JPH10127823A - Solid golf ball - Google Patents

Abstract

(57) [Problem] To provide a solid golf ball, particularly a solid golf ball having excellent flight performance, controllability and shot feeling. The present invention relates to a solid golf ball comprising a core and a cover formed on the core, wherein the cover has a thickness of 1.0 to 2.1 mm, a JIS-C hardness of 75 to 95, and the core is It is obtained from a rubber composition containing 30 to 40 parts by weight of a metal salt of an unsaturated carboxylic acid with respect to 100 parts by weight of cis-1,4-polybutadiene rubber, and the difference between the surface hardness of the core and the hardness of the cover is The present invention relates to a solid golf ball having a JIS-C hardness of 10 or less.

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 having excellent flight performance and excellent controllability and shot feeling.

[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, and is composed of a core made 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,
It is covered with a cover of a 2 mm thick ionomer resin or balata. Solid golf balls have a longer flight distance and are superior in flight characteristics due to a higher durability and a higher ball speed at the time of hitting as compared with thread-wound golf balls, and are used by many golfers, especially amateur golfers. On the other hand, solid golf balls have a low hitting feel, a high ball speed at the time of hitting, and a small spin due to a small contact area with the hitting surface of the golf club. There was a problem of lack of controllability. Therefore, solid golf balls
Professional golfers and advanced golfers who value the shot feeling and controllability tend to shy away.

[0003] In order to solve this problem, attempts have been made to improve the controllability and shot feeling by softening the cover of a solid golf ball by using various means. However, when the cover is softened, rebound is reduced, and the launch angle is low when shot with a driver or a long iron, and the spin rate is increased. .

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional solid golf balls, and has excellent flight performance, excellent controllability, and excellent shot feeling. Aim to provide the ball.

[0005]

The present inventors have made intensive studies to achieve the above object, and as a result, softened the cover.
By reducing the rebound by reducing the thickness of the cover, reducing the difference between the surface hardness of the core and the hardness of the cover,
The inventor has found that controllability and shot feeling can be improved without impairing flight performance, and the present invention has been completed.

That is, the present invention relates to a solid golf ball comprising a core and a cover formed on the core, wherein the cover has a thickness of 1.0 to 2.1 mm, a JIS-C hardness of 75 to 95, and Is obtained from a rubber composition containing 30 to 40 parts by weight of a metal salt of an unsaturated carboxylic acid with respect to 100 parts by weight of cis-1,4-polybutadiene rubber, and a difference between the surface hardness of the core and the hardness of the cover. Is a solid golf ball having a JIS-C hardness of 10 or less. Furthermore, in order to more preferably carry out the present invention, the hardness of the core further increases substantially linearly from the center to the surface, and the difference in hardness between the center and the surface is 15 or more in JIS-C hardness. It is desirable that the deformation amount when an initial load of 10 kgf is applied to a final load of 130 kgf is 2.3 to 3.2 mm. The cover has a flexural rigidity of 800 to 1,800 kgf / cm ²
It is desirable that

Hereinafter, the present invention will be described in more detail. In the solid golf ball of the present invention, a cover layer is formed on a core. The core is obtained by heating, pressing and molding a rubber composition containing cis-1,4-polybutadiene rubber as a base rubber, a metal salt of an unsaturated carboxylic acid, a crosslinking agent, an inert filler and the like. Can be

In the present invention, the base rubber is cis-1,4-
Polybutadiene rubber is used. The cis-1,4-polybutadiene rubber has a high cis-1,4-structure having at least 40% or more, preferably at least 80% or more.
1,4-polybutadiene rubber is preferred, and if desired, natural rubber, polyisoprene rubber, styrene polybutadiene rubber, ethylene-propylene-diene rubber (EPDM) and the like may be blended.

Examples of metal salts of unsaturated carboxylic acids acting as co-crosslinking agents include, in particular, zinc, magnesium, etc., of α, β-unsaturated carboxylic acids having 3 to 8 carbon atoms, such as acrylic acid or methacrylic acid. Examples thereof include monovalent or divalent metal salts such as salts, and zinc acrylate which imparts high repulsion is preferable. The compounding amount is cis-1,4-polybutadiene rubber 1
The amount is preferably 30 to 40 parts by weight with respect to 00 parts by weight. If the amount is more than 40 parts by weight, the ball becomes too hard and the shot feeling becomes poor.

[0010] Crosslinking agents include organic peroxides such as dicumyl peroxide or t-butyl peroxide, with dicumyl peroxide being preferred. The amount is based on 100 parts by weight of cis-1,4-polybutadiene rubber.
It is preferably from 0.3 to 5.0 parts by weight. If the amount is less than 0.3 parts by weight, the ball becomes too soft and rebound is deteriorated, resulting in a reduced flight distance.

