Patent ID: 6017997
Filing Date: 2000-01-25
Classification: A61F,A61L,C08G,Y10T

Abstract:
A waterborne polyurethane dispersion wherein the polyurethane comprises the reaction product of(a) a polyisocyanate component selected from the group consisting of an aliphatic polyisocyanate, an aromatic polyisocyanate, a cycloaliphatic polyisocyanate, and an araliphatic polyisocyanate;(b) a long-chain, active hydrogen containing material, containing 2 or more active hydrogens per molecule selected from the group consisting of a polyamide, a polyester polyol, a polyether polyol and mixtures thereof, having an average molecular weight from about 2900 to about 5500 Daltons, and being a liquid at 90.degree. F. or lower; and(c) a water-solubilizing compound having water-solubilizing groups selected from the group consisting of dimethylol propanoic acid, tartaric acid, dimethylol butanoic acid, glycollic acid, thioglycollic acid, lactic acid, malic acid, dihydroxymalic acid, dihydroxytartaric acid, and 2,6-dihydroxybenzoic acid and present in a range of from about 2 wt. % to about 4 wt. % of the total prepolymer,to form an isocyanate prepolymer, having a NCO to OH ratio of about 1.3/1 to about 4.0/1, which is neutralized by reaction with a tertiary amine, dispersed in water, and chain extended by reaction with an amine, said polyurethane dispersion, when in the form of a film, having elastic properties comparable to rubber, a tensile strength greater than about 3500 psi, a 100% modulus below 450 psi, a 500% modulus below 1500 psi, and a percentage elongation greater than about 700% at 72.degree. F.