HK1105669B - Bicomponent fiber and yarn comprising such fiber - Google Patents

Description

Bicomponent fibers and yarns comprising such fibers

Technical Field

The present invention relates to polyester staple fibers, and spun yarn (spun yarn) comprising such polyester staple fibers and cotton. More particularly, the present invention relates to side-by-side or eccentric sheath-core bicomponent polyester staple fibers comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate) which are particularly suitable for processing on cotton systems and from which spun yarns of high uniformity and high stretch-recovery can be produced. The invention also relates to fabrics made from spun yarns comprised of such bicomponent staple fibers.

Background

Bicomponent fibers comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate) are well known, as disclosed, for example, in U.S. Pat. Nos. 3,671,379 and 6,656,586 and in Japanese published patent application Nos. JP2002-180333A and JP2002-180332A, as well as in U.S. published patent application Nos. 2003/0056553 and 2003/0108740. Yarns comprising polyester fibers and cotton are disclosed in US6,413,631, japanese published patent application No. JP2002-115149a, and US published patent application No. 2003/0159423a 1. However, processing of these bicomponent fibers and cotton staple fibers can be difficult and the quality of spun yarns made from these fibers in combination with cotton can be less than desirable. Blending of these fibers often requires lower percentage usage relative to other fibers because increasing the percentage usage of bicomponent fibers deteriorates the quality. Furthermore, processing difficulties of such fibers can limit the range of spun staple yarn counts that can be produced with acceptable quality.

Bicomponent fibers comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate) that are well suited for processing on cotton systems are sought after. High uniformity spun staple yarns comprising bicomponent staple fibers and cotton and having excellent stretch-recovery are also sought after, as are stretch fabrics with uniform appearance made from cotton/polyester spun staple yarns.

Summary of The Invention

The present invention provides a bicomponent staple fiber comprising polyethylene terephthalate and 1, 3-propanediol terephthalate, wherein the bicomponent fiber has a substantially elliptical cross-sectional shape having an aspect ratio A: B of from about 2: 1 to about 5: 1, wherein A is the length of the major (major) axis of the fiber cross-section and B is the length of the minor (minor) axis of the fiber cross-section, the polymer interface is substantially perpendicular to the major axis, the cross-sectional configuration is selected from the group consisting of side-by-side and eccentric sheath-core, the strength at 10% elongation is from about 1.1cN/dtex to about 3.5cN/dtex, the free fiber length memory is from about 40% to about 85%, and the fiber bundle crimp development value is from about 30% to about 55%.

The present invention also provides a spun yarn having a cotton count of from about 14 to about 60 and comprising bicomponent staple fiber comprising polyethylene terephthalate and poly-1, 3-propylene terephthalate, wherein the spun yarn has from about 0.1 to about 150 fine domains per 1000m, from about 0.1 to about 300 coarse domains per 1000m, from about 0.1 to about 260 wool nodules (neps)/1000m, and from about 27% to about 45% boiling water (boil-off) shrinkage, wherein the bicomponent staple fiber is present in an amount of from about 30% to about 100% by weight (based on the total weight of the spun yarn).

The invention also provides a fabric selected from the group consisting of knits and wovens and comprising spun yarns comprising the fibers of the invention.

Brief Description of Drawings

FIG. 1A is an optical micrograph image (3000 magnification) of a round bicomponent fiber comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate).

FIG. 1B is an optical micrograph image (1000 Xmagnification) of a bicomponent fiber comprising a "fan-edge oval" cross section of polyethylene terephthalate and poly (1, 3-trimethylene terephthalate) with the polymer interface parallel to the major axis.

FIG. 1C is an optical micrograph image (1000 times magnification) of an embodiment of a bicomponent fiber of the present invention having an "oval" cross section with a long to short axis ratio of about 2.1: 1.

FIG. 1D is an optical micrograph image (1000 times magnification) of a preferred embodiment of a bicomponent fiber of the present invention having an "oval" cross section with a long to short axis ratio of about 3.5: 1.

FIG. 2A is an optical micrograph image (32 times magnification) of a bicomponent fiber with a round cross section comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate).

FIG. 2B is an optical micrograph image (32 times magnification) of a bicomponent fiber with a scalloped oval cross section comprising polyethylene terephthalate and poly 1, 3-trimethylene terephthalate with the polymer interface parallel to the major axis.

