JPH09308709A - Solid golf ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid golf ball which is composed of a hollow core and a cover layer, which gives in particular a satisfactory feeling upon hitting, having a large moment of inertia, and which has a large angle of ejection upon hitting so as to increase a carry. SOLUTION: In a solid golf ball composed of a hollow core and a cover layer 3, the hollow core is composed of a hollow part 1 having a diameter of 5 to 30mm and an hollow core outer layer part 2 other than the hollow part 1, and the hollow core outer layer part 2 is composed of a vulcanized molding composed of base material rubber, unsaturated carboxylic acid type metal salt, organic peroxide, a rubber composition containing a filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid golf ball composed of a hollow core and a cover layer. More specifically, the golf ball has a good feel at impact, a large moment of inertia, and a large launch angle at impact. The present invention relates to a golf ball having an increased flight distance.

[0002]

2. Description of the Related Art In the prior art, there are mainly two types of golf balls. One is a solid golf ball such as a solid two-piece ball, which is composed of a core formed of an integrally molded rubber member and a thermoplastic resin cover such as an ionomer resin coated on the core. The other is a thread-wound golf ball, in which a solid or liquid core at the center is wound with a rubber thread winding, and then 1 to
It is covered with a cover of 2 mm thick ionomer resin or balata. The two-piece solid golf ball has a long flight distance because of its high durability and high ball speed at the time of hitting, compared with a thread-wound golf ball.
It has excellent flight characteristics and is used by many golfers, especially amateur golfers. On the other hand, the two-piece solid golf ball has a problem that it feels hard when hit.

[0003]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional two-piece solid golf ball as described above, and strikes without deteriorating the excellent flight performance which is a characteristic of the two-piece solid golf ball. An object of the present invention is to provide a solid golf ball having an improved feeling at the time.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a hollow core composed of a hollow portion (1) having a diameter of 5 to 30 mm and a hollow core outer layer portion (2). By using, the feel at the time of hitting becomes good, the moment of inertia becomes large, and therefore the launch angle is large and the spin amount immediately after launch is small, and the spin decay rate from the ball rising to the descent is By making it smaller, it was found that the flight distance could be increased, and the present invention was completed based on this.

When a golf ball is hit with a golf club, spin occurs in the ball, and this spin causes a lift force in a direction normal to the flight curve of the ball. As for the force, a negative force acts on the ball in the traveling direction of the ball, and thus a large ball speed immediately after launch is reduced by the lift force. On the other hand, when the ball descends after passing the highest point of the flight curve, the lift due to the spin acts as a positive force in the traveling direction with the horizontal component, so the lift when the ball descends is It is preferable that the distance is large to increase the flight distance. Therefore, in order to increase the ball flight distance, it is preferable that the spin amount when the ball rises immediately after hitting is small and the spin amount when the ball descends is large. For that purpose, it is more preferable that the moment of inertia of the ball is large.

That is, the present invention comprises a hollow core and a cover layer (3) formed on the core, the hollow core having a diameter of 5 to 3
Hollow part (1) having 0 mm and hollow core outer layer part other than the hollow part
In the solid golf ball consisting of (2), the hollow core outer layer part comprises a vulcanized molded product of a rubber composition containing a base rubber, a metal salt of an unsaturated carboxylic acid, an organic peroxide, and a filler. The present invention relates to a solid golf ball, which is characterized in that it further preferably includes a high specific gravity metal powder in the filler.

Hereinafter, the present invention will be described in more detail. The golf ball of the present invention comprises a hollow portion (1) and a hollow core outer layer portion (2).
Hollow core consisting of and cover layer (3) formed on the core
Consisting of The larger the diameter of this hollow core hollow part,
Although it is possible to obtain a golf ball having a large moment of inertia, the hollow portion has a diameter of 5 to 30 mm because the vulcanized molded article layer of the rubber composition having impact resilience is reduced in the core.
Is preferably within the range. If it is larger than 30 mm, it is necessary to use a large amount of filler for adjusting the specific gravity in the outer layer of the hollow core, and the rebound is too low. If it is smaller than 5 mm, the hollow effect cannot be seen. Moreover, since the diameter of the hollow core is 37 to 39.5 mm, the thickness of the outer layer of the hollow core is 3.5 to 17.25 mm.

