Abstract
A preparation method of polyurethane is provided. The preparation method of polyurethane includes the following steps. A liquid polyamine compound is entered to a continuous reactor system, and the liquid polyamine is circulated in the continuous reactor system. A solid bis(cyclic carbonate) and a solid catalyst are entered to the continuous reactor system, so as to mix the solid bis(cyclic carbonate), the solid catalyst and the liquid polyamine compound to form a heterogeneous mixture. The heterogeneous mixture is heated in a microwave manner in the continuous reactor system, such that the heterogeneous mixture reacts to form a polyurethane.