US 7,582,026 B2Granted

Golf ball

AssigneeSRI Sports Limited

InventorsKazuya Kamino, Seiichiro Endo, Tsutomu Hirau

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Abstract

Golf ball 2 has a spherical core 4, a reinforcing layer 6 positioned outside of the core 4 and a cover 8 positioned outside of the reinforcing layer 6. The core 4 has a inner sphere 10, a first mid layer 12 positioned outside of the inner sphere 10, and a second mid layer 14 positioned outside of the first mid layer 12. The principal component of the first mid layer 12 and the second mid layer 14 is an ionomer resin. The principal component of the cover 8 is a thermoplastic polyurethane elastomer. The second mid layer 14 has a hardness Hs which is greater than a hardness Hf of the first mid layer 12 and a hardness Hc of the cover 8. The hardness Hc of the cover 8 is equal to or less than 50. A product (Tc·Hc) of a thickness Tc (mm) and a hardness Hc of the cover 8 is equal to or less than 25.

Claims7

Dependent claims

A golf ball which comprises a spherical core and a cover positioned outside of the core and formed by a thermoplastic resin composition,

said core having an inner sphere, a first mid layer positioned outside of the inner sphere and formed by a thermoplastic resin composition, and a second mid layer positioned outside of the first mid layer and formed by a thermoplastic resin composition,
said second mid layer having a hardness Hs which is greater than a hardness Hf of the first mid layer and a hardness Hc of the cover,
said cover having the hardness Hc of equal to or less than 50, and a product (Tc·Hc) of a thickness Tc (mm) of the cover and a hardness Hc of the cover being equal to or less than 25, wherein a sum (Tf+Ts+Tc) of a thickness Tf of said first mid layer, a thickness Ts of said second mid layer and a thickness Tc of said cover is 0.5 mm or greater and 3.7 mm or less, and wherein the hardness Hc of said cover is smaller than a central hardness Hi of the inner sphere.

Dependencies are inferred from the claim text.