Abstract: A problem of the invention is to provide a method which targets on polyethylene terephthalate-made bottle scraps composed mainly of polyethylene and/or polypropylene, polystyrene and a polyester and which is able to treat continuously a large amount of the polyester component with a high purity and sort and recover it in a high recovery. The problem of the invention can be solved by a separation method of waste plastics, which is characterized by forming previously a crushed plastic into a water slurry, feeding the water slurry in a fixed rate range such that a swirling flow is generated within a cylindrical tank and that water rises in a fixed rate range and recovering a polyester with a high specific gravity as a precipitated component within the cylindrical tank and a plastic with a low specific gravity as an overflow component from the top of the cylindrical tank, respectively.

Abstract: A liquid mixture of terephthalic acid with an alkylene glycol suitable as a starting material mixture for a polyester polycondensation reaction is produced by preparing a liquid mixture of terephthalic acid particles prepared by the hydrolysis of a dialkyl terephthalate with at least one type of alkylene glycol and having a temperature of 100 to 130° C., and then stirring the liquid mixture for 15 minutes to 3 hours while the temperature of the liquid mixture is maintained in the above-mentioned range, to control the slurry properties of the liquid mixture.

Abstract: A problem of the invention is to provide a method which targets on polyethylene terephthalate-made bottle scraps composed mainly of polyethylene and/or polypropylene, polystyrene and a polyester and which is able to treat continuously a large amount of the polyester component with a high purity and sort and recover it in a high recovery. The problem of the invention can be solved by a separation method of waste plastics, which is characterized by forming previously a crushed plastic into a water slurry, feeding the water slurry in a fixed rate range such that a swirling flow is generated within a cylindrical tank and that water rises in a fixed rate range and recovering a polyester with a high specific gravity as a precipitated component within the cylindrical tank and a plastic with a low specific gravity as an overflow component from the top of the cylindrical tank, respectively.