| 摘要 |
The invention relates to a process for producing expandable pelletized material which comprises polylactic acid which comprises the following steps: a) melting and incorporation by mixing of the following components: i) from 61.9 to 98.9% by weight, based on the total weight of components i to iv, of polylactic acid, ii) from 1 to 38% by weight, based on the total weight of components i to iv, of at least one polyhydroxyalkanoate, iii) from 0 to 30% by weight, based on the total weight of components i to iv, of at least one polyester based on aliphatic and/or aromatic dicarboxylic acids and on aliphatic dihydroxy compounds; iv) from 0.1 to 2% by weight, based on the total weight of components i to iv, of a copolymer which comprises epoxy groups and which is based on styrene, acrylate, and/or methacrylate, and v) from 0 to 10% by weight, based on the total weight of components i to v, of one or more additives, b) incorporation by mixing of vi) from 3 to 7% by weight, based on the components i to v) of an organic blowing agent into the polymer melt by means of a static or dynamic mixer at a temperature of at least 140� C., c) discharging through a die plate with holes, the diameter of which at the exit from the die is at most 1.5 mm, and d) pelletizing the melt comprising blowing agent directly downstream of the die plate, and under water, at a pressure in the range from 1 to 30 bar. |
