Multi-piece solid golf ball

Abstract

A multi-piece solid golf ball has a core, an intermediate layer encasing the core, and a cover layer which encases the intermediate layer and has a plurality of dimples on an outer surface thereof. The intermediate layer is formed primarily of a material which includes specific amounts of a fatty acid and / or fatty acid derivative having a molecular weight of from 228 to 1500 and a basic inorganic metal compound capable of neutralizing un-neutralized acid groups per 100 parts by weight of a resin component composed primarily of a specific olefin-unsaturated carboxylic acid copolymer, and in which at least 82 mol % of acid groups in the above components are neutralized. The cover layer is formed of a thermoplastic resin composed primarily of an ionomer resin, and has a Shore D hardness of from 50 to 85. This invention makes it possible to achieve both an increased distance owing to a reduced spin rate, and also an improved durability.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a multi-piece solid golf ball of three or more pieces which has a core, an intermediate layer and a cover. More specifically, the invention relates to a multi-piece solid golf ball which achieves an increased distance owing to a reduced spin rate, and also has an improved durability.[0002]Low-compression golf balls are known to have a poor durability. As a result, the use of ionomers, which are resistant to cracking and relatively soft, as the cover material has become commonplace.[0003]On the other hand, in order to further increase the distance traveled by the ball, it is necessary to make the cover harder and thereby lower the spin rate of the ball. In such cases, when a hard ionomer is used as the cover, the cover has a tendency to crack, in addition to which the ball durability becomes very poor. Also, if the spin rate of the ball is reduced too much, the lift of the ball after being struck will decrease, possibl...

AI Technical Summary

Benefits of technology

[0006]It is therefore an object of the present invention to provide a multi-piece solid golf ball which achieves an increased distance owing to a reduced spin rate, and also has an improved durability.

[0007]The inventors have conducted extensive investigations in order to attain the above object. As a result, they have discovered that, in a multi-piece solid golf ball having a core, an intermediate layer and a cover, by using a hard ionomer material as the cover material in order to lower the spin rate and by also selecting a highly neutralized ionomer resin composition as the intermediate layer material, the adherence between the intermediate layer and the cover increases, resulting in a dramatic improvement in the durability to cracking. Moreover, a lower spin rate is achieved on full shots, increasing the distance traveled by the ball. This discovery ultimately led to the present invention.

[0008]In this invention, because the cover has a very strong tendency to crack, particularly in those cases where a high-acid ionomer is used as the cover material, the durability can be increased by adding a granular inorganic filler.

[0009]One of the drawbacks of using a hard cover material is that the feel on impact worsens. In addition, a hard cover causes the ball to separate rapidly from the club when struck with a W#1, leaving the golfer with an impression that the ball is difficult to control. Therefore, to improve the feel of the ball on impact, it is preferable to provide between the intermediate layer and the core a relatively soft elastomer layer, i.e., an envelope layer. As a result, a soft feel and good controllability can be obtained.

Problems solved by technology

One of the drawbacks of using a hard cover material is that the feel on impact worsens.

In addition, a hard cover causes the ball to separate rapidly from the club when struck with a W#1, leaving the golfer with an impression that the ball is difficult to control.

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