FIG. 2C is an optical micrograph image (32 times magnification) of a preferred embodiment of a bicomponent fiber of the present invention having an "oval" cross section with a long to short axis ratio of about 3.3: 1.

Figure 3 shows a typical spinning orifice for spinning fibers having a fan-shaped edge oval cross-section.

Detailed Description

It has now been found that bicomponent staple fibers comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate) and having a particular cross-sectional shape, as well as other specific characteristics, can produce spun yarns having an unexpected combination of high uniformity and high boiling water shrinkage. High boiling water shrinkage indicates high stretch-recovery of the yarn, which is desirable in today's fabrics. The finding that fine spun yarns achieve high uniformity is very difficult and is therefore particularly unexpected from the standpoint of the high cotton count of the spun yarns of the present invention.

As used herein, "bicomponent fibers" refers to staple fibers in which 2 polymers of the same general class are in a side-by-side or eccentric sheath-core relationship.

The term "side-by-side" as used herein means that the 2 components of the bicomponent fiber are directly adjacent to each other and no more than a small portion of either component is present within the recessed portion of the other component. By "eccentric sheath-core" is meant that one of the 2 components completely surrounds the other component, but the 2 components are not coaxial.

As used herein, "substantially elliptical" means that the cross-sectional area of the fiber as measured perpendicular to the longitudinal axis of the fiber deviates from the elliptical shape by less than about 20%. The general term "ellipse" is meant to include "ellipse-like" (oval) and "ellipse". Such a shape typically has 2 orthogonal axes passing through the centroid, 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. In the special case of a perfect ellipse, the ellipse is described by the locus of points whose sum of the distances from the 2 foci is constant and equal to a. In the more general case of an ellipse, one end of the ellipse may be larger than the other, so that the sum of the distances from the 2 foci is not necessarily constant and may differ from the ellipse by 20% or more. As used herein, the "substantially elliptical" cross-sectional perimeter may or may not have a constant curvature.

"major to minor axis ratio" refers to the ratio of the length of the major axis of the ellipse to the length of the minor axis of the ellipse, in other words A: B.

"Polymer interface" refers to the boundary between polyethylene terephthalate and poly (1, 3-trimethylene terephthalate), which may be substantially linear or curved.

"draw-frame blending" refers to the process of blending a carded bi-component fiber sliver with 1 or more other carded fiber slivers (slivers) simultaneously as the sliver is drawn on the draw frame by gravity and thoroughly mixing the different fibers in an open space (e.g., a hopper feeder with a weighing pan) before feeding the mixture to a carding machine or mixing the fibers in a double feed chute (flute) on the carding machine.

The fibers of the present invention have a substantially elliptical cross-sectional shape with an axial to longitudinal ratio of from about 2: 1 to about 5: 1 (examples include from about 2.6: 1 to about 3.9: 1 and from about 3.1: 1 to about 3.9: 1). When the long-to-short axis ratio is too high or too low, the fibers may exhibit undesirable glitter and low color yield, and spun yarns comprising the fibers may be insufficiently uniform. The fibers also have a polymer interface substantially perpendicular to the long axis of the cross-section and a free fiber length memory of about 40% to about 85%. Such elliptical filaments can be spun from a slot (flat or with side horns), elliptical or the like spinning orifice.

The oval cross-sectional shape is substantially free of grooves on its cross-sectional perimeter. That is, when the length of the minor axis is plotted against the length of the major axis, there are only 1 maximum. Examples of cross-sectional shapes that do have grooves are "snowman", "scalloped oval" and "keyhole" cross-sections.

The fibers comprise 2 polyesters, e.g., polyethylene terephthalate and poly (1, 3-trimethylene terephthalate), preferably having different intrinsic viscosities, although different combinations, e.g., polyethylene terephthalate and poly (1, 4-butylene terephthalate), are also possible. Alternatively, the compositions may be similar, for example, polyethylene terephthalate homopolyesters and polyethylene terephthalate copolyesters, optionally also having different viscosities.

The bicomponent fibers have a free fiber length memory of from about 40% to about 85%. Free fiber length memory is a useful measure of how "straight" a crimped fiber is in its relaxed state, in other words, how tightly the crimped fiber is wound when not under tension. Spun yarns comprising bicomponent staple fibers may exhibit poor uniformity when having too low a free fiber length memory and may be difficult to card.

