JPH031337B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel solid golf ball. Solid golf balls include one-piece golf balls consisting of one composition, two-piece golf balls having a solid core covered with a cover, and multilayer golf balls having one or more suitable intermediate layers between the solid core and the cover. . In order to improve the coefficient of restitution and impact resistance of these solid golf balls, we co-crosslink monomers with unsaturated bonds such as metal salts of α,β-monoethylenically unsaturated carboxylic acids. It is known that it is formulated as an agent. Although these solid golf balls themselves have fairly good performance, there is a need for golf balls that have better coefficients of restitution and durability. Conventionally, solid golf balls containing α,β-ethylenically unsaturated carboxylic acid metal salt monomers, which are added to solid golf ball compositions, are produced by grafting these monomers onto the polybutadiene main chain using a free initiator. and acts as a co-crosslinking agent,
This was thought to give the ball appropriate hardness (compression ratio) and durability. However, if the graft chains produced during this co-crosslinking become longer, the result will be the same as when other polymers are blended with polybutadiene rubber, that is, the repulsion performance of the golf ball will be reduced. By adjusting the length of the graft chains generated during co-crosslinking of the α,β-ethylenically unsaturated carboxylic acids, the present inventors have achieved a method that significantly improves repulsion performance while imparting appropriate hardness and durability. While trying this, the inventors discovered that dipentamethylenethiuram tetrasulfide and/or its derivatives have very excellent performance as a molecular weight regulator for graft chains, and completed the present invention. That is, the present invention provides a golf ball formed from a rubber composition containing an α,β-ethylenically unsaturated carboxylic acid or a metal salt thereof, a free initiator, and dipentamethylenethiuram tetrasulfide and/or a derivative thereof. do. The α,β-monoethylenically unsaturated carboxylic acid used in the present invention is, for example, acrylic acid or methacrylic acid as described in Japanese Patent Publication No. 55-19615, with acrylic acid being particularly preferred. Of course, acrylic acid and methacrylic acid may be used together. The metal salt of the α,β-monoethylenically unsaturated carboxylic acid mentioned above is a divalent metal salt such as a zinc salt, a calcium salt, a magnesium salt, a zirconium salt, etc., and a zinc salt is particularly preferred. The amount of dipentamethylenethiuram tetrasulfide and/or its derivatives used is about 0.1 to about 5 parts by weight per 100 parts by weight of the rubber component, and if it is less than 0.1 part by weight, the added effect will not be fully exhibited. . As the rubber component used in the practice of the present invention, polybutatadiene is used alone, or natural rubber, synthetic polyisoprene rubber, etc. are used in a mixture of not more than about 10% by weight of the rubber component. Synthetic polyisoprene and natural rubber are 10
If more than % is added, the coefficient of restitution of the resulting ball will be significantly lowered. The solid golf ball of the present invention may further contain a free radical initiator for polymerizing the α,β-ethylenically unsaturated carboxylic acid, such as dicumyl peroxide, an antiaging agent, and a filler such as zinc oxide. Mix the amounts. As mentioned above, the solid golf ball obtained by the present invention may be a one-piece golf ball, a two-piece golf ball, or a golf ball with a multilayer structure, and in any of them, α,β-ethylenically unsaturated carboxylic acid metal It exhibits significantly superior repulsion performance, durability, and flight carry characteristics compared to when monomers such as salts are used alone. The present invention will be explained below with reference to Examples. Examples 1 to 3 and Comparative Examples 1 to 4 Golf ball cores having a diameter of about 39 mm were manufactured using the formulations shown in Table 1, and their coefficient of restitution and durability index were measured by conventional methods. Further, a cover (Surlyn 1601) having a thickness of approximately 2 mm was coated on the surface of this golf ball core, and its flight carry was measured. The results are shown in Table-1 and Table-2.

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Claims (1)

[Scope of Claims] 1. A sol formed from a rubber composition containing an α,β-ethylenically unsaturated carboxylic acid or a metal salt thereof, a free initiator, and dipentamethylenethiuram tetrasulfide and/or a derivative thereof. Tsudo golf ball. 2. The golf ball according to item 1, which contains dipentamethylenethiuram tetrasulfide and/or its derivatives in an amount of 0.1 to 5% by weight based on the rubber component. 3. The golf ball according to item 1, wherein the rubber component contains polybutadiene rubber in an amount of 90% or more by weight of the total rubber component.