), 6910 (Mg) , 6120 (Mg), 7930 (Li), 7940 (Li), AD8546 (Li) (manufactured by DuPont); IOTEC (registered trademark) 8000 (Na), 8030 (Na), 7010 (Zn), 7030 (Zn) (manufactured by Exxon Mobil Chemical Company) and the like.

The ternary ionomer resins include Himilan AM7327 (Zn), 1855 (Zn), 1856 (Na), AM7331 (Na) (manufactured by Mitsui Dow Polychemicals); Surlyn 6320 (Mg), 8120 (Na). , 8320 (Na), 9320 (Zn), 9320W (Zn), HPF1000 (Mg), HPF2000 (Mg) (manufactured by DuPont); IOTEC 7510 (Zn), 7520 (Zn) (manufactured by ExxonMobil Chemicals), etc. mentioned. Incidentally, Na, Zn, Li, Mg, etc. described in parentheses after the ionomer resin product names indicate the metal species of these neutralized metal ions.

The thermoplastic polyurethane elastomer has a urethane bond in its molecule. The urethane linkages can be formed by reaction of polyols and polyisocyanates. The polyol, which is a raw material for urethane bonds, has a plurality of hydroxyl groups, and low molecular weight polyols and high molecular weight polyols can be used.

Specific examples of the thermoplastic polyurethane elastomer include Elastollan (registered trademark) NY80A, NY84A, NY88A, NY95A, ET885 and ET890 (manufactured by BASF Japan).

As the thermoplastic styrene-based elastomer, a thermoplastic elastomer containing a styrene block can be suitably used. The styrene block-containing thermoplastic elastomer comprises polystyrene blocks as hard segments and soft segments.

The styrene block-containing thermoplastic elastomer includes styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isoprene-butadiene-styrene block copolymer (SIBS). , hydrogenates of SBS, hydrogenates of SIS and hydrogenates of SIBS. Hydrogenated products of SBS include styrene-ethylene-butylene-styrene block copolymers (SEBS). Hydrogenated products of SIS include styrene-ethylene-propylene-styrene block copolymers (SEPS). Hydrogenated products of SIBS include styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS).

Examples of the thermoplastic styrene elastomer include Tefablock T3221C, T3339C, SJ4400N, SJ5400N, SJ6400N, SJ7400N, SJ8400N, SJ9400N, and SR04 (manufactured by Mitsubishi Chemical Corporation).

The cover composition constituting the outermost layer cover preferably contains polyurethane and/or ionomer resin as a resin component, and more preferably contains polyurethane. When the outermost cover layer contains polyurethane as a resin component, the outermost cover layer grips the club face more on driver shots, which tends to increase the spin rate.

When the cover composition contains polyurethane as a resin component, the polyurethane content in the resin component 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 polyurethane (preferably thermoplastic polyurethane elastomer) as the resin component.

When the cover composition contains an ionomer resin as a resin component, the content of the ionomer resin in the resin component is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. . When containing an ionomer resin, it is also preferable to use a thermoplastic styrene elastomer together.

The intermediate layer composition preferably contains an ionomer resin as a resin component. When containing an ionomer resin, it is also preferable to use a thermoplastic styrene elastomer together. The content of the ionomer resin in the base resin of the intermediate layer 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 composition for the outermost cover layer and the composition for the intermediate layer contain, in addition to the resin components described above, pigment components such as white pigments (e.g., titanium oxide), blue pigments, and red pigments, zinc oxide, calcium carbonate, barium sulfate, and the like. weight adjuster, dispersant, anti-aging agent, ultraviolet absorber, light stabilizer, fluorescent material or fluorescent whitening agent.

The content of the white pigment (for example, titanium oxide) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, with respect to 100 parts by mass of the base resin constituting the outermost layer cover, 10 parts by mass or less is preferable, and 8 parts by mass or less is more preferable. By setting the content of the white pigment to 0.5 parts by mass or more, it is possible to impart hiding power to the cover. Further, when the content of the white pigment is 10 parts by mass or less, the durability of the resulting cover is improved.

