Methods for manufacturing bulked continuous filament from recycled PET
A method of manufacturing bulked continuous carpet filament that includes providing a polymer melt and separating the polymer melt from the extruder into at least eight streams. The multiple streams are exposed to a chamber pressure within a chamber that is below approximately 25 millibars, or another predetermined pressure. The streams are recombined into a single polymer stream. Polymer from the polymer stream is then formed into bulked continuous carpet filament.
1. A method of manufacturing bulked continuous carpet filament, the method comprising:
providing a polymer melt;
increasing a surface area of the polymer melt by dividing the polymer melt into at least eight streams;
passing the at least eight streams of polymer melt into an interior of a chamber such that a respective surface area of each of the at least eight streams is exposed to a chamber pressure within the chamber of between about 0.5 millibars and about 12 millibars;
recombining the at least eight streams into a single polymer stream; and
forming the single polymer stream into bulked continuous carpet filament, wherein:
the chamber pressure corresponds to a desired moisture level or a desired intrinsic viscosity associated with a single polymer stream comprising the at least eight streams of the polymer melt.
2. The method of claim 1 , wherein the method comprises maintaining the chamber pressure within a pressure range of between about 0.5 millibars and about 12 millibars while the at least eight streams of polymer melt pass from an inlet of the chamber to an outlet of the chamber.
3. The method of claim 1 , wherein the chamber pressure is a pressure between about 0.5 millibars and about 5 millibars.
4. The method of claim 1 , wherein the chamber pressure corresponds to the desired moisture level associated with the single polymer stream.
5. The method of claim 1 , wherein the chamber pressure corresponds to the desired intrinsic viscosity associated with the single polymer stream.
6. The method of claim 1 , wherein dividing the polymer melt into at least eight streams comprises separating the polymer melt into at least eight streams within the chamber.
7. The method of claim 1 , further comprising:
providing a PET crystallizer;
passing a plurality of flakes of recycled PET through the PET crystallizer; and
after passing the plurality of flakes through the PET crystallizer, at least partially melting the plurality of flakes into the polymer melt, wherein:
the step of at least partially melting the plurality of flakes into the polymer melt is executed before the step of dividing the polymer melt into at least eight streams.
8. The method of claim 7 , wherein the PET crystallizer comprises:
a hopper screw configured to feed the plurality of flakes into the PET crystallizer; and
a blower configured to blow hot air over the plurality of flakes as the plurality of flakes pass through the crystallizer.
9. The method of claim 8 , wherein the crystallizer is configured to maintain a temperature of between about 140 degrees Celsius and about 180 Celsius within the crystallizer.
10. The method of claim 7 , wherein the crystallizer is configured to at least partially crystallize the plurality of flakes.
11. The method of claim 10 , wherein the crystallizer is configured to at least partially dry at least a portion of a surface of the plurality of flakes.
12. The method of claim 7 , wherein the crystallizer is configured to reduce a moisture content of the plurality of flakes to between about 30 ppm and about 50 ppm.
13. The method of claim 7 , further comprising:
adding one or more color concentrates to the plurality of polymer flakes or to the single polymer stream.
14. The method of claim 13 , further comprising:
providing a color sensor configured to determine a color of the single polymer stream; and
substantially automatically adjusting an amount of the one or more color concentrates added to the plurality of polymer flakes or the single polymer stream based at least in part on the determined color of the single polymer stream.
15. The method of claim 1 , further comprising:
determining the intrinsic viscosity of the single polymer stream; and
in response to determining the intrinsic viscosity, adjusting the chamber pressure until the single polymer stream comprises the desired intrinsic viscosity.
16. The method of claim 1 , further comprising directing the single polymer stream formed from the at least eight streams directly into a spinning machine to form the single polymer stream into bulked continuous carpet filament.
17. A method for manufacturing bulked continuous carpet filament, the method comprising:
providing an extruder;
providing a plurality of polymer flakes to the extruder;
melting the plurality of polymer flakes within the extruder to create a polymer melt;
increasing a surface area of the polymer melt by dividing the polymer melt into at least eight streams of polymer melt;
passing the at least eight streams of polymer melt through an interior of a chamber while the interior of the chamber is maintained within a pressure range of between about 0.5 millibars and about 12 millibars;
after passing the at least eight streams of polymer melt through the chamber, recombining the at least eight streams into a single polymer stream; and
forming the single polymer stream into bulked continuous carpet filament.
18. The method of claim 17 , wherein the pressure range is between about 0.5 millibars and about 5 millibars.
19. The method of claim 17 , further comprising adding one or more color concentrates to the plurality of polymer flakes or to the polymer stream.
20. The method of claim 19 , wherein the plurality of polymer flakes comprises between about six percent and about ten percent colored PET flakes and balance substantially clear recycled PET flakes.
21. The method of claim 20 , wherein a resulting mixture of the one or more color concentrates and the plurality of polymer flakes or the polymer stream comprises between about zero percent and about three percent of the one or more color concentrates by weight.
22. The method of claim 20 , wherein the colored recycled PET flakes consist essentially of colored PET flakes derived from recycled PET bottles.
23. The method of claim 16 , further comprising:
determining the intrinsic viscosity of the single polymer stream; and
in response to determining the intrinsic viscosity, adjusting the chamber pressure until the single polymer stream comprises a desired intrinsic viscosity.
24. The method of claim 16 , further comprising:
providing a PET crystallizer;
passing the plurality of polymer flakes through the PET crystallizer; and
after passing the plurality of polymer flakes through the PET crystallizer, at least partially melting the plurality of polymer flakes into the polymer melt, wherein:
the step of at least partially melting the plurality of polymer flakes into the polymer melt is executed before the step of passing the at least eight streams of polymer melt through the interior of the chamber.
25. The method of claim 24 , wherein the PET crystallizer comprises:
a hopper screw configured to feed the plurality of flakes into the PET crystallizer; and
a blower configured to blow hot air over the plurality of flakes as the plurality of flakes pass through the crystallizer.
26. The method of claim 24 , wherein the PET crystallizer is configured to at least partially dry at least a portion of a surface of the plurality of flakes.
27. A method for manufacturing bulked continuous carpet filament, the method comprising:
providing an extrusion means;
providing a plurality of polymer flakes to the extrusion means;
melting the plurality of polymer flakes within the extrusion means to create a polymer melt;
using a dividing means to increase a surface area of the polymer melt by dividing the polymer melt into at least eight streams of polymer melt;
passing the at least eight streams of polymer melt through an interior of a chamber while the interior of the chamber is maintained within a pressure range of between about 0.5 millibars and about 5 millibars;
after passing the at least eight streams of polymer melt through the chamber, using a recombining means to recombine the at least eight streams into a single polymer stream; and
forming the single polymer stream into bulked continuous carpet filament.