Patent ID: 7582698
Filing Date: 2009-09-01
Classification: C08G,Y10S,Y10T

Abstract:
1. A method of preparing an aqueous dispersion of at least two polyurethane prepolymers having different hydrophilicities, wherein said prepolymers are prepared in the same reactor which comprises: (a) preparing a first isocyanate terminated prepolymer; (b) protecting (blocking) the unreacted isocyanate groups in the first isocyanate terminated prepolymer by reacting it with a blocking agent to obtain a blocked first prepolymer; (c) preparing a second isocyanate terminated prepolymer in the presence of said first prepolymer to form a mixture of said prepolymers, wherein said mixture is devoid of water; (d) optionally protecting the unreacted isocyanate groups of the second prepolymer; (e) optionally repeating the preparation and protecting steps of subsequent prepolymers; (f) optionally deblocking said protected groups after all prepolymers have been prepared; and (g) dispersing said mixture of prepolymers in an aqueous medium.