US 7,727,084 B2Granted

Multi-piece solid golf ball

AssigneeBridgestone Sports Co., Ltd.

InventorsHideo Watanabe, Akira Kimura

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Abstract

The present invention provides a multi-piece solid golf ball having 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, the envelope layer and the intermediate layer are each formed primarily of the same or different resin materials, and 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. 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. The golf ball has an outstanding flight performance and controllability which are acceptable to professionals and other skilled players, in addition to which it has an excellent durability to cracking under repeated impact and an excellent scuff resistance.

Claims15

Dependent claims

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.

14 more elements

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 hardness increases from the center to the surface of the core, and the hardness difference therebetween in JIS-C units is at least 5 but not more than 30.

14 more elements

Dependencies are inferred from the claim text.