Method for producing expandable granulates containing polylactic acid

The invention relates to a method for producing expandable granulates containing polylactic acid, comprising the following steps: a) melting and mixing the constituents i) between 50 and 99.9 wt. %, relative to the total weight of constituents i) to iii), of polylactic acid, ii) between 0 and 49.9 wt. %, relative to the total weight of constituents i) to iii), of at least one other polymer, iii) between 0.1 and 2 wt. %, relative to the total weight of constituents i) to iii), of a diepoxide or polyepoxide, and iv) between 0 and 10 wt. % of at least one additive, b) mixing v) between 3 and 7 wt. %, relative to the total weight of constituents i) to iv), of an organic blowing agent, into the melted polymer mass, by means of a static or dynamic mixer, at a temperature of at least 40°C, c) discharging the mixture via a nozzle plate with boreholes having a maximum on the nozzle outlet diameter of 1.5 mm, and d) granulating the melted mass containing the blowing agent directly behind the nozzle plate, under water, at a pressure of between 1 and 20 bar. The invention also relates to expandable granulates containing polylactic acid, that can be obtained according to said method, and to special expandable granulates containing polylactic acid, and between 3 and 7 wt. % of an organic blowing agent, preferably n-pentane, and especially preferably iso-pentane. The invention also relates to a preferred method for producing expandable granulates containing polylactic acid and a blowing agent, with a low bulk density.