Patent ID: 7361707

Claim:
A formulation comprising an aqueous dispersion; said aqueous dispersion comprising an unsaturated polyurethane, at least a portion of which comprises at least one anionic, cationic, allyl, or vinyl group; and latex comprising an elastomeric polymer; the unsaturated groups of the polyurethane being capable of chemically bonding with the latex; said formulation being formable into a film having an air permeability not greater than 3.5×10 −5 cm 3 cm/m 2 hour Pa at 25° C. wherein said air permeability is calculated as: ( Flow ⁢ ⁢ rate ⁢ ⁢ of ⁢ ⁢ air ⁢ ⁢ in ⁢ ⁢ cm 3 / hour ) × ( Thickness ⁢ ⁢ of ⁢ ⁢ film ⁢ ⁢ in ⁢ ⁢ cm ) ( Permeation ⁢ ⁢ area ⁢ ⁢ of ⁢ ⁢ film ⁢ ⁢ in ⁢ ⁢ m 2 ) × ( Pressure ⁢ ⁢ differential ⁢ ⁢ across ⁢ ⁢ film ⁢ ⁢ i ⁢ n ⁢ ⁢ Pa ) ⁢ wherein a pressure differential of 50 psig is maintained during measurement.