Patent ID: 6955778

Claim:
A process for the preparation of a syntactic polyurethane by mixing hollow microspheres with a polyurethane preparable by reacting a) a polyisocyanate with b) a compound which has at least two hydrogen atoms reactive toward isocyanate, in the presence or absence of c) a catalyst, d) a blowing agent and e) an additive, which process comprises in a first step, reacting the components a) and b) and, if required, c) to d) to obtain a polyurethane mixture, and in a second step, mixing the polyurethane mixture with the hollow microspheres in a mixing apparatus which is free of dead space and which comprises i) a mixing pot, ii) a feed for polyurethane, iii)a feed for hollow microspheres, iv) a stirring element and v) a regulatable outlet orifice, to obtain the syntactic polyurethane, and wherein the syntactic polyurethane has a viscosity of from 1 000 to 30 000 mPa·s at the outlet orifice.