JPH0357789B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a golf ball with a reduced flight distance. With the golf boom, the number of golf practice ranges has increased significantly, but each practice range has a different size, so if you use a conventional golf ball, there is a risk that the golf ball you hit will fly out of the range in a narrow practice range. There is also the problem that if the ball hits the net mid-flight, it is difficult to determine the trajectory of the ball. However, most of the research to date on golf balls has aimed to increase flight distance, and very few studies have attempted to adjust the flight distance of the ball to match the size of the driving range. The only possible example is a rubber blend in which the rubber is blended with polybutadiene rubber. However, when using such a rubber blend, the workability during blending is extremely poor, and in other aspects of workability, the workability is also poorer than when manufacturing one-piece balls that are generally used in driving range golf balls. Moreover, there is a problem in that the durability of the resulting ball is inferior to that of conventionally used balls. In view of such circumstances, the present inventor has conducted various studies and found that when a magnesium salt of acrylic acid or methacrylic acid is co-existed in a system using a zinc salt of acrylic acid or methacrylic acid as a co-crosslinking agent, Magnesium salt of acrylic acid or methacrylic acid acts as a co-crosslinking agent with the above zinc salt of acrylic acid or methacrylic acid, while maintaining good hitter, good feeling based on the above zinc salt, magnesium salt of acrylic acid or methacrylic acid It has been discovered that the rebound elasticity of the ball can be reduced in accordance with the amount of . That is, the present invention provides for the production of golf balls by adding 15 parts of acrylic acid or methacrylic acid to 100 parts (by weight, same hereinafter) of polybutadiene rubber.
~35 parts, zinc oxide 30-50 parts, magnesium oxide 3
It is characterized in that a rubber composition containing ~25 parts and 1 to 5 parts of a peroxide such as dicumyl peroxide or benzoyl peroxide is heated and molded under pressure. As mentioned above, in rubber compositions in which acrylic acid or methacrylic acid, zinc oxide, magnesium oxide, etc. are blended with polybutadiene rubber, acrylic acid or methacrylic acid and zinc oxide react during mixing when preparing the rubber composition. Acrylic acid or methacrylic acid reacts with magnesium oxide to form a magnesium salt of acrylic acid or a magnesium salt of methacrylic acid. Each acts as a co-crosslinking agent as described above. As mentioned above, when the flying distance is reduced by using the magnesium salt of acrylic acid or the magnesium salt of methacrylic acid, the durability does not decrease as in the case of using a rubber blend. The present invention is mainly applied to the production of one-piece golf balls, but can also be applied to the production of multilayer golf balls such as two-piece golf balls and three-piece golf balls. And for one-piece golf ball, add 0.1 anti-aging agent to improve its aging resistance.
About 5 parts may be added. Furthermore, when the present invention is applied to the production of multilayer golf balls such as two-piece golf balls and three-piece golf balls, a core may be produced using the features of the present invention and a cover may be placed over the core. In the present invention, the blending amount of magnesium oxide is in the range of 3 to 25 parts per 100 parts of polybutadiene rubber.If the blending amount of magnesium oxide is less than the above range, the effect of reducing flight distance is insufficient. Moreover, if the amount of magnesium oxide added exceeds the above range, the impact sound and feeling will deteriorate, making it undesirable as a golf ball. By increasing the amount of magnesium oxide within the range of 3 to 25 parts, it is possible to further reduce the rebound while maintaining good impact sound and feel, making it possible to reduce the size of the golf driving range. It is possible to reduce the flight distance of the golf ball in accordance with the situation, and take measures tailored to the actual situation at each golf driving range. In the present invention, zinc oxide reacts with acrylic acid or methacrylic acid during the preparation of the rubber composition to become a zinc salt of acrylic acid or a zinc salt of methacrylic acid, which is the source of rebound elasticity and is a good hitter and a good hitter. It creates a feeling. The upper limit of the amount of zinc oxide blended is slightly lower than the conventional case in consideration of the inclusion of magnesium oxide, but other than that,
This is almost the same as in the conventional case, and if the amount of zinc oxide added is less than the above range, the rebound resilience of the ball will be greatly reduced, the hardness of the ball will be too low, and the weight of the ball will be too light to meet the standard weight. If the amount of zinc oxide added exceeds the above range, there will be no major change in the ball's rebound properties, but the weight of the ball will become too heavy, making it unsuitable for use. If the amount of zinc oxide is large, a portion of the zinc oxide may remain unreacted. Also, if magnesium oxide is included in a large amount,
A portion may remain unreacted. Acrylic acid or methacrylic acid is reacted with zinc oxide or magnesium oxide to produce their zinc salts or magnesium salts, which play the roles described above. If the blending amount is less than the above range, it will not be possible to generate the required amount of zinc salt or magnesium salt, and therefore,
The desired golf ball cannot be obtained. Furthermore, if the amount of acrylic acid or methacrylic acid added exceeds the above range, crosslinking will become too intense and the polybutadiene rubber will deteriorate, making it impossible to obtain the desired golf ball. Peroxide acts as a crosslinking agent, bonds rubber molecules, and also initiates a bonding reaction between rubber molecules caused by zinc or magnesium salts of acrylic acid or methacrylic acid. If the amount of peroxide is less than the above range, sufficient crosslinking will not occur, and if the amount of peroxide is more than the above range, crosslinking will become too intense, causing deterioration of the polybutadiene rubber. The composition is prepared, for example, by adding and mixing an antioxidant, zinc oxide, magnesium oxide, acrylic acid or methacrylic acid to polybutadiene rubber, and adding and mixing peroxide immediately before use. Preparation of the composition is easy and does not involve the difficulties associated with rubber blends. In addition, with the above configuration, flight distance can be easily adjusted by changing the amount of magnesium oxide added, making it extremely easy to respond to the various demands of each golf driving range. can. Next, the present invention will be explained with reference to Examples. Examples 1 to 4 and Comparative Examples 1 to 2 Rubber compositions having the compositions shown in Table 1 were prepared, and 100
Heat compression molded at 170℃ for 18 minutes under pressure of kg/ ^cm2 ,
A one-piece golf ball with a diameter of 41.5 mm was manufactured. In addition, the numerical values in Table 1 are blended parts by weight parts. Table 2 shows the results of examining the weight, ball hardness, rebound index, durability index, and flight distance (carry) of the golf balls obtained.

