Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Staple length fiber
Reexamination Certificate
2001-08-22
2002-10-01
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Staple length fiber
C428S397000, C428S364000, C442S357000
Reexamination Certificate
active
06458455
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to tetrachannel cross-section staple fibers, as well as yarn, fabrics and fiberfill made therewith and the process of making such staple fibers.
BACKGROUND OF THE INVENTION
Polyethylene terephthalate (“2GT”) and polybutylene terephthalate (“4GT”), generally referred to as “polyalkylene terephthalates”, are common commercial polyesters. Polyalkylene terephthalates have excellent physical and chemical properties, in particular chemical, heat and light stability, high melting points and high strength. As a result they have been widely used for resins, films and fibers, including staple fibers and fiberfill comprising such staple fibers.
Synthetic fibers made from 2GT are well known in the textile industry. Further, the properties and processing parameters of 2GT polymer are well known. Such synthetic fibers are commonly classified into two groups: (1) continuous filaments and (2) discontinuous fibers, often referred to as “staple” or “cut” fibers. Common end-use products made from 2GT staple fibers include yarn, fabric and fiberfill.
2GT staple fibers are desirable in such end-use products because of certain characteristics. For example, fabric and yarns from staple fibers from 2GT are known to produce yarns having desirable characteristics for downstream processing as disclosed by Aneja in U.S. Pat. No. 5,736,243. For instance, such fibers are suitable for processing on worsted systems. Furthermore, yarns made from such fibers are useful in manufacturing lightweight fabrics having good moisture wicking ability. Moisture wicking is desirable in fabrics used in many types of clothing items, e.g., sporting apparel, because they help keep moisture away from the wearer. Similarly, lightweight fabrics are desirable because they are less cumbersome than heavier fabrics.
Certain 2GT staple fibers are even more desirable in such end-use products because of special shape characteristics. For example, U.S. Pat. No. 5,736,243 discloses fabric and yarns of 2GT staple fibers having a tetrachannel cross-section, more specifically a scalloped-oval cross-section with channels that run along the length of the filament. Yarns made from such fibers are particularly useful in manufacturing lightweight fabric having good moisture wicking ability.
Recently, polytrimethylene terephthalate (3GT), also called polypropylene terephthalate, has achieved growing commercial interest as a fiber because of the recent developments in lower cost routes to 1,3-propane diol (PDO), one of the polymer backbone monomer components. 3GT has long been desirable in fiber form for its disperse dyeability at atmospheric pressure, low bending modulus, elastic recovery and resilience. However, the manufacture of 3GT staple fiber suitable for high-strength, high-elasticity yarns poses a number of special problems, particularly in obtaining satisfactory fiber crimp and yarn strength. The solutions to these problems developed over the years for 2GT or 4GT fibers frequently do not apply to 3GT fibers because of 3GT's unique properties.
U.S. patent application Ser. Nos. 09/795,518 (Attorney Docket: DP6535 US CIP, now U.S. Pat. No. 6,383,632) and 09/795,520, both filed Feb. 28, 2001 (Attorney Docket: DP6535 US CIP1, published as U.S. 2001/0030377 A
1
), and both of which claim priority from U.S. patent application Ser. No. 09/518,759 filed Mar. 3, 2000, now abandoned (Attorney Docket: DP6535), are directed to 3GT drawn yarn and a process of making the drawn yarn from 3GT partially oriented feed yarn, as well as 3GT fine denier partially oriented undrawn feed yarn and its preparation. The very fine filament yarns are suitable for warp drawing, air jet texturing, false-twist texturing, gear crimping, and stuffer-box crimping, for example. Tows made from these filament may also be crimped, if desired, and cut into staple and flock.