The bicomponent staple fiber can have a tenacity at break (tenacity) of about 3.6 to about 5.0cN/dtex, a tenacity at 10% elongation (T10) of about 1.1cN/dtex to about 3.5cN/dtex (preferably about 2.0 to 3.0cN/dtex), and a weight ratio of polyethylene terephthalate to poly (1, 3-trimethylene terephthalate) of about 30: 70 to about 70: 30, preferably about 40: 60 to about 60: 40. When the breaking strength is too low, the fibers may break during carding. When the breaking strength is too high, the fabric comprising the fibers may exhibit undesirable pilling.

One or both of the polyesters comprising the fibers of the present invention may be a copolyester, and such copolyesters are included in the meaning of "polyethylene terephthalate" and "poly (1, 3-trimethylene terephthalate"). For example, a co (ethylene terephthalate) can be used wherein the comonomer used to make the copolyester is selected from linear, cyclic and branched aliphatic dicarboxylic acids having from 4 to 12 carbon atoms (e.g., succinic, glutaric, adipic, dodecanedioic and 1, 4-cyclohexanedicarboxylic acids); aromatic dicarboxylic acids other than terephthalic acid and having 8 to 12 carbon atoms (e.g., isophthalic acid and 2, 6-naphthalenedicarboxylic acid); linear, cyclic and branched aliphatic diols having 3 to 8 carbon atoms (e.g., 1, 3-propanediol, 1, 2-propanediol, 1, 4-butanediol, 3-methyl-1, 5-pentanediol, 2-dimethyl-1, 3-propanediol, 2-methyl-1, 3-propanediol and 1, 4-cyclohexanediol); and aliphatic and araliphatic ether glycols having from 4 to 10 carbon atoms (e.g., hydroquinone bis (2-hydroxyethyl) ether, or poly (ethylene ether) glycols having a molecular weight of less than about 460, including diethylene ether glycol). The comonomer is present in an amount not detrimental to the benefits of the invention, for example, between about 0.5 and 15 mole percent based on the total polymer composition. Isophthalic acid, glutaric acid, adipic acid, 1, 3-propanediol, and 1, 4-butanediol are preferred comonomers.

Such other comonomers include 5-sodium-sulfoisophthalate, the sodium salt of 3- (2-sulfoethyl) adipic acid and its dialkyl esters, which may be added at about 0.2-4 mol% based on the total polyester to improve acid dye dyeability, the (co) polyester may also be mixed with a polymeric secondary amine additive, such as poly (6, 6' -imino-bis (hexamethylene) terephthalamide) and its copolyamide with hexamethylene diamine, preferably with phosphoric acid and its phosphite, small amounts, such as about 1-6 milliequivalents per kilogram of polymer, tri-or tetra-functional comonomers, such as trimellitic acid (including its precursors) or pentaerythritol, may be blended in to control viscosity.

The fibers of the present invention may also contain conventional additives such as antistatic agents, antioxidants, antibacterial agents, flame retardants, dyes, light stabilizers, and delustrants such as titanium dioxide, so long as they do not detract from the benefits of the invention.

After drawing and heat treatment of the fiber, the bicomponent fiber is advantageously oiled (finish), for example, applied to the tow just before it is cut into staple fibers. The oiling rate (percentage relative to the total weight) can be between 0.05 and 0.30 percent. The finish may comprise 1) a blend of alkyl or branched phosphate esters, or 2) potassium, calcium or sodium salts of the corresponding phosphoric acids, or a blend of these 2 types in any proportion, each of which may contain a total of 6 to 24 carbon atoms in its aliphatic segment. The finish may also comprise polyethylene oxide and/or polypropylene oxide, or short segments of such polyethers may be linked to aliphatic acids such as lauric acid by esterification, or to alcohols such as sorbitol, glycerol, castor oil, coconut oil or the like by ether linkages. Such compounds may also contain amine groups. The finish may also contain minor amounts (e.g., < 10%) of functional additives, such as silicones or fluorochemicals. The finish may comprise a blend of potassium salts of mono-and di-acids containing about 18 carbon atoms with an ethoxylated polyether containing 4 to 10 oxyethylene linkages, wherein the ethoxylated polyether may be prepared by reaction between a n-alkyl alcohol of 12 to 18 carbon atoms and the blend of polyethers.

