A golf ball includes an inner core layer formed from a thermoset rubber composition. The inner core layer has a first outer surface Shore D hardness and an outer diameter of about 0.8 to 1.40 inches. A thermoplastic outer core layer is formed around the inner core layer, has a second outer surface Shore D hardness, and is formed from a copolymer of ethylene and an ,-unsaturated carboxylic acid, a metal salt of an organic acid, and sufficient cation source to neutralize about 90% to about 100% of acid groups of the copolymer. The golf ball includes an inner cover layer and an outer cover layer. The first outer surface Shore D hardness is greater than the second outer surface Shore D hardness and the outer core layer has a thickness of about 0.01 inches to 0.05 inches.

A golf ball includes an inner core layer formed from a thermoset rubber composition. The inner core layer has a first outer surface Shore D hardness and an outer diameter of about 0.8 to 1.40 inches. A thermoplastic outer core layer is formed around the inner core layer, has a second outer surface Shore D hardness, and is formed from a copolymer of ethylene and an ,-unsaturated carboxylic acid, a metal salt of an organic acid, and sufficient cation source to neutralize about 90% to about 100% of acid groups of the copolymer. The golf ball includes an inner cover layer and an outer cover layer. The first outer surface Shore D hardness is greater than the second outer surface Shore D hardness and the outer core layer has a thickness of about 0.01 inches to 0.05 inches.

Provided is a golf ball comprising a spherical core including an inner layer and an outer layer, an intermediate layer and a cover, wherein a difference (H.sub.X+1H.sub.X1) is 0 or more in Shore C hardness, a surface hardness (H.sub.X+Y) of the spherical core is more than 70 in Shore C hardness, an angle of a hardness gradient of the inner layer is 0 or more, a difference () between the angle and an angle of a hardness gradient of the outer layer is 0 or more, the intermediate layer has a material hardness (Hm) ranging from 65 to 80 in Shore D hardness, and the intermediate layer has a highest hardness among the constituent members of the golf ball.

The present invention is directed to golf balls consisting of a multi-layer core and a cover. The multi-layer core includes at least one layer formed from a relatively soft or low modulus HNP composition and at least one layer formed from a relatively hard or high modulus HNP composition.

Multi-layered golf balls having at least one layer made of a polyester composition containing a polyester thermoplastic elastomer and plasticizer are provided. The plasticizers help reduce the glass transition temperature (Tg) of the composition and various plasticizers may be used. For example, the composition may include alkyl oleate plasticizers such as ethyl oleate and octyl oleate. Polyester-ether block copolymers are particularly preferred. The golf ball includes a core having at least one layer and a cover having at least one layer. The polyester composition may be used to form any core, cover, or other layer in the golf ball.

A golf ball comprising: (a) a core; (b) an inner mantle layer; (c) an intermediate mantle layer; (d) an outer mantle layer; and (e) at least one cover layer; wherein the core has a PGA compression of less than 70, and the core/inner mantle layer/intermediate mantle layer combined construct has a PGA compression of at least 30.

The present invention is directed to multi-layer golf balls including a layer formed from a composition comprising a relatively soft or low modulus HNP, a layer formed from a composition comprising a relatively hard or high modulus HNP, an inner cover layer formed from a thermoplastic composition, and an outer cover layer.

An object of the present invention is to provide a golf ball traveling a great flight distance. The present invention provides a golf ball comprising a spherical core and a cover covering the spherical core, wherein the golf ball has a ratio (t2/t1) of a time (t2) to a time (t1) of 1.05 or more in a hitting test using a driver (at a head speed of 40 m/sec), wherein the time (t1) is a time taken from a moment that the driver begins to contact with the golf ball to a moment that the golf ball reaches a maximum deformation amount, and the time (t2) is a time taken from the moment that the golf ball reaches the maximum deformation amount to a moment that the golf ball leaves the driver.

A golf ball includes a core, a mantle and a cover layer. The core includes polybutadiene and has a diameter of less than 1.45 inches. The core has a deflection of at least 0.225 inches under an applied static load of 200 pounds. The mantle includes at least one fully neutralized ionomer terpolymer comprising ethylene, carboxylic acid and an acrylate. The mantle composition has a flexural modulus of less than 10,000 psi. The core and the mantle form a core-mantle assembly having a diameter of between 1.540 inches and 1.580 inches with a deflection of greater than 0.210 inches under an applied static load of 200 pounds. The cover layer includes one or more ionomer materials and has a Shore D hardness of greater than 62.

An object of the present invention is to provide a material for obtaining a golf ball having excellent shot feeling and flight distance. The present invention provides a golf ball resin composition having a ratio (flexural elastic modulus/slab hardness) of a flexural elastic modulus (MPa) to a slab hardness (Shore D hardness) in a range from 3 to 5, and containing, as a resin component, (A) a polyamide resin, (B) at least one selected from the group consisting of (b-1) a binary copolymer, (b-2) a metal ion-neutralized product of a binary copolymer, (b-3) a ternary copolymer and (b-4) a metal ion-neutralized product of a ternary copolymer, and (C) a thermoplastic elastomer.