Highly-neutralized thermoplastic copolymer center for improved multi-layer core golf ball

A golf ball comprising:

• a center having a diameter of from 0.80 inches to 1.40 inches, a compression of from 62 to 107, and formed from a composition comprising:
• a copolymer of ethylene and an α, β-unsaturated carboxylic acid, optionally including a softening monomer selected from the group consisting of alkyl acrylates and methacrylates;
• an organic acid or salt thereof present in an amount of from 5 wt% to 50 wt %, based on the total weight of the copolymer and organic acid or salt thereof;
• and
• a cation source present in an amount sufficient to neutralize greater than 80% of all acid groups present in the composition;
• an outer core layer having a thickness of 0.090 inches or greater and formed from a composition having a Shore D hardness of from 40 to 70;
• and
• a cover formed from a polyurethane;
• wherein the golf ball has a first coefficient of restitution of 0.81 or greater when measured at an incoming velocity of 125 ft/s and a second coefficient of restitution of 0.76 or greater when measured at an incoming velocity of 160 ft/s;
• and
• wherein a sphere resulting from a combination of the center and the outer core layer has a compression of 80 or greater;
• and
• wherein the Shore D hardness of the center composition is less than the Shore D hardness of the outer core layer composition.