As the inert filler, zinc oxide, barium sulfate, calcium carbonate and the like may be used alone or in combination. The compounding amount depends on the size or specific gravity of the core or the cover and is not particularly limited, but is usually preferably 5 to 50 parts by weight based on 100 parts by weight of the cis-1,4-polybutadiene rubber. If it is less than 5 parts by weight, the core becomes too light,
If it exceeds 50 parts by weight, it becomes too heavy.

The rubber composition of the core of the present invention may contain an antioxidant, a peptizer and the like other than the above components. Further, the core of the present invention may be a single layer or may be composed of two or more layers.

In the present invention, it is desirable that the hardness of the core increases substantially linearly from the center to the surface, and that the hardness difference between the center and the surface is 15 or more in JIS-C hardness. If it is smaller than 15, the shot feeling will be too hard, and the ball will blow up when shot with a driver or long iron, and the flight distance will be reduced. The surface hardness of the core is JIS-C hardness, preferably 75 to 95, more preferably 80 to 92.

In the present invention, the amount of deformation of the core when the initial load of 10 kgf is applied to the final load of 130 kgf is preferably 2.3 to 3.2 mm. If it is smaller than 2.3 mm, the ball becomes too hard and the shot feeling becomes poor, and if it exceeds 3.2 mm, it is too soft and rebound is poor and the flight distance is reduced.

Next, a cover layer having a hardness such that the hardness difference from the surface hardness of the core is 10 or less in JIS-C hardness is coated on the core. If it is smaller than 10, the hardness difference between the core and the cover is small, so that an appropriate deformation can be obtained when hitting the ball, the shot feeling is improved, and the appropriate launch angle (11.3 to 12.8
°), spin (2,200-2,900 rpm). The cover can be formed of an ionomer resin commonly used as a cover material for a solid golf ball, and a small amount of another resin may be added.

The above-mentioned 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, usually, the amount of the coloring agent is preferably 0.1 to 0.5 part by weight based on 100 parts by weight of the cover resin.

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.

In the present invention, it is desirable that the cover has a thickness of 1.0 to 2.1 mm, preferably 1.2 to 1.9 mm and a JIS-C hardness of 75 to 95, preferably 80 to 92. Cover thickness is 1.0
If it is smaller, the effect of the cover is weakened, and if it exceeds 2.1 mm, the effect of the core does not appear. If the JIS-C hardness is less than 75, the ball is too soft and rebound is poor, and the flight distance is reduced. The cover has a flexural rigidity of 800 to 1,800 kgf / cm ²
It is desirable that If it is less than 800 kgf / cm ² , the ball becomes too soft, resulting in a reduced flight distance and poor shot feeling. 1,80
If it exceeds 0 kgf / cm ² , controllability will be poor and the shot feeling will be too hard.

The golf ball cover of the present invention has a JIS-C hardness of 75 to 95, which is smaller than the conventional ionomer resin cover having a JIS-C hardness of about 100. If the cover is soft, the rebound is reduced, so the cover thickness should be 1.0-2.1mm (conventionally about 2.0-2.3m
By reducing the thickness to m), the reduction in repulsion is suppressed, and the feeling is improved. The difference between the cover hardness and the core surface hardness was conventionally 15 or more (core surface hardness 70 to 85). In the present invention, by increasing the surface hardness of the core, making the cover thinner and softer, and reducing the hardness difference to 10 or less, the feeling becomes better, the initial flight conditions are improved, and high flight performance is achieved.

When the core is covered with the cover, usually, many depressions called dimples are formed on the surface. This dimple is composed of multiple types, the number of dimples is 330 to 450
Preferably, the number is Outside of this range, good trajectory will not be obtained, and the flight distance will not be achieved. 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.

In the present invention, without impairing flight performance,
A golf ball having excellent controllability and shot feeling is provided.

[0022]

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 Core A core having the composition shown in Table 1 was kneaded and then subjected to heat compression molding to prepare a spherical solid core.

The diameter, deformation and hardness of the obtained solid core were measured, and the results are shown in Table 1. The test method was performed as described below.

[0025]

Table 1 Example of core preparation (parts by weight) Type I II III IV V VI BR-18 (Note 1) 100 100 100 100 100 100 Zinc acrylate 34 34 34 34 25 34 Zinc white 18 16 14 16 20 9 Yoshinox 425 (Note 2) 0.5 0.5 0.5 0.5 0.5 0.5 Shikimyl peroxide 1.2 1.2 1.2 1.2 1.2 1.4 156 ° C 156 ° C 156 ° C 140 ° 156 ° C 156 ° C × 20 minutes × 20 minutes × 20 minutes × 40 minutes × 20 minutes × 20 minutes Pressing conditions +++ +++ 170 ° C 170 ° C 170 ° C 170 ° C 170 ° C × 8 minutes × 8 minutes × 8 minutes × 8 minutes × 8 minutes Core diameter (mm) 38.2 39.0 39.6 39.0 39.0 40.2 Core deformation ( mm) 2.4 2.6 2.8 2.2 3.5 2.7 Center 65 65 65 79 65 65 A 5mm from center 75 75 74 79 73 70 Hard 10mm from center 78 79 80 79 76 79 degrees 15mm from center 84 86 85 79 80 86 Surface 88 88 90 70 78 91

Examples 1 to 4 and Comparative Examples 1 to 5 Cover layers The cover compositions having the formulations shown in Table 2 were coated on the cores I to V obtained as described above by injection molding to form cover layers. Then, paint painting was performed to produce a solid golf ball.