【table】

[Table] (Note) Ball hardness: Ball hardness display according to the USGA (United States Golf Association) system Repulsion index: Repulsion was measured using a compressed air resilience gun at a projectile speed of 45 m/sec. 100 balls of comparative example 1
It was displayed as Durability index: 45 using a compressed air hammering tester
A ball was fired at a speed of m/sec, and the number of times until the ball cracked was determined, and the number of times the ball was fired in Comparative Example 1 was set as 100. Carry: True Temper Swing Robot with 43 inch driver installed and head speed 45.1
Measurements were made by striking at ±0.2 m/sec. As shown in Tables 1 and 2, the addition of magnesium oxide reduces the rebound resilience of the ball,
Flight distance becomes smaller. However, the ball hardness and durability were almost unchanged and comparable to conventional balls. It should be noted that the ball of Comparative Example 2, which was blended with butyl rubber, had a shorter flight distance, but had a corresponding decrease in durability. Further, the preparation of the compositions of Examples 1 to 4 was as easy as in Comparative Example 1, which is a conventional example, but the composition of Comparative Example 2 required time and labor for rubber blending. The preparation was very time consuming.

Claims (1)

[Claims] 1. In manufacturing golf balls, 15 to 35 parts by weight of acrylic acid or methacrylic acid, 30 to 50 parts by weight of zinc oxide, per 100 parts by weight of polybutadiene rubber,
3 to 25 parts by weight of magnesium oxide and 1 part peroxide
A method for manufacturing a golf ball, which comprises heating and molding a rubber composition containing ~5 parts by weight under pressure.