The present invention relates to a solid golf ball having a solid core and a cover layer which encases the core. More particularly, the invention relates to a solid golf ball which has a good deformation, especially on full shots with a driver at low head speeds, and thus an excellent flight performance, which also has a good controllability on approach shots and a good feel on impact, and which moreover has an excellent scuff resistance and durability to cracking.
Two-piece solid golf balls designed to satisfy the overall characteristics desired in a golf ball, such as good flight performance, feel on impact and controllability on approach shots, have hitherto been improved in various ways. One example is the golf ball described in JP-A 6-98949.
However, because such a golf ball has a hard cover, there are problems with its spin performance.
In addition, JP-A 9-308708, JP-A 2003-70936 and JP-A 2003-180879, for example, disclose solid golf balls in which the feel and controllability have been improved without a loss of rebound or cut resistance by setting the thickness, flexural rigidity and Shore D hardness of the cover within specific ranges.
Yet, because these golf balls have an inadequate core resilience and the core hardness distribution has not been optimized, properties such as the distance and the spin performance leave something to be desired.
JP-A 9-215778, JP-A 9-271538 and JP-A 11-178949 disclose solid golf balls in which a polyurethane material is used as the cover material. However, in these golf balls, the core lacks an adequate resilience and the resin from which the cover is formed has a less than adequate scuff resistance. Hence, there remains room for improvement in the distance traveled by the ball and the scuff resistance of the cover.
The golf balls described in JP-A 2002-355338 and JP-A 2004-180793 do have a good core resilience, but because these balls have a large deflection hardness and are soft, the rebound by the ball decreases, resulting in a less than satisfactory distance.
Moreover, in JP-A 2002-355338, an ionomer is used as the cover material, but the golf ball has a poor scuff resistance and the core does not have an optimized hardness distribution, as a result of which the ball rebound remains insufficient.
With regard to two-piece solid golf balls, JP-A 11-290479, JP-A 10-127823 and JP-A 2001-25908 describe art in which the hardness distribution such as at the center and surface of a rubber core is optimized. Yet, the rubber core in these golf balls has a resilience which falls short of what is desired, leaving room for improvement in the distance traveled by the ball.
Accordingly, it is an object of the present invention to provide a solid golf ball which has a good deformation, especially on full shots with a driver at low head speeds, and thus an excellent flight performance, which also has a good controllability on approach shots and a good feel on impact, and which moreover has an excellent scuff resistance and durability to cracking.
USPTO Backgrounds
USPTO Backgrounds