A golf ball comprising a core composed of a fully neutralized polymer material is disclosed herein. The golf ball also preferably has multiple mantle layers and a cover.

Golf ball having CoR of at least 0.700 and Atti compression of at least about 50 and comprising layer comprising a mixture of ionomer composition and a plurality of particulates, at least some being surface-treated with alkoxylated siloxanes and/or polyether-modified siloxanes, and selected from titanium dioxide particles, barium sulfate particles, zinc sulfide particles, and/or zinc oxide particulates. At least some particulates may be contacted with compound having the formula: ##STR00001## Compound (I) may be included in amount of 0.01 to 2% by weight based on total weight of portion of plurality being contacted. The plurality may be included in mixture in amount such that the layer has specific gravity of from 0.5 to about 5.0, tensile strength of from about 300 psi to about 50,000 psi, and elongation at break of from about 20% to about 1000%, each being greater than that of the ionomer composition portion of the mixture.

A method of producing a golf ball applies ultrasonic welding on two half shells to form at least one intermediate layer, at least one cover layer, or at least one intermediate layer and at least one cover layer. The ultrasonic welding may include pressing the two half shells together, delivering a high power electrical signal to a welding stack, and converting the high power electrical signal at the welding stack to ultrasonic energy. The converting may include converting the high power electrical signal into a mechanical vibration, modifying an amplitude of the mechanical vibration to generate a modified mechanical vibration, and applying the modified mechanical vibration to an interface of the two half shells to weld them together ultrasonically. Aspects also relate to golf balls, or one or more layers thereof, made using ultrasonic welding.

A method of producing a golf ball applies ultrasonic welding on two half shells to form at least one intermediate layer, at least one cover layer, or at least one intermediate layer and at least one cover layer. The ultrasonic welding may include pressing the two half shells together, delivering a high power electrical signal to a welding stack, and converting the high power electrical signal at the welding stack to ultrasonic energy. The converting may include converting the high power electrical signal into a mechanical vibration, modifying an amplitude of the mechanical vibration to generate a modified mechanical vibration, and applying the modified mechanical vibration to an interface of the two half shells to weld them together ultrasonically. Aspects also relate to golf balls, or one or more layers thereof, made using ultrasonic welding.

A golf ball having a cover with a plurality of dimples on the surface thereof is provided with a coat of mutually differing properties on dimple areas of the surface and on land areas between the dimples. The dimple areas are formed with a coat having a low coefficient of friction, do not affect the spin performance when the ball is struck and are not prone to staining. The land areas are formed with a coat having a high coefficient of friction, enabling a lower spin rate to be achieved and thus increasing the distance traveled by the ball, particularly when struck with a middle iron, and also help impart a high spin rate and a good controllability on approach shots.

A golf ball a core, one or more intermediate layers, and one or more cover layers. The core may comprise an inner portion and an outer portion. One or more layers of the golf ball may be formed by the application of ultrasonic welding on two half shells to form. One or more of the layers may be formed by a number of different chemical compositions, and may have varying thicknesses, hardnesses, coefficients of restitution, and PGA compression. The golf ball itself may have varying coefficient of restitution and PGA compression, depending on the layers.

A golf ball comprising: (a) a core; (b) at least one mantle layer adjacent to the core; (c) an inner cover layer adjacent to the mantle layer; and (d) an outer cover layer adjacent to the inner cover layer, wherein the inner cover layer has a material Shore D hardness that is at least 3 less than the material Shore D hardness of the outer cover layer, and the inner cover layer has a thickness of less than 0.050 in.

An object of the present disclosure is to provide a golf ball having excellent durability and flight distance and good shot feeling for an average golfer who hits a golf ball at a slow head speed. The present disclosure provides a golf ball comprising a spherical core and at least two cover layers covering the spherical core, wherein a difference between a core surface crosslinking density and a core center crosslinking density is more than 1.0×10.sup.2 mol/m.sup.3 and less than 9.0×10.sup.2 mol/m.sup.3, a hardness difference between a core surface hardness Cs (Shore C hardness) and a core center hardness Co (Shore C hardness) is 13.0 or more and 30.0 or less, a compression deformation amount of the core when applying a load from an initial load of 98 N to a final load of 1275 N to the core is less than 3.8 mm, and the at least two cover layers include a first cover layer and a second cover layer positioned closer to the spherical core than the first cover layer, an average hardness Dave=(Ti×Hi+To×Ho)/(Ti+To) of the first cover layer and the second cover layer is 55 or more, wherein To (mm) is a thickness of the first cover layer, Ho (Shore D) is a slab hardness of the first cover layer, Ti (mm) is a thickness of the second cover layer, and Hi (Shore D) is a slab hardness of the second cover layer.

Golf balls having cores with increased hardness gradients are provided. The cores have an increased “positive” hardness gradient (or a “hard-to-soft” hardness) where the outer surface of the core is harder than the center. The increased positive hardness gradient can be achieved by introducing a water-releasing agent into the core rubber formulation during the curing process. The resulting golf balls have reduced spin and sufficient impact durability.

Golf balls having cores with increased hardness gradients are provided. The cores have an increased “positive” hardness gradient (or a “hard-to-soft” hardness) where the outer surface of the core is harder than the center. The increased positive hardness gradient can be achieved by introducing a water-releasing agent into the core rubber formulation during the curing process. The resulting golf balls have reduced spin and sufficient impact durability.