Process for recycling polyethylene terephthalate determined by intrinsic viscosity of polyethylene terephthalate

A method for producing a first intermediate product, comprising the steps of

• a. providing a feedstock that comprises a first polyester;
• b. contacting the feedstock with a first amount of a first organic compound in a volume section V1 to obtain a first initial mixture, wherein the first amount is in the form of a liquid and wherein the intrinsic viscosity of the first polyester in the volume section V1 varies by less than 15%;
• c. transporting the first polyester to a volume section V2 from the volume section V1;
• d. contacting the first polyester with a further amount of the first organic compound in the volume section V2;
• e. reducing an intrinsic viscosity of the first polyester in the volume section V2, wherein after the reduction step has been completed in the volume section V2, the first polyester has an intrinsic viscosity in the range of 0.10 dL/g to 0.45 dL/g;
• f. transporting the first polyester to a volume section V3;
• g. contacting the first polyester with a further organic compound in the volume section V3 to obtain a further initial mixture;
• h. reducing a weight average molar mass of the first polyester in the volume section V3 to obtain a first intermediate mixture, wherein the first intermediate mixture comprises
• i. a first intermediate product that has an intrinsic viscosity in the range of 0.010 dL/g to 0.090 dL/g,
• ii. the further organic compound;
• wherein the first polyester is transported
• I./ in a first direction that is at least partially opposite the direction of gravity when the first polyester has an intrinsic viscosity that is larger than or equal to YIV,1, where YIV,1 is 0.10 dL/g;
• II./ in further direction that is at least partially along the direction of gravity when the first polyester has an intrinsic viscosity that is less than or equal to YIV,2, where YIV,2 is 0.09 dL/g;
• and
• III./ the transport of the first polyester along the first direction comprises transport from the volume section V1 to the volume section V and transport through the volume section V2,
• with the intrinsic viscosity determined according to the method described herein.