JP2669051B2 - Solid golf ball - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid golf ball having excellent flight performance.

2. Description of the Related Art Solid golf balls include a completely integrated one-piece golf ball, a two-piece golf ball in which a core ball is covered with a cover, and one layer between the core ball and the cover layer. Alternatively, there is a multi-layer golf ball having two or more intermediate layers.

These solid golf balls have an elastic part obtained by vulcanizing and molding a rubber composition in a part (core ball of a multi-layer structure ball) or all (one-piece golf ball). Conventionally, in a rubber composition for forming such an elastic portion, in order to improve the repulsion coefficient and impact resistance of the ball together with a base rubber such as polybutadiene rubber,
It is known that a monomer having an unsaturated bond such as a metal salt of an α, β-ethylenically unsaturated carboxylic acid is blended as a co-crosslinking agent. This co-crosslinking agent is grafted or cross-linked to, for example, a polybutadiene rubber main chain by the action of a co-crosslinking initiator such as a peroxide to form a three-dimensional cross-linked polymer of polybutadiene and the monomer. The one that imparts appropriate hardness and durability to the core ball of the ball, and the one-piece golf ball formed of the rubber composition containing such a co-crosslinking agent or the multilayer solid golf ball in which the core ball is covered with a cover is It is known to exhibit good flight performance and durability.

However, golf players have very strong demands on the flight performance of golf balls, and thus further improvement in flight performance is desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid golf ball with further improved flight performance.

Means and Action for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, a rubber obtained by blending a metal salt of an unsaturated carboxylic acid as a co-crosslinking agent with a base rubber such as polybutadiene rubber. By adding an organic sulfur compound selected from thiophenols, thiocarboxylic acids and metal salts thereof to the composition, the rebound resilience of a rubber elastic body obtained by vulcanizing the compound is improved. By forming a core ball of a one-piece golf ball or a multilayer solid golf ball using a rubber composition, the initial velocity at the time of hitting the ball is improved, and it is found that a solid golf ball having excellent flight performance can be obtained. The present invention has been completed.

Accordingly, the present invention provides a core ball of a one-piece golf ball or a multi-layer golf ball coated with a cover material directly or via an intermediate layer, comprising a base rubber, a metal salt of an unsaturated carboxylic acid, a thiophenol, A solid golf ball formed of a rubber composition containing an organic sulfur compound selected from acids and metal salts thereof.

 Hereinafter, the present invention will be described in more detail.

The solid golf ball of the present invention, as described above,
A core ball of a one-piece golf ball or a solid golf ball having a multilayer structure is formed of a rubber composition containing a base rubber, a metal salt of an unsaturated carboxylic acid, and an organic sulfur compound selected from thiophenols, thiocarboxylic acids and their metal salts. It was formed.

Here, as the base rubber, those used as a core ball material of an ordinary one-piece golf ball or a multi-layer solid golf ball can be used, and are not particularly limited, but have a cis structure of at least 40% or more. ,Four
-Polybutadiene rubber is particularly preferably used in view of high rebound resilience, extrudability, high strength of vulcanized product, and the like. In this case, natural rubber, polyisoprene rubber, styrene-butadiene rubber, or the like can be appropriately compounded with such 1,4-polybutadiene rubber as required. In addition, 1,4-
The polybutadiene rubber is preferably contained in the base rubber component in an amount of 80% by weight or more. If the amount is less than 80% by weight, the excellent rebound resilience of the polybutadiene rubber may be impaired.

The metal salt of the unsaturated carboxylic acid is blended as a co-crosslinking agent. Specific examples thereof include unsaturated fatty acids having 3 to 8 carbon atoms such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Examples thereof include zinc salts and magnesium salts, and particularly, zinc salts of acrylic acid or methacrylic acid are preferably used. These unsaturated carboxylic acid metal salts may be prepared in advance in the form of a metal salt. However, in the rubber composition, an α, β-unsaturated carboxylic acid and a metal oxide or a metal hydroxide may be used. Can be reacted to form a metal salt. The amount of the unsaturated carboxylic acid metal salt is not particularly limited, but is preferably 25 to 40 parts by weight based on 100 parts by weight of the base rubber.

