VERFAHREN ZUR REZYKLIERUNG VON PET-FLASCHEN

摘要

Recycling method of polyethylene terephthalate (PET) bottles comprises passing resin bottle waste containing PET and other components through 17 processes including crushing, grinding, separating into various polymers, washing, depolymerizing, filtering, purifying components, transesterifying, polycondensing and polymerizing : Recycling method of polyethylene terephthalate (PET) bottles comprises passing resin bottle waste containing PET and other components through the following processes. (1) Unpacking collected and recovered PET bottle packed bales; (2) Grinding into flakes of 2-30mm 2> after removing iron and aluminum with a metal detector from the PET bottles; (3) Separating other polymer of e.g. labels comprising such as polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), etc., from the flake PET, with a wind power selection; (4) Washing foreign matter of the PET bottle bits and/or the contents residues in the PET bottles with water, removing e.g. sandstone of larger specific gravity than water and PET and separating other plastics such as PE or polypropylene (PP) of larger specific gravity than water; (5) Introducing the PET flakes into ethylene glycol (EG) including a PET depolymerization catalyst and producing bis-beta -hydroxyethyl-terephthalate (BHET) by treating under 0.1-0.5MPa at 175-190[deg]C to effect depolymerization; (6) Removing solid foreign matter not dissolved in the reaction solution; (7) BHET condensation process where the liquid from (6) is distilled and condensed; (8) Transesterifying the BHET in the presence of a transesterification catalyst and methanol to produce crude dimethyl terephthalate (DMT) and EG, and recrystallizing this reaction liquid from a methanol solution; (9) Purifying DMT by distilling methanol from the DMT cake; (10) Hydrolysing DMT by hydrolysis of the pure DMT and water at 230-250[deg]C to give terephthalic acid; (11) Cooling the slurry of terephthalic acid (TA) and water; (12) Producing a TA cake by solid-liquid separation from the slurry; (13) Drying the TA cake, supplying to a slurry adjusting tank, and the slurry so the mol ratio of TA/EG is 1:1-1:3; (14) Obtaining a PET oligomer by the esterification of TA and EG; (15) Adding polycondensation catalyst and stabilizer to the oligomer and performing a solution polycondensation reaction at 260-300[deg]C and 1.3-4.0kPa to remove EG and increase the polymerization degree; (16) Performing a solution polycondensation reaction at 270-300[deg]C and 67Pa - 0.7kPa to remove EG and increase the polymerization degree; and, (17) Solid phase polymerization process to raise the polymerization degree to produce PET suitable for bottles. Independent claims are also included for: (1) The PET obtained by the recycling method of inherent viscosity 0.70-0.90, oligomer content =0.50 weight% and acetaldehyde content =5ppm; and, (2) A molding comprising PET.