Claims
- 1. A process for preparing drawn spin-oriented polyester fine filaments of denier, after boil-off shrinkage, in the range 0.2 to 0.8 dpf, wherein said process comprises:
- (i) selecting a polyester polymer to have a relative viscosity (LRV) in the range of about 13 to about 23, a zero-shear melting point (T.sub.M.sup.o) in the range about 240.degree. C. to about 265.degree. C., and a glass-transition temperature (T.sub.g) in the range of about 40.degree. C. to about 80.degree. C.;
- (ii) melting and heating said polyester polymer to a temperature (T.sub.p) in the range about 25.degree. C. above the apparent polymer melting point (T.sub.M).sub.a ;
- (iii) filtering the resulting melt sufficiently rapidly that the residence time (t.sub.r) is less than about 4 minutes;
- (iv) extruding the filtered melt through a spinneret capillary at a mass flow rate (w) in the range about 0.07 to about 0.7 grams per minute, and said capillary being selected to have a cross-sectional area (A.sub.c) in the range about 125.times.10.sup.-6 cm.sup.2 to about 1250.times.10.sup.-6 cm.sup.2, and a length (L) and diameter (D.sub.RND) such that the (L/D.sub.RND)-ratio is at least about 1.25 and less than about 6,
- (v) protecting the extruded melt from direct cooling as it emerges from the spinneret capillary over a distance (L.sub.DQ) of at least about 2 cm and less than about (12 dpf)cm, where dpf is the denier per filament of the fine spin-oriented polyester filament,
- (vi) cooling the extruded melt to below the polymer glass-transition temperature (T.sub.g) and attenuating to an apparent spinline strain (.epsilon..sub.a) in the range of about 5.7 to about 7.6, and to an apparent internal spinline stress (o.sub.a) in the range of about 0.045 to about 0.195 g/d,
- (vii) then converging the cooled filaments into a multifilament bundle by use of a low friction surface at a distance (L.sub.c) from the spinneret capillary in the range about 50 cm to about 140 cm,
- (viii) withdrawing the multifilament bundle as a yarn at a speed (V) in the range of about 2 to about 6 km/min, and
- (ix) drawing the resulting undrawn yarn of spin-oriented polyester filaments to provide a drawn yarn having an elongation-at-break (E.sub.B) of about 15% to about 55%, tenacity-at-7% elongation (T.sub.7) at least about 1 g/d such that the [(T.sub.B).sub.n /(T.sub.7)]-ratio is at least [5/(T.sub.7)], wherein (T.sub.B).sub.n is normalized tenacity-at-break, a post-yield modulus (M.sub.py) of about 5 to about 25 g/d, a boil-off-shrinkage (S) and dry heat shrinkage (DHS) of about 2% to about 12%, and an average denier spread (DS) less than about 4%.
- 2. A process for preparing bulked spin-oriented polyester fine filaments of denier in the range 0.2 to 0.8 dpf, wherein said process comprises:
- (i) selecting a polyester polymer to have a relative viscosity (LRV) in the range of about 13 to about 23, a zero-shear melting point (T.sub.M.sup.o) in the range about 240.degree. C. to about 265.degree. C., and a glass-transition temperature (T.sub.g) in the range of about 40.degree. C. to about 80.degree. C.;
- (ii) melting and heating said polyester polymer to a temperature (T.sub.p) in the range about 25.degree. C. above the apparent polymer melting point (T.sub.M).sub.a ;
- (iii) filtering the resulting melt sufficiently rapidly that the residence time (t.sub.r) is less than about 4 minutes;
- (iv) extruding the filtered melt through a spinneret capillary at a mass flow rate (w) in the range about 0.07 to about 0.7 grams per minute, and said capillary being selected to have a cross-sectional area (A.sub.c) in the range about 125.times.10.sup.-6 cm.sup.2 to about 1250.times.10.sup.-6 cm.sup.2, and a length (L) and diameter (D.sub.RND) such that the (L/D.sub.RND)-ratio is at least about 1.25 and less than about 6,
- (v) protecting the extruded melt from direct cooling as it emerges from the spinneret capillary over a distance (L.sub.DQ) of at least about 2 cm and less than about (12 dpf)cm, where dpf is the denier per filament of the fine spin-oriented polyester filament,