It is not necessary to de-align the crimp of the bicomponent fibers in the tow precursor of the staple fibers in order to de-align the crimp of the fibers (misalign). Similarly, bicomponent staple fiber tow does not require a mechanical crimping treatment in order for the staple fibers made therefrom to exhibit good processability and useful properties.

The bicomponent fibers may have an elongation at break of from about 15% to about 35%, such as from about 15% to about 25%, with typical values of from about 15% to about 20%.

The bicomponent staple fibers have a tow crimp development ("CD") value of from about 30% to about 55% and a crimp index ("CI") value of from about 15% to about 25%. When the CD is below about 30%, the spun yarn comprising the fiber is generally too little in total boil-off shrinkage to give good recovery properties to fabrics made from it. When the CI value is (too) low, a mechanical crimping process is required to achieve satisfactory carding and spinning. When the CI value is high, the crimp of the bicomponent staple fiber may be too large to be easily carded, and the uniformity of the spun yarn may be insufficient. When CI is at the lower end of the acceptable value range, higher proportions of polyester bicomponent staple fibers can be used without compromising combability and yarn uniformity. When the CD is at the higher end of the acceptable range of values, lower proportions of bicomponent staple fibers can be used without compromising total boiling water shrinkage.

The bicomponent staple fiber may have a length of about 1.3cm to about 5.5 cm. When the bicomponent fiber is shorter than about 1.3cm, it may be difficult to card, and when it is longer than about 5.5cm, it may be difficult to spin on cotton system equipment. The length of the cotton is about 2-4 cm. The bicomponent fibers have a linear density of about 0.7 dtex (dtex), preferably about 0.9 dtex, up to about 3.0 dtex, preferably to about 2.5 dtex. When the linear density of the bicomponent staple fibers is above about 3.0 dtex, the hand of the yarn can be harsh and it can be difficult to blend (blend) with cotton. When its linear density is below about 0.7 dtex, it may be difficult to comb.

The spun yarn of the invention has a cotton count of from about 14 to about 60 (preferably from about 16 to about 40) and comprises: a bicomponent staple fiber comprising polyethylene terephthalate and poly (1, 3-trimethylene terephthalate), and a second staple fiber selected from the group consisting of cotton (preferred), synthetic cellulosic fibers, and acrylic fibers. The spun yarn is very uniform and has a total boil-off shrinkage of from about 0.1 to about 150 (preferably from about 1 to about 70) fine areas/1000 m, from about 0.1 to about 300 coarse areas/1000 m, from about 0.1 to about 260 wool particles/1000 m, and from about 27% to about 45%, for example from about 30% to about 45%. When the total boiling water shrinkage is less than about 27%, the elongation-recovery of the yarn will be too low when the yarn is woven or knitted into a fabric.

Yarn quality factor is a very useful measure of yarn quality, and can be calculated from the fine area, coarse area, number of fuzz, coefficient of variation in quality, and yarn strength yarn spun yarns can have a yarn quality factor in the range of about 0.1 to about 650, for example about 1 to about 300.

Another method of describing spun yarn Uniformity is by a coefficient of variation, which is measured using the Uniformitty 1-B Tester. The spun yarn of the invention may have a coefficient of variation of mass of from about 10% to about 18%, for example from about 12% to about 16%.

Preferably, the spun staple yarn of the invention comprises the fiber of the invention and the spun staple yarn has a tenacity at break of from about 10 to about 22 cN/tex. When the strength is too low, the spinning process of the yarn may be difficult, and weaving efficiency and fabric strength may be both reduced. Also preferred, the spun yarn has a linear density of from about 100 to about 700 denier (111 to 778 dtex).

In the spun yarn, the bicomponent staple fiber is present in an amount of about 30 wt% to about 100 wt%, based on the total weight of the spun yarn. When the yarn of the present invention comprises less than about 30 wt% polyester bicomponent, the yarn may exhibit insufficient stretch-recovery properties. When the bicomponent staple fiber is present at a level of less than 100 wt% but greater than 30 wt%, the spun yarn comprises a second staple fiber selected from the group consisting of monocomponent polyethylene terephthalate, monocomponent polypropylene-1, 3-terephthalate, cotton, wool, acrylic and nylon staple fibers, which may be present at a level of from about 1 wt% to about 70 wt%, based on the total weight of the spun yarn. Optionally, the spun yarn of the invention may further comprise a third staple fiber selected from the same group and present in an amount of from about 1 wt% to about 69 wt% (based on the total weight of the spun yarn); together, the second and third staple fibers may be present in an amount of from about 1 wt% to about 70 wt%, based on the total weight of the spun yarn.

