US Patent 7306528 Golf ball with vapor barrier layer

A multi-layer golf ball comprising a core, a water vapor barrier layer and a cover is provided. The core may have multiple layers. The core may also have a solid or liquid center or wound layers, and may be constructed from a polybutadiene with mid to high Mooney viscosity. The water vapor barrier layer preferably comprises a copolymer of ethylene and methacrylic acid. The water vapor barrier layer may also have a high flow melt index, such that a thin layer from about 0.030 inch to about 0.005 inch can be achieved.