The method for forming the intermediate layer is not particularly limited, but for example, a method in which the intermediate layer composition is preliminarily formed into a hemispherical half shell, two half shells are used to wrap the spherical core, and pressure molding is performed. Alternatively, the intermediate layer composition may be injection-molded directly onto the spherical core to enclose the sphere.

As a method of molding the cover, for example, a method of molding a hollow shell from a cover composition, covering a sphere with an intermediate layer formed thereon with a plurality of shells, and compression molding (preferably, a method for forming a cover) a method of molding a hollow half-shell from the composition, covering the sphere with two half-shells and compression molding), or a method of directly injection-molding the covering composition onto the sphere. .

It is preferable that the golf ball body having the cover formed thereon is removed from the mold and, if necessary, subjected to surface treatments such as deburring, cleaning, and sandblasting.

Also, if desired, a coating film or a mark can be formed. The film thickness of the coating film is not particularly limited, but is preferably 5 µm or more, more preferably 6 µm or more, still 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 film thickness is 5 μm or more, the coating film is less likely to wear out even after continuous use, and if the film thickness is 50 μm or less, a sufficient dimple effect can be obtained. In addition, since the thickness of the coating film is very thin, the effect of the present invention is not impaired.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following examples, and modifications and embodiments within the scope of the gist of the invention can be made according to the invention. Included in scope.

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

(2) Amount of compression deformation (mm)
A YAMADA type compression tester "SCH" was used to measure the amount of compression deformation. In this tester, a golf ball or spherical core is placed on a rigid metal plate. A metal cylinder gradually descends toward the golf ball or spherical core. A golf ball or spherical core sandwiched between the bottom surface of the cylinder and the rigid plate deforms. The distance traveled by the cylinder from the initial load of 98 N to the final load of 1275 N on the golf ball or spherical core was measured. The amount of compression deformation (mm) is this moving distance. The moving speed of the cylinder until the initial load is applied is 0.83 mm/s. The moving speed of the cylinder from when the initial load is applied to when the final load is applied is 1.67 mm/s.

(3) Core hardness distribution (Shore C hardness)
The hardness measured at the surface portion of the core was defined as the core surface hardness. Also, the core was cut into a hemispherical shape, and the hardness was measured at the center of the cut surface and at a predetermined distance radially from the center. Each hardness was measured at 4 points and calculated by averaging them. The hardness was measured using an automatic hardness tester (manufactured by H. Burleith, Digitest II). The detector used was "ShoreC".

(4) Golf Ball Surface Hardness and Intermediate Layer Surface Hardness The surface hardness of the golf ball was determined by measuring the land portion of the surface of the golf ball. Further, the hardness measured at the surface portion of the intermediate layer-covered sphere having the intermediate layer formed on the surface of the spherical core was defined as the intermediate layer surface hardness. Each hardness was measured at 4 points and calculated by averaging them. The hardness was measured using an automatic hardness tester (manufactured by H. Burleith, Digitest II). The detector used was "ShoreC".

(5) Measurement of Bending Width (m) and Rolling Distance (m) of Iron Shot A 7-iron (I#7) (Sumitomo Rubber Industries, "SRIXON ZX7", shaft hardness: X) was used on a golf laboratory swing machine. , loft angle: 32°). The hitting point was set at a point 10 mm on the toe side from the center of the face. A golf ball was hit at a head speed of 39 m/sec, and the side spin rate, rolling distance (distance from the falling point to the stopping position), and trajectory were measured immediately after hitting. The spin rate immediately after hitting was measured by taking continuous photographs of the golf ball immediately after hitting. Ballistic measurement was performed using a ballistic measuring instrument "TRACK MAN4" manufactured by TRACK MAN. As shown in Fig. 5, when the trajectory seen from the sky is coordinated, the line connecting the launch position and the landing position is the Y axis, and the orthogonal coordinate is the X axis (the right direction from the launch direction is +). , and the maximum value in the X-axis direction was defined as the bending width. Each golf ball was tested 12 times, and the average value was taken as the measured value for that golf ball.

