Method for preparing PU (polyurethane) oleoresin from gutter oil

The invention relates to a method for preparing PU (polyurethane) oleoresin, in particular to a method for preparing the PU oleoresin from gutter oil. Refined gutter oil and polyols are mixed and added to a reactor in the mass ratio, and water in the reactor is removed with pressure reduction and heating methods; a catalyst is added to the reactor, the mixture is continuously heated to have an alcoholysis reaction, and mixed polyol ester is synthesized; the mixed polyol ester and polyisocyanate have a thermal reaction, and a polymer with a carbamate repletion structure unit, namely, the PU oleoresin, can be obtained. According to the method, the gutter oil is taken as a main raw material, mixed fatty glyceride is synthesized through alcoholysis and then reacts with the polyisocyanate, and the PU oleoresin is prepared. Conditions that the gutter oil flows into the food oil market and harm human health are reduced. The novel PU oleoresin with the gutter oil serving as the main raw material is synthesized, so that varieties and application fields of PU are increased.