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 any construction and 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 include either an acid terpolymer, such as a terpolymer of ethylene, methyl acrylate and acrylic acid, or a copolymer of ethylene and acrylic acid, or both. Preferably, the water vapor barrier layer has an acid content of about 3% by weight to about 25% by weight. In accordance to another aspect of the invention, the water vapor barrier layer has a high flow melt index, such that a thin layer from about 0.030 inch to about 0.005 inch can be achieved. The outer cover can be made from any suitable material. Preferably, the outer cover is made from a thermoset polyurethane.
1 . A golf ball comprising a core, a moisture vapor barrier layer, and a cover, wherein the moisture vapor barrier layer has a moisture vapor transmission rate that is lower than that of the cover, and comprises:
a copolymer of ethylene and methacrylic acid; and
a terpolymer of ethylene, a softening acrylate class ester, and a carboxylic acid.
2 . The golf ball of claim 1 , wherein the terpolymer is a terpolymer of ethylene, methyl acrylate and acrylic acid.
3 . The golf ball of claim 1 , wherein at least one of the copolymer and the terpolymer is non-ionomeric.
4 . The golf ball of claim 1 , wherein the terpolymer is a terpolymer of ethylene, an ester being methyl acrylate, n-butyl acrylate or iso-butyl acrylate, and an acid being acrylic acid or methacrylic acid.
5 . The golf ball of claim 1 , wherein the moisture vapor barrier layer further comprises a copolymer of ethylene and acrylic acid.
6 . The golf ball of claim 1 , wherein the water vapor barrier layer has a Shore D hardness of about 23 to about 63.
7 . The golf ball of claim 1 , wherein the water vapor barrier layer has a moisture vapor transmission rate of less than about 0.95 grams·mm/m 2 ·day.
8 . The golf ball of claim 1 , wherein the water vapor barrier layer further comprises a second non-ionomeric material having a melt flow index of greater than 14 grams/10 minutes.