Golf ball comprising a core having a hardness gradient and an outer cover layer having a microhardness gradient and being formed from a thermoset polyurethane material throughout, and having: i) a treated region that is contacted with a thermoset polyurethane microhardness-increasing solution consisting of an isocyanate portion and at least one non-aqueous solvent; and ii) an untreated region that is not contacted with the thermoset polyurethane microhardness-increasing solution. The treated region comprises the isocyanate portion, whereas the untreated region does not comprise the isocyanate portion. Treated region has a microhardness M.sub.1 that is greater than microhardness M.sub.2 of untreated region to define the outer cover layer positive microhardness gradient M=M.sub.1M.sub.2. The treated region may have a depth Dtr that extends inward from the cover outer surface and in some embodiments is less than a thickness of the untreated region. Treated region may alternatively extend from the inner surface toward outer surface.

Golf ball incorporating thermoplastic blend of (i) ionomer(s); (ii) different thermoplastic polymer(s) selected from thermoplastic polyurethane(s), thermoplastic urea(s), and/or thermoplastic urea-urethane hybrid(s); and (iii) polyester elastomer(s) and/or polyamide elastomer(s) (PEPA). Ionomer is present in amount of about 45 wt % or greater and PEPA present in amount of from about 2 wt % to about 35 wt %. Thermoplastic polymer(s) may be present in amount of from about 8 wt % to about 50 wt %; or from about 25 wt % to about 45 wt %; or from about 35 wt % to about 50 wt %. Ionomer amount may be greater than amount of thermoplastic polymer. Thermoplastic polymer may be a polyurethane present in amount of greater than 20 wt % and to about 40 wt %; while the PEPA is present in amount of from about 5 wt % to about 30 wt %. PEPA is sometimes present in an amount of from about 15 wt % to about 35 wt %.

A golf ball includes a core having an outer surface and a geometric center. The core is formed from a substantially homogenous rubber composition. An ionomeric inner cover layer is formed about the core and has a material hardness of about 60 Shore D or greater. The golf ball includes an outer cover layer formed from a polyurea or a polyurethane and having a material hardness of about 60 Shore D or less. The outer surface of the core has a trans content of about 12% or less and a hardness of about 71 to 88 Shore C. The geometric center of the core has a trans content of about 10% or less and a hardness of about 60 to 80 Shore C. The core has an outer surface hardness greater than a geometric center hardness by about 5 to 19 Shore C to define a positive hardness gradient.

Multi-layered, golf balls having a core made of a foamed composition are provided. The core preferably has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. The core also includes a structural insert such as, for example, a solid shell, perforated shell, a lattice or mesh, or a central hub with extending arms, and the like. The core layers have different hardness gradients and specific gravity values. The ball further includes a cover having at least one layer. By adjusting the respective specific gravity values of the core layers, the Moment of Inertia (MOI) of the ball can be increased or decreased. In one embodiment, the ball has generally good flight distance and low spin rate.

Methods for making multi-piece golf balls comprising at least one component made of ethylene-propylene diene copolymer (EPDM) rubber and the resulting balls are provided. The multi-piece golf ball includes a cover, preferably a dual-cover having inner and outer cover layers. The outer cover is preferably made of a liquid rubber composition based on liquid EPDM rubber. In one version, the ball sub-assembly is dipped in a bath containing liquid EPDM rubber to form the outer cover. In another version, a casting method is used and the liquid EPDM rubber is dispensed into mold cavities to form the outer cover. The inner core of the ball may be made of polybutadiene rubber and the outer core layer may be made of EPDM rubber. The resulting golf ball has high resiliency, a soft feel, and good weatherability.

A golf ball (2) includes a core (4), an inner cover (6), a main cover (8), and an outer cover (10). X=HcRc0.05, S=HsRc0.05, M=HmTm, I=HiTi, O=HoTo, and Q=(I+O)/2 that are calculated from a radius Rc of the core (4), a Shore C hardness Hc at a central point of the core (4), a Shore C hardness Hs at a surface of the core (4), a thickness Tm of the main cover (8), a Shore C hardness Hm of the main cover (8), a thickness Ti of the inner cover (6), a Shore C hardness Hi of the inner cover (6), a thickness To of the outer cover (10) and a Shore C hardness Ho of the outer cover (10), satisfy 15MS100, 0.25<Q/M<0.5, 10IO30, and Q/X<0.8.

A golf ball can include a core, a mid layer, and a cover. In the golf ball, a hardness Ho at a central point of the core, a core surface hardness Hs, a hardness H1 at a point to which a distance from the central point of the core can be equal to 25% of a radius of the core, a hardness H2 at a point to which a distance from the central point of the core can be equal to 75% of the radius of the core, a hardness Hm of the mid layer, and a hardness Hc of the cover can satisfy all of the following relational expressions:

[00001]$\begin{array}{cc}\mathrm{Ho}?H1?H2?\mathrm{Hs}& \left(1\right)\end{array}$$\begin{array}{cc}\mathrm{Ho}<\mathrm{Hs}& \left(2\right)\end{array}$$\begin{array}{cc}\left(\mathrm{Hm}-\mathrm{Hc}\right)?\left(\mathrm{Hs}-\mathrm{Ho}\right)& \left(3\right)\end{array}$$\begin{array}{cc}\left(\mathrm{Hs}-\mathrm{Hc}\right)?\left(\mathrm{Hm}-\mathrm{Hs}\right).& \left(4\right)\end{array}$

Golf balls having cores with increased hardness gradients are provided. The cores have an increased positive hardness gradient (or a hard-to-soft hardness) where the outer surface of the core is harder than the center. The increased positive hardness gradient can be achieved by introducing a water-releasing agent into the core rubber formulation during the curing process. The resulting golf balls have reduced spin and sufficient impact durability.

Golf ball comprising a core having a hardness gradient and an outer cover layer having a microhardness gradient and being formed from a thermoset polyurethane material throughout, and having: i) a treated region that is contacted with a thermoset polyurethane microhardness-increasing solution consisting of an isocyanate portion and at least one non-aqueous solvent; and ii) an untreated region that is not contacted with the thermoset polyurethane microhardness-increasing solution. The treated region comprises the isocyanate portion, whereas the untreated region does not comprise the isocyanate portion. Treated region has a microhardness M.sub.1 that is greater than microhardness M.sub.2 of untreated region to define the outer cover layer positive microhardness gradient M=M.sub.1M.sub.2. The treated region may have a depth Dtr that extends inward from the cover outer surface and in some embodiments is less than a thickness of the untreated region. Treated region may alternatively extend from the inner surface toward outer surface.

Multi-layered, golf balls having a core made of a foamed composition are provided. The core preferably has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. The core also includes a structural insert such as, for example, a solid shell, perforated shell, a lattice or mesh, or a central hub with extending arms, and the like. The core layers have different hardness gradients and specific gravity values. The ball further includes a cover having at least one layer. By adjusting the respective specific gravity values of the core layers, the Moment of Inertia (MOI) of the ball can be increased or decreased. In one embodiment, the ball has generally good flight distance and low spin rate.