Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/14—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyester as constituent
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/253—Formation of filaments, threads, or the like with a non-circular cross section; Spinnerette packs therefor
• • D—TEXTILES; PAPER
  • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
  • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
  • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
  • D02G3/02—Yarns or threads characterised by the material or by the materials from which they are made
  • D02G3/04—Blended or other yarns or threads containing components made from different materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2904—Staple length fiber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2915—Rod, strand, filament or fiber including textile, cloth or fabric
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2922—Nonlinear [e.g., crimped, coiled, etc.]
  • Y10T428/2924—Composite
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2929—Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/2929—Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
  • Y10T428/2931—Fibers or filaments nonconcentric [e.g., side-by-side or eccentric, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/30—Woven fabric [i.e., woven strand or strip material]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/30—Woven fabric [i.e., woven strand or strip material]
  • Y10T442/3065—Including strand which is of specific structural definition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/40—Knit fabric [i.e., knit strand or strip material]
  • Y10T442/425—Including strand which is of specific structural definition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]

Definitions

• This invention relates to a polyester staple fiber, and to a spun yarn comprising such polyester staple fiber and cotton. More particularly, this invention relates to a side-by-side or eccentric sheath-core bicomponent polyester staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) which is particularly well suited for processing on the cotton system and from which spun yarn of high uniformity and high stretch-and-recovery can be produced. This invention also relates to fabrics made from the spun yarn comprised of such bicomponent staple fiber.
• Bicomponent fibers comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) are generally known, as disclosed, for example, in United States Patent N ⁇ s. 3,671 ,379 and 6,656,586 and in Japanese Published Patent Applications No. JP2002-180333A and JP2002-180332A, as welfas in United States Published Patent Applications No. 2003/0056553 and 2003/0108740.
• Yarn comprising polyester fiber and cotton is disclosed in US 6,413,631, Japanese Published Patent Application "No. JP2002-115149A, and in United States Published Patent Application No. 2003/0159423 A1.
• processing these bicomponent fibers with cotton staple can be difficult and spun yarns made from these fibers in combination with cotton can have lower quality than desired. Blending of these fibers often requires reduced percentages relative to the other fiber due to deteriorating quality at increased percentage levels of bicomponent fiber. Furthermore, the processing difficulty of these fibers can limit the range of spun yarn counts that may be produced with acceptable quality. Bicomponent fibers comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) which are better suited for processing on the cotton system are sought. High uniformity spun yarn comprising bicomponent staple fibers and cotton and having good stretch and recovery is also sought, as are stretch fabrics with uniform appearance made from cotton/polyester spun yarns.
• the present invention provides a bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) wherein the bicomponent fiber has a substantially oval cross-section shape having an aspect ratio A:B of about 2:1 to about 5:1 wherein A is a fiber cross-section major axis length and B is a fiber cross- section minor axis length, a polymer interface substantially perpendicular to the major axis, a cross-section configuration selected from the group consisting of side-by-side •and eccentric sheath-core, a tenacity at 10% elongation of about 1.1 cN/dtex to about 3.5 cN/dtex, a free-fiber length retention of about 40% to about 85%, and a tow crimp development value of about 30 to 55%.
• the invention also provides a spun yarn having a cotton count of about 14 to about 60 and comprising bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) wherein the spun yarn has about 0.1 to about 150 thin regions per 1000 meters, about 0.1 to about 300 thick regions per 1000 meters, about 0.1 to about 260 neps per 1000 meters, ' and a boil-off shrinkage of about 27% to about 45%, wherein the bicomponent staple fiber is present at a level of about 30 wt% to about 100 wt%, based on total weight of the spun yarn.
• FIG. 1A is an image of a photomicrograph (3000x magnification) of a round bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate): '
• FIG. 1 B is an image of a photomicrograph (1000x magnification) of a bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) having a, "scalloped oval" cross-section wherein the polymer interface is parallel to the major axis.
• FIG. 1A is an image of a photomicrograph (3000x magnification) of a round bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate): '
• FIG. 1 B is an image of a photomicrograph (1000x magnification) of a bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) having a, "scalloped oval"
• FIG. 1C is an image of a photomicrograph (1000x magnification) of an embodiment of the bicomponent fiber of the invention having an "oval" cross-section with an aspect ratio of about 2.1 :1.
