Patent ID: 8771103

Claim:
A multi-piece solid golf ball comprising a core, an envelope layer which encloses the core, an intermediate layer which encloses the envelope layer, and a cover which encloses 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 envelope layer is formed primarily of a mixture comprising: 100 parts by weight of a resin component composed of, in admixture, a base resin of (a) an olefin-unsaturated carboxylic acid binary random copolymer and/or a metal ion-neutralized product of an olefin-unsaturated carboxylic acid binary random copolymer mixed with (b) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer and/or a metal ion-neutralized product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester ternary random copolymer in a weight ratio between 100:0 and 0:100, and (e) a non-ionomeric thermoplastic elastomer in a weight ratio between 100:0 and 50:50, (c) 5 to 80 parts by weight of a fatty acid and/or fatty acid derivative having a molecular weight of 280 to 1500, and (d) 0.1 to 10 parts by weight of a basic inorganic metal compound capable of neutralizing un-neutralized acid groups in the base resin and component (c); the intermediate layer is formed primarily of a resin material; the cover is formed primarily of polyurethane; and the intermediate layer and the cover have surface hardnesses (Durometer D hardness) which satisfy the relationship intermediate layer surface hardness>cover surface hardness; the envelope layer and the intermediate layer have surface hardnesses which satisfy the relationship envelope layer surface hardness<intermediate layer surface hardness; and the envelope layer, the intermediate layer and the cover have thicknesses which satisfy the relationship cover thickness<intermediate layer thickness<envelope layer thickness.