HARD SEGMENT SIZE CONTROL IN POLYURETHANE FORMATION

摘要

Improved methods for forming urethane elastomers and corresponding urethaneprepolymers are disclosed wherein diiso-cyanate and a low molecular weight diol are simultaneously mixed and reactedto form a hard segment which is subsequentlyreacted with a long chain diol to form the elastomer. Aliphatic diisocyanatesare particularly desirable for the manufacture ofcontact lenses from the urethane prepolymers of this invention.