A multi-piece solid golf ball for professional golfers and skilled amateurs in particular is endowed with an excellent distance, a soft yet good feel at impact and a good durability. In the ball, which includes a core, an envelope layer, an intermediate layer and a cover, the core has a hardness profile which satisfies specific conditions, the envelope layer has a thickness of from 0.3 to 1.2 mm, the intermediate layer has a thickness of from 0.3 to 1.2 mm, and the envelope and intermediate layers have a combined thickness from of 0.8 to 1.7 mm.

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.

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.

A golf ball has a plurality of dimples 12 and a land 14 on a surface thereof. The golf ball further has a large number of minute projections 18 formed on surfaces of the dimples 12 and the land 14. The surface of the golf ball has an arithmetic average height Sa of not less than 0.5 m and not greater than 30 m. An average value Hav of heights H of the minute projections 18 is not less than 0.5 m and not greater than 50 m. A ratio Pp of a sum of areas of all the minute projections 18 to a surface area of a phantom sphere of the golf ball is not less than 7%. An average value Dav of diameters D of the minute projections 18 is not less than 5 m and not greater than 50 m.

A golf ball with a core comprising polybutadiene and graphene, and a soft cover is disclosed herein. The golf ball has a dual core with an outer core comprising polybutadiene and graphene. The soft cover is preferably composed of a highly neutralized polymer, a first ionomer, a second ionomer, and an impact modifier.

Golf balls having covers made of thermoplastic polyurethane compositions are provided. Multi-piece golf balls can be made. Polyurethane primer coatings and polyurethane top-coatings are applied to the thermoplastic polyurethane cover. Isocyanate-rich and polyol-rich polyurethane coatings can be applied. In one embodiment, multi-functional imine and amine compounds can be used to treat the golf ball. The resulting coating may contain polyurethanes, polyureas, and hybrids, copolymers, and blends thereof. The cover composition and surface coatings can further include catalysts, ultraviolet (UV)light stabilizers, and other additives. Heat is used to cure the coatings. The coating methods have many benefits and the finished balls have good physical properties.

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).

In a multi-piece solid golf ball having a core, an intermediate layer encasing the core and a cover which encases the intermediate layer and has numerous dimples on an outside surface thereof, the intermediate layer is formed of a resin material, the cover is formed of a urethane resin material, the core has a diameter of at least 38.0 mm, the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of at least 3.9 mm, the core has a center and a surface such that the value obtained by subtracting the JIS-C hardness at the core center from the JIS-C hardness at the core surface is at least 15, the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) has a surface hardness on the Shore D hardness scale of at least 69, the ball has a surface hardness on the Shore D hardness scale of 62 or less, and the (intermediate layer thickness)/(core diameter) value is from 0.025 to 0.043, the (cover thickness)/(core diameter) value is from 0.014 to 0.027.

A method for manufacturing a golf ball having a core, an intermediate layer and a cover that is formed of a resin material composed primarily of a polyurethane resin and has a thickness of 0.1 mm to 0.7 mm by injection molding the cover using a vertically separating two-part injection mold having specific gate and support pin configurations. This method enables a relatively soft urethane resin cover that is thin and of high quality to be formed, and has a good golf ball productivity.

To provide a golf ball that can prevent a decrease in carry distance of a driver shot when it rains and also, can exert excellent spinning performance upon an approach shot. The golf ball of the present invention includes a core, a cover that is provided on an outer side of the core and is provided with dimples, and an outermost layer that is formed on an outer side of the cover and made of a material having a contact angle of 90 or more. The golf ball has a dynamic friction coefficient of 0.52 or more. The material constituting the outermost layer comprises a urethane coating that contains a water repellent additive, and the water repellent additive includes a fluorinated surfactant, silicone-modified acrylate or hydrophobic silica.