Multi-piece solid golf ball

Abstract

A multi-piece solid golf ball has a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and an outer layer which encases the intermediate layer and has formed on a surface thereof a plurality of dimples. The core is made of an elastomer. The envelope layer is formed of an inner envelope layer and an outer envelope layer, and the intermediate layer is formed of an inner intermediate layer and an outer intermediate layer. The outer layer has a hardness which is higher than the average core hardness, and each of the envelope layers and the intermediate layers is softer than the outer layer.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in-part of copending application Ser. No. 12 / 971,795 filed on Dec. 17, 2010, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to a multi-piece solid golf ball composed of a core, an envelope layer, an intermediate layer and an outer layer that have been formed as successive layers. More specifically, the invention relates to a multi-piece solid golf ball which is intended primarily to achieve an excellent flight when played by an ordinary amateur golfer with a head speed that is not very high, and to have a good, soft feel on impact.[0003]Key performance features required in a golf ball include distance, controllability, durability and feel on impact. Balls endowed with these qualities in the highest degree are constantly being sought. Among recent golf balls, there has emerged a succession of balls which have multilayer struc...

AI Technical Summary

Benefits of technology

[0007]It is therefore an object of the present invention to provide a multi-piece solid golf ball which is able to achieve an excellent flight when played by ordinary amateur golfers having head speeds that are not very high, and which has a good, soft feel on impact.

[0009]average core hardness (Shore D)=[core surface hardness (Shore D)+core center hardness (Shore D)] / 2, the outer layer hardness (Shore D) is higher than the average core hardness and each of the envelope layers and the intermediate layers is softer than the outer layer, the ball can achieve an excellent flight when played by ordinary amateur golfers having head speeds that are not very high and can exhibit a good, soft feel on impact. In particular, it is possible in this invention to further reduce the spin rate on shots with a driver and thus to achieve a further increase in distance.

[0010]That is, the multi-piece solid golf ball of the present invention, by basically having a multilayer construction of six or more layers in which at least five cover layers are formed over a core and having the outer layer be relatively hard, is able to achieve both a low spin rate and a high rebound. In addition, owing to an exquisite combination of hardnesses and thicknesses among the respective layers other than the outer layer (i.e., the inner envelope layer, outer envelope layer, inner intermediate layer and outer intermediate layer, which layers are collectively referred to herein as the “inner layers”), the spin rate is reduced and the rebound is increased on full shots, enabling an excellent distance to be achieved. Moreover, a good, soft feel can be obtained on full shots.

Problems solved by technology

However, there are limitations in the design of hardnesses and thicknesses in two-piece solid golf balls and three-piece solid golf balls.

However, in such prior-art golf balls with a multilayer structure, because a strong emphasis is often placed on numerous qualities other than flight, such as the spin rate on approach shots, the feel on impact and durability, they lack a sufficient spin rate-lowering effect on full shots, leaving room for further improvement in the distance traveled by the ball on shots with a driver.

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