Patent ID: 7654918

Claim:
A golf ball comprising at least a core layer and an outer cover layer, each comprising a cross-linked thermoset rubber composition having a primary rubber component of polybutadiene in an amount of 80% by weight or greater, wherein the polybutadiene of said core layer has a first structure and the polybutadiene of the outer cover layer has a second structure, the first structure being different than the second structure; the thermoset composition of each of the core layer and the outer cover layer further comprising balata in an amount of about 20% by weight or less; and wherein said outer cover layer is a moisture vapor barrier layer that has a moisture vapor transmission rate of less than about 0.95 grams·mm/(m 2 ·day) and is comprised of metal flakes, wherein said outer cover layer has a specific gravity of about 1.2 g/cm 3 or greater.