Patent ID: 6634961
Filing Date: 2003-10-21
Classification: A63B

Abstract:
A multi-piece solid golf ball comprising a solid core, an inner cover layer and an outer cover layer, wherein the solid core is molded from a rubber composition comprising100 parts by weight of a base rubber composed of (a) 20 to 100 wt % of a polybutadiene having a cis-1,4 content of at least 60% and a 1,2 vinyl content of at most 2%, having a viscosity &eegr; at 25Â° C. as a 5 wt % solution in toluene of up to 600 mPaÂ·s, being synthesized using a rare-earth catalyst and satisfying the relationship: 10B+5&lE;A&lE;10B+60, wherein A is the Mooney viscosity (ML1+4 (100Â° C.)) of the polybutadiene and B is the ratio Mw/Mn between the weight-average molecular weight Mw and the number-average molecular weight Mn of the polybutadiene, in combination with (b) 0 to 80 wt % of a diene rubber other than component (a), (c) 10 to 60 parts by weight of an unsaturated carboxylic acid or a metal salt thereof or both, (d) 0.1 to 5 parts by weight of an organosulfur compound, (e) 5 to 80 parts by weight of an inorganic filler, (f) 0.1 to 5 parts by weight of an organic peroxide; the inner cover layer has a Shore D hardness of 50 to 80; the outer cover layer has a Shore D hardness of 35 to 60; and the outer cover layer has a lower Shore D hardness than the inner cover layer.