An object of the present invention is to provide a golf ball having excellent approach spin performance under a dry condition and excellent approach spin performance under a condition that there is grass between the golf ball and the club face. The present invention provides a golf ball comprising a golf ball body and a paint film formed on a surface of the golf ball body, wherein the paint film is composed of at least one layer, and an outermost paint film layer located at the outermost layer of the golf ball contains, as a base resin, a polyurethane obtained by a reaction between (A) a polyisocyanate composition and (B) a polyol composition, (B) the polyol composition contains a urethane polyol as a polyol component, and the outermost paint film layer has a dynamic friction coefficient of from 0.65 to 1.2 measured with a dynamic friction tester under specific conditions.

A golf ball with embedded electronics to allow proximity to be tracked and to monitor golfer performance is disclosed. The golf ball comprises a processor connected to an accelerometer, communications circuitry, a spin detector, and memory, wherein the processor stores accelerometer data from the accelerometer and rotation data regarding rotation of the spin detector in the memory. The processor converts the data regarding the rotation of the spin detector into a rotation speed and a rotation direction, said rotation speed determined by a frequency of the data, and said rotation direction determined by a magnitude of the data. The communications circuitry is configured to communicate the accelerometer data, the rotation direction, and the rotation speed to a central interrogator for analysis of a golfer's performance.

Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided.

Buoyant dimpled golf ball having CoR0.810, specific gravity <1.00 g/cc, initial velocity 250 ft/s, first aerodynamic coefficient magnitude between about 0.25 and about 0.30 and first aerodynamic force angle between about 29 degrees and 34 degrees at Reynolds Number of 230000 and spin ratio of 0.085; and second aerodynamic coefficient magnitude between about 0.26 and about 0.31 and second aerodynamic force angle between about 31 degrees and 36 degrees at Reynolds Number of 180000 and spin ratio of 0.101. Golf ball may additionally have third aerodynamic coefficient magnitude between about 0.27 and about 0.32 and third aerodynamic force angle between about 34 degrees and 39 degrees at Reynolds Number of 133000 and spin ratio of 0.133; and fourth aerodynamic coefficient magnitude between about 0.33 and about 0.38 and fourth aerodynamic force angle between about 38 degrees and 43 degrees at Reynolds Number of 89000 and spin ratio of 0.183.

An object of the present invention is to provide a cured product of a golf ball rubber composition capable of imparting excellent durability to a golf ball. The present invention provides a cured product of a golf ball rubber composition, wherein the golf ball rubber composition contains (a) a base rubber, (b) an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator, and wherein an effective crosslinking density DC (mmol/cm.sup.3) of the cured product of the golf ball rubber composition and a tensile elastic modulus TM (MPa) between 0.05% strain and 0.25% strain of the cured product of the golf ball rubber composition satisfy a relation of TM3.33In(DC)>(0.10).

A golf ball 2 includes a main body 4 and a paint layer 6 positioned outside the main body 4. The main body 4 includes a spherical core 8, a mid layer 10 positioned outside the core 8, and a cover 12 positioned outside the mid layer 10. An outer surface of the paint layer 6 forms a surface of the golf ball 2. A contact angle CAw with respect to water measured on the surface of the golf ball 2 is not less than 70 degrees. The paint layer 6 is preferably formed from a resin composition. A preferable resin composition includes a polyurethane as a base resin and includes a silicone compound and/or a fluorine compound. Another preferable resin composition includes a silicone compound and/or a fluorine compound as a base resin and includes no polyurethane.

A golf ball includes a main body and a paint layer positioned outside the main body. The paint layer includes an inner layer and an outer layer positioned outside the inner layer. When an indentation depth (nm) is measured on a cross-section along a plane passing through a central point of the golf ball when a force of 30 mgf is applied to the cross-section in a direction perpendicular to the cross-section, an indentation depth Di on a cross-section of the inner layer is smaller than an indentation depth Do on a cross-section of the outer layer. A thickness To of the outer layer is larger than a thickness Ti of the inner layer.

An object of the present invention is to provide a cured product of a golf ball rubber composition imparting excellent durability. The present invention provides a cured product of a golf ball rubber composition cured from a golf ball rubber composition containing (a) a base rubber, (b) an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator, wherein the cured product of the golf ball rubber composition satisfies the following mathematical formula (1):

Y<0.1X1.30(1) in the formula (1), Y represents an effective crosslinking density of the cured product of the rubber composition (mmol/cc), and X represents an amount of the component (b) with respect to 100 parts by mass of (a) the base rubber (parts by mass).

Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. In one embodiment, the outer cover layer is formed from a composition comprising a thermoplastic polyurethane and polydimethylsiloxane compound. Functionalized polydimethylsiloxane compounds also can be used to treat thermoplastic polyurethane golf ball covers. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)-light stabilizers, and other additives. The coating methods have many benefits and the finished balls with thermoplastic polyurethane covers have good physical properties.

Multi-piece golf balls having a multi-layered solid core and multi-layered cover are provided.