BigPatents India

The present invention provides a process for the preparation of at least one of a polyurethane prepolymer and a polyurethane-urea prepolymer involving mixing in a mixing nozzle at least one disocyanate with at least one of a polyhydroxyl compound and a polyamino compound having a molecular weight of from about 400 to about 10,000, the mixing nozzle including a first inlet, an annular nozzle channel having a substantially constant diameter, a second inlet and connected through a channel to a dwell line, wherein the first inlet is inlet is in communication with the annular nozzle channel through one or more apertures therein, introducing the polyhdroxyl compound and/or polyamino compound into the annular nozzle channel via the second inlet, injecting the diisocyanate through the one or more apertures into the polyhdroxyl compound and/or polyamino compound in the annular nozzle channel and reacting the mixture of diisocyanate and polyhdroxyl compound and/or polyamino compound in the dwell line.