Multi-piece golf balls containing a dual-layered core are provided. The ball further includes single or multi-layered covers. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, and a surrounding outer core layer. The core layers may have different hardness gradients. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and combinations and alloys thereof preferably dispersed in a thermoplastic polymeric matrix. The outer core layer is preferably formed from a thermoset composition such as polybutadiene. These multi-layered core constructions with metal-containing centers have selective specific gravity relationships between the different layers. This helps provide the ball with good flight distance and spin control. The resulting balls have good resiliency and other playing performance properties.

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 at least one layer consisting of a non-isocyanate-containing polyurethane composition comprising the reaction product of: at least one amine or polyamine, having an average functionality of 2.0 or greater, and at least one cyclo-carbonate. The amine may be selected for example from the group consisting of: ethylenediamine, hexamethylenediamine, or tris(2-aimnoethyl)amine, or blends thereof; and the polyamine may be selected for example from the group consisting of polyoxypropylene diamines, polyoxypropylene triamines, and combinations thereof. The cyclo-carbonate may comprise for example bis(cyclo-carbonate). Other possible reaction products include: (i) the at least one amine or polyamine and at least one epoxy-cyclo-carbonate oligomer, wherein the non-isocyanate-containing polyurethane composition can be modified with at least one of acrylic or siloxane; or (ii) the at least one amine or polyamine and at least one cyclo-carbonated soybean oil; or (iii) at least one lignin-based polyamine and at least one cyclo-carbonated soybean oil.

Multi-piece golf balls having a solid core and cover are provided. The ball contains a small, heavy inner core and surrounding outer core layer. The inner core preferably contains metal powder such as copper, steel, brass, tungsten, titanium, nickel, iron, tin, and bronze particles dispersed in a thermoset or thermoplastic polymeric matrix. For example, a polybutadiene rubber matrix may be used. In one preferred embodiment, the inner core contains elemental iron powder. Preferably, the particles have a weight average size in the range of about 10 μm to about 450 μm. In one embodiment, the outer surface of the inner core has a structure with projecting members. For example, the outer surface may contain multiple projecting ribs with gaps located between the ribs. The ball includes a cover surrounding the core structure. The cover may be multi-layered.

A golf ball comprising layers that have from 0.05% to 70% by weight of a radio-opaque filler, and wherein the concentration of the radio-opaque filler is measurably different in each layer is disclosed herein. The radio-opaque filler is preferably a compound based on barium, bismuth, tungsten, iodine, or reduced iron.

Multi-layer golf balls having a hard, high compression center, a relatively soft intermediate layer, and a stiff outer cover layer, are provided. The outer surface hardness of the intermediate layer is less than that of both the center and the outer cover layer.

The invention provides a golf ball having a core and a cover of one layer or a plurality of layers, wherein the core is formed of a material molded under heat from a rubber composition containing (A) a base rubber, (B) an organic peroxide, and (C) water and/or a metal monocarboxylate, and has a hysteresis loss of 50% or less when compressed at a load cell speed of 500 mm/min and under a constant load of 5,000 N.

A cured elastomer golf ball component is made by heating an elastomer compound containing an ethylenically unsaturated elastomer, an ethylenically unsaturated monomer, and first and second free radical initiators to a first crosslinking temperature T.sub.1 in a compression mold and partially crosslinking the elastomer, then heating to a second crosslinking temperature T.sub.2 and curing the elastomer component of the golf ball. Either: (i) the first initiator has a half-life of about 0.2-5 minutes at T.sub.1, the second initiator has a half-life of about 0.2-5 minutes at T.sub.2, and T.sub.2 is higher T.sub.1 by at least about 30° C.; or (ii) the second initiator's one-minute half-life temperature is at least about 30° C. higher than the first initiator's one-minute half-life temperature, T.sub.1 is within about 20° C. of the first initiator's one-minute half-life temperature, and T.sub.2 is within about 20° C. of the second initiator's one-minute half-life temperature.

A golf ball resin composition contains a base resin for which, in dynamic viscoelasticity measurement, the storage modulus of the base resin measured at 23° C., 15 Hz and 1.0% strain, and tan δ determined under the same conditions, satisfy specific values; and for which the storage modulus of the base resin measured at 23° C., 15 Hz and 10% strain, and tan δ determined under the same conditions, satisfy specific values. By using this resin composition as a golf ball cover material, the force delivered to the ball while the ball and the clubface are in contact from impact to follow-through is more easily felt, facilitating distance control of the ball. Controllability with a short iron such as a sand wedge around the green is also excellent.

Golf balls having multi-layered covers, wherein at least one of the cover layers is substantially transparent, are provided. The cover includes an inner cover layer made of an ionomer composition; an intermediate cover layer made of an aromatic polyurethane composition; and outer cover layer made of an aliphatic polyurethane composition, wherein the total thickness of the multi-layered cover is no greater than 0.110 inches. In one version, the outer cover layer is substantially transparent and the underlying intermediate cover layer is colored. In another version, both the outer and intermediate cover layers are substantially transparent. Light-reflective fillers such as pearlescent pigments, glitter, and metallics may be added to the cover layers. The resulting ball has pleasing decorative effects.