The yarn can be spun using commercially available methods such as ring spinning, air end, air jet and vortex spinning.

Knitted and woven stretch fabrics can be made from the spun yarns of the present invention. Examples of stretch fabrics include circular, flat and warp knit fabrics and plain, twill and satin woven fabrics. The high uniformity and elongation properties of spun yarns are generally carried through to the fabric, becoming a uniform appearance and high elongation-recovery, some of the highly desirable properties.

Test method

The intrinsic viscosity ("IV") of the polyester was determined using a Viscotek formed Flow ViscometerModel Y-900 at 0.4% in accordance with ASTM D-4603-96 but in 50/50 wt% trifluoroacetic acid/methylene chloride instead of the 60/40 wt% phenol/1, 1, 2, 2-tetrachloroethane at 19 ℃. The measured viscosity was then correlated with the standard viscosity in 60/40 wt% phenol/1, 1, 2, 2-tetrachloroethane to arrive at the reported intrinsic viscosity value.

Linear Density and tensile Properties of the fibers the linear density and elongation were measured using a Favimat instrument from Textech (Germany) according to ASTM method D1577, D3822. The measurements were made for at least 25 fibers and averaged to write the report.

In each bicomponent staple fiber sample, the fibers had substantially equal linear density and polymer ratio of polyethylene terephthalate to poly (1, 3-trimethylene terephthalate). In the examples, no mechanical crimp was applied to the bicomponent staple fibers.

The oiling rate is given as the weight percent of the finish on the fiber, and is determined by shearing the bicomponent fiber from the tow, extracting the finish from the fiber with methanol, evaporating the methanol, and then determining the weight of the extracted finish by weighing. Calculating the weight percentage of the oil agent according to the following formula I:

to determine the free fiber length memory, fibers that have not been heat treated to fully develop crimp are stretched to just straighten the existing low crimp and cut to length L₁(38mm in the examples). When cut, the fiber will retract to its free (relaxed) length L₂And regaining its curl. Free length L₂Is measured from a bundle of cut fibres at zero tension using a ruler, the measurement is repeated 3 times and the results averaged free length memory is determined by the free fibre length L₂Divided by the length of the elongated fiber L₁And the results are expressed as a percentage, as indicated by formula II below:

free fiber length memory (L)₂/L₁)×100 (II)

Fig. 2 quantitatively shows the free fiber length memory difference between the non-inventive fibers (fig. 2A and 2B) and the inventive fibers (fig. 2C).

Unless otherwise indicated, the following methods for determining tow crimp development and tow crimp index for bicomponent fibers were used in the examples. The methods described herein are numerically equivalent to the methods employed in U.S. published patent application No. 2003/0159423a 1. A slight modification is shown here to improve the efficiency of operation. To determine the tow crimp index ("CI"), a 1.2m sample of polyester bicomponent tow was weighed and its denier calculated; the linear density of the tow is generally between about 40,000 and 50,000 denier (44,000 and 55,000 dtex). One knot at each end of the tow. The vertical tow sample was tensioned as follows: the first clamp was placed on the lower knot clamp and at least a 40 mg/denier (0.035dN/tex) weight was suspended at the knot of the upper end of the tow which was directed over a stationary roller located 1.1m from the lower end of the tow. The weight is selected to just straighten the crimp on the tow but not to break the fibers. At this point, the tow is substantially straight and all fiber crimp has disappeared. Subsequently, a second clamp was applied to the tow 100cm above the first clamp while maintaining the weight intact. Next, the weight of the upper end of the tow was removed and a 1.5 mg/denier (0.0013dN/tex) weight was fixed immediately below the lower clamp, and the first clamp was removed from the lower knot, whereupon the sample was allowed to retract against this 0.0013dN/tex weight. The length of the retracted tow from the second clamp to the lower knot is measured in centimeters and designated Lr. C.i was calculated according to formula III. To determine tow crimp development ("CD"), the same procedure was carried out except that a 1.2m sample-in the unconstrained state-was placed into an oven at 105 ℃ for 5min, and then after allowing it to cool to room temperature for at least 2min, the measurement procedure was restarted.

