JPH10137367A - Golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf ball having a satisfactory stopping function on a green without greatly decreasing the carry distance. SOLUTION: In a golf ball having a core 1 and a cover 2 covering the core, the frictional coefficient between the golf ball and an iron face of a golf club is set to a value of 0.22 to 0.44. The ratio of the part of the outer surface of the golf ball, where no dimples are present, to the overall outer surface thereof, is preferably set to 14 to 30%. Further, the cover 2 preferably has a Shore D hardness of 50 to 65, and a thickness of 1.1 to 2.1mm. Further, the core is deformed by 2.5 to 3.1mm when the load applied to the core is changed from its initial value of 10kg to its final value of 130kg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball, and more particularly, to a golf ball having good stopping performance on a green.

[0002]

2. Description of the Related Art The magnitude of the flight distance is a very important characteristic for golf balls, and it is said that it is necessary to suppress the spin rate at the time of hitting in order to increase the flight distance. It has also been confirmed by various experiments.

[0003] Therefore, most golf balls currently on the market are structurally designed to suppress the spin rate. As a result, golf balls and golf clubs (hereinafter, simply referred to as "clubs") are designed. Has a coefficient of friction with the iron face of less than 0.22.

[0004] As a result, the amount of spin in the club aiming at the pin, that is, in the short iron, is reduced, and as a result, the stopping performance on the green is deteriorated, which is a cause of being disliked by professional golfers and advanced players.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a golf ball having a good stopping performance on a green without causing a significant decrease in flight distance. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION The present invention provides a golf ball having a coefficient of friction between the golf ball and the club iron face of 0.2.
By setting the ratio to 2 to 0.44, the above object is achieved.

That is, in the present invention, by setting the friction coefficient to 0.22 or more, the spin performance is improved and the golf ball can easily stop on the green. However, if the coefficient of friction is too large, the amount of spin on a shot by a long club such as a driver (wood No. 1 club) increases, and the flight distance decreases.

Therefore, in the present invention, the friction coefficient is set to 0.1.
In the range of 22 or more and 0.44 or less, a decrease in the flight distance is suppressed, and even in a short iron in which the amount of deformation of the golf ball upon impact is small, the contact area between the golf ball and the iron face of the club is increased. By improving the spin performance, the golf ball can easily stop on the green.

In the present invention, the coefficient of friction between the golf ball and the iron face of the club is determined as follows.

As shown in FIG. 1, a golf ball 11 is fixed on a fixing jig 13 so that the golf ball 11 does not move.
In order to obtain the same amount of deformation as when hit with the club No. 13), a 300 kg load is applied to the golf ball 11 from above the iron face 12 and the golf ball 11 fixed on the fixing jig 13 is fixed to the fixing jig 13. 18mm with fixture 13
/ Horizontal movement at a speed of / sec, and at the time of the movement, a frictional force generated between the golf ball 11 and the iron face 12 is measured, and a ratio of the frictional force to a 300 kg load (frictional force / load) is calculated. A coefficient of friction is determined.

The iron face 12 has a thickness of 2.5 m.
m, the shape of which is as shown in FIG. 2, and a plurality of grooves 12a are formed on the surface thereof at an inter-groove pitch of 3.2.
The cross-sectional shape of the groove 12a is triangular as shown in FIG. 3, and the depth of the groove 12a is 0.35 m.
m, the width of the opening is 0.70 mm. 2 and 3, numerals other than reference numerals 12 and 12a indicate dimensions, and the unit is mm. In addition, the underside of the reference numerals 12 and 12a is underlined to make it easier to distinguish them from the numerals indicating the dimensions.

