An object of the present invention is to provide a golf ball showing a low spin rate on driver shots and a high spin rate on approach shots. The present invention provides a golf ball comprising a spherical center, at least two envelope layers covering the spherical center, and a cover covering the envelope layers, wherein an envelope layer (Es1) formed from a material having a lowest material hardness among a center constituent material and envelope layers constituent materials, is disposed in a region located at a distance from 36.0% to 65.0% of a golf ball radius from a center point of the golf ball.

An object of the present invention is to provide a golf ball resin composition having a high resilience, flexibility and high fluidity. The present invention provides a golf ball resin composition having a bending stiffness (M.sub.21-30) ranging from 600 kgf/cm.sup.2 to 5,000 kgf/cm.sup.2 within a bending angle from 21 to 30, a rebound resilience (R) of 50% or more, a slab hardness (Shore D) ranging from 40 to 65, a melt flow rate (190 C., 2.16 kgf) of 1.0 g/10 min or more, and a resilience index value ((M.sub.21-30).sup.0.5(R/100).sup.3) of 8.5 or more.

An object of the present invention is to provide a golf ball exhibiting an excellent shot feeling and resilience, and a constituent material thereof. The present invention provides a golf ball resin composition having a bending stiffness (M.sub.3-12) ranging from 300 kgf/cm.sup.2 to 24,000 kgf/cm.sup.2 at a bending angle from 3 to 12, a ratio (M.sub.3-12/M.sub.24-30) of the bending stiffness (M.sub.3-12) at the bending angle from 3 to 12 to a bending stiffness (M.sub.24-30) at a bending angle from 24 to 30 ranging from 0.20 to 2.00, and a slab hardness ranging from 30 to 65 in Shore D hardness.

Multi-layered golf balls having a dual-layered core and cover of at least one layer are provided. The dual-core construction includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An outer core layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. In one version, the foamed outer core layer is made of a relatively soft foam composition having low flex modulus and density. The foamed outer core layer may specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. A cover may be disposed about the core structure. For example, an inner cover made of ethylene acid copolymer ionomer and outer cover made of polyurethane may be used.

A golf ball comprising at least one layer comprised of a neutralized acid polymer composition consisting of a mixture of: (a) at least one low molecular weight acid-containing wax; (b) at least one non-acid-polymer; (c) at least one organic acid or salt thereof; and (d) at least one plasticizer. Each low molecular weight acid-containing wax may have a molecular weight of from about 500 to about 7000, and in some embodiments, the molecular weight may be considered low up to 30,000. Interactions between components (a), (b), (c) and (d) as disclosed herein advantageously produce a layer of ionomeric material having desirable physical properties, such as heat stability, and processability (excellent melt flow) and softer feel without the need for blending high and low molecular weight acid-containing polymer(s).

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.

Multi-layered golf balls having a dual-layered core and cover of at least one layer are provided. The dual-core construction includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An outer core layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. In one version, the foamed outer core layer is made of a relatively soft foam composition having low flex modulus and density. The foamed outer core layer may specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. A cover may be disposed about the core structure. For example, an inner cover made of ethylene acid copolymer ionomer and outer cover made of polyurethane may be used.

An object of the present invention is to provide a material from which a golf ball having excellent resilience and durability can be obtained. The present invention provides a golf ball resin composition containing: (A) at least one member selected from the group consisting of a polyamide, an ethylene-vinyl alcohol copolymer, a partially saponified product of an ethylene-vinyl acetate copolymer, and a polyvinyl alcohol, (B) at least one resin component selected from the group consisting of (b-1) a binary copolymer composed of an olefin and an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) a metal ion-neutralized product of a binary copolymer composed of an olefin and an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-3) a ternary copolymer composed of an olefin, an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and an ,-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and an ,-unsaturated carboxylic acid ester, and (C) a fatty acid metal salt having 18 or less carbon atoms.

Multi-layered golf balls having at least one layer made of a polyamide composition containing a transparent polyamide polymer and fatty acid salt are provided. In one preferred version, the polyamide composition consists essentially of a blend of 40 to 99% by weight transparent polyamide and 1 to 60% by weight fatty acid salt. The golf ball includes a core having at least one layer and a cover having at least one layer. The polyamide composition may be used to form any core, cover, or other layer in the golf ball. The polyamide compositions have a good combination of properties including Coefficient of Restitution (COR) and compression.