CI and CD (%) ═ 100X (100cm-Lr)/100cm (III)

It is intended and understood that reference herein to the crimp value of the staple fibers is a reference to the determination of the tow precursor for such fibers, since merely cutting the tow into staple fibers does not affect crimp.

The combing performance of staple fibers containing an amount of finish sufficient to control static electricity was evaluated by visual inspection of the curl of the carded web and sliver. Fibers that produce a carded web that is uniform in appearance and free of lint and that has no can coiler clogging during processing into slivers are believed to exhibit good carding performance. Fibers that do not meet these criteria are considered poor in combing properties.

In the embodiment, it isThe boiling water shrinkage ("b.o.s.") of the spun yarn was determined and the yarn was made into 25 turns of hank on a standard hank winder. A length ("L") of 10 inches (25.4cm) was marked on the sample with a dye marker pen while the sample was held taut on a winder₀"). The skein was removed from the winder, left unconstrained in boiling water for 1min, removed from the water and allowed to dry at room temperature. The dry skein was laid flat and the distance between the dye marks ("L") was again determined_b0"). The total boiling water shrinkage was calculated according to formula IV.

Total b.o.s (%). 100 × (L)₀-L_bo)/L₀ (IV)

The "true" shrinkage of the spun yarn was determined by applying a load of 200 mg/denier (0.18dN/tex) using the same sample subjected to the boiling water total shrinkage test, determining the length of elongation and calculating the difference in percent between the length of elongation before boiling water treatment and after boiling water treatment. The true shrinkage of the samples is generally less than about 5%. Since the true shrinkage constitutes only a very small fraction of the total boiling water shrinkage, the latter is used here as a reliable measure of the stretch-recovery properties of spun yarns. Higher total boiling water shrinkage corresponds to desirably higher stretch-recovery.

Yarn count is a common term used to describe the density of spun staple yarns.

Uniformity of spun yarn was measured along with its length in a Uniformity 1-B Tester (manufactured by Zellweger Uster) and given as a coefficient of variation ("CV") in percent in this test, the yarn was fed to the Tester at 400 yards/minute (366m/min) for 2.5min, and the mass of the yarn per about 8mm length during this period was measured.a standard deviation of the measured data was calculated, multiplied by 100, and divided by the average mass of the measured yarn to give% CV. The thick regions in the yarn are those where the mass is at least 50% greater than the average mass. The fine areas in the yarn are those areas where the mass is at least 50% less than the average mass. Wool is where the mass in the yarn is at least 200% greater than the average mass.

The tensile properties of the spun yarns were determined using a Tensojet (also manufactured by Zellweger Uster Co.). The intensity is given in cN/tex.

The yarn quality factor is calculated according to formula V:

yarn quality factor ([ E + F + G ] xH)/J (V)

Wherein

E is the number of thick areas per 1000 yards of yarn,

f is the number of fine areas per 1000 yards of yarn,

g is the number of wool particles per 1000 yards of yarn,

h is the coefficient of variation ("CV") in percent of the yarn mass, each measured by the Uster Uniformity 1-B Tester, and

j is the yarn breaking strength expressed in cN/tex.

In example 1 and comparative examples 1, 2, 3 and 4, the ratio of the first draw ratio to the total draw ratio is between 0.78 and 0.88 and the time of the heat treatment step is at least 3 s. The section major-minor axis ratio A: B is determined by measuring optical micrographs and is generally accurate to 5%. The conditions and properties of the fiber preparation which are not mentioned in the text are given in tables 1 and 2, respectively.

In the table, "comp." means comparative example, "b.o.s." means boiling water shrinkage, "Ne" means cotton count (english), "nm" means "no measurement," "CV" means coefficient of mass variation, as measured by the user Uniformity 1-B Tester, "T10" means strength of the bicomponent fiber at 10% elongation, "let-down ratio" means the ratio of the speed of the take-off roll to the speed of the last draw roll, and "Bico" means bicomponent. "thick" refers to the number of places where the mass per 1000 yards of yarn is at least 50% greater than the average mass. "thin" refers to the number of those places per 1000 yards of yarn where the mass is at least 50% less than the average mass. "Neps" refers to the number of those places per 1000 yards of yarn where the mass is at least 200% greater than the average mass. The number of coarse, fine and gross particles given are determined by the Uster Unifornity 1-B Tester.

