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 3.8 mm or more, 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, where 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.

In a golf ball comprising a core, a cover layer, an intermediate layer between the core and the cover layer, the cover layer is formed of a resin material composed primarily of polyurethane or polyurea, a sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) has a lightness (Li value) in the L*a*b* color space of at least 25 on its surface, and the cover layer has a visible light transmittance of at least 0.6%. The golf ball has a surface with a distinctive aesthetic appearance and retains both a good spin performance and a good scuff resistance, making it useful as a ball for professional and skilled amateur golfers.

In a golf ball having a rubber core of at least one layer and a cover of at least one layer that encases the core, at least one layer of the cover is formed of a resin composition which includes (A) a polyurethane or a polyurea, (B) an alkyl methacrylate/alkyl acrylate copolymer, and (C) a fatty acid amide. The golf ball has an excellent mold releasability during molding of the cover while retaining a good spin rate on approach shots, scuff resistance and paint film durability.

A method for forming a golf ball with a graphene core disclosed herein. The method includes mixing a graphene masterbatch material with a polybutadiene material to form a core mixture, wherein the graphene masterbatch material comprises graphene in an amount from 0.1 to 80.0 weight percent of the graphene masterbatch material mixed with a carrier polymer in an amount from 99.9 to 20 weight percent of the graphene masterbatch material.

A golf ball with a cover layer composed of a blend of non- or partially neutralized copolymeric or terpolymeric ionomer(s), hydroxyl-functionalized styrenic block copolymer and silane coupling agent (SCA). The amount of SCA is preferably between 0.01 and 2.0 weight percent based on the total weight of the polymer composition. The cover layer preferably has a Shore A hardness less than 90.

The present invention provides methods for producing molded golf balls and the resultant balls. The methods of this invention involve producing foamed polyurethane covers and these methods help reduce dimple distortions and other surface imperfections. These golf balls contain an inner core and outer foamed polyurethane cover. One or more intermediate layers can be disposed between the core and cover. In one embodiment, a castable liquid polyurethane composition containing a foaming agent is dispensed into mold cavities, which are then pressed together to form a foam cover for the ball.

A golf ball wherein a slide amount Ds is 1.05 mm or less and a post-slide contact time Tc is 600 μs or more in the case where a golf ball 140 is dropped freely from a height position of 3 m above and away from a collision surface 130a inclined 58 degrees with respect to a horizontal direction to collide with the collision surface, the slide amount Ds being a vertical displacement of the golf ball from when the golf ball starts sliding on the collision surface to when the golf ball stops sliding on the collision surface, and the post-slide contact time Tc being a period from when the golf ball stops sliding on the collision surface to when the golf ball leaves the collision surface.

An object of the present invention is to provide a golf ball having improved ball speed or aerodynamic performance on a rainy day or the like by controlling the formulation of the paint film. The present invention provides a golf ball comprising a golf ball body and a paint film covering the golf ball body, wherein a paint film surface of the golf ball has a water contact angle A1 of 70° or more and a water sliding angle B1 of less than 50°. The present invention also provides a golf ball comprising a golf ball body and a paint film covering the golf ball body, wherein when a sheet consisting of a slab formed from a composition constituting a golf ball body surface and a coating film formed by applying a paint constituting the paint film on the slab is prepared, a coating film surface of the sheet has a water contact angle A2 of 90° or more and a water sliding angle B2 of less than 52°.

A golf ball with improved durability is disclosed herein. The golf ball has a mantle layer comprising a blend of ionomers and methyl methacrylate, butadiene, styrene (MBS) with a weight percentage of MBS ranging from 5 to 15 weight percent of the mantle layer.

A golf ball with a center core comprising 1,4 polybutadiene with a cis content more than 50% and containing a metal salt of acrylate, wherein the 1,4 polybutadiene has 5 to 60 weight percent of a metal salt of acrylate, is disclosed herein. The metal salt of acrylate is preferably selected from zinc, magnesium, sodium, and calcium.