Claims
- 1. An apparel yarn suitable for use as a feed yarn for drawtexturing, said yarn having an elongation betwee 45% and 150% and comprising filaments consisting essentially of nylon 66 polymer containing between 0.01 and 1 mole percent of a branching agent and having an elongation at least 5% greater than that of an otherwise identical yarn containing no branching agent.
- 2. The yarn defined in claim 1, wherein said branching agent constitutes between 0.05 and 0.15 mol percent of said polymer.
- 3. The yarn defined in claim 1, wherein said yarn was spun at a spinning speed greater than 2200 MPM.
- 4. The yarn defined in claim 1, wherein said filaments have a normalized SAXS peak intensity greater than 1.1.
- 5. The yarn defined in claim 1, wherein said filaments have a normalized SAXS peak intensity greater than 1.3.
- 6. The yarn defined in claim 1, wherein said filaments have a normalized SAXS peak intensity greater than 1.75.
- 7. The yarn defined in claim 1, wherein said filaments have a lamellar dimensional product of at least 1.1.
- 8. The yarn defined in claim 5, wherein said filaments have a lamellar dimensional product of at least 1.3.
- 9. The yarn defined in claim 6, wherein said filaments have a lamellar dimensional product of at least 1.3.
- 10. The yarn defined in claim 6, wherein said filaments have a lamellar dimensional product of at least 1.75.
- 11. The yarn defined in claim 1, wherein said branching agent is a trifunctional amine.
- 12. The yarn defined in claim 1, wherein said branching agent is TAN.
- 13. The yarn defined in claim 1, wherein said branching agent is bis-hexamethylene triamine.
- 14. The yarn defined in claim 1, wherein said branching agent is a trifunctional acid.
- 15. The yarn defined in claim 1, wherein said branching agent is trimesic acid.
- 16. An apparel yarn suitable for use as a feed yarn for drawtexturing, said yarn having an elongation between 45% and 150%, comprising filaments consisting essentially of nylon 66 polymer containing between 0.01 and 1 mole percent branching agent and having a normalized crimp development of at least 1.05.
- 17. The yarn of claim 16 wherein said filaments have a normalized SAXS peak intensity greater than 1.1 and a lamellar dimensional product of at least 1.3.
- 18. The yarn of claim 17 wherein said normalized SAXS peak intensity is greater than 1.75.
- 19. The yarn of claim 17 wherein the branching agent is a trifunctional amine.
- 20. The yarn of claim 19 wherein the branching agent is TAN.
- 21. The yarn of claim 19 wherein the branching agent is bis-hexamethylene amine.
- 22. The yarn of claim 19 wherein the branching agent is trimesic acid.
Parent Case Info
This application is a continuation in part of U.S. patent application Ser. No. 690,705 filed Jan. 11, 1985.
As used in the specification and claims, the term "nylon 66" means those synthetic polyamides containing in the polymer molecule at least 85% by weight of recurring structural units of the formula ##STR1##
Historically, certain nylon 66 apparel yarns were spun at low speeds of up to about 1400 meters per minute and packaged. The spun yarns were then drawn on a second machine and packaged again. The drawn yarn was then false-twist textured at slow speeds of the order of 55-230 meters per minute by the pin-twist method, yielding a very high quality stretch yarn suitable for stretch garments such as leotards. An exemplary false-twisting element for the pin-twist texturing process is disclosed in Raschle U.S. Pat. No. 3,475,895.
More recently, various other types of false twisting apparatus have come into commercial use, and are collectively referred to as "friction-twist". Some of the most widely used of these include a disc aggregate of the general type illustrated in U.S. Pat. Nos. 3,973,383, Yu, 4,012,896 to Fishbach or 3,885,378 to Schuster. Friction-twisting permits considerably higher texuring speeds than pin-twisting, with yarn speeds currently at about 700-900 mpm. Such high texturing speeds are more economical than those attained by the pin-twist process.
Along with the shift to friction-twisting has come a shift to partially-oriented nylon 66 (PON) yarns as the feeder yarns for the friction-twist process. In the conventional PON spinning process, the winding speed is merely increased from the previous standard of about 900-1500 meters per minute to speeds generally in the 2750-4000 meters per minute range, resulting in a PON yarn. PON yarn performs better in the high speed friction-twist texturing process than either the earlier drawn yarn or the low-speed spun yarn mentioned above. However, heretofore yarns textured by the friction-twist process were of distinctly lower quality in terms of crimp development than yarns textured by the pin-twist process. The apparel nylon 66 false-twist textured yarn market is accordingly in essentially two distinct segments: the older, expensive, high quality pin-twist yarns, and the newer, less costly, lower quality friction-twist yarns.