[Table 2] Table 2 Example of cover preparation (parts by weight) Type A B C D Himilan 1605 (Note 3) 5 25 50 Himilan 1706 (Note 4) 25 50 Himilan 1555 (Note 5) 5 10 Himilan 1855 (Note 6) 95 85 50 Titanium dioxide 2 2 2 2 Hardness (JIS-C) 83 87 97-(Note 7) (Shore D) (56) (59) (66) (69) Flexural rigidity (kgf / cm ² ) 1000 1300
2500 3500

(Note 1) Hicis-1,4- manufactured by Nippon Synthetic Rubber Co., Ltd.
Polybutadiene (Note 2) Anti-aging agent manufactured by Yoshitomi Pharmaceutical Co., Ltd. (Note 3) Na ion neutralized ethylene / methacrylic acid copolymer ionomer resin manufactured by Mitsui Dupont Polychemical Co., Ltd. (Note 4) Mitsui Dupont Polychemical Zn ion neutralized ethylene / methacrylic acid copolymer-based ionomer resin manufactured by Co., Ltd. (Note 5) Na ion-neutralized ethylene / methacrylic acid copolymer-based ionomer resin manufactured by Mitsui Dupont Polychemicals (Note) 6) Mitsui DuPont Polychemical Co., Ltd. Zn ion neutralized ethylene / methacrylic acid / isobutyl acrylate terpolymer copolymer ionomer resin (Note 7) 100 or more and measurement is not possible Type Hardness Flexural rigidity JIS C * Shore D ** (kgf / cm ² ) *** Himilan 1605 97 67 3,700 Himilan 1706 96 66 3,300 Himilan 1555 91 62 2,500 Himilan 1855 83 56 900 * JIS K 6301 ** ASTM D-2240 *** ASTM D-709A

The golf balls obtained were evaluated for flight performance, controllability, and feel at impact by a driver (Wood No. 1 club). 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. Controllability and hitting feel Controllability is evaluated by using a sand wedge by 10 top professionals, and hitting feeling is evaluated by actually hitting with a driver. The evaluation criteria are as follows. Evaluation criteria 〇: 10 to 8 persons answered that they were good. Δ: 7 to 4 persons answered that they were good. ×: Three or less persons answered that it was good.

(Test results)

TABLE 3 Example Comparative Example 1 2 3 4 1 2 3 4 5 Core formulation II II III VI I IV V II II covers formulations A B B B B B B C D ball diameter (mm) 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 Ball weight (g) 45.4 45.4 45.4 45.4 45.4 45.4 45.4 45.4 45.4 Flight performance W # 1 Launch angle (°) 11.8 12.0 12.3 12.5 11.2 11.0 11.8 12.4 12.5 Spin amount (rpm) 2700 2600 2500 2400 3000 3100 2500 2300 1900 Flight distance (yards) 254 255 256 257 250 251 248 255 255 40 Yart ゛ Controllability 〇 〇 〇 〇 〇 〇 〇 × × Shot feeling 〇 〇 〇 〇 〇 × △ × ×

From the above results, Examples 1-4 of the present invention
Indicates that the golf ball has excellent flight distance with a driver, controllability on a 40-yard shot, and excellent shot feeling.

[0031]

According to the solid golf ball of the present invention, the cover is softened, the reduction in rebound is suppressed by making the cover thinner, and the flying performance and control are improved by reducing the difference between the surface hardness of the core and the hardness of the cover. It has improved properties and shot feeling.

Claims (3)

[Claims] 1. A solid golf ball comprising a core and a cover formed on the core, wherein the cover has a thickness of 1.
0-2.1 mm, JIS-C hardness 75-95, and the core is cis-
It is obtained from a rubber composition containing 30 to 40 parts by weight of a metal salt of an unsaturated carboxylic acid with respect to 100 parts by weight of 1,4-polybutadiene rubber, and the difference between the surface hardness of the core and the hardness of the cover is
A solid golf ball having a JIS-C hardness of 10 or less. 2. The hardness of the core increases linearly substantially from the center to the surface, and the hardness difference between the center and the surface is JIS-C.
Hardness is 15 or more, and the core has an initial load of 10 kgf and a final load of 130
The amount of deformation when a kgf is loaded is 2.3 to 3.2 mm.
A solid golf ball as described. 3. The cover has a flexural rigidity of 800 to 1,800 kg.
The solid golf ball according to claim 1, wherein f / cm ² is f / cm ² .