Patent ID: 7510489

Claim:
A solid golf ball comprising a solid core and a cover layer that encases the core and has an outermost layer on an outside surface of which are formed a plurality of dimples, wherein the solid core is formed of a rubber composition composed of 100 parts by weight of a base rubber that includes from 60 to 100 parts by weight of a polybutadiene rubber having a cis-1,4 bond content of at least 60% and having a Mooney viscosity (ML 1+4 (100Â° C.)) of from 30 to 100 and synthesized using a rare-earth catalyst, from 0.1 to 5 parts by weight of an organosulfur compound, an unsaturated carboxylic acid or a metal salt thereof, an inorganic filler, and an antioxidant; the solid core has a deformation, when compressed under a final load of 130 kgf from an initial load of 10 kgf, of from 2.0 to 4.0 mm, and has the hardness distribution shown in the table below; the cover layer is formed primarily of a polyurethane material and has a thickness of from 0.5 to 2.5 mm, a Shore D hardness at the surface of from 50 to 70 and a flexural rigidity of from 50 to 300 MPa; and the golf ball has a deformation, when compressed under a final load of 130 kgf from an initial load of 10 kgf, of from 2.0 to 3.8 mm; Hardness Distribution in Solid Core Shore D hardness Center 30 to 48 Region located 5 mm from center 34 to 52 Region located 10 mm from center 40 to 58 Region located 15 mm from center (Q) 43 to 61 Region located 2 to 3 mm inside of surface (R) 36 to 54 Surface (S) 41 to 59 Hardness difference ((Q) âˆ’ (S)] 1 to 10 Hardness difference [(S) âˆ’ (R)] 3 to 10.