The present invention provides the rubber composition for a golf ball comprising (a) a base rubber, (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid or a metal salt thereof or both, (c) a crosslinking initiator, and (d) an alcohol, wherein the amount of component (d) is from 0.1 to 10 parts by weight per 100 parts by weight of the base rubber (a) and the compounding ratio between component (b) and component (c) is set to at least 60 of E value that is represented by “E=the molar amount of component (b)/the molar amount of the active oxygen of component (c), and a golf ball using the rubber composition, in order to achieve the object that good durability of the golf ball to impact is maintained.

The present invention provides a golf ball comprising a core of one or more layers and a cover of one or more layers which encases the core, wherein at least one layer of the cover is formed of the resin composition comprising (a′) a polyester resin and (b) an amine-containing polymer having a branched structure. In the golf ball of the present invention, the adhesion property between the core and each cover layer adjacent to the core can be improved and the excellent durability can be obtained.

In a golf ball having a core, a cover and a coating layer, the coating layer is formed of a urethane coating that includes an organic solvent having a boiling point of 80° C. or less, a silicone-based additive and, as a curing agent, a polyisocyanate which contains an adduct and an isocyanurate of hexamethylene diisocyanate. Although the golf ball includes a silicone-based additive in the outer surface (coating layer) of the ball, it has a good spin performance on approach shots not only when wet but also when normally dry, and is capable of exhibiting both a good water-repelling performance and a good friction performance.

A golf ball according to the present invention includes a core, a cover located outside the core and having a plurality of dimples, and a coating layer located outside the cover and containing a delusterant, the surface of the coating layer having an average roughness Ra of at least 0.35. The surface of the golf ball has a static friction coefficient of at least 0.20. A method for producing a golf ball according to the present invention includes forming a coating layer on the surface of a cover having a plurality of dimples by using a coating material composition including a polyurethane coating material, a delusterant, and a solvent having a boiling point of at least 130° C.

Golf ball molds and methods for molding golf balls, particularly golf balls having thermoplastic polyurethane covers, are provided. The molds and methods are particularly suitable for manufacturing covers for golf balls. Multi-piece golf balls having inner cores, outer cores, inner covers, and intermediate layers can be made. Retractable pins are used for holding the golf ball within the mold, wherein each retractable pin has a primary vent section, secondary vent section, and tertiary vent section for removing air and other gasses from the interior spherical cavity of the mold.

In a golf ball having a core of at least one layer and a cover of at least one layer encasing the core, at least one layer of the cover is formed of a resin composition which includes (I) a polyurethane or a polyurea, (II) a thermoplastic polyester elastomer and (III) an aromatic vinyl elastomer. The thermoplastic polyester elastomer serving as component (II) and the aromatic vinyl elastomer serving component (III) have specific respective contents and properties, including Shore D hardnesses and rebound resiliences. The golf ball has an excellent controllability on approach shots without a loss of distance on driver shots. In addition, the scuff resistance and moldability are good.

In a golf ball having a core and a cover, the cover is formed primarily of polyurethane, the ball has a weight of 44.8 g or less and, in an impact test carried out by hitting the ball with a driver at a head speed of 40 m/s, the sum t1+t2 of the time t1 required from initial contact by the driver with the ball for deformation of the ball to reach a maximum and the time t2 required from the state of maximum ball deformation for the ball and driver to separate is 650 μsec or less. This golf ball makes it possible for golfers who have a high head speed and ordinary golfers who do not to compete without relying excessively on superiority in terms of distance.

In a golf ball having a core and a cover, the cover is formed primarily of polyurethane, the ball has a diameter of at least 43.0 mm and, in an impact test carried out by hitting the ball with a driver at a head speed of 40 m/s, the sum t1+t2 of the time t1 required from initial contact by the driver with the ball for deformation of the ball to reach a maximum and the time t2 required from the state of maximum ball deformation for the ball and driver to separate is 650 μsec or less. This golf ball makes it possible for golfers who have a high head speed and ordinary golfers who do not to compete without relying excessively on superiority in terms of distance.

In a golf ball having a core and a cover with a plurality of dimples on the surface, the cover is formed primarily of polyurethane, the dimples have a specific volume occupancy ratio and the ball has a diameter of at least 42.8 mm. In an impact test carried out by hitting the ball with a driver at a head speed of 40 m/s, the sum t1+t2 of the time t1 required from initial contact by the driver with the ball for deformation of the ball to reach a maximum and the time t2 required from the state of maximum ball deformation for the ball and driver to separate is 660 μsec or less. This golf ball makes it possible for golfers who have a high head speed and ordinary golfers who do not to compete without relying excessively on superiority in terms of distance.

In an aspect, a sports ball includes a core including a negative Poisson's ratio (NPR) foam material, in which the core has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR polymer foam; and a cover layer surrounding the core. In an aspect, a golf club includes an elongated shaft; a grip disposed at a first end of the elongated shaft; and a head connected to a second end of the elongated shaft, the head having a flat face configured for contact with a golf ball, in which the flat face is formed of a negative Poisson's ratio (NPR) foam material, in which the head has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.