Dual core golf ball having negative-hardness-gradient thermoplastic inner core and shallow negative-hardness-gradient outer core layer

US7942761B2 · kind B2 · utility

Assignee

• Acushnet Company · US

Inventors

• Michael J. Sullivan · Old Lyme, US
• Brian Comeau · Berkley, US
• William B. Lacy · Plymouth, US

Key dates

• Filing date: Dec 18, 2008
• Grant date: May 17, 2011
• Expiry date: Jan 24, 2029

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A63B37/02
• WIPO field: Furniture, games
• WIPO sector: Other fields

Abstract

A golf ball comprising a thermoplastic inner core layer that has a geometric center hardness greater than its surface hardness to define a first “negative” hardness gradient. An outer core layer is disposed about the inner core and is formed from a substantially homogenous thermoset composition, typically rubber, and has an inner surface hardness greater than its outer surface hardness to also define a “negative” hardness gradient. An inner cover layer is disposed about the outer core layer and an outer cover layer is disposed about the inner cover layer. The “negative” hardness gradient of the inner core is typically −1 to −5 Shore C and the “negative” hardness gradient of the core layer is typically at least −1 Shore C but less than −7 Shore C. The difference between the inner core surface hardness and the outer core inner surface hardness, Δh, should be at least −3 Shore C.