• FIG. 1 D is an image of a photomicrograph (1000x magnification) of a preferred embodiment of the bicomponent fiber of the invention having an "oval" cross-section with an aspect ratio of about 3.5:1.
• FIG. 2A is an image of a photomicrograph (32x magnification) of a bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) having a round cross-section.
• FIG. 2B is an image of a photomicrograph (32x magnification) of a bicomponent fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) having' a scalloped oval cross-section with polymer interface parallel to the : major axis.
• FIG. 2C is an image of a photomicrograph (32x magnification) of a preferred embodiment of the' bicomponent fiber of the invention having an "oval" cross-section with an' aspect ratio of about 3.3:1.
• FIG. 3 shows a typical spinneret orifice for spinning fibers with scalloped oval cross-section. " ' ' '
• bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) and having a certain cross-sectional shape,-as well as other specific characteristics, gives spun yarns with-an unexpected combination of high uniformity and high boil-off shrinkage.
• High boil-off shrinkage indicates that the yarn possesses high stretch-and-recovery, which is desirable for today's fabrics.
• Fine spun yarns are very difficult to make highly uniform, and the finding is particularly unexpected in view of the high cotton count of the spun yarn of the invention.
• "bicomponent As used herein, "bicomponent.
• fibers means staple fibers in which two polymers of the same general class are in a side-by-side or eccentric sheath-core relationship.
• side-by-side means that the two components of the bicomponent fiber are immediately adjacent to one another and that no more than a minor portion of either component is within a concave portion of the other component.
• eccentric sheath-core means that one of the two components completely surrounds the other component but that the two components are not coaxial.
• substantially oval means that an area of a cross- section of the fiber, measured perpendicular to the longitudinal axis of the fiber, deviates by less than about 20% from that of an oval shape.
• oval includes.”qyoid” (egg-shaped) and "elliptical” within its meaning.
• a shape typically has two axes at right angles through the center of the shape, a major axis (A), and a minor axis (B), where the length of the major axis A is greater than the length of the minor axis B.
• A major axis
• B minor axis
• the oval is described by a locus of points whose sum of whose distances from two foci is constant and equal to A.
• one end of the oval can be larger than the other, so that the sum of the distances from two foci is not necessarily constant and can vary by 20% or more from elliptical.
• a "substantially oval” cross-section periphery may have or may lack constant curvature. . ?
• “Aspect ratio” means the ratio of the length of the major axis of the oval to the length of the minor axis of the oval, in other words A:B.
• “Polymer interface'' means the boundary between the poly(ethylene terephthalate) and the p ⁇ ly(trimethy ⁇ ene terephthalate), which can be substantially linear or curved.
• “Intimate blending” means the process of gravimetrically and thoroughly mixing dissimilar ' fibers in an opening room (for example with a weigh-pan hopper feeder) before feeding the mixture to the card or of mixing the fibers in a dual feed chute oh the card.
• “Drawframe blending” means the process of blending carded bicomponent fiber sliver with one or more other carded fiber slivers as the slivers are being drawn on the draw- frame.
• the fiber of the invention has a substantially oval cross-section shape with an aspect ratio A:B 'of about 2:1 to about 5:1 , (examples include about 2.6:1 to about-3.9:1, and about 3.1 :1 to about 3.9:1).
• the aspect ratio is too high ortoo low, the fiber can exhibit undesirable glitter and low dye yield, and spun yarn comprising the fiber can be insufficiently uniform.
• the fiber also has a polymer interface substantially perpendicular to the major axis of the cross-section, and a free-fiber length retention from about 40% to about 85%.
• Such oval filaments can be spun from spinneret orifices that are slot-shaped (flat or with side bulges), oval, and the like.
• the oval cross-section shape is substantially free of grooves in the cross-section periphery. That is, there is only one maximum when the length of the minor axis is plotted against the length of the major axis.
• the fiber comprises two polyesters, for example poly(ethylene terephthalate) and poly(trimethylene terephthalate), preferably of different intrinsic viscosities, although different combinations such as poly(ethylene terephthalate) and poly(tetrabu ' tylene terephthalate) are also possible.
• the compositions can be similar, for example a poly(ethylene terephthalate) homopolyester and a poly(ethylene terephthalate) copolyester, optionally also of different viscosities.
