Golf ball

摘要

A golf ball 2 includes a spherical core 4 and a cover 6 covering the core 4. The cover 6 includes an inner cover 8 and an outer cover 10 positioned outside the inner cover 8. The core 4 is obtained by a rubber composition being crosslinked. The rubber composition includes a base rubber (a), a co-crosslinking agent (b), a crosslinking initiator (c), and a carboxylate (d). The co-crosslinking agent (b) is: (b1) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms; or (b2) a metal salt of an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms. The amount of the carboxylate (d) is equal to or greater than 1 parts by weight but less than 40 parts by weight per 100 parts by weight of the base rubber (a). A hardness of an innermost layer of the cover is greater than a surface hardness of the core.

主权项

1. A golf ball comprising a spherical core and a cover which covers the core and has two or more layers, wherein the core is formed from a crosslinked rubber composition that includes:
(a) base rubber; (b) a co-crosslinking agent; (c) a crosslinking initiator; and (d) a carboxylate having a carboxylic acid component that includes 4 to 14 carbon atoms, wherein the co-crosslinking agent (b) is: (b1) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms; and/or (b2) a metal salt of an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, the carboxylate (d) is present in an amount that is equal to or greater than 1 parts by weight but less than 10 parts by weight per 100 parts by weight of the base rubber (a), the carboxylate carboxylic acid component excludes the α,β-unsaturated carboxylic acid, a JIS-C hardness Hi of an innermost layer of the cover is greater than a JIS-C hardness Hs at a surface of the core, the core has a hardness distribution such that if JIS-C hardness values are measured at eight points in the core, including the core central point, at intervals of 2.5 mm, as well as the core surface, and the hardness values are plotted versus distance in a graph, then R2 of a linear approximation curve obtained by the least-square method is equal to or greater than 0.95; the JIS-C hardness Hs at the surface of the core is equal to or greater than 78.0 but equal to or less than 95.0; the core central point JIS-C hardness H(0) is equal to or greater than 40.0 but equal to or less than 70.0; and the JIS-C hardness Hs at the surface of the core is greater than the core central point JIS-C hardness H(0) by a difference of equal to or greater than 15.