Over-indexed thermoplastic polyurethane elastomer, method of making, and articles comprising the elastomer

摘要

An over-indexed, optionally cross-linked thermoplastic polyurethane elastomer. Also, the method of making the elastomer, and articles, including golf balls, comprising the elastomer.

主权项

1. A method of making a golf ball, comprising the steps of:
forming a golf ball precursor, the precursor having at least one golf ball layer but not an outer cover layer and forming an outer cover layer substantially surrounding the golf ball precursor, wherein the outer cover layer comprises a composition of an over-indexed, crosslinked thermoplastic polyurethane elastomer including crosslinks formed from allyl groups and the thermoplastic polyurethane elastomer is a reaction product formed from reacting a mixture of a diisocyanate and:
(a) an unsaturated diol of the formula  in which R1 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted alkyl-aryl group, which may optionally include an ether or ester group or an unsaturated bond in any group, or is H; R2 is a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted alkyl-aryl group, which may optionally include an ether or ester group, and R2 includes an allyl group; and x and y are integers independently having any value from 1 to 10;(b) a chain extender having at least two reaction sites with isocyanates and having a molecular weight of less than about 450;(c) a long chain polyol having a molecular weight of between about 500 and about 4,000; and(d) a sufficient amount of free radical initiator so as to be capable of generating free radicals that induce crosslinking structures in the hard segments by free radical initiation,wherein the mixture has a stoichiometric excess of isocyanate moieties of at least about 1 mol percent;
wherein forming the outer cover layer further comprises applying the composition over the golf ball precursor and then moisture curing the composition; and wherein the outer cover layer has a flexural modulus between 400 psi and 900 psi.