In the present invention, as described above, the coefficient of friction between the golf ball and the iron face of the club is set to 0.22 to 0.44. The golf ball cannot be easily stopped on the green because the friction force is small, and the golf ball cannot easily stop on the green. When the friction coefficient is larger than 0.44, the spin amount in a long club such as a driver is small. This is because the distance becomes too large and the flight distance decreases.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the ratio of the dimple-free portion of the golf ball surface to the entire golf ball surface (hereinafter referred to as "land ratio") is 14 to 14.
Preferably it is 30%. When the land ratio is smaller than 14%, the contact area between the face surface and the golf ball with a short iron having a small deformation amount of the golf ball at the time of hitting becomes small, the spin performance is not sufficiently improved, and the golf ball is not hit on the green. There is a possibility that good stopping performance may not be obtained, and when the land ratio is more than 30%, a flight distance in a long club such as a driver may be reduced.

In the present invention, as described above, the coefficient of friction between the golf ball and the iron face of the club needs to be 0.22 or more. To achieve this, for example, the cover must be softened. Preferably, the hardness of the cover is set to 65 or less in Shore D hardness, and the thickness of the cover is reduced.
It is suitable that the core has a hardness of 2.1 mm and the core has a hardness of 2.5 to 3.1 mm under a load of 10 to 130 kg.

If the Shore D hardness of the cover is higher than 65, slippage tends to occur between the golf ball and the iron face, and the friction coefficient may not be able to be increased to 0.22 or more. Lower cover hardness is suitable for increasing the coefficient of friction.However, if the cover hardness is too low, the amount of spin in a long club such as a driver will be too large, and the flight distance may be reduced. A Shore D hardness of 50 or more is suitable.
That is, the hardness of the cover is 50 to 65 in Shore D hardness.
Is preferred.

When the thickness of the cover is in the range of 1.1 to 2.1 mm, good spin performance, feeling and durability can be obtained, but when the thickness of the cover is thinner than 1.1 mm, the durability is improved. If the cover is thicker than 2.1 mm, the spin performance may be reduced and the ball may not easily stop on the green.

The amount of deformation of the core under a load of 10 to 130 kg, that is, the amount of deformation from when an initial load of 10 kg is applied to the core to when a final load of 130 kg is applied is 2.5 to 3.
When the diameter is within 1 mm, the core is maintained at an appropriate hardness, which causes good resilience and spin performance. However, when the deformation of the core is smaller than 2.5 mm, the core is too hard. However, if the feel at the time of hitting is deteriorated and the practicality is lost, and if the deformation amount of the core is larger than 3.1 mm, the core becomes too soft, the resilience performance is reduced, and both the flight performance and the spin performance are reduced. It may be worse.

In the golf ball of the present invention, the cover is usually composed mainly of an ionomer resin.
The present invention is not limited thereto, and may be, for example, a balata cover. The core may be either a solid core or a wound core. The solid core is not particularly limited, but a material mainly composed of butadiene rubber is suitable, and the wound core may be either a solid center or a liquid center.

Next, the golf ball of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view schematically showing one example of the golf ball of the present invention. The golf ball shown in FIG. 4 has a core 1 made of a vulcanized molded product of a rubber composition.
And a cover 2 covering the two-piece solid golf ball. The core 1 is not particularly limited to a specific one, but as described above,
It is preferable that the deformation amount under a kg load is 2.5 to 3.1 mm. Although the cover 2 is not particularly limited to a specific one, as described above, the hardness is 5 in Shore D hardness.
It is preferably 0 to 65 and the thickness is 1.1 to 2.1 mm.

Reference numeral 2a denotes dimples provided on the cover 2. The dimples 2a are provided in a suitable number and manner in order to reduce the drag of the golf ball during flight and increase the lift. Although provided on the ball surface, in the present invention, it is preferable that the land ratio, that is, the ratio of the portion 2b of the golf ball surface where the dimples 2a are not provided to the entire golf ball surface be 14 to 30%. , The coefficient of friction between the golf ball and the iron face needs to be 0.22 to 0.44.

In the solid golf ball shown in FIG. 4, the core 1 is made of a vulcanized molded product of a rubber composition having a one-layer structure. Instead of this, for example, a rubber composition mainly composed of butadiene rubber is used. A solid core having a two-layer structure in which an outer core formed of a vulcanized molded body of a rubber composition mainly containing butadiene rubber is further formed around an inner core formed of a vulcanized molded body.

