Patent ID: 9566476
Date: 2017-02-14
CPC Classifications: A63B,C08K

Claim:
1. A golf ball having a spherical core and at least one cover layer covering the spherical core, wherein the spherical core is formed from a rubber composition consisting essentially of: (a) a base rubber consisting of a polybutadiene having a Mooney viscosity (ML (b) an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, (c) a crosslinking initiator, (d) an aliphatic saturated carboxylic acid and/or an aromatic carboxylic acid, (f) an organic sulfur compound which is a compound or metal salt of thiophenol or a derivative thereof, diphenyl disulfide or a derivative thereof, or thionaphthol or a derivative thereof, and at least one inorganic filler selected from the group consisting of zinc oxide, barium sulfate, calcium carbonate, magnesium oxide, tungsten powder, and molybdenum powder, wherein the rubber composition contains (d) the aliphatic saturated carboxylic acid and/or the aromatic carboxylic acid in an amount ranging from 7.5 parts to 40 parts by mass with respect to 100 parts by mass of (a) the base rubber, wherein if the JIS-C hardness is measured in the spherical core at nine points, including the core center and core surface, obtained by dividing the radius of the spherical core into equal parts having 12.5% intervals therebetween, and is plotted against distance (%) from the spherical core center, the R wherein the spherical core has a hardness difference of 15 or more in JIS-C hardness between a surface hardness and a center hardness thereof.