Method for manufacturing expandable granulates containing polylactic acids

摘要

Producing expandable polylactic acid-containing granules, comprises: (a) melting and mixing (i) polylactic acid, (ii) at least one additional polymer, (iii) a diepoxide or polyepoxide and (iv) at least one additive, preferably nucleating agent; (b) mixing (v) an organic blowing agent and (vi) a co-blowing agent including nitrogen, carbon dioxide, argon and/or helium, into the polymer melt via a static or dynamic mixer; (c) discharging the mixture via a nozzle plate with holes; and (d) granulating the blowing agent-containing melt directly behind the nozzle plate under water. Producing expandable polylactic acid-containing granules, comprises: (a) melting and mixing (i) polylactic acid (50-99.9 wt.%, based on the total weight of the components (i)-(iii)), (ii) at least one additional polymer (0-49.9 wt.%, based on the total weight of the components (i)-(iii)), (iii) a diepoxide or polyepoxide (0.1-2 wt.%, based on the total weight of the components (i)-(iii)) and (iv) at least one additive, preferably nucleating agent (0-10 wt.%, based on the total weight of the components (i)-(iii)); (b) mixing (v) an organic blowing agent (3-7 wt.%, preferably 1-7 wt.%, based on the total weight of the components (i)-(iv)) and (vi) a co-blowing agent including nitrogen, carbon dioxide, argon and/or helium (0.01-5 wt.%), into the polymer melt via a static or dynamic mixer at a temperature of at least 140[deg] C; (c) discharging the mixture via a nozzle plate with holes, whose diameter at the nozzle outlet is not > 1.5 mm; and (d) granulating the blowing agent-containing melt directly behind the nozzle plate under water at a pressure of 1-20 bar. Independent claims are also included for: (1) the expandable polylactic acid-containing granules with cavities with an average diameter of 0.1-50 mu m and a solid proportion of 93-97 wt.% obtained by the above method, comprising (in wt.%) (i) the polylactic acid (50-98.9, based on the total weight of components (i)-(iii)), (ii) at least one polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds (1-49.9, based on the total weight of components (i)-(iii)), (iii) an epoxide group-containing copolymer based on styrene, acrylic acid ester and/or methacrylic acid ester (0.1-2, based on the total weight of components (i)-(iii)), (iv) the additive (0-10, based on the total weight of components (i)-(iii)), and (v) the organic blowing agent (3-7), or a polylactic acid-containing polymer mixture; (2) producing particles of foam molded parts, comprising pre-foaming the expandable polylactic acid-containing granules with hot air or steam to form the foam particles with a density of 8-100 kg/m 3>, and then welding the foam particles in a closed mold; (3) the polylactic acid-containing polymer mixture comprising (in wt.%) (i) the polylactic acid (60-98.9, based on the total weight of components (i)-(iii)), (ii) at least one polyester (1-39.9, based on the total weight of components (i)-(iii)), based on (a) succinic acid (90-99.5 mol.%, based on the components (i)-(ii)), (b) at least one dicarboxylic acids with 8-20 carbon atoms (0.5-10 mol.%, based on the components (i)-(ii)), (c) 1,3-propanediol or 1,4-butanediol (98-102 mol.%, based on the components (i)-(ii)), (iii) the epoxide group-containing copolymer (0.1-2, based on the total weight of the components (i)-(iii)), and (iv) the nucleating agent (0-1, based on the total weight of components (i)-(iii)); and (4) foam materials comprising the polylactic acid-containing polymer mixture.