Golf ball incorporating a thin moisture barrier layer

A golf ball comprising:

• a core;
• a first layer, disposed concentrically about the core;
• a thin moisture vapor barrier layer having a thickness of less than about 0.010 in. and disposed concentrically about a spherical outer surface of the first layer;
• and
• a second layer disposed concentrically about a spherical outer surface of the thin moisture vapor barrier layer;
• wherein the first layer comprises an inner cover layer, the thin moisture vapor barrier layer comprises a second inner cover layer, and the second layer comprises an outer cover layer;
• wherein the first layer is formed from an ionomeric composition that has a moisture vapor transmission rate that is higher than that of the thin moisture vapor barrier layer;
• wherein the thin moisture vapor barrier layer is formed from an ionomer composition consisting of a 1-50 percent aqueous mono-valent high acid ionomer dispersion;
• and
• wherein the ionomer of the ionomer composition:
• (i) has an acid level greater than 18%;
• (ii) has more than 45% of acid groups that are neutralized with a monovalent cation;
• and (iii) is formed from an acid copolymer having a starting melt index of greater than 180 g/10′ as measured by ASTM D1238 at 190° C. using a 2160 g load.