In a golf ball having a core, a cover and at least one intermediate layer therebetween, the cover is formed of a rubber composition which includes a diene rubber, methacrylic acid, a metal oxide and an organic peroxide. The cover has a specific Poisson's ratio, Shore D hardness and thickness. At least one intermediate layer has a specific Shore D hardness and thickness. This golf ball, even with the use of a rubber cover, compares favorably with balls having conventional resin covers, both in that it can achieve a lower spin rate on shots with a driver (W #1) and thus has an excellent flight performance and also in that it can improve controllability in the short game.

An object of the present invention is to provide a golf ball travelling a great flight distance on driver shots on a rainy day and having excellent spin performance on approach shots. The present invention provides a golf ball comprising a golf ball body and a paint film covering the golf ball body and composed of at least one layer, wherein an outermost layer of the paint film is formed from a paint containing a polyol, a polyisocyanate, and a carbinol modified silicone oil different from the polyol compound.

A golf ball can have a large number of dimples on a surface thereof. A trajectory of the golf ball can be calculated under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm satisfying the following mathematical formula,

[00001]$\text{Amax}\ge \text{4}\text{.0}\text{*}\text{Vave + 13}\text{.10,}$

wherein Amax represents a maximum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm.sup.3) of the dimples. The vector angle A can be calculated by the mathematical formula

[00002]$\text{A}\text{=}\text{ATAN}\left(\text{Vy}/\text{Vx}\right),$

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

An object of the present disclosure is to provide a golf ball having an increased spin rate when being hit with an 8-iron while suppressing rise in a spin rate when being hit with a driver. The present disclosure provides a golf ball comprising a spherical core having an inner core and an outer core, and a cover positioned outside the spherical core, wherein A×a is 12,200 or less and B×b is 20,400 or more, where “a” represents an average hardness (Shore C) of a hardness (H2.5) at a point of 2.5 mm from a center of the spherical core and a hardness (H5) at a point of 5 mm from the center of the spherical core, “b” represents an average hardness (Shore C) of a hardness (H7.5) at a point of 7.5 mm from the center of the spherical core and a hardness (H9) at a point of 9 mm from the center of the spherical core, “A” represents an impulse difference (kN.Math..Math.s) between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with a driver, and “B” represents an impulse difference (kN.Math..Math.s) between a back spin impulse and a top spin impulse measured using a contact force tester under a condition corresponding to a condition when the golf ball is hit with an 8-iron.

An object of the present invention is to provide a golf ball travelling a great flight distance on driver shots on a rainy day and having excellent spin performance on approach shots. The present invention provides a golf ball comprising a golf ball body and a paint film covering the golf ball body and composed of at least one layer, wherein an outermost layer of the paint film is formed from a paint containing a polyol, a polyisocyanate, and a carbinol modified silicone oil different from the polyol compound.

A rubber composition for golf balls includes (a) a base rubber, (b) a co-crosslinking agent which is an α,β-unsaturated carboxylic acid and/or a metal salt thereof, (c) a crosslinking initiator, (d) an alcohol and (e-1) an organosulfur, and 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 organosulfur of component (e-1) is alkylphenoldisulfide polymers represented by the specific chemical formula. When the rubber composition is used in a golf ball having a core and a cover of one or more layers encasing the core, by setting the hardness difference in the core interior hardness profile to a large value while maintaining a desired core hardness, low spin properties can be manifested on golf ball shots, enabling the flight performance of the ball to be improved.

In a golf ball having a core of one or more layer and a cover of one or more layer encasing the core, the core has a deflection when compressed under a specific load of at least 3.8 mm; at least an innermost portion of the core has a specific difference between maximum and minimum values in cross-sectional hardnesses (JIS-C) from a center to a surface thereof; and the center core is formed of a rubber composition that includes (a) a base rubber, (b) an α,β-unsaturated carboxylic acid and/or metal salt thereof, (c) a diacyl peroxide and/or a peroxyester, and (d) a dialkyl peroxide and/or a peroxyketal. The golf ball has a low spin rate on driver shots by low head speed golfers, and thus achieves an improved distance, while minimizing any decrease in durability.

An object of the present invention is to provide a golf ball travelling a great flight distance on driver shots on a rainy day and having excellent spin performance on approach shots. The present invention provides a golf ball comprising a golf ball body and a paint film covering the golf ball body and composed of at least one layer, wherein an outermost layer of the paint film is formed from a paint containing a polyol, a polyisocyanate, and a carbinol modified silicone oil different from the polyol compound.

Golf balls having a single or dual-layered solid core are provided. In one embodiment, the golf ball has dimensions and properties that do not conform to the rules of the United States Golf Association (USGA). For example, the ball weight; ball size; ball spherical symmetry; ball initial velocity; and/or ball overall distance may fall outside of the USGA standards. The dual-layered core can have an inner core comprising a thermoplastic composition and surrounding outer core comprising a thermoset composition. In another embodiment, the dual-layered core has an inner core comprising a thermoplastic composition and outer core comprising a thermoset composition. The thermoplastic composition preferably comprises an ethylene acid copolymer ionomer and plasticizer. The thermoset composition preferably comprises polybutadiene rubber. The ball further includes a cover of at least one layer.

A golf ball having a cover with a plurality of dimples on the surface thereof is provided with a coat of mutually differing properties on dimple areas of the surface and on land areas between the dimples. The land areas are formed with a coat having a high coefficient of friction and the dimple areas have a surface energy of not more than 32 dynes, enabling a lower spin rate to be achieved and thus increasing the distance traveled by the ball, particularly when struck with a middle iron, and also help impart a high spin rate and a good controllability on approach shots.