Three-piece solid golf ball

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be explained in detail.
Firstly, the construction of the three-piece golf ball of the present invention will be explained with reference to the accompanying drawing.
FIG.
1 is a schematic cross section illustrating one embodiment of the three-piece golf ball of the present invention.
In FIG.
1, 1 is a core and 2 is a cover.
The core 1 has a two-layer structure comprising a center 1a and an outer shell 1b which is formed to coat the outer periphery side of the center 1a.
The core 1 having a two-layer structure is covered by a cover 2.
As the base rubber used for the core 1, there can be used butadiene rubber, preferably butadiene rubber containing a cis-1,4 structure of 40% or more, particularly 85% or more.
Further, if necessary, natural rubber, isoprene rubber, styrene-butadiene rubber, etc.
may be formulated in this butadiene rubber.
As the crosslinking agent, there can be used an .
alpha.
,.
beta.
-unsaturated carboxylic acid metallic salt.
Preferred examples of the .
alpha.
,.
beta.
-unsaturated carboxylic acid metallic salt include metallic salts such as zinc salt, magnesium salt, etc.
of .
alpha.
,.
beta.
-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, etc.
Among them, zinc acrylate and zinc methacrylate are particularly preferred.
Further, the .
alpha.
,.
beta.
-unsaturated carboxylic acid metallic salt may be formed in a rubber composition by formulating .
alpha.
,.
beta.
-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, etc.
and metallic compounds such as zinc oxide, magnesium oxide, etc.
when the rubber composition is prepared.
The amount of the .
alpha.
,.
beta.
-unsaturated carboxylic acid metallic salt to be formulated in the center 1a is preferably 13 to 28 parts by weight, particularly 15 to 25 parts by weight, based on 100 parts by weight of the base rubber.
When the amount of the .
alpha.
,.
beta.
-unsaturated carboxylic acid metallic salt to be formulated in the center 1a is smaller than the above range, the resulting rubber composition is too soft and it is difficult to mold a core