FIG. 5 is a cross-sectional view schematically showing another example of the golf ball of the present invention. In the drawing, reference numeral 1 denotes a core.
Is composed of a center 1a and a thread rubber layer 1b and is called a wound core, 2 is a cover for covering the core 1, 2a is a dimple provided on the cover, and 2b is not provided with a dimple. Part.

The center 1a is a solid type,
Any of a liquid type may be used, and the wound core is not particularly limited, but the wound core has a deformation amount of 2.5 to 3.1 under a load of 10 to 130 kg.
mm, and the cover 2 is not particularly limited, but preferably has a Shore D hardness of 50 to 65 and a thickness of 1.1 to 2.1 mm.

Also, in the golf ball having a multilayer structure having a wound core shown in FIG.
The coefficient of friction between the golf ball and the iron face should be 0.22 to 0.44.

[0025] These golf balls are painted or marked on the surface of the ball as necessary.

In the present invention, as described above, the coefficient of friction between the golf ball and the iron face is 0.22 to 0.22.
0.44, and the land ratio of the golf ball surface is preferably 14 to 30%.
Regarding the friction coefficient and the land ratio, it is preferable that the value of friction coefficient × land ratio (%) ÷ 100 is 0.045 to 0.07. If the value of the coefficient of friction × land ratio (%) ÷ 100 is smaller than 0.045, the golf ball may not easily stop on the green, and the value of the coefficient of friction × land ratio (%) ÷ 100. Is greater than 0.07, the flight distance may be reduced.

[0027]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

Examples 1-4 and Comparative Examples 1-2 The solid core golf balls of Examples 1-4 and Comparative Examples 1-2 were produced through the following steps.

Preparation of solid core: A rubber composition having the composition shown in Table 1 was prepared, filled in a mold, and vulcanized to form a spherical solid core. The vulcanization conditions are as shown in Table 1, and the numbers indicating the vulcanization conditions are displayed in two stages because vulcanization was performed in two stages. Table 1 shows the diameter of the core and 10 to 130 k of the core.
g Deformation amount under load (that is, initial load 10k
g) until the final load of 130 kg is applied. The butadiene rubber used was BR-11 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd., and the antioxidant was Yoshinox 425 (trade name) manufactured by Yoshitomi Pharmaceutical Co., Ltd. Is a part by weight.

[0030]

[Table 1]

Preparation of cover composition: The compounding materials having the compositions shown in Table 2 were mixed by a twin-screw kneading extruder.
A pellet-shaped cover composition was prepared. The amount of each component in Table 2 is parts by weight, and the extrusion conditions were a screw diameter of 4
3 mm, screw L / D = 35 and the formulation was heated to 220-260 ° C. at the extruder die. Table 2 also shows the Shore D hardness of the obtained cover composition. The Shore D hardness is about 2 from each cover composition.
A hot-pressed sheet having a thickness of 25 mm
And stored for 2 weeks, and measured according to ASTM D-2240.

[0032]

[Table 2]

"Himilan" in Table 2 above is a trade name of an ionomer resin manufactured by DuPont-Mitsui Polychemicals Co., Ltd., and the number after "Himilan" indicates the product number. “Surlyn” is a product name of an ionomer resin manufactured by DuPont, and the display after “Surlyn” indicates a product number. "ESBS AT014" is a product name of a block copolymer having a polybutadiene block containing an epoxy group, manufactured by Daicel Chemical Industries, Ltd.

Preparation of Golf Ball: The above-mentioned core composition was injection-molded on the above-mentioned core, the core was covered with a cover, and the surface was painted with paint to obtain an outer diameter of 42.7 m.
m golf balls. At this time, the thickness of the cover was variously changed in accordance with the diameter of the core, and the portion of the ball surface where no dimple was provided was also variously changed so as to obtain a desired land-to-land ratio.

