Polyester fiber blends and methods of manufacturing same

1. A fiber comprising a polymer blend, said polymer blend comprising:

a) about 1% by weight—about 15% by weight polytrimethylene terephthalate polymer; and

b) about 1% by weight—about 15% by weight polyethylene naphthalate polymer;

wherein the remainder of said polymer blend is polyethylene terephthalate polymer;

wherein the fiber is a bulked continuous filament (BCF).

2. The fiber of claim 1 , comprising about 5% by weight to about 15% by weight polytrimethylene terephthalate polymer.

3. The fiber of claim 1 , comprising about 5% by weight to about 15% by weight polyethylene naphthalate polymer.

4. The fiber of claim 1 , comprising about 8% by weight polytrimethylene terephthalate polymer and about 10% by weight polyethylene naphthalate polymer.

5. The fiber of claim 1 , wherein the fiber is as-spun, or is heat-set.

6. The fiber of claim 1 , wherein the fiber exhibits increased dyeability compared to a similar fiber where a portion of or all of the polytrimethylene terephthalate polymer or polyethylene naphthalate polymer is replaced by polyethylene terephthalate polymer; and wherein the increase in dyeability is at least about 1%.

7. The fiber of claim 1 , wherein the fiber exhibits an improvement in a physical characteristic selected from the group consisting of total recovery, elongation, crimp, tenacity, and shrinkage, compared to a similar fiber where a portion of the polyethylene naphthalate polymer is replaced by polyethylene terephthalate polymer; and wherein the improvement is at least 1%.

8. The fiber of claim 1 , wherein one, two, or all three of the polyethylene terephthalate polymer, the polytrimethylene terephthalate polymer, and the polyethylene naphthalate polymer are recycled.

9. The fiber of claim 1 , further comprising a component selected from the group consisting of finishing agents, delusterants, viscosity boosters, optical brighteners, matting agents, thermal stabilizing agents, anti-oxidative agents, anti-static agents, pigments, ultra-violet blocking agents, and combinations thereof.

10. A yarn or a carpet comprising a fiber according to claim 1 .

11. A method of manufacturing bulked continuous carpet filament, said method comprising:

(A) providing a multi-screw extruder that comprises:

(i) a first satellite screw extruder, said first satellite screw extruder comprising a first satellite screw that is mounted to rotate about a central axis of said first satellite screw;

(ii) a second satellite screw extruder, said second satellite screw extruder comprising a second satellite screw that is mounted to rotate about a central axis of said second satellite screw; and

(iii) a pressure regulation system that is adapted to maintain a pressure within said first and second satellite screw extruders between about 0 millibars and about 1.8 millibars;

(B) using said pressure regulation system to reduce a pressure within said first and second satellite screw extruders to between about 0 millibars and about 1.8 millibars;

(C) while maintaining said pressure within said first and second satellite screw extruders between about 0 millibars and about 1.8 millibars, passing a melt comprising a polymer through said multi-screw extruder so that: (1) a first portion of said melt passes through said first satellite screw extruder, and (2) a second portion of said melt passes through said second satellite screw extruder; and

(D) after said step of passing said melt of polymer through said multi-screw extruder, forming said polymer into a bulked continuous carpet filament;

wherein said bulked continuous carpet filament comprises a polymer blend comprising

a) about 1% by weight—about 15% by weight polytrimethylene terephthalate polymer (PTT); and

b) about 1% by weight—about 15% by weight polyethylene naphthalate polymer (PEN);

wherein the remainder of said polymer blend is polyethylene terephthalate polymer (PEN); and

wherein the PTT is or is not dried prior to step (C).

12. The method of claim 11 , wherein said polymer is a polyethylene terephthalate polymer, and further comprising after step (C) and before step (D), cooling said melt of polymer so as to form pellets, and mixing said pellets with polytrimethylene terephthalate polymer pellets, and polyethylene naphthalate polymer pellets.

13. The method of claim 11 , wherein said multi-screw extruder is a first extruder;

and said method further comprises:

i) passing a plurality of flakes of PET through a second extruder; and

ii) while passing said plurality of flakes through said second extruder, using said second extruder to heat said plurality of flakes to a temperature that is sufficient to at least substantially melt said plurality of flakes to form said polymer melt.

14. The method of claim 13 , wherein said PET flakes are recycled PET flakes, and wherein said method further comprises, before said step of passing said plurality of flakes through said second extruder:

washing said plurality of PET flakes;

scanning said washed plurality of PET flakes to identify any of said plurality of flakes that comprise material other than PET; and

removing at least one of said identified flakes that comprise material other than PET.

15. The method of claim 11 , wherein the melt in step (C) is a melt comprising polyethylene terephthalate, polyethylene naphthalate, and polytrimethylene terephthalate.

16. The method of claim 15 , wherein a mixture of PET flakes, PEN pellets, and PTT pellets is fed into the multi-screw extruder, or a compounded pellet comprising PET, PEN, and PTT is fed into the multi-screw extruder.

17. A method of manufacturing a fiber comprising a polymer blend of PET, PEN, and PTT, comprising:

a) providing a plurality of pellets, each pellet comprising PET, PEN, and PTT; and

b) melting said plurality of pellets with an extruder so as to form a melt; and

c) processing said melt with a spinning machine, so as to form said fiber;

wherein said fiber is a bulked continuous filament (BCF); and

wherein said fiber comprises a polymer blend, said polymer blend comprising:

c) about 1% by weight—about 15% by weight polytrimethylene terephthalate polymer; and

d) about 1% by weight—about 15% by weight polyethylene naphthalate polymer;

wherein the remainder of said polymer blend is polyethylene terephthalate polymer.

18. The method of claim 11 , wherein said polymer blend comprises about 5% by weight to about 15% by weight polytrimethylene terephthalate polymer, or

wherein said polymer blend comprises about 5% by weight to about 15% by weight polyethylene naphthalate polymer.

19. A yarn comprising the fiber of claim 1 .

20. A carpet comprising the fiber of claim 1 .