The outer layer of the hollow core is obtained by heating, pressing and molding a rubber composition containing a base rubber, a metal salt of an unsaturated carboxylic acid, an organic peroxide, a filler and the like.

As the base rubber, a natural rubber and / or a synthetic rubber which has been conventionally used for a solid golf ball is used, and particularly, it has a cis-1,4-structure of at least 40% or more, preferably 80% or more. So-called high-cis polybutadiene rubber is preferable, and if desired, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, EP
You may mix DM etc.

The metal salts of unsaturated carboxylic acids act as co-crosslinking agents, especially zinc, magnesium salts and the like of α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms such as acrylic acid or methacrylic acid. Although a monovalent or divalent metal salt is mentioned, zinc acrylate which gives high repulsion is suitable. The compounding amount is preferably 25 to 45 parts by weight with respect to 100 parts by weight of the base rubber. If it is more than 45 parts by weight, it will be too hard and the feel will be poor, and if it is less than 25 parts by weight, the repulsion will be poor and the flight distance will be reduced.

The organic peroxide acts as a cross-linking or curing agent and includes, for example, dicumyl peroxide or t-butyl peroxide, with dicumyl peroxide being preferred. The compounding amount is 0.5 to 100 parts by weight of the base rubber.
It is preferably ˜3.0 parts by weight. If it is less than 0.5 part by weight, it will be too soft and the repulsion will be poor and the flight distance will be reduced.
If it exceeds 3.0 parts by weight, it will be too hard and the feeling will be poor.

The filler may be any filler that is usually blended with the core of a golf ball, for example, an inorganic salt (specifically,
Zinc oxide, barium sulfate, calcium carbonate), high specific gravity metal powder (for example, tungsten powder, molybdenum powder, etc.) and mixtures thereof. Since the hollow core used in the present invention tends to be insufficient in weight as compared with a normal solid core, it is preferable to use a mixture of an inorganic salt and a high specific gravity metal powder. The compounding amount is preferably 10 to 110 parts by weight with respect to 100 parts by weight of the base rubber. If it is less than 10 parts by weight, it is difficult to adjust the weight, and if it exceeds 110 parts by weight, the repulsion becomes too low.

The hollow core can be obtained by vulcanizing and molding a rubber composition containing the above components, but it is necessary to devise a hollow core. For example, two semi-vulcanized hemispherical shells may be formed and combined together for post-vulcanization. In this case, the vulcanization conditions for semi-vulcanization are 110-130 ℃ and 10-
The time is 20 minutes, and the post-vulcanization conditions are 140 to 165 ° C. and 10 to 40 minutes.

The hollow core obtained by vulcanization preferably has a JIS C hardness (equal to Shore C hardness) of 50 to 90, more preferably 60 to 85. If it is less than 50, the core becomes too soft and the rebound decreases. On the other hand, when it exceeds 90, it becomes too hard and the feeling is deteriorated.

The specific gravity of the outer layer portion of the hollow core must be slightly higher than the specific gravity of the core of a conventional golf ball.
This is because the hollow portion has a high specific gravity to compensate for the weight of the hollow portion. The specific gravity of conventional golf balls is 1.
Since it is 0 to 1.17, the specific gravity of the hollow core of the present application is 1.1 to 2.0.
It is.

Next, a cover layer is coated on the hollow core. The cover can be formed of an ionomer resin commonly used as a cover material for solid golf balls, and a small amount of another resin may be added.

The cover composition may contain an additive such as titanium dioxide for coloring and other additives such as an ultraviolet absorber, a light stabilizer, a fluorescent material or a fluorescent brightener, and the like. Although it may be contained within a range that does not impair the desired properties of the ball cover, the amount of the coloring agent is usually preferably 0.1 to 0.5 part by weight.

The cover layer of the present invention is formed by a generally known method used for forming a cover of a golf ball, for example, injection molding, press molding or the like. The cover layer thickness is preferably 1 to 3 mm, and when the cover layer is covered,
A large number of dimples called dimples are formed on the surface.
The golf ball of the present invention is usually coated with paint and put on the market in order to enhance aesthetic appearance and commercial value.

The present invention provides a golf ball which has a good feel when hit, a large moment of inertia, a large launch angle when hit, and an increased flight distance.

