DEVICE AND METHOD FOR SEPARATING FOREIGN POLYMERS FROM A POLYMER MIXTURE.

摘要

The method of separating foreign polymers (6) from a polymer mixture (2) comprising amorphous polyethylene terephthalate (PET) (4) particles and crystalline PET particles, where the softening point of the foreign polymers is lower than that of the crystalline PET particles, comprises: separating the amorphous PET particles from the polymer mixture; and heating the resulting polymer mixture (5) to a temperature between the softening point of the foreign polymers and that of the crystalline PET particles, where heating causes a change of color of the foreign polymers. The method of separating foreign polymers (6) from a polymer mixture (2) comprising amorphous polyethylene terephthalate (PET) (4) particles and crystalline PET particles, where the softening point of the foreign polymers is lower than that of the crystalline PET particles, comprises: separating the amorphous PET particles from the polymer mixture; heating the resulting polymer mixture (5) to a temperature between the softening point of the foreign polymers and that of the crystalline PET particles, where heating causes a change of color of the foreign polymers; separating the foreign polymers from the resulting polymer mixture by an air separation process; transforming the separated amorphous PET particles into thermally crystallized PET particles by thermal crystallization, where thermal crystallization causes a change of color of remaining foreign polymers; returning the separated amorphous PET particles to the crystalline PET particles; and manufacturing purified thermally crystallized PET particles by separating the foreign polymers by detecting and sorting them out from the thermally crystallized PET particles due to their change of color. The step of separating the foreign polymers comprises contacting the foreign polymers with a mechanical contact body to which the foreign polymers adhere, and detecting and sorting out the foreign polymers on the basis of the change of color, where the step of heating the resulting polymer mixture is effected by heating the mechanical contact body. The air separation process is a zigzag separation process, a pneumatic sorting process and/or a separation table sorting process. The mechanical contact body is a rotating metal roller. The change of color is a darkening. The air separator is a zigzag separator, a pneumatic sorter and/or a separation table sorter. An independent claim is included for a device for separating foreign polymers from a polymer mixture..