JPH064104B2 - Golf ball - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to golf balls.

In recent years, in Japan, balls having a two-piece structure have become mainstream instead of the conventional wound balls. The two-piece ball has a structure in which a uniformly hardened and uniformly vulcanized rubber inner core having high hardness and high elasticity and an ionomer resin as an outer cover are coated by an injection molding method or a compression molding method.

The performance advantage of this two-piece ball is that the coefficient of restitution is high and the initial velocity of the ball is fast, and that the number of spins generated when hitting the ball with a golf club is smaller than that of a conventional wound ball, so that the ball can be in flight during flight. It is hard to hop and falls sharply, and the rolling after the fall increases, so-called run. From these two points, the two-piece ball can obtain a flight distance that surpasses the wound ball. Further, since spin is hard to be applied, the number of side spins of hook spin and slice spin is naturally reduced. Therefore, it is also an excellent feature of the two-piece ball that the bending of the ball during flight is reduced and the directionality is stable.

On the other hand, a drawback of the two-piece ball is that it is hard to hit the ball and generally has a bad feeling as compared with the conventional wound ball. In particular, it is unpopular with female or senior golfers because it causes discomfort such as hand numbness when taking a miss shot when the driver tops or hits the heel.

The present invention provides a golf ball having a strikingly improved feel when hit, without impairing the advantages of the two-piece golf ball that are excellent in flight distance and directionality.

That is, according to the present invention, a highly elastic vulcanized rubber inner core having a hardness of 65 to 90 (JISC type hardness rubber hardness meter) and an inner core diameter of 33 to 38 mm is wrapped with a thread rubber to a thickness of 1 mm to 2.5 mm, The present invention relates to a golf ball having an outer cover coated thereon.

As the rubber used for the vulcanized rubber inner core of the present invention, a vulcanized rubber having a high hardness and a high elasticity which is conventionally used for solid golf balls, for example, a rubber composition containing cis polybutadiene as a main component is acrylic acid. There are rubbers cross-linked with a metal salt of carboxylic acid such as methacrylic acid, and these are disclosed, for example, in JP-B-55-19615 and JP-B-57-5.
The rubber composition described in Japanese Patent No. 5059 is included. Of course, it is not limited to this.

The vulcanized rubber used in the present invention has a high hardness such as JI.
A hardness of 65 to 90, preferably 70 to 80 and a high elasticity measured by a hardness meter for SC type hard rubber are suitable. If the hardness is less than 65, the feel on impact is poor and the flight is poor. If the hardness exceeds 90, the feel on impact becomes too hard.

Further, the inner core of the golf ball of the present invention has a diameter of 33 mm to 38 mm.
And In this respect, the diameter of the core of a conventional thread-wound golf ball is usually 26 mm to 29 mm, and a relatively soft rubber, for example, the hardness is JIS A in the range of 65 to 95 (measured by a hardness meter for soft rubber). Differently.

In the golf ball of the present invention, a thinner rubber thread layer is provided on the surface of the vulcanized rubber inner core. The thickness of the rubber thread layer is 1 mm to 2.5 mm
And the thread rubber layer of the conventional thread wound golf ball is 5 to 8
It is markedly different from mm.

The rubber thread is wound such that the compression hardness (compression) after winding up is almost the same as or higher than the compression hardness of the rubber inner core.

For the rubber thread, a cis-polyisoprene-based pure rubber vulcanizate is suitable because it is oriented and crystallized during high stretching and has high strength and is hard and easy to wind.

If the thickness of the rubber thread layer is smaller than the above range, the effect of improving the feel is small, and if it is thicker, the spin is too much and the flight distance is reduced. Furthermore, if the rubber thread is not wound tightly, the coefficient of restitution will decrease, and the flight distance will also decrease.

The golf ball of the present invention is completed by further coating the outer cover. The outer shell may be made of a resin used for ordinary two-piece golf balls and thread-wound golf balls, and is typically an ionomer resin. For this purpose, several kinds of ionomer resins may be blended and used, or several parts by weight of a coloring agent such as titanium oxide may be blended. A suitable outer skin thickness is about 1 to 3 mm.

The sectional structure of the golf ball of the present invention is shown in FIG. In the figure
(1) shows the inner core, (2) shows the thread rubber layer, and (3) shows the outer coat.

