In a golf ball having a core and a cover of at least one layer, the outermost layer of the cover is formed of a resin composition that includes (A) 100 parts by weight of a thermoplastic resin, and (B) 1 to 30 parts by weight of a compound having a fluorene skeleton, or a derivative thereof, and the resin composition has a melt flow rate of at least 3.0 g/10 min. This resin composition for golf balls has an improved injection-moldability and thus enables the ball to achieve both a reduced spin rate and a good durability (scuff resistance).

Golf ball comprising layer(s) comprised of plasticized neutralized acid polymer composition consisting of mixture of: (a) low molecular weight acid-containing wax(es); (b) non-acid-polymer(s) including at least one low molecular weight non-acid wax such as high density oxidized polyethylene homopolymers; ethylene maleic anhydride copolymers; polypropylene maleic anhydride copolymers; polypropylene homopolymers; ethylene-vinyl acetate copolymers; high density oxidized homopolymers; oxidized copolymers; polyethylene micronized waxes; polytetrafluoroethylene micronized waxes; emulsifiable low molecular weight non-acid waxes; non-emulsifiable low molecular weight non-acid waxes; and/or chemically modified low molecular weight non-acid waxes; (c) organic acid(s) or salt thereof; and (d) plasticizer(s). Molecular weight of each low molecular weight acid-containing wax is about 500 to 7000, or up to 30,000. Interactions between components (a), (b), (c) and (d) advantageously produce layer of ionomeric material having heat stability, processability, and well-retained durability, adhesion, CoR, compression and softer feel without need for blending high and low molecular weight acid-containing polymer(s).

Golf ball comprising layer(s) comprised of neutralized acid polymer composition consisting of mixture of: (a) low molecular weight acid-containing wax(es); (b) non-acid polymer(s) including at least one low molecular weight non-acid wax such as high density oxidized polyethylene homopolymers; ethylene maleic anhydride copolymers; polypropylene maleic anhydride copolymers; polypropylene homopolymers; ethylene-vinyl acetate copolymers; high density oxidized homopolymers; oxidized copolymers; polyethylene micronized waxes; polytetrafluoroethylene micronized waxes; emulsifiable low molecular weight non-acid waxes; non-emulsifiable low molecular weight non-acid waxes; and/or chemically modified low molecular weight non-acid waxes; and (c) organic acid(s) or salt thereof. Molecular weight of each low molecular weight acid-containing wax is about 500 to 7000, or up to 30,000. Interactions between components (a), (b), and (c) advantageously produce layer of ionomeric material having heat stability, processability, and well-retained durability, adhesion, CoR, compression and targeted feel without need for blending high and low molecular weight acid-containing polymer(s).

Golf ball having CoR of at least 0.700 and comprising: a substantially spherical subassembly having diameter of 1.3 inches or greater and compression of from about 15-60; and a thin outer layer having a compression molded thickness of about 0.015-0.055 inches and consisting of first and second hemispherical cups consisting of a polymer composition having a melt flow index at 190 C. under a 2.16-kg load of from about 0.8 g/10 min. to about 4 g/10 min. and having a cup thickness ratio of from about 1.10 to 1.70 as well as an inner surface that is sized, shaped and contoured to receive and conformally and adhesively mate onto and about the subassembly during compression molding such that the subassembly in the finished golf ball is substantially spherical and disposed concentrically within the thin outer layer. Also, the novel hemispherical cups and the method of making the golf ball.

A golf ball can include a core, a mid layer, and a cover. An amount P(Na) of a sodium ion-neutralized ionomer resin in abase resin of the cover can be not greater than 5 parts by mass. The golf ball can satisfy the following mathematical formulas (1) and (2):

[00001]$\begin{array}{cc}\mathrm{Fm}/\left(\mathrm{Hm}*\mathrm{Tm}\right)-\mathrm{Fc}/\left(\mathrm{Hc}*\mathrm{Tc}\right)3.,\mathrm{and}& \left(1\right)\end{array}$$\begin{array}{cc}\mathrm{Mc}*\mathrm{Tc}10.,& \left(2\right)\end{array}$

where Hm: hardness (Shore D) of the mid layer, Tm: thickness (mm) of the mid layer, Fm: bending stiffness (MPa) of the mid layer, Tc: thickness (mm) of the cover, Fc: bending stiffness (MPa) of the cover, and Mc: melt flow rate (g/10 min) of the cover at a temperature of 190 C. under a load of 2.16 Kg.

An object of the present disclosure is to provide a golf ball having good shot feeling and excellent durability while having non-lowered resilience. The present disclosure provides a golf ball comprising a spherical core and one or more cover layers disposed outside the spherical core, wherein at least one layer of the cover layers contains (A) a base resin and (B) a polyethylene oxide.

In a golf ball having a rubber 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 that includes (I) a polyurethane or a polyurea and (II) an aromatic vinyl elastomer, the amount of component (II) included per 100 parts by weight of component (I) is less than 15 parts by weight, and the CS.sub.1 value calculated by formula (1) below

[00001]$\begin{array}{cc}C{S}_1=\left(C{V}_{50}-C{V}_{12}\right)/38& \left(1\right)\end{array}$

(wherein CV.sub.50 is the coefficient of restitution at an incident velocity of 50.0 m/s and CV.sub.12 is the coefficient of restitution at an incident velocity of 12.0 m/s) is larger than 4.0810.sup.3, so that the golf ball has both an excellent controllability and a good feel at impact on approach shots together with a good scuff resistance.

In a golf ball having a rubber core and a cover of at least one layer encasing the core, at least one cover layer is formed of a resin composition that includes a thermoplastic polyurethane and an inorganic filler. The inorganic filler content is at least 5 parts by weight per 100 parts by weight of the thermoplastic polyurethane. The resin composition has an abrasion volume in the Taber abrasion test according to JIS-K 7311 of more than 0.003 cm.sup.3 and satisfies formula (1) below

[00001]$\begin{array}{cc}7.010^4>\left(1-2\right)/H^3,& \left(1\right)\end{array}$

wherein H is the Shore D hardness and 1 and 2 are respectively the 210 C. and 220 C. melt viscosities (Pa.Math.s) at a shear rate of 6,080 sec.sup.1 when measured with a capillary rheometer in accordance with ISO 11443: 1995. The cover resin material has improved flowability when molded and improved trimmability after molding.

An object of the present disclosure is, for a golf ball comprising a cover containing a polyurethane as a resin component, to improve the moldability of the cover and increase the productivity of the golf ball while suppressing lowering in the scratch resistance of the cover. The present disclosure provides a golf ball comprising a spherical core and a cover covering the spherical core, wherein the cover is formed from a cover composition containing (A) a thermoplastic polyurethane and (B) an olefin/unsaturated carboxylic acid copolymer and/or an olefin/unsaturated carboxylic acid/unsaturated carboxylic acid ester copolymer as a resin component, and an amount of (A) the thermoplastic polyurethane is 50 mass % or more in the resin component.

A golf ball includes a core, a mid layer, and a cover. A slope A1 of a straight line connecting a central point of the core and a point at 2.5 mm from the central point and a slope A2 of a straight line connecting the point at 2.5 mm and a point at 5.0 mm from the central point are each 1.00 or more. A slope A5 of a straight line connecting a point at 10.0 mm from the central point and a point at 12.5 mm from the central point and a slope A6 of a straight line connecting the point at 12.5 mm and a point at 15.0 mm from the central point are each 1.50 or more. The cover is formed of a resin composition containing an ionomer resin, with the ionomer resin present in an amount of 60% by mass or more.