Examples

Example 1A

Continuous bicomponent filaments from polyethylene terephthalate (T211, manufactured by Interconnective Polymers, 0.56dl/g IV) andpoly (1, 3-propylene glycol terephthalate) ((Is a registered trademark of dupont) with an IV equal to 0.98dl/g, extruded at 50/50 weight ratio from a tank (bolck) operating at 272 c through a metering pump to a bicomponent spinning pack equipped with a corroded metering plate which joins the polymer streams above a counterbore (counterbore) next to the spinning orifice. The particulate titanium dioxide matting agent is added to both polymers in an amount of 0.1 to 0.4 wt% each. The polymer was spun from a 288-hole spinneret with holes 0.38mm deep and having a cross-section of 0.64mm long modified slits, with a smoothly outward bulge (maximum width 0.18mm) in the middle of each long side and with a radius of 0.06mm at the ends of the arc. The polymer interface is substantially perpendicular to the long axis of the resulting oval cross-section fiber.

The nascent fiber is cooled by cross-air blowing with a mass ratio (air/polymer) of about 10-14; the spin finish was applied at a finish rate of 0.1% by weight by means of a metered contact applicator roll, and the oval (long-to-short axis ratio 2.1: 1 (measurement-see FIG. 1C)) fibers were wound onto bobbins at a speed of 1000 m/min.

The fibres from a number of bobbins are combined into a tow of about 50,000 dtex and drafted in 2 stages with a first and a second draft ratio of 2.69 and 1.28 respectively, to a final speed of 50 m/min. The first drawing was carried out in a hot water bath at 35 ℃ and the second drawing was carried out with a hot water shower at 90 ℃. The drawn tow is heat treated at 150 c, cooled to less than 30 c using a diluent/water spray (0.20 wt% based on fiber) and then sent to a take-off roll operating at a lower speed than the final draw roll. The tow was dried at room temperature and cut to a staple length of 1.5 "(3.8 cm).

Example 1B

Polyester bicomponent staple fibers as described in example 1A were made, but with the following modifications. The major-minor axis ratio of the elliptical fibers spun was 3.3: 1 (measurement-see fig. 1D), and a 288-hole spinneret was used in which the spinning holes were 0.38mm deep and the cross-section was 0.76mm long modified slits, and in the middle of each long side had an enlarged portion (maximum width 0.14mm) smooth to the outer circle and had a circular arc end with a radius of 0.05 mm. let-down ratio is 0.942. Figure 2C shows that the fiber has a low spiral behavior.

Example 1C

Polyester bicomponent staple fibers as described in example 1A were made, but with the following modifications. The IV of polyethylene terephthalate is 0.54 and the IV of poly (1, 3-trimethylene terephthalate) is 0.95. The cross-section of the fibres is elliptical, the ratio between the long and short axes is equal to 2.4: 1 (measured), the spinning speed is 1200m/min, the first draw ratio is 2.23 and the heat treatment temperature is 170 ℃.

Example 1D

Polyester bicomponent staple fibers as described in example 1A were made, but with the following modifications. The elliptical fibers were spun at a major to minor axis ratio of about 3: 1 (estimated), and the holes were formed as in example 1B. The IV of polyethylene terephthalate was 0.54, the IV of poly (1, 3-propylene terephthalate) was 0.95, the spinning speed was 1200m/min, the first draw down ratio was 2.44, and the heat treatment temperature was 170 ℃.

Example 1E

Polyester bicomponent staple fibers as described in example 1D were made, but with the following modifications. The major to minor axis ratio of the spun oval fibers was 3.3: 1 (measured), the first draw ratio was 2.52, and the let-down ratio was 0.97.

Example 1F

Polyester bicomponent staple fiber as described in example 1D was made, except that the first draw down ratio was 2.54 and the heat treatment temperature was 165 ℃.

Example 1G

Polyester bicomponent staple fibers as described in example 1D were made, but with the following modifications. The major axis ratio of the spun oval fibers was 3.5: 1 (measured), the first draw ratio was 2.56, and the heat treatment temperature was 165 ℃. The low T10 value obtained indicates that the target let-down ratio 1.0 has not been reached. The actual let-down ratio is below 1.0.

