Patent ID: 8568633

Claim:
A process for producing a thermoplastic particle foam molding which has cells having a mean cell size in the range from 20 to 500 μm, wherein the cell membranes have a nanocellular or fibrous structure having pore or fiber diameters below 1500 nm, which comprises a) producing a polymer mixture having a continuous phase and a disperse phase by mixing two incompatible thermoplastic polymers, b) impregnating this mixture with a blowing agent and pelletizing it to produce expandable thermoplastic polymer particles, c) prefoaming the expandable, thermoplastic polymer particles to produce foam particles and d) fusing the prefoamed foam particles in a mold by means of hot air or steam at a processing pressure which is kept sufficiently low for the nanocellular or fibrous structure in the cell membranes to be retained to produce a particle foam molding.