Preparation and Properties of Polyurethane and Polyurethaneurea Elastomers from Methylene Bis(4-Cyclohexylisocyanate).

Transport polyurethane elastomers have been prepared and evaluated as flexible lens materials. The main ingredients of the polymers include methylene bis4-cyclohexylisocyanate, polytetramethylene oxide polyols, and 1,4-butane-diol, with small amounts of ethylene glycol and trimethylol propane added to improve properties. The polymers exhibit very good mechanical properties for the desired use, however, the low temperature -20 C bend recovery needs to be improved. Additional problems include the lack of a completely suitable mold release system, in which the molds could be used repeatedly and produce consistently good optical quality samples. This difficulty arises from the exceptionally strong adherence of polyurethane elastomers to mold surfaces compared to other polymers. Excellent samples were prepared on polypropylene sheets which had been press polished, but the repeated use of this material as a mold at 100 C under pressure might not be possible.