METHOD FOR THE PRODUCTION OF EXPANDED GRANULES

摘要

The invention relates to a process for production of expanded pellets from a thermoplastic elastomer having an elongation at break of more than 100% measured to DIN EN 150 527-2, said process comprising the steps of: (a) pressing a polymer melt comprising a blowing agent through a perforated disk (18) controlled to a temperature between 150° C. and 280° C. and into a pelletizing chamber (26), (b) using a cutting device (20) to comminute the polymer melt pressed through the perforated disk (18) into individual expanding pellets, (c) discharging the pellets from the pelletizing chamber (26) using a liquid stream (36), wherein the blowing agent comprises CO2 or N2 or a combination of CO2 and N2 and the amount of blowing agent in the polymer melt comprising a blowing agent lies in the range from 0.5 to 2.5 wt % and wherein the pelletizing chamber (26) is traversed by a stream of liquid which is controlled to a temperature between 5° C. and 90° C. and the pressure of which is from 0.1 bar to 20 bar above ambient pressure, the pressure and temperature for the liquid in the pelletizing chamber (26) and also the temperature for the perforated disk (18) being chosen such that the pellets are expanded in the pressurized liquid by the blowing agent they contain so as to produce expanded pellets having an uninterrupted skin.