Golf ball cover formed from blend of ionomer, acid copolymer and ethylene-propylene rubber, and method of making same

A golf ball having a cover layer with a composition comprising a combination of (1) ionomeric copolymer, (2) ethylene-propylene rubber, and (3) substantially unneutralized terpolymer, the terpolymer being formed from ethylene, an acid which includes at least one member selected from the group consisting of acrylic, maleic, itaconic, fumaric, and methacrylic acids, and half esters of maleic, fumaric, and itaconic acids, and an unsaturated monomer of the acrylate ester class including at least one member selected from the group consisting of methyl-, ethyl-, n-propyl-, n-butyl-, n-octyl-, 2-ethylhexyl-, and 2-methoxyethyl-1-acrylates, the ethylene-propylene rubber and terpolymer being combined in a weight ratio of 40:60 to 60:40, the ratio of the sum of the weights of ethylene-propylene rubber and terpolymer to the weight of ionomeric copolymer in the combination being in the range of 20:80 to 80:20.

A method of making a golf ball comprising:

• providing a golf ball core, and
• forming a cover layer over the core, the cover layer having a composition comprising a combination of (1) ionomeric copolymer, (2) ethylene-propylene rubber, and (3) substantially unneutralized copolymer formed from (a) an .alpha.-olefin having two to eight carbon atoms, (b) an unsaturated monomer of the acrylate ester class having from 1-21 carbon atoms, and (c) an acid which includes at least one member selected from the group consisting of .alpha., .beta.-ethylenically unsaturated mono- or dicarboxylic acids, the weight ratio of the ethylene-propylene rubber to substantially unneutralized copolymer being in the range of 25:75,to 75:25.

A golf ball having a cover layer with a composition comprising a combination of (1) ionomeric copolymer, (2) ethylene-propylene rubber having a broad molecular weight distribution, and (3) substantially unneutralized copolymer formed from (a) an .alpha.-olefin having two to eight carbon atoms, (b) an unsaturated monomer of the acrylate ester class having from 1-21 carbon atoms, and (c) an acid which includes at least one member selected from the group consisting of .alpha., .beta.-ethylenically unsaturated mono- and dicarboxylic acids, the weight ratio of the ethylene-propylene rubber to copolymer formed from .alpha.-olefin, acrylate ester and acid being in the range of 25:75 to 75:25.