Patent ID: 6596801
Filing Date: 2003-07-22
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, and satisfying the relationship: 10B+5&lE;A&lE;10B+60, wherein A is the Mooney viscosity (MLl+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, and (f) 0.1 to 5 parts by weight of an organic peroxide; and both the inner cover layer and the outer cover layer have a Shore D hardness of 45 to 65, and the outer cover layer and the inner cover layer have a hardness difference of up to 5 Shore D hardness units.