THERMOPLASTIC POLYURETHANE CONTAINING STRUCTURAL UNITS OF POLYESTER AND POLYETHER DIOLS

摘要

The present invention is a transparent thermoplastic polyurethane (TPU) comprising structural units of: a.) a diisocyanate; b.l) a polyester diol and b.2) a specific polyether diol and c.) a chain extender. The TPU has good combinations of light transmission and clarity, tensile strength, low temperature flexibility, and high moisture vapor transition rates compared to other commercial or known TPUs. A preferred example composition is a TPU that is based on MDI as the diisocyanate monomer, polycaprolactone as a polyester diol, an EO capped EO/PO polyether diol containing less than 20% EO, and butanediol as chain extender. These compositions have good combinations of clarity, tensile strength, hydrolytic stability and processability compared to TPUs prepared using either polyester or polyether diols alone or the combination with a higher EO polyether diol.