US Patent 7,654,916
Golf balls having a low modulus HNP layer and a high modulus HNP layer
Abstract
The present invention is directed to golf balls consisting of a dual-layer core and a cover. The core consists of a center having a center hardness of 50 Shore C or greater and formed from a low modulus HNP composition, and an outer core layer having a surface hardness of 75 Shore C or greater and formed from a high modulus HNP composition. Low modulus HNP compositions of the present invention have a modulus of from 1,000 psi to 50,000 psi. High modulus HNP compositions of the present invention have a modulus of from 25,000 psi to 150,000 psi. The modulus of the highly neutralized copolymer of the low modulus HNP is at least 10% less than the modulus of the highly neutralized copolymer of the high modulus HNP composition. The cover consists of an inner cover layer formed from a thermoplastic composition and an outer cover layer formed from a polyurethane or polyurea composition.