a novel composition useful for golf ball covers that comprises a blend of a diisocyanate / polyol polyurethane prepolymer with a curing agent comprising a blend of slow - reacting diamine with a fast - reacting diamine such as dimethylthio 2 , 4 - toluenediamine and diethyl 2 , 4 - toluenediamine , respectively . a golf ball cover made with this composition exhibits the characteristic feel and playability of a balata cover with superior durability characteristics which exceed those of a balata or ionomer cover .