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US 6,685,859 B2Granted
Processes for making poly(trimethylene terephthalate) yarn
AssigneeE. I. Du Pont de Nemours and Company
InventorsJames M. Howell, Joe Forrest London, Jr.
Life of this patent
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AssigneeE. I. Du Pont de Nemours and Company
InventorsJames M. Howell, Joe Forrest London, Jr.
Estimating the term…
Processes for making poly(trimethyelene terephthalate) yarn are provided. The process includes extruding a polyester polymer through a spinneret to form non-round filaments at a spinning speed less than 4500 mpm and a temperature between about 255° C. and about 275° C. The polyester polymer composition includes at least 85 mole percent poly(trimethylene terephthalate) wherein at least 85 mole percent of the repeating units consist of trimethylene units, and the polyester polymer has an intrinsic viscosity of at least 0.70 dl/g.
A process for spinning a direct-use yarn, comprising extruding a polyester polymer through a spinneret to form molten streams of polymer at a spinning speed less than 4500 mpm and a temperature between about 255° C. and about 275° C., wherein said polymer comprises at least 85 mole % poly(trimethylene terephthalate) wherein at least 85 mole % of repeating units consist of trimethylene units, and wherein said polymer has an intrinsic viscosity of at least 0.70 dl/g, solidifying said molten streams to form non-round filaments, and converging said filaments to form said yarn.
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
From homopolycondensation products: from polyesters
Formation of filaments, threads, or the like: with a non-circular cross section; Spinnerette packs therefor
Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof: rod, strand,…
Chemical features in the manufacture of artificial filaments, threads, fibres, bristles or
Term ended 27 Jun 2021 (estimated)
1. Field of the Invention
The present invention relates to polyester yarn made from poly(trimethylene terephthalate) fibers. More particularly, the present invention relates to poly(trimethylene terephthalate) yarns fully oriented during the spinning process.
2. Background of the Invention
FIG. 1 is a schematic diagram of an exemplary spinning position for making the direct-use poly(trimethylene terephthalate) yarns of the present invention.
FIG. 2 is a schematic diagram of a hypothetical filament having an octalobal cross-section.
FIG. 3 is a schematic diagram of another hypothetical filament having an octalobal cross-section.
The present invention provides a method for spinning a fully oriented poly(trimethylene terephthalate) yarn suitable for direct-use in textile operations without intermediate drawing or texturing. The present invention further provides such direct-use poly(trimethylene terephthalate) yarns. The method of the present invention provides direct-use yarns spun at much lower spinning speeds than required in the past. Using the method of the present invention, a direct-use fully oriented poly(trimethylene terephthalate) yarn can be spun at less than 4500 meters per minute (“mpm”). Spin speeds can be as low as 3,000 mpm, or even slower, at commercial throughputs. The direct-use yarns of the present invention are characterized by having a boil off shrinkage less than 15% and are made from filaments having non-round cross-sections. (Some boil off shrinkage is desired for fabric processing. Boil off shrinkage as low as about 2% can be useful.)
It has been found that direct-use fully oriented poly(trimethylene terephthalate) yarns can be made using melt-spinning processes at a spinning speed lower than 4500 mpm if the cross-sectional shape of the yarn filaments are non-round. As used herein, a filament of non-round cross-section satisfies the following conditions: 0.5 ≤ A 1 A 2 ≤ 0.95 and ( I ) A 2 = P 1 2 4 π , ( II )
where A1 is the actual cross-sectional area of the individual yarn filament, P1 is the perimeter of the cross-section of the individual yarn filament, and A2 is the maximum area of a cross-section having the same perimeter, P1. According to this definition, for a perfectly round cross-section, the ratio of actual cross-sectional area to maximum cross-sectional area is exactly 1. The examples below show that if conditions (I) and (II) are satisfied, a lower spinning speed can be used to achieve the desired direct-use yarns.