abstract |
A golf ball 2 includes a core 4, a first mid layer 6, a second mid layer 8, and a cover 12. The core 4 includes a center 18 and an envelope layer 20. The center 18 is formed by crosslinking a first rubber composition, and the envelope layer 20 is formed by crosslinking a second rubber composition. The first rubber composition or the second rubber composition includes a base rubber, a co-crosslinking agent, a crosslinking initiator, and an acid and/or a salt. The co-crosslinking agent is: n(1) an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms; and/or n(2) a metal salt of an α, β-unsaturated carboxylic acid having 3 to 8 carbon atoms. n nA hardness Hm2 of the second mid layer 8 is greater than a hardness Hm1 of the first mid layer 6. The hardness Hm2 is greater than a hardness Hc of the cover 12. |