The rubber composition used in the production of the solid golf ball of the present invention comprises an organic sulfur compound selected from thiophenols, thiocarboxylic acids and metal salts thereof in addition to the base rubber and the co-crosslinking agent. Here, thiophenols and thiocarboxylic acids include pentachlorothiophenol, 4-t-butyl-o-thiophenol, 4-t-butylthiophenol, 2-benzamidothiophenol, and other thiophenols, and thiobenzoic acid. And the like. As the thiophenols or metal salts of thiocarboxylic acids, the above-mentioned thiophenols and zinc salts of thiocarboxylic acids are preferably used. These may be used alone or in combination of two or more. The amount of these compounds is 0.05 to 2 parts by weight per 100 parts by weight of the base rubber.
It is preferable that the amount be 0.1 parts by weight, especially 0.1 to 0.5 parts by weight.

A co-crosslinking initiator can be added to the rubber composition. In this case, the co-crosslinking initiator may be a peroxide-based initiator such as dicumyl peroxide, t-butylperoxybenzoate, di-t-butyl peroxide, 1,1-bis (t-butylperoxy). Organic peroxides such as 3,3,5-trimethylcyclohexane are preferably used, and dicumyl peroxide is particularly preferably used. The compounding amount of this co-crosslinking initiator is 100
It is preferably 0.5 to 3 parts by weight, particularly preferably 1 to 2.5 parts by weight based on parts by weight. Further, in the rubber composition, zinc oxide, a plasticizer, an antioxidant, and other components which can be generally used for manufacturing core balls of one-piece golf balls and multilayer solid golf balls may be appropriately compounded as necessary. it can.

The solid golf ball of the present invention is one in which the rubber composition is vulcanized by heating or the like and molded to produce a core ball of a one-piece golf ball or a multi-layer soled golf ball. Methods, conditions and the like can be ordinary methods and conditions.

When a multi-layer solid golf ball such as a two-piece ball is used, a core ball formed of the rubber composition is covered with a cover. In this case, the cover material may be a normal material such as ionomer, Surlyn, polyester, and nylon. A cover material can be suitably used.

Effects of the Invention The solid golf ball of the present invention can achieve further improvement in flying performance by adopting the above-described configuration.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Prior to the Examples and Comparative Examples, an experimental example is shown in which a solid core (core ball) for a two-piece golf ball constituting the solid golf ball of the present invention is manufactured and its performance is compared with that of a conventional two-piece golf ball core.

(Experimental example)

Six types of rubber compositions were prepared by mixing the components shown in Table 1. This was vulcanized at 155 ° C. for 20 minutes using a mold to produce a solid core for a two-piece golf ball having a diameter of 38.0 mm. Next, according to the USGA method, the initial velocity when hitting at a head speed of 38 m / sec was measured using a flywheel hitting tester. The results are shown in Table 1.

From the results shown in Table 1, it was confirmed that the core performance (initial impact speed) was improved by adding a zinc salt of pentachlorothiophenol, which is a metal salt of an organic sulfur compound, to the rubber composition. .

[Examples and comparative examples]

Two types of rubber compositions were prepared by mixing the components shown in Table 2 and then vulcanized at 155 ° C. for 20 minutes using a mold to obtain two types of solid cores for 38 mm diameter two-piece golf balls. Manufactured. Next, these cores were coated with an ionomer resin to produce a two-piece golf ball having a diameter of 42.7 mm.

The initial velocity of these golf balls when hit with a head speed of 38 m / sec was measured according to the USGA method using a flywheel hitting tester. The results are shown in Table 2.

From the results in Table 2, it was confirmed that the golf ball of the present invention had a high initial ball speed and improved flight performance.

Claims (1)

(57) [Claims] 1. A core ball of a one-piece golf ball or a multi-layer golf ball coated directly or via an intermediate layer with a cover material, comprising a base rubber, a metal salt of an unsaturated carboxylic acid, thiophenols and thiocarboxylic acids. And a rubber composition containing an organic sulfur compound selected from metal salts thereof.