• the bicomponent fiber has a free fiber length retention of about
• the free fiber length retention is a useful measure of how "straight" the crimped fiber is in its ' relaxed state, in other words, how tightly the crimped fiber coils When it is not under tension.
• a spun yarn comprising a bicomponent staple fiber having a free fiber length retention that is too low can exhibit poor uniformity, and can be difficult to card.
• the bicomponent staple fiber can have a tenacity-at-break of about 3.6 to about 5.0 cN/dtex, tenacity at 10% elongation (T10) of about 1.1 cN/dtex to about 3.5 cN/dtex (preferably about 2.0 to 3.0 cN/dtex), and a weight ratio of poly(ethylene terephthalate) to poly(trimethylene terephthalate) of about 30:70 to about 70:30, preferably about 40:60 to about 60:40.
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% elongation
• T10 tenacity at 10% e
• polyesters comprising the fiber of the invention can be copolyesters, and "poly(ethylene terephthalate)" and “poly(trimethylene terephthalate)” include sjjch copolyesters within their meanings.
• a cppoly(ethylene terephthalate) can be used in which the comonomer used to; make the copolyester is selected from the group consisting of linear, cyclic, and branched aliphatic dicarboxylic acids having 4-12 carbon atoms (for example butanedioic acid, pentanedioic acid, hexanedioic acid, dodecahedio ⁇ c acid, and 1 ,4-cyclo- hexanedicarboxylic acid ⁇ aromatic dicarboxylic acids other than terephthalic acid and having 8-12 carbon atoms (for example isophthalic acid and 2,6-naphthalenedicarboxylic acid); linear, cyclic, and branched aliphatic diols having 3-8 carbon atoms (for example 1 ,3-propane diol, 1 ,2- propanediol, 1 ,4-butanediol, 3-r ⁇ eth
• the com ⁇ n ⁇ mer can be present to the extent that it does not compromise the benefits of the invention, for example at levels of about 0.5-15 mole percent based on total polymer ingredients.
• Isophthalic acid, pentanedioic acid, hexanedioic acid, 1 ,3-propane diol, and 1 ,4-butanediol are preferred comonomers.
• the copolyester(s) can' also be made with minor amounts of other comonomers, provided such comonomers do not have an adverse effect on the physical properties of the fiber.
• Such other comonomers include 5- sodium-sulfoisophthalate, the sodium salt of 3-(2-sulfoethyl) hexanedioic acid, and dialkyl esters thereof, 'which can be incorporated at about 0.2-4 mole percent based on total polyester.
• the (co)polyester(s) can also be mixed with polymeric secondary amine additives, for example poly(6,6'-imin ⁇ -bishexamethylene terephthalamide) and copolyamides thereof with'hexamethylenediamine, preferably phosphoric acid and phosphorous acid salts thereof.
• the fiber of the present invention can also comprise conventional additives such as antistats, antioxidants, antimicrobials, flameproofing agents, dyestuffs, light stabilizers, and delustrants such as titanium dioxide, provided they do not detract from the benefits of the invention.
• the finish can be applied at a level (% by total weight) of 0.05-0.30%.
• the finish can comprise 1) a blend of alkyl or branched phosphate ester ' s, or 2) the potassium, calcium, or sodium salts of the corresponding phospha'te ' acids, or a blend of the those two classes in any proportion, each of which can contain from 6 to 24 total carbon atoms in the aliphatic segments.
• the finish can also contain poly(ethylene oxide) and/ ⁇ r polypropylene oxide), or short chain segments of such polyethers can be attached by esterification to aliphatic acids such as lauric acid, or by an ether linkage to alcohols such as sorbitol, glycerol, castor oil', coconut oil, or the like. Such compounds can also comprise amine groups.
• the finish can also contain minor amounts (for example ⁇ 10%) of functional additives such as silicones or fluorochemicals.
• the finish can contain a blend of the potassium salts of mono- and di-acids containing about 18 carbons and an ethoxylated polyether containing 4-10 ethylene oxide segments made by reaction of an n-alkyl alcohol containing from 12 t ⁇ ' 18 carbon atoms with a blend of polyethers. ' . ' ⁇ •" ⁇ ' -" It is unnecessary that the crimps of the bicomponent fibers in the tow precursor to the staple fiber be deregistered, that is treated in such a way as to misalign the crimps of the fibers. Similarly, the bicomponent staple tow does not require mechanical crimping in order for staple made therefrom to display good processability and useful properties.
