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.

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 acid copolymer ionomer. The cover composition also can contain hydroxyl-containing compounds. The golf ball having the thermoplastic polyurethane cover can be treated with an isocyanate compound. The golf ball also can be treated with an amine and/or silane-containing compound. 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 have good physical properties.

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.

A resin composition for golf balls is made of (A) polyurethane or polyurea and (B) an acrylic resin or a methacrylic resin, component (B) being included in an amount of from 0.5 to 50 parts by weight per 100 parts by weight of component (A). In a golf ball having a core and a cover of one or more layer encasing the core, at least one cover layer is formed of this resin composition. The resin composition is especially useful as a golf ball cover material because it makes it possible to achieve a higher ball initial velocity on shots with a driver and a lower ball initial velocity on approach shots.

An object of the present invention is to provide a golf ball resin composition having improved rebound resilience performance. The present invention provides a golf ball resin composition containing: (A) a thermoplastic resin having an infrared absorption peak in a region from 3200 cm.sup.1 to 3600 cm.sup.1, and (B) at least one resin component selected from the group consisting of (b-1) a binary copolymer composed of an olefin and an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-2) a metal ion-neutralized product of a binary copolymer composed of an olefin and an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms, (b-3) a ternary copolymer composed of an olefin, an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and an ,-unsaturated carboxylic acid ester, and (b-4) a metal ion-neutralized product of a ternary copolymer composed of an olefin, an ,-unsaturated carboxylic acid having 3 to 8 carbon atoms and an ,-unsaturated carboxylic acid ester, wherein when a relaxation modulus Er (20 C., 9%) of the golf ball resin composition is measured under conditions of 20 C. and a strain of 9%, a relaxation curve is plotted with the relaxation modulus (MPa) as the vertical axis and a logarithm (ln(t)) of time (sec) as the horizontal axis, and the relaxation curve is linearly approximated to obtain a linear approximation curve, the linear approximation curve has a slope in an absolute value of 7 or more.

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.

In a golf ball having a core of at least one layer and a cover encasing the core, the cover is formed of a resin composition composed primarily of a polyurethane or a polyurea. Letting HMa (N/mm.sup.2) be the Martens hardness of the cover measured at a position 0.3 mm toward the center of the ball from the cover surface and Ita (%) be the elastic recovery of the cover, HMa and Ita satisfy the following conditions: (1) Ita1.16HMa+79, (2) 10.0HMa38.0, and (3) 40Ita80. The ball has an excellent spin performance on approach shots and an excellent scuff resistance.

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 acid copolymer ionomer. The cover composition also can contain hydroxyl-containing compounds. The golf ball having the thermoplastic polyurethane cover can be treated with an isocyanate compound. The golf ball also can be treated with a hydroxyl and/or silane-containing compound. 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 have good physical properties.

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 a loss tangent (tan ) of the outermost paint film layer measured with a dynamic viscoelasticity measuring apparatus under specific conditions has a peak temperature in a range of from 40 C. to 40 C.

An object of the present invention is to provide a golf ball having excellent spin performance on approach shots under a dry condition and excellent spin performance on approach shots under the condition that there is grass between the golf ball and the club face. The present invention provides golf ball comprising a golf ball body and a paint film formed on a surface of the golf ball body, wherein the paint film has a multi-layered construction composed of two or more layers, a ratio (M1/E1) of a 10% elastic modulus (kgf/cm.sup.2) (M1) of an innermost layer of the paint film to a maximum elongation (%) (E1) of the innermost layer of the paint film is 10 or more and 50 or less, and the ratio (M1/E1) of the innermost layer of the paint film is greater than a ratio (M2/E2) of a 10% elastic modulus (kgf/cm.sup.2) (M2) of an outermost layer of the paint film to a maximum elongation (%) (E2) of the outermost layer of the paint film.