Curable blend of blocked and unblocked polyurethanes

Abstract

Abstract There are disclosed curable polyurethane compositions comprising: I. A normally-liquid, free isocyanate-blocked urethane prepolymer composition comprising the reaction product of (A) a diisocyanate-polyol urethane prepolymer containing free isocyanate groups, and (B) an isocyanate-reactive oxime, said reaction product being made by reaction of an essentially stoichiometric equivalent of (B) per equivalent of free isocyanate in (A); and II. an elastomeric, polyamine-extended polyurethane comprising the reaction product of (A) a diisocyanate-polyol urethane prepolymer containing free isocyanate groups, and (B) an isocyanate-reactive polyamine, said reaction product being made by the reaction of an essentially stoichiometric equivalent of (B) per equivalent of free isocyanate in (A). The compositions are normally cured at temperatures above room temperature, especially above about 70* C. and advantageously above about 130* or even above about 145* C. Additionally, the cured compositions are useful as coatings for both flexible and rigid articles such as textiles, leather, vinyl and rubber materials, metal, wood are rigid plastic materials. In a preferred embodiment, the oxime in (I) is methyl ethyl ketoxime and the polyamine in (II) is 1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane, while the urethane prepolymer in both (I) and (II) is prepared from toluene diisocyanate or 1-isocyanato-3isocyanato methyl-3,5,5-trimethyl cyclohexane with trimethyol propane as the polyol in (I) and a polyester of a glycol and adipic acid as the polyol in (II). The coatings prepared from the compositions of this invention are normally highly resistant to abrasion and chemical attack.

Inventors

• 👤 B Farah

Bibliographic Details