| 摘要 |
The invention provides 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. The core is formed primarily of a rubber material, and has a hardness which gradually increases from a center to a surface thereof, the hardness difference in JIS-C hardness units between the core center and the core surface being at least 15 and, letting (I) be the average value for cross-sectional hardnesses at a position 15 mm from the core center and at the core center and letting (II) be the cross-sectional hardness at a position 7.5 mm from the core center, the hardness difference (I)-(II) therebetween in JIS-C units being not more than ±2. 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 relationship cover thickness<intermediate layer thickness<envelope thickness; and the envelope layer, intermediate layer and cover have surface hardnesses (JIS-C hardness) which satisfy the relationship envelope layer surface hardness<intermediate layer surface hardness>cover surface hardness, -10<=(JIS-C hardness of cover surface-JIS-C hardness of intermediate layer surface)<0, and 1<=(JIS-C hardness of intermediate layer surface-JIS-C hardness of envelope layer surface)<=30. The golf ball has an excellent flight performance and controllability that are acceptable to professionals and other skilled golfers, while also having an excellent durability to cracking on repeated impact and an excellent scuff resistance.
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