- (vi) cooling the extruded melt to below the polymer glass-transition temperature (T.sub.g) and attenuating to an apparent spinline strain (.epsilon..sub.a) in the range of about 5.7 to about 7.6, and to an apparent internal spinline stress (o.sub.a) in the range of about 0.045 to about 0.195 g/d,
- (vii) then converging the cooled filaments into a multifilament bundle by use of a low friction surface at a distance (L.sub.c) from the spinneret capillary in the range about 50 cm to about 140 cm,
- (viii) withdrawing the multifilament bundle as a yarn at a speed (V) in the range of about 2 to about 6 km/min, and
- (ix) bulking the resulting undrawn yarn of spin-oriented polyester filaments to provide a bulked yarn having a boil-off-shrinkage (S) and dry heat shrinkage (DHS) of about 2% to about 12%, tenacity-at-7% elongation (T.sub.7) at least about 1 g/d, elongation-at-break (E.sub.B) of about 15% to about 55%, and a post-yield modulus (M.sub.py) of about 5 to about 25 g/d.
- 3. A process according to claim 2, wherein said bulking comprises draw false-twist texturing said undrawn yarn to provide said bulked yarn.
- 4. A process according to claim 2, wherein said bulking comprises drawing said undrawn yarn, and air-jet texturing to provide said bulked yarn.
- 5. A process according to claim 1, wherein said resulting undrawn yarn is warp-drawn.
- 6. A process according to any one of claims 1 to 5, wherein the drawing conditions are such as to provide drawn filaments having a dynamic loss modulus peak temperature T(E".sub.Max) of no more than about 115.degree. C.
- 7. A process according to any one of claims 1 to 5, wherein the drawing conditions are such as to provide drawn filaments having a relative disperse dye rate (RDDR) of at least 0.1.
- 8. A process according to any one of claims 1 to 5, wherein non-round filaments are spun and the drawing conditions are such as to provide drawn cross-sections having non-round filaments of shape factor (SF) at least 1.25.
- 9. A process according to claim 1, wherein the drawing conditions are such as to provide drawn filaments of average along-end denier spread (DS) less than about 2%.
- 10. A process according to any one of claims 1 to 5, wherein said polyester contains in the range of 1 to 3 mole % of ethylene-M-sulfo-isophthalate structural units, wherein M is an alkali metal cation.
- 11. A process according to any one of claims 1 to 5, wherein said polyester is essentially poly(ethylene terephthalate), composed of first alternating glycol structural units A, [--O--C.sub.2 H.sub.4 --O--], and di-carboxylate structural units B, [--C(O)--C.sub.6 H.sub.4 --C(O)--], modified with minor amounts of other structural units selected from the group consisting of glycol structural units A' and di-carboxylate structural units B', that differ from said first alternating glycol structural units A and di-carboxylate structural units B, such as to provide a polyester polymer with a zero-shear melting point (T.sub.M.sup.o) in the range 240 C. to 265 C., and a glass-transition temperature (T.sub.g) in the range 40 C. to 80 C.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No. 08/015,733 (DP-4555-G), filed Feb. 10, 1993, and now U.S. Pat. No. 5,250,245 itself a continuation-in-part of application Ser. No. 07/860,776, now abandoned, filed Mar. 27, 1992, as a continuation-in-part of application Ser. No. 07/647,371 filed Jan. 29, 1991, now abandoned, and also of application Ser. No. 08/005,672 (DP-4555-F) filed Jan. 19, 1993, and now U.S. Pat. No. 5,288,553 as a continuation-in-part of application Ser. No. 07/647,381 also filed Jan. 29, 1991, and now abandoned.
US Referenced Citations (7)
Related Publications (1)
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5672 |
Jan 1993 |
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Continuations (1)
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15733 |
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Continuation in Parts (3)
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647381 |
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647381 |
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