JPH054110B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a solid golf ball that has a core ball made of a polymer compound material and a resin cover that covers the core ball. This invention relates to a solid golf ball that allows the ball to easily stop on the green and has high rebound resilience. Solid golf balls, such as two-piece golf balls, have been known in the past, which are made by kneading and heat-molding polybutadiene rubber, methacrylic acid, zinc oxide, peroxide, etc. and covering a core ball with a cover such as ionomer resin. . Solid golf balls, such as two-piece golf balls,
It has less spin than a threaded ball,
Also, because the falling angle is small, the ball rolls (runs) more than a threaded ball, so it has excellent characteristics in shots aimed at distance, such as driver shots, but on the other hand, it has excellent characteristics in shots aimed at distance, such as driver shots. In a shot where the aim is to drop the ball directly onto the green and bring it to the pin, the run after hitting the green is larger than that with a threaded ball, making it difficult to calculate the run. It has the disadvantage that it is difficult to bring the ball close to the pin. This is because solid golf balls such as two-piece balls use a cover material with a higher modulus of elasticity than the cover material of regular wound-up balls, resulting in high rebound resiliency. Since the contact area of the ball is small and the friction is small, the ball spins less and is therefore thought to have a harder time stopping on the green than a winding ball. In view of the above circumstances, the inventors of the present invention have conducted intensive studies to obtain a solid golf ball that has good spin, little rolling after falling onto the green, and high rebound resilience. When manufacturing a solid golf ball by covering a core ball made of a polymer compound material such as polybutadiene rubber with a cover made of a thermoplastic resin whose main component is an ionomer resin, the above-mentioned cover is used.
Flexural modulus according to ASTM D-790 is 30~
With outer layer of 0.05~0.4mm thickness at 280MPA, ASTM
D-790 has a multilayer structure with a bending modulus of 300 to 600 MPa and an inner layer with a thickness of 1 to 4 mm, which increases the friction between the ball and the club face and improves spin application. It was discovered that the spin can be controlled appropriately, and the high elasticity of the ball can be maintained due to the high elastic modulus resin in the inner layer, and that the above objectives can be effectively achieved. This led to the invention. According to the studies of the present inventors, by forming the cover into a multilayer structure having an outer layer and an inner layer, and setting the elastic modulus and thickness of the outer layer and inner layer to the above ranges, it is possible to obtain good spin and high A solid golf ball with rebound resilience can be obtained. On the other hand, if the elastic modulus and thickness of the inner and outer layers of the cover are outside the above range, the spin resistance will be poor and the impact resilience will decrease, making it difficult to achieve both good spin characteristics and excellent impact resilience. It is not possible to obtain a solid golf ball, and in particular, if the thickness of the outer layer is made thinner than the above range, the spin will be poor, and if the thickness of the outer layer is made thicker than the above range, the rebound resilience will be reduced. However, when the present inventors formed a cover having inner and outer layers as described above,
It has been discovered that a solid golf ball having such excellent properties can be obtained. Hereinafter, the present invention will be explained in more detail with reference to the drawings. As an example of the solid golf ball according to the present invention is shown in FIG. In the golf ball, the cover 2 is formed into a multilayer structure having an outer layer 3 and an inner layer 4 having a predetermined elastic modulus and thickness. In this case, there is no particular restriction on the composition of the polymer compound material forming the core material, but polybutadiene rubber is cross-linked and cured with an unsaturated carboxylic acid or its metal salt, polybutadiene rubber is cross-linked and cured with an unsaturated carboxylic acid ester, etc. Polybutadiene rubber, which is obtained by crosslinking and curing polybutadiene rubber using a combination of an unsaturated carboxylic acid or a metal salt thereof and an unsaturated carboxylic acid ester, can be suitably used. Further, in the above composition, other components such as zinc oxide, organic peroxide, filler, etc. may be blended in appropriate proportions. In addition, the core ball is
For small size, the diameter is usually 36.4-37.4mm,
The weight is 35.4 to 36.2 g, and in the case of large size, the diameter is usually 37.4 to 38.4 mm and the weight is 33.4 to 34.2 g. In the present invention, the core ball is covered with a multilayered cover having an outer layer made of a resin with a low modulus of elasticity and an inner layer made of a resin with a high modulus of elasticity. In this case, the outer layer of the cover is ASTM D-790
The flexural modulus is 30~280MPA,
In particular, it is preferable to use a resin having a pressure in the range of 70 to 200 MPa. The thickness of the outer layer is 0.05~
It is necessary to set it to 0.40mm, but especially 0.1 to 0.3
It is preferable to set it to mm. Further, the inner layer of the cover is preferably formed of a resin having a bending elastic modulus of 300 to 600 MPA according to ASTM D-790, preferably in the range of 300 to 500 MPA. In addition, the thickness of the inner layer is 1 to 4
It is necessary to set it to mm, but it is particularly preferable to set it to 1.4 to 2.6 mm. In the present invention, the composition of the resin forming the cover is mainly composed of ionomer resin, and resins having different elastic modulus are appropriately selected from among those mainly composed of ionomer resins to form the outer layer and the inner layer, respectively. It is preferable. For example, a blend of a soft ionomer resin and a polyester elastomer or a blend of a soft ionomer resin and ethylene-vinyl acetate copolymer (EVA) can be suitably used as the resin for the outer layer, and a hard ionomer can be used as the resin for the inner layer. A blend product of a resin and a hard (high impact resilience) polymer can be preferably used. The ionomer resin is a polymer of monoolefin and one or more selected from the group consisting of unsaturated mono- or dicarboxylic acids having 3 to 8 carbon atoms and esters thereof, to which a cross-metallic bond is added. are preferably used. The thickness of the entire cover is usually around 2mm for small size and 2.5mm for large size.
The weight of the entire cover is usually about 9.0g for a small size, and about 11.2g for a large size. In the present invention, the core ball can be formed by a conventional method. Furthermore, the method of covering the core ball with the cover is not particularly limited; for example, a method of wrapping the core ball with a pair of multi-layered covers formed in advance into a hemispherical shell shape and heat-forming them to integrate the core ball, or Alternatively, a method may be adopted in which the inner layer cover material and the outer layer cover material are sequentially injection molded and integrated. As mentioned above, the solid golf ball of the present invention includes a core ball formed of a polymer compound material,
In a solid golf ball, the core ball is covered with a cover made of a thermoplastic resin mainly composed of ionomer resin, and the cover has a bending elastic modulus of 30 to 280 MPA and a thickness of 0.05 to 0.4 mm, and a bending elastic modulus of 0.05 to 0.4 mm. By forming the ball into a multi-layer structure with a rate of 300-600MPA and an inner layer 1-4mm thick, it provides good spin and less rolling, making it easier for the ball to stop on the green, etc., and has high rebound resilience. be. Next, examples and comparative examples will be shown to specifically explain the present invention. [Examples, Comparative Examples] 100 parts by weight of polybutadiene rubber, methacrylic acid
18 parts by weight of zinc oxide, 47.5 parts by weight of zinc oxide, and 6.0 parts by weight of dicumyl peroxide were kneaded using a kneading roll, and the mixture was press-molded at 150° C. for 40 minutes to produce a core sphere with a diameter of 37.2 mm. Next, a hemispherical shell-like cover with a thickness of 2 mm as shown in Table 1 was molded, and the core sphere was wrapped in a pair of hemispherical shell-like covers and pressure-molded at about 170°C for 2 minutes to form a 41.2 mm diameter Solid golf balls (small size) of Examples 1, 2, and 3 and Comparative Examples 1 and 2 were prepared, and their surfaces were coated. In Table 1, Surlyn 1855 (flexural modulus of elasticity 90 MPA according to ASTM D-790) was used as the outer layer resin, and a 50:50 (weight ratio) mixture of Surlyn 1706 and Surlyn 1707 (ASTM Flexural modulus according to D-790
325MPA) was used.