• the bicomponent fiber can have an elongation to break of about 15% to about 35%, for example- about 15% to about 25%, and typically of about 15% to about 20%.? ' ;
• the bicomponent staple, fiber can have a tow crimp development ("CD") value of about 30% to about ' 55% and a crimp index (“CI”) value of about 15% to about 25%.
• CD tow crimp development
• CI crimp index
• the bicomponent staple fiber can have a length of about 1.3 cm to about 5.5 cm. When the bicomponent fiber is shorter than about 1.3 cm, it can be difficult to card, and when it is longer than about 5.5 cm, it can be difficult to spin on cotton system equipment.
• the cotton can have a length of from about 2 to about 4 cm.
• the bicomponent fiber can have a linear density of about 0.7 dtex, preferably about 0.9 dtex, to about 3.0 dtex, preferably to about 2.5 dtex.
• the yarn can have a harsh hand, and it can be hard to blend with the cotton.
• it has a linear density below about 0.7 dtex, it can be difficult to card.
• the spun yarn of the invention has a cotton count of about 14 to about 60 (preferably about 16 to about 40) and comprises a bicomponent staple fiber comprising poly(ethylene terephthalate) and poly(trimethylene terephthalate) and a second staple fiber selected from the group consisting of cotton (preferred), synthetic cellulosic, and acrylic fibers.
• the spun yarn is very uniform and has about 0.1 to about 150 (preferably about 1 to 70) thin regions ' per 1000 meters, about 0.1 to about 300 thick regions per 1000 meters, about 0.1 to about 260 neps per 1000 meters, and a total boil-off shrinkage of about 27% to about 45%, for example about 30% to about 45%.
• Yarn quality factor is a very useful measure of yarn quality, which can be calculated from the number of thin regions, thick regions, neps, coefficient of variation of mass, and yarn strength.
• the spun yarn can have a yarn quality factor of about 0.1 to about 650, for example about 1 to about 300. When the quality factor is too high, the yarn can be insufficiently uniform. Another way to describe uniformity of spun yarn is in terms of the coefficient of variation as determined with a Uniformity 1-B Tester.
• the spun yarn of the invention can have a coefficient of variation of mass of about 10% to about 18%, for example about 12% to about 16%. It is preferred that the spun yam of the invention comprise the fiber of the invention, and that the spun yarn have a tenacity-at-break of about 10 to about 22 cN/tex. When the tenacity is too low, yarn spinning can be difficult and weaving efficiency and fabric strength can be reduced. It is also preferred that the linear density of ' the spun yarn be about 100 to about 700 denier (111 to 778 dtex). ' In the spun yarn, the bicomponent staple fiber is present at a level of about 30 wt% to about 100 wt%, based on the total weight of the spun yarn.
• the yarn of the invention comprises less than about 30 wt% polyester bicomponent
• the yarn can exhibit inadequate stretch and recovery properties.
• the bicomponent staple fiber is present at a level below 100 wt% but above 30 wt%
• the spun yarn comprises a second staple fiber selected from the group consisting of monocomponent poly(ethylene terephthalate), monocomponent poly(trimethylene terephthalate), cotton, wool, acrylic, arid nylon staple fibers which can be present at about 1 wt% to about 70 wt%; based on total weight of the spun yarn.
• the spun yarn of the invention can further comprise a third staple fiber selected from the same group and present at about 1 wt% to about 69 wt% based on the total weight of the spun yarn; together, the second and third staple fibers can be present at about 1 wt% to about 70 wt%, based on total weightOf the spun yarn.
• the yarn may be spun, by commercially available processes such as ring, open end, air jet, and. vortex spinning. Knit and woven stretch fabrics can be made from the spun yarn of the invention. Stretch fabric examples include circular, flat, and warp knits, and plain, twill, and satin wovens. The high uniformity and stretch characteristics of the spun yarn are typically carried through into the fabric as uniform appearance and high stretch and recovery, which are highly desirable.
