| abstract |
A breathable polyurethane having an upright moisture vapor transmission rate (MVTR) of more than about 500 gms/m2/24 hr comprises: a) poly(alkylene oxide) side-chain units in an amount comprising about 12 wt.% to about 80 wt.% of said polyurethane, wherein (i) alkylene oxide groups in said poly(alkylene oxide) side units have from 2 to 10 carbon atoms and are unsubstituted, substituted, or both unsubstituted and substituted, (ii) at least about 50 wt.% of said alkylene oxide groups are ethylene oxide, and (iii) said amount of said side-chain units is (i) at least about 30 wt.% when the molecular weight of said side-chain units is less than about 600 grams/mole, (ii) at least about 15 wt.% when the molecular weight of said side-chain units is from about 600 to 1,000 grams/mole, and at least about 12 wt.% when the molecular weight of said side-chain units is more than about 1,000 grams/mole, and b) poly(ethylene oxide) main-chain units in an amount comprising less than about 25 wt% of said polyurethane. Coatings and films for textiles and other articles and applications using such polyurethanes have excellent breathability, i.e., high moisture vapor transmission rates (MVTR). |