B - Operations – Transporting – 32 – B
Patent
B - Operations, Transporting
32
B
18/16, 154/123.1
B32B 7/02 (2006.01) B32B 27/08 (2006.01)
Patent
CA 1321864
TITLE VAPOR-PERMEABLE, WATERPROOF BICOMPONENT STRUCTURE ABSTRACT OF THE DISCLOSURE A bicomponent film of a hydrophobic layer and a hydrophilic layer of copolyetherester elastomers bonded together which permits differential transfer of water vapor to prevent buildup of moisture comprising: (A) a continuous layer of a hydrophobic elastomer 0.05-0.8 mil thick and having a water vapor transmission rate of 400-2500 gm?mil/m2/24 hrs. according to ASTM E96-66 (Procedure BW), said hydrophobic elastomer is a copolyetherester elastomer or a mixture of two or more copolyetherester elastomers having a multiplicity of recurring long-chain ester units and short-chain ester units joined head-to-tail through ester linkages, 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, and further, the amount of ethylene oxide groups incorporated in the copolyetherester or mixture of two or more copolyetheresters by the poly(alkylene oxide)glycol is not greater than about 20 weight percent based upon the total weight of the copolyetherester or mixture of two or more copolyetheresters; 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; and said hydrophobic copolyetherester or mixture of two or more copolyetheresters has from about 25-80 weight percent short-chain ester units; (B) a continuous layer of a hydrophilic elastomer 0.3-6 mil thick and having a water vapor transmission rate of at least 3500 gm?mil/m2/24 hrs. according to ASTM E96-66 (Procedure BW), said hydrophilic elastomer is a copolyetherester elastomer or a mixture of two or more copolyetherester elastomers having a multiplicity of long-chain ester units and short-chain ester units joined head-to-tail through ester linkages 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 or mixture of two or more copolyetheresters by the poly(alkylene oxide)glycol is from about 25-68 weight percent based on the total weight of the copolyetherester or mixture of two or more copolyetheresters, and the hydrophilic copolyetherester or mixture of two or more copolyetheresters contain about 25-80 weight percent short-chain ester units; and said bicomponent film of the hydrophobic and hydrophilic layers has a separation ratio for water vapor of at least 1.2, preferably at least about 1.4, as determined by ASTM E96-66 (Procedure BW).
549978
E.i. Du Pont de Nemours And Company
Sim & Mcburney
LandOfFree
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