• free-fiber length retention (L 2 /L ⁇ ) x 100 (II)
• Figure 2 qualitatively illustrates the difference in free-fiber length retention between fibers not of the invention ( Figures 2A and 2B) and a fiber of the invention ( Figure 2C). Unless otherwise noted, the following methods of measuring tow
• tow Crimp Index a 1.2-meter sample of polyester bicomponent tow was weighed, and its denier was calculated; the tow linear density was typically about 40,000 to 50,000 denier (44,000 to 55,000 dtex). A single knot was tied at each end of the tow.
• Tension was applied to the vertical tow sample by applying a first clamp at the lower knot and hanging at least 40 mg/den (0.035 dN/tex) of weight on the knot at the upper end of the tow, which was directed over a stationary roller located at 1.1 m from the bottom end of the tow.
• the weight was selected so as to straighten the crimp from the tow without breaking the fibers. At this point the tow was essentially straight and all fiber crimp: ' was removed.
• a second clamp was applied to the tow 100 cntab ⁇ ve the first clamp while the weight was in place.
• references herein to crimp values of staple fibers indicate measurements made on the tow precursors to such fibers.
• f ' ' Cardability of staple fibers which contained adequate finish to control static was evaluated by visual inspection of the card web and the coiling of the sliver. Fibers which produced a card web which was uniform in appearance and free of neps, and which had no coiler chokes during processing into sliver, were considered to exhibit good cardability. Fibers which did not meet these criteria were considered to have poor cardability.
• Total B.O.S (%) .100 x (Lb - L bo )/L 0 (IV) : ' - , ' " : ' : :' ' ' .
• the 'true' shrinkage of the spun yarn was measured by applying a 200 mg/den (0.18 dN/tex) load, measuring the extended length, and calculating the percent difference between the before-boil-off and extended after-boil-off lengths.
• the true shrinkage of the samples was generally less than about 5%.
• E is the number of thick regions 1 per 1000 yards of yarn
• F is the number of thin regions per 1000 yards of yarn
• G is the number of neps per 1000 yards of yarn
• H is the coefficient of variation of yarn mass ("CV") in percentage units, each as measured by the Uster Uniformity 1-B tester
• J is the tenacity-at-break of the yarn in cN/tex.
• Example 1 the ratio of first draw ratio to total draw ratio was 0.78 to 0.88, and the duration of the heat-treating step was at least 3 seconds.
• Cross-section aspect ratios A:B were determined by measurement of photomicrographs and were typically accurate to within 5%. Fiber preparation conditions and properties not described in the text are presented in Tables 1 and 2, respectively.
• Neps refers to the number of places per 1000 yards of yarn having a mass at least 200% more than the average mass. The number of thicks, thins, and neps reported is as measured by the UsterUniformity 1-B tester.
• DuPont de Nemours and Company having an IV of 0.98 dl/g, were extruded in a 50/50 weight ratio from a block operated at 272 °C via metering pumps to a bicomponent spin pack provided with etched metering plates which joined the polymer streams directly above the counterbore of the spinneret capillaries.
• a delusterant of particulate TiO 2 was added to both polymers at a level of 0.1-0.4% by weight.
• the polymers were spun from a 288-hole x spinneret in which the capillaries were 0.38 mm in depth and had cross-sections that were 0.64 mm long modified slots, with outward-rounded bulges in the middle of each long side (maximum width 0.18' mm) and rounded ends with 0.06 mm radii.
• the polymer interface was substantially perpendicular to the major axis of the resulting oval cross-section fiber.
• the just-spun fibers were cooled with a cross-flow of air applied at a mass ratio (air/polymer) of about 10 ⁇ 14; spin finish was applied with a metered contact applicator at ' 0.1wt%, and the oval (aspect ratio of 2.1 :1 (measured - see Figure 1C) fibers were wound up on bobbins at 1000 m/min. Fibers from a plurality of bobbins were combined into a tow of approximately 50,000 dtex and drawn in two stages using first and second draw ratios of 2.69 and 1.28, respectively, with a final speed of 50 m/min. The first draw was performed at 35 °C in a water bath, and the second draw, under a hot-water spray at 90 C.
• the drawn tow was heat-treated at 150 °C, cooled to below 30 °C with a dilute finish oil/water spray (0.20 wt% on fiber), and passed to a puller roll operated at a slower speed than the last draw roll.