[Production of Golf Ball]
(1) Preparation of core composition Each raw material was kneaded with kneading rolls so as to have the composition shown in Table 1, to obtain a core composition.

The materials used in Table 1 are as follows.
Polybutadiene: "BR-730" manufactured by JSR
Zinc acrylate: "ZN-DA90S" manufactured by Nisshoku Techno Fine Chemical Co., Ltd.
Zinc oxide: "Ginrei R" manufactured by Toho Zinc Co., Ltd.
Barium sulfate: "Barium sulfate BD" manufactured by Sakai Chemical Co., Ltd.
Benzoic acid: manufactured by Tokyo Chemical Industry Co., Ltd. (purity of 98% or more)
Bis (pentabromophenyl) disulfide: manufactured by Kawaguchi Chemical Industry Co., Ltd. Diphenyl disulfide: manufactured by Sumitomo Seika Dicumyl peroxide: manufactured by NOF Corporation, "Percumyl (registered trademark) D"

(2) Preparation of Intermediate Layer/Cover Composition The raw materials were extruded with a twin-screw kneading extruder so as to have the formulation shown in Tables 2 and 3 to prepare a pellet-like intermediate layer/cover composition. did.

Surlyn (registered trademark) 8150: manufactured by DuPont, sodium ion-neutralized ethylene-methacrylic acid copolymer ionomer resin Himilan (registered trademark) 1605: manufactured by Mitsui-Dow Polychemicals, sodium ion-neutralized ethylene-methacrylic acid copolymer Systematic ionomer resin Himilan (registered trademark) AM7329: manufactured by Mitsui Dow Polychemicals, sodium ion neutralized ethylene-methacrylic acid copolymer ionomer resin Himilan (registered trademark) 1555: manufactured by Mitsui Dow Polychemicals, sodium ion Neutralized ethylene-methacrylic acid copolymer ionomer resin Himilan (registered trademark) 1557: manufactured by Mitsui Dow Polychemicals, zinc ion neutralized ethylene-methacrylic acid copolymer ionomer resin Tefabloc T3221C: manufactured by Mitsubishi Chemical Co., heat Plastic styrene elastomer titanium dioxide: A-220 manufactured by Ishihara Sangyo Co., Ltd.

Elastollan (registered trademark) NY80A: Thermoplastic polyurethane elastomer manufactured by BASF Japan Elastollan (registered trademark) NY84A: Thermoplastic polyurethane elastomer manufactured by BASF Japan Elastollan (registered trademark) NY88A: Thermoplastic polyurethane manufactured by BASF Japan Elastomer Elastollan (registered trademark) NY95A: manufactured by BASF Japan, thermoplastic polyurethane elastomer Tinuvin (registered trademark) 770: manufactured by BASF Japan, hindered amine light stabilizer Titanium dioxide: manufactured by Ishihara Sangyo Co., Ltd., A-220

(3) Production of Core A core composition shown in Table 1 was hot-pressed in upper and lower molds having hemispherical cavities to obtain spherical cores. An appropriate amount of barium sulfate was added so that the mass of the resulting golf ball was 45.3 g.

(4) Formation of Intermediate Layer and Cover The intermediate layer composition was injection molded onto a spherical core to obtain an intermediate layer-covered sphere. The intermediate layer-coated sphere thus obtained was put into a final mold having a large number of dimples on the cavity surface. A half shell was obtained from the cover composition by compression molding. Two half shells were placed on the intermediate layer-covered sphere placed in the final mold, and a golf ball having a large number of dimples formed on the outermost cover layer, the shape of which was the reverse of the shape of the pimples on the cavity surface, was obtained. Tables 4 and 5 show the specifications of the dimples formed on the outermost layer cover. Tables 6 and 7 show the evaluation results of the obtained golf balls.

