(19)
(11) EP 0 897 732 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
06.06.2001 Bulletin 2001/23

(43) Date of publication A2:
24.02.1999 Bulletin 1999/08

(21) Application number: 98306409.8

(22) Date of filing: 11.08.1998
(51) International Patent Classification (IPC)7: A63B 37/00
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 11.08.1997 JP 22890297

(71) Applicant: BRIDGESTONE SPORTS CO., LTD.
Tokyo (JP)

(72) Inventors:
  • Yamagishi, Hisashi, Bridgestone Sports Co., Ltd.
    Chichibu-shi, Saitama-ken (JP)
  • Higuchi, Hiroshi, Bridgestone Sports Co., Ltd.
    Chichibu-shi, Saitama-ken (JP)
  • Hayashi, Junji, Bridgestone Sports Co., Ltd.
    Chichibu-shi, Saitama-ken (JP)
  • Kawata, Akira, Bridgestone Sports Co., Ltd.
    Chichibu-shi, Saitama-ken (JP)

(74) Representative: Whalley, Kevin 
MARKS & CLERK, 57-60 Lincoln's Inn Fields
London WC2A 3LS
London WC2A 3LS (GB)

   


(54) Multi-piece solid golf ball


(57) A multi-piece solid golf ball is provided which is improved in spin, feeling, and durability, prevents its trajectory from rising or dropping, and offers an increased flight distance.
A multi-piece solid golf ball comprising a solid core and a cover having an inner and an outer layer surrounding the core wherein the outer cover layer has a surface formed with a plurality of dimples is characterized in that a product of the Shore D hardness of the inner cover layer multiplied by the Shore D hardness of the outer cover layer and a proportion VR (%) of the total of the volumes of dimple spaces each defined below a plane circumscribed by the dimple edge to the overall volume of a phantom sphere given on the assumption that the golf ball surface is free of dimples satisfy any one of the following combinations (1) to (5):
  • (1) the product of Shore D hardnesses of inner and outer cover layers: 1,500 to less than 2,000    VR: 0.8 to 1.1%
  • (2) the product of Shore D hardnesses of inner and outer cover layers: 2,000 to less than 2,500    VR: 0.75 to 1.05%
  • (3) the product of Shore D hardnesses of inner and outer cover layers: 2,500 to less than 3,000    VR: 0.7 to 1%
  • (4) the product of Shore D hardnesses of inner and outer cover layers: 3,000 to less than 3,500    VR: 0.65 to 0.95%
  • (5) the product of Shore D hardnesses of inner and outer cover layers: 3,500 to 4,000    VR: 0.6 to 0.9%,
and the dimples include at least three types of dimples which are different in at least one of a diameter, a depth, and a value V0 which is the volume of one dimple space defined below a plane circumscribed by the dimple edge divided by the volume of a cylinder whose bottom is the plane and whose height is the maximum depth of the dimple from the bottom.






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