[Table] Next, the weight hardness of the golf balls of Examples 1, 2, and 3 and Comparative Examples 1 and 2 was examined, and each ball was tested using a golf ball hitting tester with a No. 1 wood club and a No. 9 iron club. Approximately 43m/sec
The ball was hit at a head speed of 1, and the initial velocity of the ball when hitting the No. 1 wood, the amount of spin when hitting the No. 9 iron, and the carry distance and run distance when hitting the No. 1 wood and the No. 9 iron were examined. In this case, the amount of spin was measured by taking a high-speed flash photograph of a ball hit with a batting tester. The results are shown in Table 2.

【table】

[Table] Figure 2 shows the relationship between the thickness of the outer cover layer and the amount of spin when hitting a 9-iron (indicated by a in Figure 2), and the relationship between the thickness of the outer cover layer and the run distance when hitting a 9-iron. The relationships (indicated by b in FIG. 2) are shown respectively. From the results shown in Table 2 and Figure 2, the golf balls of Examples 1, 2, and 3, in which the cover was formed within the range of the present invention, had a large amount of spin when hit with a 9-iron, a short run distance, and had high rebound resilience. is high,
It was found that the golf ball of the present invention had excellent flight performance and was easy to stop. On the other hand, the golf ball of Comparative Example 1 in which the cover was formed only from a resin with a high modulus of elasticity had a small spin rate, and therefore had a long run distance and was difficult to stop. The thickness of 0.7
The golf ball of Comparative Example 2 was formed to mm. The rebound resilience was low, and the flight distance when hitting the ball was poor.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the solid golf ball of the present invention, and FIG.
It is a graph showing the relationship between the amount of spin when hitting a No. 9 iron and the run distance when hitting a No. 9 iron. 1...Core ball, 2...Cover, 3...Outer layer, 4...
...inner layer.

Claims (1)

[Claims] 1. In a solid golf ball that includes a core ball made of a polymer compound material and a cover made of a thermoplastic resin whose main component is an ionomer resin, the cover has a bending modulus of elasticity.
A solid golf ball characterized by being formed into a multilayer structure having an outer layer having a thickness of 0.05 to 0.4 mm and having a bending modulus of elasticity of 300 to 600 MPA and an inner layer having a thickness of 1 to 4 mm.