[0020]

The present invention will be described in more detail with reference to examples.
However, the present invention is not limited to these examples.

Preparation of Hollow Core The rubber composition shown in Table 1 was put on both sides of a semi-breaking mold for core press, and a semi-spherical convex core mold having a hollow center diameter was sandwiched between the molds and preformed at 155 ° C. for 10 minutes. After that, the core mold is removed and vulcanized at 155 ° C for 30 minutes to give a diameter of 39 m.
m hollow cores A to D were obtained.

[0022]

[Table 1] (Parts by weight) Type ABCD EF BR-18 (Note 1) 100 100 100 100 100 100 Zinc acrylate 37 37 37 37 37 37 Zinc oxide 5 5 22.6 5 52 15.2 Tungsten 12.3 14.8-37.9 106.0-Anti-aging agent (Note 2) 0.5 0.5 0.5 0.5 0.5 0.5 Dicumyl peroxide 1 1 1 1 1 1 Hollow center diameter (mm) 5 10 10 20 30 0 Core weight (g) 36.1 36.1 36.1 36.1 36.1 36.1

Examples 1 to 5 and Comparative Example 1 Cover Layer The hollow cores A to D obtained as described above were coated with a cover composition having the composition shown in Table 2 to form a cover layer, and paint coating was performed. Then, a hollow solid golf ball having a diameter of 42.7 mm was produced.

[Table 2] Type Weight part Himilan (Note 3) # 1605 50 Himilan # 1706 50 Titanium dioxide 2

(Note 1) High-cis-1,4-polybutadiene manufactured by Japan Synthetic Rubber Co., Ltd. (Note 2) Manufactured by Yoshitomi Pharmaceutical (Note 3) Ionomer resin manufactured by Mitsui Polychemicals

With respect to each of the obtained golf balls, flight performance by a driver (No. 1 wood club) and feel at the time of hitting were evaluated, and the results are shown in Table 3.
The test method was performed as follows. (Test method) Launch angle, spin amount and flight distance A driver is attached to a swing robot manufactured by True Temper, and a golf ball is hit at a head speed of 45 m / sec.
The launch angle (ballistic height) is measured, the distance to the drop point (carry) is measured as the flight distance, and the shot amount of the golf ball is continuously photographed to determine the spin amount. Feeling at the time of hitting It is evaluated by actually hitting with a driver by a professional golfer.
The evaluation criteria are as follows. Evaluation criteria ◎… very soft and good ○… soft and good ×… hard and bad

(Test results)

[Table 3] Table 3 Examples Comparative Examples 1 2 3 4 5 1 Hollow center diameter (mm) 5 10 10 20 30 0 Blended with core rubber composition A B C D E F Flight performance W # 1 (45 m / sec) Launch angle (°) 11.27 11.45 11.38 11.67 11.80 10.73 Spin amount (rpm) 2880 2770 2800 2660 2500 3050 Flying distance (yard) 229.3 231.5 227.5 229.8 228.4 225.0 Feeling at impact 〇 ◎ ◎ ◎ ◎ × Ball weight (g) 45.3 45.3 45.3 45.3 45.3 45.2

From the above results, in comparison with the solid golf ball of Comparative Example 1, Examples 1 to 5 of the present invention have a good feel at impact, a large launch angle at impact and a large flight distance. Was recognized.

[0028]

EFFECTS OF THE INVENTION The solid golf ball of the present invention uses a hollow core composed of a hollow portion having a diameter of 5 to 30 mm and a hollow core outer layer portion other than the hollow portion to improve the feel on impact. By increasing the moment of inertia, the launch angle at impact is increased, and the flight distance is increased.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a golf ball of the present invention.

[Explanation of symbols]

 1 ... Hollow part 2 ... Hollow core outer layer part 3 ... Cover layer

Claims (2)

[Claims] 1. A hollow core (1) comprising a hollow core and a cover layer (3) formed on the core, the hollow core having a diameter of 5 to 30 mm, and a hollow core outer layer part (2) other than the hollow part. In the solid golf ball consisting of the above), the hollow core outer layer portion is composed of a vulcanized molded product of a rubber composition containing a base rubber, a metal salt of an unsaturated carboxylic acid, an organic peroxide, and a filler. A solid golf ball. 2. The solid golf ball of claim 1, wherein the filler contains a high specific gravity metal powder.