Process of preparing polyester yarn

Claim 2

A process of preparing polyester yarn having predetermined limits with respect to tenacity and boiling water shrinkage comprising: (a) drawing at ambient temperature a partially oriented feeder yarn comprising polyester filaments having a birefringence of at least 0.0175 at a draw ratio in the range of from about 1.75 to about 260; (b) partially annealing the drawn feeder yarn of step (a) at a temperature in the range of from about 70° C. to about 110° C., said drawing and said partial annealing occurring substantially sequentially; and, (c) annealing the partially annealed feeder yarn of step (b) at a tension in the range of from about at least 0.001 grams to about 50 grams and at a temperature of from about 110° C. to about 160° C.

Claim 3

The process recited in claim 1 wherein said polyester yarn has a tenacity in the range of from about 4.5 to about 7.0 g/denier and a boiling water shrinkage of from about 2 to about 10 percent.

Claim 4

The process recited in claim 2 wherein said polyester is a linear terephthalate polyester.

Claim 5

The process recited in claim 3 wherein said linear terephthalate polyester is poly(ethylene terephthalate).

Claim 6

The process recited in claim 4 wherein said birefringence of said feeder yarn is in the range of from about 0.020 to about 0.037.

Claim 7

The process recited in claim 5 wherein the preparation of said feeder yarn comprises: (i) extruding molten poly(ethylene terephthalate) having an intrinsic viscosity in the range of from about 0.4 to about 0.8 through a spinneret to form one or more filaments; (ii) quenching said filaments; (iii) applying an aqueous lubricating finish to said quenched filaments; and, (iv) taking up said filaments at a speed in the range of from about 2,200 to about 3,000 meters per minute.

Claim 8

The process recited in claim 6 wherein said fibers are taken up at a speed of about 2,750 meters per minute.

Claim 9

The process recited in claim 7 wherein said draw ratio of step (a) is from about 2.00 to about 2.50.

Claim 10

The process recited in claim 8 wherein said annealing temperature of step (b) is in the range of from about 90° to about 110° C.

Claim 11

The process recited in claim 9 wherein said tension of step (c) is an amount in the range of from about 20 to about 50 grams.

Claim 12

The process recited in claim 9 wherein said tension of step (c) is an amount in the range of from about 0.001 to about 10 grams.

Claim 13

A process of preparing polyester yarn having a tenacity in the range of from about 6.0 to about 7.5 grams per denier, a boiling water shrinkage in the range of from about 5 to about 10%, and an elongation in the range of from about 12 to about 15%, comprising: (a) drawing at ambient temperature a partially oriented feeder yarn comprising polyester filaments having a birefringence of at least 0.0175 at a draw ratio in the range of from about 2.20 to about 2.60; (b) partially annealing the feeder yarn of step (a) at a temperature in the range of from about 90° C. to about 110° C., said drawing and said partial annealing occurring substantially sequentially; and, (c) annealing the partially annealed feeder yarn of step (b) at a tension in the range of from about at least 20 grams to about 50 grams and at a temperature of from about 130° C. to about 160° C.

Claim 14

A process of preparing polyester yarn having a tenacity in the range of from about 6.0 to about 7.5 grams per denier, a boiling water shrinkage in the range of from about 5 to about 10%, and an elongation in the range of from about 12 to about 15%, comprising: (a) drawing at ambient temperature a partially oriented feeder yarn comprising polyester filaments having a birefringence of at least 0.0175 at a draw ratio in the range of from about 2.20 to about 2.60; (b) partially annealing the feeder yarn of step (a) at a temperature in the range of from about 90° C. to about 110° C., said drawing and said partial annealing occurring substantially sequentially; and, (c) annealing the partially annealed feeder yarn of step (b) at a tension in the range of from about at least 20 grams to about 50 grams and at a temperature of from about 130° C. to about 160° C.

Claim 15

The process recited in claim 12 wherein said polyester is poly(ethylene terephthalate).

Claim 16

A process of preparing polyester yarn having a tenacity in the range of from about 4.5 to about 5.5 grams per denier, a boiling water shrinkage in the range of from about 2 to about 3%, and an elongation in the range of from about 25 to about 35% comprising: (a) drawing at ambient temperature a partially oriented feeder yarn comprising polyester filaments having a birefringence of at least 0.0175 at a draw ratio in the range of from about 1.95 to about 2.05: (b) partially annealing the drawn feeder yarn of step (a) at a temperature in the range of from about 80° C. to about 100° C., said drawing and said partial annealing occurring substantially sequentially; and, (c) annealing the partially annealed feeder yarn of step (b) at a tension in the range of from about at least 0.001 grams to about 5 grams and at a temperature of from about 140° C. to about 160° C.

Claim 17

A process of preparing polyester yarn having a tenacity in the range of from about 4.5 to about 5.5 grams per denier, a boiling water shrinkage in the range of from about 2 to about 3%, and an elongation in the range of from about 25 to about 35% comprising: (a) drawing at ambient temperature a partially oriented feeder yarn comprising polyester filaments having a birefringence of at least 0.0175 at a draw ratio in the range of from about 1.95 to about 2.05: (b) partially annealing the drawn feeder yarn of step (a) at a temperature in the range of from about 80° C. to about 100° C., said drawing and said partial annealing occurring substantially sequentially; and, (c) annealing the partially annealed feeder yarn of step (b) at a tension in the range of from about at least 0.001 grams to about 5 grams and at a temperature of from about 140° C. to about 160° C.

Claim 18

The process recited in claim 14 wherein said polyester is poly(ethylene terephthalate).