| abstract |
The invention relates to a method for producing expanded granulate from a thermoplastic elastomer having a breaking elongation of more than 100% measured according to DIN EN ISO 527-2, comprising the steps: (a) pressing a polymer melt comprising a propellant through a perforated plate (18) which is temperature-controlled to a temperature between 150°C and 280 °C into a granulating chamber (26), (b) reducing the polymer melt pressed through the perforated plate (18) by means of a cutting device (20) into individual, expanding granulate grains, (c) removal of the granulate grains from the granulating chamber (26) by means of a fluid flow (36), wherein the propellant contains CO2 or N2 or a combination of CO2 and N2 and the volume of propellant in the polymer melt comprising propellant lies in the range from 0.5 to 2.0 wt% and wherein a liquid which is temperature-controlled to a temperature between 5°C 20 and 90°C, having a pressure of 0.1 bar to 20 bar above the environmental pressure, flows through the granulating chamber (26), wherein the pressure and temperature of the liquid in the granulating chamber (26) and the temperature of the perforated plate (18) are selected such that the granulate grains in the pressurized liquid are expanded by the contained propellant such that expanded granulate grains having a closed skin result. |