Golf ball

Abstract

To provide a golf ball that ensures both an improved durability and an extended flight distance, in which cracks or breakage of a core can be prevented while making the hardness of the core surface greater so as to obtain the greater difference in hardness between the core surface and the core center. The golf ball of the present invention includes a core and a cover that surrounds the core, in which the core includes a base rubber and an unsaturated carboxylic acid or its salt as a co-crosslinking agent, the core has a surface hardness of 80 or more in terms of JIS-C hardness, and the unsaturated carboxylic acid or its salt contained in a region ranging from a surface of the core toward its center by less than 2 mm has an average particle diameter of less than 90 μm.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This Application claims priority from Japanese Patent Application No. 2016-256210 filed Dec. 28, 2016, which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]The present invention relates to a golf ball, and more particularly, relates to a golf ball that ensures both improved durability and extended flight distance.[0003]The core of a golf ball is manufactured by molding a rubber composition, in which an unsaturated carboxylic acid or its salt as a co-crosslinking agent is contained in a base rubber such as butadiene rubber, under heat and pressure. In this rubber composition, the unsaturated carboxylic acid or its salt is contained in a large amount with respect to the base rubber. However, the unsaturated carboxylic acid or its salt is more likely to adhere to the surface of the inner wall of a kneading machine during kneading, thereby hindering kneading operation. Furthermore, since the unsaturated ca...

AI Technical Summary

Benefits of technology

The present invention relates to a golf ball with improved durability and increased flight distance. The invention prevents cracks or breakage of the core while making the hardness of the core surface greater to achieve the larger difference in hardness between the core surface and the core center. The invention also addresses the problem of cracks occurring due to the hardness of the core surface by excluding the unsaturated carboxylic acid or its salt with larger particles. However, this solution requires a longer manufacturing time and increased manufacturing cost. To address this problem, the invention suggests a multi-layer structure with at least a center core and an outer core, where the average particle diameter of the unsaturated carboxylic acid or its salt in the center core is 90 μm or more to reduce the amount of usage of the unsaturated carboxylic acid or its salt with smaller average particle diameter and shorten its manufacturing time, thereby reducing manufacturing cost.

Problems solved by technology

However, a golf ball, which adopts a core having a harder core surface to obtain the greater difference in hardness between the core surface and core center, has such problems in durability that cracks occur in the core and the core breaks at the time of impact of the golf ball.

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