U.S. patent application Ser. No. 09/796,785, filed Mar. 1, 2001 (Attorney Docket: DP6540, published as U.S. 2001/0033929 A
1
), which claims priority from U.S. Provisional Patent Application Ser. No. 60/187,244, filed Mar. 3, 2000, is directed to 3GT direct-use yarns comprising non-round filaments and a process for spinning such yarn. The non-round cross-section yarns include those cross-sections described in the art as “octa-lobal”. “sunburst” (also known as “sol”), “scalloped oval”, “tri-lobal”, “tetra-channel” (also known as “quatra-channel”), “scalloped ribbon”, “ribbon”, “starburst”, etc.” Example II is directed to preparing a direct-use yam having filaments of varying cross-sections. Half of the resulting filaments had an octalobal cross-section and half had a sunburst cross-section. Example III is directed to octa-lobal cross-section filaments.
FIGS. 2 and 3
are schematic diagrams of hypothetical filaments having an octalobal cross-section.
FIG. 5
is a micrograph (750×magnification) of filaments having an octa-lobal cross-section prepared as described in Example III.
U.S. patent application Ser. Nos. 09/518,732, filed Mar. 3, 2000 (issue fee paid) (Attorney Docket: CH2756, now U.S. 6,287,688) and 09/795,933, filed Feb. 28, 2001 (Attorney Docket: CH2756 US DIV, published as U.S. 2001/0030378 A
1
), are directed to a 3GT partially oriented yarn, a process for spinning a stable 3GT partially oriented yarn, and a process for continuous draw-texturing a 3GT partially oriented yarn. The yarns can have round, oval., octa-lobal, tri-lobal, scalloped oval, and other shapes, with round being most common. Sample IIB (See, Example II, Table 2) is an octa-lobal partially oriented yarn.
JP 11-189938 teaches making 3GT short fibers (3-200 mm), and describes a moist heat treatment step at 100-160° C. for 0.01 to 90 minutes or dry heat treatment step at 100-300° C. for 0.01-20 minutes. In Working Example 1, 3GT is spun at 260° C. with a yarn-spinning take-up speed of 1800 m/minute. After drawing the fiber is given a constant length heat treatment at 150° C. for 5 minutes with a liquid bath. Then it is crimped and cut. Working Example 2 applies a dry heat treatment at 200° C. for 3 minutes to the drawn fibers.
JP 11-107081 describes relaxation of 3GT multifilament yarn unstretched fiber at a temperature below 150° C., preferably 110-150° C., for 0.2-0.8 seconds, preferably 0.3-0.6 seconds, followed by false twisting the multifilament yarn. This document does not teach a process for making a high tenacity crimped 3GT staple fiber.
U.S. Pat. No. 3,584,103 describes a process for melt spinning 3GT filaments having asymmetric birefringence. Helically crimped textile fibers of 3GT are prepared by melt spinning filaments to have asymmetric birefringence across their diameters, drawing the filaments to orient the molecules thereof, annealing the drawn filaments at 100-190° C. while held at constant length, and heating the annealed filaments in a relaxed condition above 45° C., preferably at about 140° C. for 2-10 minutes, to develop crimp. All of the examples demonstrate relaxing the fibers at 140° C.
EP 1 016 741 describes using a phosphorus additive and certain 3GT polymer quality constraints for obtaining improved whiteness, melt stability and spinning stability. The filaments and short fibers prepared after spinning and drawing are heat treated at 90-200° C., but are not crimped and relaxed. It states (page 8, line 18) that the cross-sectional shape of the fiber is not particularly limited and may be round, trilobal, flat, star-shaped, w-shaped, etc., and either solid or hollow. WO 01/16413, to the same applicant, claims special advantages for a 3GT fiber extruded with a convex-modified trilobal cross-section.
All of the documents described above are incorporated herein by reference in their entirety.
None of the cited documents teach a process for making a tetrachannel 3GT staple fiber, nor teach the special advantages of such a 3GT staple fiber.
SUMMARY OF THE INVENTION
This invention comprises a poly(trimethylene terephthalate) staple fiber having a tetrachannel cross-section. Preferably the tetrachannel cross-section comprises a scalloped-oval shape
Hernandez Ismael A.
Hietpas Geoffrey David
Howell James M.
Schultze Claudia
E. I. du Pont de Nemours and Company
Edwards N.
Kuller Mark D.
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