Patent ID: 8216090
Filing Date: 2012-07-10
Classification: A63B

Abstract:
1. A golf ball comprising a core, an intermediate layer encasing the core, and a cover which encases the intermediate layer and has formed on a surface thereof a plurality of dimples, wherein the core is formed primarily of a rubber material; the intermediate layer and the cover are formed primarily of like or unlike resin materials; the core has a hardness which gradually increases from a center to a surface thereof, the hardness difference in JIS-C hardness units between the core center and the core surface being at least 15 and, letting (I) be the average value for cross-sectional hardnesses at a position about 15 mm from the core center and at the core center and letting (II) be the cross-sectional hardness at a position about 7.5 mm from the core center, the hardness difference (I)-(II) in JIS-C units being not more than +2; and the intermediate layer and cover have hardnesses which satisfy the condition: cover hardness>intermediate layer hardness, wherein the core is a single layer, the intermediate layer is a single layer and the cover is a single layer, wherein the resin material of the intermediate layer is a mixture comprising: 100 parts by weight of a resin component comprised of (A) a base resin containing (a-1) an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer and (a-2) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer in proportions of (a-1)/(a-2)=100/0 to 0/100 (weight ratio), and (B) a non-ionomeric thermoplastic elastomer in proportions of A/B=100/0 to 50/50 (weight ratio); (C) from 85 to 110 parts by weight of an organic fatty acid and/or organic fatty acid derivative having a molecular weight of from 228 to 1500; and (D) from 0.1 to 17 parts by weight of a basic inorganic metal compound capable of neutralizing unneutralized acid groups in the resin component and component C, wherein the golf ball comprises three layers and the intermediate layer contacts the cover and the core.