The golf ball of the present invention has the advantages that the initial velocity is high, the spin is small, the run is large, and the flight distance is long, which are the characteristics of the two-piece golf ball, and that the golf ball has the same excellent feel as a wound ball.

Hereinafter, the present invention will be described with reference to examples.

Examples 1 and 2 Preparation of Vulcanized Rubber Inner Core: A rubber compound having the following formulation was placed in an inner core mold having a predetermined size shown in Table 1 and vulcanized and molded at 160 ° C. for 25 minutes. The size and compression hardness of the inner core are shown in Table-1. In the formulation, the amount of zinc white was adjusted in the range of 50 to 100 parts by weight in order to adjust the weight of the final golf ball within a certain range.

Process parts by weight BR ₀₁ (1) 100 Zinc acrylate 34 Zinc Hua No. 1 50-100 Dicumyl peroxide 1.0 Note (1) Polybutadiene rubber manufactured by Japan Synthetic Rubber Co., Ltd.

Preparation of thread rubber layer: Pure rubber vulcanized thread rubber of cis-polyisoprene rubber was uniformly wound on the surface of the inner core with the thickness and winding hardness shown in Table 1 to obtain a thread winding core.

Golf ball preparation: Ionomer resin (Salene 170) on the surface of the wound core.
7) was coated by compression molding.

All balls have an outer diameter of 41.2 mm and a weight of 45.2 to 4
It was adjusted to be 5.5 g.

Comparative Example 1 A two-piece golf ball in which the inner core of the vulcanized rubber of Example 1 is directly coated with the ionomer resin. The special features are shown in Table 1. Outer diameter and weight are the same as in Example 1.

Comparative Examples 2, 3 and 4 Golf balls prepared in the same manner as in Example 1 except that the diameter of the vulcanized rubber inner core and the thickness of the wound layer in Example 1 were changed. Outer diameter and weight are the same as in Example 1.

Comparative Example 5 A commercially available first-class ionomer cover thread-wound golf ball.

Note 1) The ball is pre-compressed with an initial load of 1.5 pounds,
This is further loaded to give a final weight of 100 pounds, and the amount of ball distortion between 1.5 and 100 pounds is displayed in 0.001 inch-mil unit. Therefore, the smaller the numerical value, the harder the static compression hardness.

Note 2) Set the driver on the swing robot and
Flying distance when hitting a ball at a head speed of m / sec. "Carry" is the distance from the launch point to the fall point, and "Total" is the final reach that is the carry plus the rolling distance after the ball falls.

Note 3) When performing the test of Note 2) with a swing robot, an accelerometer was attached to the rear part of the head of the driver to measure the impact force when hitting the ball. The measured values are values obtained when the head speed is 40 m / sec and 45 m / sec, respectively.

The balls of Examples 1 and 2 were tested by a male professional golfer, a female professional golfer, and an amateur golfer in actual shooting, and they were found to have a favorable hitting feeling and to fly well.

Similar to the two-piece golf ball of Comparative Example 1, the maximum impact force of Examples 1 and 2 was closely related to the feeling, and the value was close to that of the normally wound ball of Comparative Example 5.

Comparative Example 2 is an example in which the rubber thread layer is too thin, and the maximum impact amount does not decrease.

In Comparative Example 3, the flight distance was inferior when the rubber thread layer was slightly thicker.

Comparative Example 4 is an example in which the rubber thread layer is loosely wound, and the coefficient of restitution and the flight distance are reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of the golf ball of the present invention. In the figure, (1) shows the inner core, (2) the thread rubber layer, and (3) the outer skin.

(72) Kaname Yamada, 1-1 1-1 Tsutsui-cho, Chuo-ku, Kobe-shi, Hyogo Sumitomo Rubber Industries, Ltd. (56) Reference JP-A-51-92225 (JP, A) JP-A-SHO 54-135037 (JP, A) JP-A-56-68466 (JP, A)

Claims (3)

[Claims] 1. A rubber thread having a thickness of 1 mm to 2.5 mm is wound around a highly elastic vulcanized rubber inner core having a hardness of 65 to 90 (JISC type hardness rubber hardness meter) and a diameter of 33 to 38 mm, and further. A golf ball with an outer cover. 2. A golf ball according to claim 1, wherein the rubber thread is a cis polyisoprene pure rubber vulcanizate. 3. The golf ball according to claim 1, wherein the outer cover is an ionomer resin.