The coefficient of friction of the obtained golf ball with the iron face, the land ratio of the golf ball surface, the spin amount and stopping performance at the 9th iron (iron 9th club), the spin amount at the approach shot by the sand wedge, and The stopping performance and the flight distance with a driver (Wood No. 1 club) were examined. Further, a value of friction coefficient × land ratio (%) か ら 100 was determined from the friction coefficient and the land ratio. The results are shown in Table 3 together with the Shore D hardness of the cover, the thickness, and the amount of deformation of the core. The value of friction coefficient × land ratio (%) ÷ 100 is simply shown in Table 3 as “MR value”. The method of obtaining the coefficient of friction is as described above. The method of determining the land-to-land ratio, the method of measuring the spin amount with a 9-iron, and the method of evaluating the stopping performance, the method of measuring the spin amount in the approach shot, and the method of evaluating the stopping performance The method of measuring the flight distance with a driver is as follows.

Land ratio: Assuming that the golf ball is a true sphere, the total area of the dimple portion is obtained, and it is subtracted from the spherical surface area to obtain the area of the dimple-free portion, and the ratio of the dimple-free area to the spherical surface area is calculated. To determine land-to-land ratio.

Spin amount at No. 9 iron: A No. 9 iron is attached to a swing robot manufactured by True Temper , and the spin amount when the ball is hit at a head speed of 34.5 m / sec is measured with a CCD camera and a micro flash. .

Stop performance with 9th iron: 1 composed of a professional golfer and a top amateur golfer
Zero golfers shot a golf ball full with a ninth iron and evaluated the stopping performance when the golf ball was dropped on a green.

：: 6 or more out of 10 people stopped and evaluated that the performance was good. X: Five or less out of ten people evaluated that the stopping performance was good.

Spin amount on approach shot: A sand wedge is attached to a swing robot manufactured by True Temper , and the spin amount when a golf ball is hit at a head speed of 20 m / sec is measured by a CCD camera and a microflash.

Stopping performance on approach shot: A golf ball is hit with a sand wedge from a position approximately 40 yards away from the green, and the easiness of the ball stopping on the green is evaluated.

：: 6 or more out of 10 people stopped and evaluated that the performance was good. X: Five or less out of ten people evaluated that the stopping performance was good.

Flying distance: A driver (Wood No. 1 club) was attached to a swing robot made by True Temper, Inc.
Hitting a golf ball at a head speed of 45 m / s,
Measure the distance to the stop point.

[0044]

[Table 3]

As is clear from the results shown in Table 3, Examples 1 to 4 in which the coefficient of friction is in the range of 0.22 to 0.44
Had good stopping performance on the green and a long flight distance.

On the other hand, in Comparative Example 1 having a small friction coefficient of 0.201, the flight distance was long, but the stopping performance on the green was poor, and in Comparative Example 2 having a large friction coefficient of 0.450, The stopping performance on the green was good, but the flight distance was short.

Example 5 and Comparative Example 3 The thread-wound core golf balls of Example 5 and Comparative Example 3 were produced through the following steps (1) to (3).

Preparation of Wound Core: First, a center used for the wound core golf ball of Example 5 was prepared as described below.

A rubber composition for a center cover comprising 100 parts by weight of natural rubber, 5 parts by weight of zinc oxide, 56 parts by weight of calcium carbonate, 2 parts by weight of sulfur and 2 parts by weight of a vulcanization accelerator (CZ) was prepared.

Also, a paste consisting of 88 parts by weight of water, 12 parts by weight of glycerin, 20 parts by weight of clay and 114 parts by weight of barium sulfate was prepared and poured into a mold cooled with a refrigerant to produce a spherical core. Molding the rubber composition for a center cover into a sheet, covering the frozen spherical core with the sheet, and placing it in a mold at 150 ° C.
For 30 minutes to produce a liquid center having a diameter of 28.1 mm.

On the other hand, a center used for the thread-wound core golf ball of Comparative Example 3 was produced as follows.

