Vapor-permeable, waterproof bicomponent structure

摘要

(A) A continuous layer of a hydrophobic elastomer having a water vapor transmission rate of 400-2500 gm.mil/m2/24 hrs., said hydrophobic elastomer is a copolyetherester having a multiplicity of recurring long-chain ester units and short-chain ester units, said long-chain ester units being represented by the formula <IMAGE> (I) and said short-chain ester units being represented by the formula <IMAGE> (II) where G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly(alkylene oxide)glycol having an average molecular weight of about 400-3500, the amount of ethylene oxide groups incorporated in the copolyetherester by the poly(alkylene oxide)glycol is not greater than about 20 weight percent; R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight less than 300; D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about 250; (B) a continuous layer of a hydrophilic elastomer having a water vapor transmission rate of at least 3500 gm.mil/m2/24 hrs. said hydrophilic elastomer is a copolyetherester having a multiplicity of long-chain ester units and short-chain ester units represented by formulae (I) and (II) above and having the values given above with the proviso that the amount of ethylene oxide groups incorporated in the copolyetherester by the poly(alkylene oxide)glycol is from about 25-68 weight percent and said bicomponent film has a separation ratio for water vapor of at least 1.2.