Patent ID: 7727084

Claim:
A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover which encases 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 and the intermediate layer are each formed primarily of the same or different resin materials; the cover is formed primarily of a thermoplastic resin or a thermoplastic elastomer; the envelope layer, intermediate layer and cover have thicknesses which satisfy the condition cover thickness<intermediate layer thickness<envelope layer thickness, and the condition (cover thickness+intermediate layer thickness)<envelope layer thickness; and the core surface, envelope layer, intermediate layer and cover have Shore D hardnesses which satisfy the condition core surface hardness≦envelope layer material hardness<intermediate layer material hardness≦cover material hardness, wherein the resin material of the envelope layer is 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 random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer mixed with (b) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random terpolymer 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 228 to 1500; and (d) 0.1 to 17 parts by weight of a basic inorganic metal compound capable of neutralizing un-neutralized acid groups in the base resin and component (c), wherein the core has a center hardness of at least 30 but not more than 72, expressed as the JIS-C hardness.