Butadiene rubber [BR manufactured by Nippon Synthetic Rubber Co., Ltd.]
-11 (trade name)] 100 parts by weight, zinc acrylate 15
Parts by weight, 15 parts by weight of zinc oxide, 41 parts by weight of barium sulfate, 1.5 parts by weight of dicumyl peroxide and an antioxidant [Yoshinox 425 (trade name) manufactured by Yoshitomi Pharmaceutical Co., Ltd.]
A rubber composition consisting of:
By vulcanizing at 65 ° for 20 minutes, a solid center having a diameter of 34.0 mm was produced.

In each of the obtained centers, the base rubber was natural rubber / low cis-isoprene rubber [Shell IR-309].
(Trade name), manufactured by Shell Chemical Co.] = 30/70 (weight ratio)
Was wound in a stretched state to form a thread rubber layer, thereby producing a thread-wound core having a diameter of 40 mm. Deformation amount of the obtained wound core under a load of 10 to 130 kg (that is, an initial load of 10 kg
Was measured from when the final load was applied to when the final load of 130 kg was applied. As a result, the deformation amount of the wound core used in the wound core golf ball of Example 5 was 2.7 mm, and the deformation amount of Comparative Example 3 was 2.7 mm. The amount of deformation of the wound core used for the wound core golf ball was 2.4 mm.

Cover composition: The cover of Example 5 was prepared by adding molybdenum disulfide to a conventionally used balata-based cover composition and using the base polymer trans-1,4-
A cover blended at 2 parts by weight with respect to 100 parts by weight of polyisoprene was used, and a cover similar to a conventionally used balata-based cover was used for the cover of Comparative Example 3. Table 4 shows the compositions of the cover compositions of Example 5 and Comparative Example 3. In addition, the compounding quantity of each component in Table 4 is a weight part.

[0055]

[Table 4]

Production of golf ball: A half shell having a hemispherical shell shape was formed from the above composition for a cover,
The above-mentioned wound core is wrapped using a plurality of pieces, a ball is formed and vulcanized, and a paint is applied to the surface thereof, and the outer diameter is 42.7 m.
m golf balls.

For the obtained golf ball, the friction coefficient, land ratio, MR value (ie, friction coefficient × land ratio (%) ÷ 100), the spin amount at the 9-iron, We measured and evaluated the stopping performance, the amount of spin on approach shots with a sand wedge, the stopping performance, and the flight distance with a driver. The results are shown in Table 5 together with the Shore D hardness of the cover, the thickness, the amount of deformation of the core, and the like.

[0058]

[Table 5]

As is clear from the results shown in Table 5, Example 5 in which the coefficient of friction was in the range of 0.22 to 0.44 was
The stopping performance on the green was good, and the flight distance was long.

On the other hand, Comparative Example 3 had a large friction coefficient and good stopping performance on the green due to the use of the balata cover, but had a short flight distance.

[0061]

As described above, according to the present invention, it is possible to provide a golf ball having a good stopping performance on the green without causing a great decrease in the flight distance.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an example of an apparatus for measuring a friction coefficient in the present invention.

FIG. 2 is a view showing a surface of an iron face of a club used for measuring a coefficient of friction in the present invention.

FIG. 3 is an enlarged sectional view showing only a groove on the surface of the iron face shown in FIG. 2;

FIG. 4 is a cross-sectional view schematically showing one example of the golf ball of the present invention.

FIG. 5 is a cross-sectional view schematically showing another example of the golf ball of the present invention.

[Explanation of symbols]

 1 core 2 cover 2a dimple 2b part without dimple

Claims (3)

[Claims] 1. A golf ball having a core and a cover covering the core, wherein a coefficient of friction between the golf ball and an iron face of the golf club is 0.22 to 0.4.
4. A golf ball, wherein 2. A ratio of a dimple-free portion on the golf ball surface to the entire golf ball surface is 14 to 30.
2. The golf ball according to claim 1, wherein the cover has a Shore D hardness of 50 to 65, and the cover has a thickness of 1.1 to 2.1 mm. 3. The golf ball according to claim 1, wherein an amount of deformation of the core from when an initial load of 10 kg is applied to the core to when a final load is applied is 130 kg is 2.5 to 3.1 mm. .