FIELD: technological processes.
SUBSTANCE: invention relates to a method of producing polyethylene terephthalate (PET) granules suitable for further processing to produce a packaging film and bottles, comprising the steps of: a) obtaining a melt of PET or molten copolyester PET in a continuous polymerisation flow system or by re-esterification of dimethyl terephthalate (DMT) with ethylene glycol (EG), or by esterification of terephthalic acid (PTA) with ethylene glycol, b) moving the melt, preferably by means of a pipeline, for further processing at step c), c) granulating the melt with cooling to form unrefined granules, wherein partial crystallisation of the polymer occurs with release of part of the heat of crystallisation of the polymer (latent heat of crystallisation), d) post-treatment of the non-purified granules to control the polymer quality parameters required for further processing, in particular characteristic viscosity, content of acetaldehyde and moisture, characterized in that post-treatment is carried out in a plurality of tubular reactors with a movable layer, operating in parallel, wherein the residence time of the granules in the reactor, the type and chemical composition of the process gas and its temperature and condensation temperature at the inlet of the reactor are controlled separately for each of the reactors. Also described is a system for carrying out said method, comprising: part of a system for producing melt PET from DMT/EG or PTA/EG raw materials, conveyor device for moving PET melt, obtained thereby, to a system for producing partially crystalline PET-granules, part of system for producing partially crystalline PET-granules, a conveyor device for partially crystalline polymer granules, at least two parts of the system for post-treatment of granules, each containing a tubular reactor with a movable layer and devices for movement, supply and removal of process gas.
EFFECT: disclosed is a method of producing PET granules suitable for further processing to produce a packaging film and bottles.
9 cl, 3 dwg, 1 tbl
