Cross-linked thermoplastic polyurethane/polyurea and method of making same

Abstract

A process for forming a cross-linked thermoplastic polymer is disclosed herein. The cross-linked thermoplastic polymer is formed by heating a first mixture containing a thermoplastic urethane base material, a monomeric diisocyanate comprising between 1 to 10% of the total weight of the first mixture, and a second mixture of a first diamine and a second diamine comprising between 1 to 10% of the total weight of a total reaction product. The heated first mixture, which is flowable, is injected into at least one injection molding device, with the second mixture injected at predetermined intervals to create a homogeneous reaction product.

We claim as our invention the following: 
     
         1 . A cross-linked thermoplastic polyurea comprising a mixture of:
 a thermoplastic urethane polymer base resin material; and   a di-isocyanate comprising between 1 to 10% of the mixture on a total weight basis, wherein the di-isocyanate is 4, 4′ diphenylmethane di-isocyanate;   
     
     
         2 . The cross-linked thermoplastic polyurea according to  claim 1  further comprising a diamine comprising between 1 to 10% of the mixture on a total weight basis. 
     
     
         3 . A method for forming a golf ball layer composed of a cross-linked thermoplastic polymer, the method comprising:
 mixing a thermoplastic urethane based resin material and 4, 4′ diphenylmethane di-isocyanate to create a first mixture, the 4, 4′ diphenylmethane di-isocyanate comprising between 1% to 10% of the total mass of the mixture;   heating the mixture to a temperature within the range of 250° F. to 550° F. to create a heated mixture;   injecting the heated mixture into a barrel of an injection molding machine through a first opening;   injecting a reaction product into at least one injection mold cavity, the reaction product formed by the reaction of the heated mixture and a liquid mixture; and   forming a golf ball layer composed of the reaction product.