• the tow was dried at room temperature and cut to 1.5" (3.8 cm) staple length.
• EXAMPLE 1B Polyester bicompone ⁇ staple fiber was made as described in Example 1A, with the following differences.
• Oval fibers of aspect ratio 3.3:1 (measured - see Fig ⁇ re D) were spun from a 288-hole spinneret in which the capillaries were 0.38 mm in depth and had cross-sections that were 0.76 mm long modified slots, with outward-rounded bulges in the middle of each long side (maximum width 0.14 mm) and rounded ends with 0.05 mm radii. Let-down ratio was 0.942.
• Figure 2C illustrates the ⁇ low coiling exhibited by the fiber.
• Polyester bicomponent staple fiber was made as described in
• Example 1A with the following ' differences.
• the poly(ethylene terephthalate) IV was 0.54, and the poly(trimethylene terephthalate) IV was 0.95.
• the fiber cross-section was oval with an aspect ratio of 2.4: 1
• the spin speed was 1200 m/min
• the first draw ratio was 2.23
• the heat-treating temperature was 170 °C.
• Polyester bicomponent staple fiber was made as described in
• Example 1A With the following differences. Oval fibers of aspect ratio of about 3:1 (estimated) were spun through ' the orifices of Example 1 B.
• the poly(ethylene terephthalate) IV was 0.54, the poly(trimethylene terephthalate) IV was 0.95, the spinning speed was 1200 m/min, the first draw ratio was 2.44, and the heat-treating temperature was 170 °C.
• Polyester bicomponent staple fiber was made as described in Example 1 D, with the following differences. Oval fibers of aspect ratio 3.3:1 (measured) were spun, the first draw ratio was 2.52, and let-down ratio was 0.97. . EXAMPLE 1F Polyester bicomponent staple fiber was made as described in Example 1 D, except that the first draw ratio was 2.54 and the heat-treating temperature was 165 °C.
• EXAMPLE 1G Polyester bicomponent staple fiber was made as described in Example 1 D, with the following differences. Oval fibers of aspect ratio 3.5:1 (measured) were spun, the first draw ratio was 2.56, and the heat- treating temperature was 165 °C. The low T10 value obtained indicated that the target letdown ratio of 1.0 was not achieved. The actual letdown ratio was below 1.0.
• Polyester bicomponent staple fiber was made as described in
• Example 1B Oval fibers of aspect ratio about 3:1 (estimated) were spun.
• the weight ratio of the polymers was 55/45 poly(ethylene terephthalate)/poly(trimethylene) terephthalate
• the poly(trimethylene terephthalate) IV was ' 0.94
• the poly(ethylene terephthalate) was KoSa 8958C
• the spinning speed was 1400 m/min
• the first draw ratio was 2.37
• the second draw ratio was 1.29
• the heat- treating temperature was 180 °C.
• COMPARISON EXAMPLE 1 Polyester bicomponent staple fiber was made as described in Example 1A, with the following differences. Scalloped oval (measured aspect ratio 2.2:1 - see Figure IB) fibers with the polymer interface parallel to the major axis of the cross-section were spun through orifices of configuration essentially as shown in FIG. 3. The orifices were arranged to give the desired interface orientation ' .
• the poly(trimethylene terephthalate) IV was 1.04
• the.first draw ratio was 2.71
• let-down ratio was 0.85.
• Figure 2B illustrates the excessive coiling exhibited by the fiber.
• COMPARISON EXAMPLE 2 Polyester bicomponent staple fiber was made as described in Example 1A, with the following differences.
• Polyester bicomponent staple fiber was made from bicomponent continuous filaments of poly(et . hyJerie terephthalate) (Crystar® 4415-763, a registered trademark of E. I. d ⁇ Pont de Nemours and Company), having an intrinsic viscosity ("IV") of 0:52 dl/g, and Sorona® brand poly(trimethylene terephthalate) (Sorona® is a registered trademark of E. I. DuPont de Nemours and Company), having an IV of 1.00, which were melt-spun through a 68-hole post-coalescing spinneret at a spin block temperature of 255-265 °C.
• the weight ratio of the polymers was 60/40 poly(ethylene terephthalate)/poly(trimethyle ⁇ e terephthalate).
• the filaments were withdrawn from the spinneret at 450-550 m/min and quenched with crossflow air.