A golf ball having a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer,
Let the center hardness (Shore C hardness) of the spherical core be Ho, the surface hardness (Shore C hardness) of the spherical core be Hs, the hardness difference S = Hs - Ho,
The material hardness (Shore D hardness) of the intermediate layer is Hm, the thickness is Tm (mm),
Let Hc be the material hardness (Shore D hardness) of the outermost layer cover, and Tc (mm) be the thickness,
When the total lower volume of the plurality of dimples is Vi (mm ³ ),
It can be seen that the golf ball of the present invention that satisfies [S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230 has a large bending width and a short rolling distance after landing.

A preferred embodiment (1) of the present invention is a golf ball having a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer. There is
Let the center hardness (Shore C hardness) of the spherical core be Ho, the surface hardness (Shore C hardness) of the spherical core be Hs, the hardness difference S = Hs - Ho,
The material hardness (Shore D hardness) of the intermediate layer is Hm, the thickness is Tm (mm),
Let Hc be the material hardness (Shore D hardness) of the outermost layer cover, and Tc (mm) be the thickness,
When the total lower volume of the plurality of dimples is Vi (mm ³ ),
The golf ball satisfies [S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230.

A preferred aspect (2) of the present invention is the above aspect (1) satisfying 0.35<(H10−Ho)/S<0.6, where H10 is the hardness at a point 10 mm from the center of the spherical core. It's a golf ball.

A preferred aspect (3) of the present invention is the golf ball of the aspect (1) or (2), wherein the hardness difference S<20.

A preferred embodiment (4) of the present invention is the golf ball according to any one of the above embodiments (1) to (3), wherein Vi<300.

Preferred embodiment (5) of the present invention is the above embodiments (1) to (4) satisfying the following conditions: spherical core surface hardness (Shore C hardness) <intermediate layer surface hardness (Shore C hardness)>golf ball surface hardness (Shore C hardness) ) is any one golf ball.

A preferred embodiment (6) of the present invention is the golf ball according to any one of the above embodiments (1) to (5), wherein the outermost cover layer contains polyurethane as the resin component.

2: golf ball, 4: spherical core, 6: intermediate layer, 8: outermost layer cover, 10: dimple, 12: land, 14: phantom sphere

Claims (6)

A golf ball having a spherical core, an intermediate layer arranged outside the spherical core, and an outermost cover layer provided with a plurality of dimples arranged outside the intermediate layer,
Let the center hardness (Shore C hardness) of the spherical core be Ho, the surface hardness (Shore C hardness) of the spherical core be Hs, the hardness difference S = Hs - Ho,
The material hardness (Shore D hardness) of the intermediate layer is Hm, the thickness is Tm (mm),
Let Hc be the material hardness (Shore D hardness) of the outermost layer cover, and Tc (mm) be the thickness,
When the total lower volume of the plurality of dimples is Vi (mm ³ ),
A golf ball satisfying [S×(Hm×Tm+Hc×Tc)]/(Tm+Tc)×Vi/1000<230. When the hardness at 10 mm from the center of the spherical core is H10,
2. The golf ball of claim 1, which satisfies 0.35<(H10-Ho)/S<0.6. 2. The golf ball of claim 1, wherein said hardness difference S<20. 2. The golf ball of claim 1, wherein Vi<300. 2. The golf ball according to claim 1, wherein surface hardness Hs (Shore C hardness) of said spherical core <surface hardness Hms (Shore C hardness) of said intermediate layer>surface hardness Hcs (Shore C hardness) of said golf ball is satisfied. 2. The golf ball according to claim 1, wherein the outermost cover layer contains polyurethane as a resin component.

Images