Conventional PON feeder yarns for false-twist texturing have had R.V.'s in the range from the middle or upper thirties to the low forties, as indicated by U.S. Pat. No. 3,994,121. More recently, Chamberlin et al. U.S. patent application Ser. No. 594,522, filed April 2, 1984, (now U.S. Pat. No. 4,583,357) and assigned to the assignee of the present application, discloses that high RV PON feeder yarns are superior to those conventional PON yarns disclosed in U.S. Pat. No. 3,994,121.
According to the present invention there are provided further novel and improved PON feeder yarns permitting manufacture of friction-twist yarns having increased crimp development, in some cases comparable to that of pin-twist yarns, and in some cases superior to the yarns of the noted Chamberlin application. This increased crimp development provides a substantial increase in fabric stretch recovery and covering power as compared to fabrics made from friction-twist yarns made from PON feeder yarns as disclosed by Adams U.S. Pat. No. 3,994,121. Accordingly, less textured yarn is required to provide a fabric of equivalent covering power, or a fabric with increased stretch recovery is produced if the same amount of textured yarn is used. Increased productivity is also provided, and in some cases the conventional heating step prior to packaging disclosed by Adams as being critical is eliminated. The improved productivity is based on an increase in the elongation-to-break of the yarns of this invention as compared to otherwise identical yarns (yarns spun under identical conditions from polymers which are the same except that the branching agent used in yarns of this invention is absent). As is known, for example from U.S. Pat. No. 4,442,057, productivity is proportional to elongation. If a spun filament has a percent elongation-to-break of E, then the maximum draw ratio to which it can subsequently be subjected is roughly (1+E/100). If a second spun filament has a larger elongation-to-break E' then it can be subjected to a larger draw ratio, roughly (1+E'/100). To make drawn filaments of equal decitex d at these maxirum draw ratios, the spun filaments must therefore have decitexes of d (1+E/100) and d(1+E'/100) respectively. If both filaments are spun at the same speed, their production rates are proportional to these decitexes and the percentage increase in productivity of the second filament is ##EQU1## Increases in elongation-to-break of 5% (that is, 5% of the percentage elongation of the yarn containing no branching agent or more are readily determinable by conventional laboratory techniques and are correlatable to significant increases in productivity.
The yarns of the invention are, broadly, false twist texturing feed yarns spun at high speeds and characterized by incorporation in the polymer from which the yarns are spun of small amounts of branching agents. While the mechanism or reason for the improved results of the present invention are not entirely understood, the yarns have increased values of normalized SAXS peak intensity and normalized lamellar dimensional product which are distinctive as compared to conventional PON yarn, and are believed to contribute to the improved results of the present invention. Values of at least 1.1 for each of these properties are generally associated with yarns according to the invention with values of 1.3 being generally preferred and values of at least 1.75 being especially preferred. One possible explanation of the normalized SAXS peak intensity is that it indicates relatively more relaxed amorphous regions and relatively more highly developed crystalline regions in the yarns of the present invention as compared to conventional PON yarn.
According to a first principal aspect of the invention there is provided an apparel yarn suitable for use as a feed yarn for drawtexturing, the yarn having an elongation between 45% and 150% and comprising filaments consisting essentially of a polyamide polymer containing a branching agent in an amount sufficient to provide improved productivity (as evidenced by at least a 5% increase in elongation) and/or crimp development.
According to a second principal aspect of the invention, there is provided a process for melt spinning a polyamide yarn suitable for drawtexturing from a molten polyamide polymer containing a branching agent, the process comprising extruding at a given extrusion rate a plurality of streams of the polymer through spinneret capillaries into a quench zone; quenching the molten streams into filaments; withdrawing the filaments from the quench zone at a spinning speed greater than 2200 MPM; and converging the filaments into a yarn; the polymer, the extrusion rate, and the spinning speed being selected such that the yarn has an elongation between 45% and 150%.
According to further aspects of the invention, the preferred polyamide is nylon 66. Preferably the branching agent constitutes between 0.01 and 1 mol percent of the polymer, and it is especially preferred that the branching agent constitute between 0.05 and 0.25 mol percent of the polymer. In the spinning process, better yarn properties are sometimes noted if the yarn is stretched at a draw ratio between 1.01 and 1.6 immediately after solidification and prior to being wound. Improved results are obtained when the filaments have a normalized SAXS peak intensity greater than 1.1, with still further improved results being obtained when the filaments have a normalized SAXS peak intensity greater than 1.75. Filaments of the invention generally have a normalized lamellar dimensional product of at least 1.1, with superior products having a normalized lamellar dimensional product of at least 1.75. If the polymer is to be melted on a conventional grid prior to the step of extruding, the polymer RV is advantageously less than 60 (preferably between 40 and 55), while if an extruder is used to melt the polymer, the polymer RV is preferably between 50 and 80.
US Referenced Citations (13)
Continuation in Parts (1)
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690705 |
Jan 1985 |
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Patent Grant
4721650