• the filaments, having a 'snowman' cross- section, were drawn 4.4X, heat-treated at 170°C, interlaced, and wound up at 2100-2400 m/min.
• the filaments had 12% CI, 51% CD, and a linear density of 2.4 dtex/filament.
• ⁇ or conversion to staple fiber filaments from wound packages were collected into a tow and fed into a conventional staple tow cutter, the blade spacings of which were adjusted to obtain a 1.5 inch (3.8 cm) staple length.
• Fibers were collected from multiple spinning positions by puller rolls operating at 1200-1500 m/min and collected into cans. Tow from about 50-cans was combined, passed around a feed roll to a first draw roll operated at (ess than 35 °C, through a steam chest operated at 80 °C, and then to a second draw roll.
• the first draw was about 80% of the total draw applied to the fibers.
• the drawn tow was about 800,000 denier (888,900 dtex) to 1 ,000,000 denier (1 ,111 ,100 dtex).
• the drawn tow was heat-treated by contact with a first group of four rolls operated at 110 °C, by a second group of four rolls at 140-160 °C, and by a third group of four rolls at 170 °C.
• the ratio of roll speeds between the first and second groups of xolls was about 0.91 to 0.99 (relaxation), between the second and third groups of rolls it was about 0.93 to 0.99 (relaxation), and between.the third group of rolls and the puller/cooler rolls it was about 0.88 to 1.03 so that the total let-down was 0.86 to 0.89.
• the final fibers were about 1.46 denier (about 1.62 dtex).
• a finish spray was applied so that the amount of finish on the tow was 0.15 to 0.35 wt%.
• the puller/cooler rolls were operated at 35-40 °C.
• the tow was then passed through a continuous, forced convection dryer operating at below 35°C and collected into boxes under, substantially no tension. Additional processing conditions and fiber properties are given in Table 3.
• the tow samples were cut to'1.75 inch (4.4 cm) staple, combined with cotton by intimate blendirig, carded on a J.D. Hollingsworth card at 60 pounds (27 kg) per hour, arid ring-spun to make yarns of various cotton counts.
• EXAMPLE 2 Spun yarns were prepared that comprised bicomponent staple samples made in Example 1 and Comparison Examples 1 , 2, 3, and 4. Unless otherwise noted, the cotton was Standard Strict Low Midland Eastern Variety with an average micronaire of 4.3 (about 1.5 denier per fiber (1.7 dtex per fiber)). For the yarns produced using intimate blending, the cotton and the polyester bicomponent staple fiber were blended by loading both into a dual feed chute feeder, which fed a standard textile card. Unless otherwise noted, the amount of bicomponent polyester staple in each yarn was 60 wt%, based on the weight of the fiber. The resulting card sliver was 70 grain/yard (about 49,500 dtex).
• the roving was ring-spun on a Saco-Lowell frame using a back draft of 1.35 and a total draft of 29 to give a 22/1 cotton count (270 dtex) spun yarn having a twist multiplier of 3.8 and 17.8 turns per inch (7.0 turns per centimeter).
• the resulting spun yarn had a total boil-off shrinkage of 5%.
• Spun yarn properties are presented in Table 4. . * '
• Example 1A 22 17 28 , 12.6 48 275 138 605 2B (1) Example 1A 22 15 32 11.9 34 110 41 226 2C (1) Example 1 B 22 15 33 11.7 30 153 43 289 2D Example 1C 22 16 38 14.2 26 174 77 314 2E (2) Example 1C 22 1 ' 8 38 17.3 24 70 10 106 2F Example 1 D 20 13 __ nm 13.9 2 9 11 20 2G (2) Example 1D 30 15 nrin 12 9 15 50 47 126 2H Example 1 D 22 16 36 - ⁇ 13.7 28 155 72 295 21 (2, 3) Example 1 D 22 16 40 17.8 16 34 5 48 2J (3, 4) Example 1 D 60 17 rim 16.0 125 233 222 606 2K Example 1 E 22 -15 36
• Example 4B Comp. 2V Comp. 20 17 34, 11.7 25 595 552 1716
• the data in Table 4 show that the staple fiber of the invention can be used to make a spun yarn' of very high quality (low thin and thick regions, low neps, low CV, and overall excellent quality) while retaining high boil-off shrinkage.

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