Diphenylmethane diisocyanate → Urea Urethane

Participants

Reaction Steps

A urethane/urea prepolymer was prepared by reacting 70 percent by weight of a poly(propylene oxide) polyol VORANOL™ 2120 polyol (a trademark of The Dow Chemical Company) with 30 percent by weight of ISONATE™ 50 MDI (a trademark of The Dow Chemical Company; a 50:50 mixture of 4,4'-diisocyanatodiphenylmethane and 2,4'-diisocyanatodiphenylmethane). The following processes were carried out at 10° C. The prepolymer was fed continuously at a rate of 31.4 g/minute through a 1/2-inch (1.25 cm) stainless-steel tube fitted to one arm of a T. A 20-percent aqueous solution of a sodium dodecylbenzene sulfonate (RHODACAL™ DS-10, a trademark of Rhone Poulenc) was fed continuously at a rate of 4.7 g/minute through a 1/8-inch (0.31 cm) stainless-steel tubing fitted to the other arm of the T. The two streams were combined and passed through a static mixer to form a non-emulsified blend. The blend was then fed into a 1/2-inch (1.25 cm) stainless-steel tube fitted to one arm of a T attached to the input of a 70-mL centrifugal pump. Concurrently, water was pumped through a 1/8-inch (0.31 cm) tetrafluoroethylene tubing fitted to the other arm of the T, at the rate of 3.0 g/minute. The two streams were merged and mixed together under shear in the centrifugal pump operating at 650 rpm to form an HIPR emulsion.

Provenance & Evidence