Example 1H

Polyester bicomponent staple fibers as described in example 1B were made, but with the following modifications. The major-minor axis ratio of the spun oval fibers was about 3: 1 (estimated). The weight ratio of the polymer was 55/45 polyethylene terephthalate/1, 3-trimethylene terephthalate, the IV of the 1, 3-trimethylene terephthalate was 0.94, the polyethylene terephthalate was KoSa 8958C, the spinning speed was 1400m/min, the first draw down ratio was 2.37, the second draw down ratio was 1.29, and the heat treatment temperature was 180 ℃.

Comparative example

Comparative example 1

Polyester bicomponent staple fibers were made as described in example 1A, with the following differences. The polymer interface of the spun scalloped oval (measured long to short axis ratio of 2.2: 1-see fig. 1B) fiber was parallel to the cross-sectional major axis and the spin orifice shape was used substantially as shown in fig. 3. The arrangement of the spinning orifices results in the desired interface orientation. The poly (1, 3-trimethylene terephthalate) IV was 1.04, the first draw ratio was 2.71, and the let-down ratio was 0.85 FIG. 2B shows that the fiber exhibited excessive coiling.

Comparative example 2

Polyester bicomponent staple fibers were made as described in example 1A, with the following differences. Round fibers (see fig. 1A) were extruded through a spinning orifice with a diameter of 0.36 mm. The first draw ratio was 2.91, the second draw ratio was 1.13, and the let-down ratio was 0.85 fig. 2A shows that the fiber exhibited excessive coiling.

TABLE 1

Examples	Cross-sectional shape	Spinning hole flux (g/min)	Total draw ratio	Let-downRatio
					1A	2.1: 1 ellipse	0.50	3.44	0.860
1B	3.3: 1 ellipse	0.50	3.44	0.942
					1C	2.4: 1 ellipse	0.52	2.85	0.970
1D	About 3: 1 ellipse	0.52	3.12	0.980
					1E	3.3: 1 ellipse	0.42	3.23	0.970
1F	About 3: 1 ellipse	0.36	3.25	0.995
					1G	3.5: 1 ellipse	0.43	3.28	1.000
1H	About 3: 1 ellipse	0.55	3.06	1.010
					Comparative example 1	Oval with fan-shaped edge	0.50	3.47	0.850
Comparative example 2	Round (T-shaped)	0.50	3.29	0.850

TABLE 2

Examples	Cl，％	CD，％	Length memory of free fiber%	Strength (c)N/dtex)	T10(cN/dtex)	Line Density (dtex)	Elongation at break%	Combing property
									1A	21.0	43	45	3.91	1.21	1.84	32.0	Good taste
1B	21.0	43	66	3.91	1.30	1.74	35.0	Good taste
									1C	23.5	48	47	3.98	2.56	1.73	27.0	Good taste
1D	20.0	42	58	3.89	2.21	1.73	24.9	Good taste
									1E	20.5	42	45	4.16	2.16	1.33	24.5	Good taste
1F	18.0	49	68	4.07	2.59	1.16	16.8	Good taste
									1G	22.0	52	nm	4.02	1.82	1.27	17.8	Good taste
1H	16.0	37	nm	4.42	2.84	1.34	21.0	Good taste
									Comparative example 1	22.0	55	24	4.24	0.95	1.83	41.0	Not good
Comparative example 2	21.0	50	24	4.02	0.92	1.86	62.0	Not good

Table 2 also shows that the fibers of the invention have very good combing properties, whereas the fibers of the invention have poor combing properties.

Comparative example 3

Polyester bicomponent staple fibers are prepared from bicomponent continuous filaments derived from polyethylene terephthalate(s) (II)4415-Poly (1, 3-propylene glycol terephthalate) ((Is a registered trademark of dupont) having IV equal to 1.00dl/g, and the bicomponent continuous filaments are melt-spun at a spinning beam temperature of 255 to 265 ℃ through a 68-hole post-coalescence spinneret. The weight ratio of polymer was 60/40 polyethylene terephthalate/1, 3-propylene terephthalate. The filaments are drawn out of the spinneret at 450-550 m/min and cooled by side blowing. The filament has a snowman section, is drawn by 4.4 times, is subjected to heat treatment at 170 ℃, is subjected to interlacing treatment and is wound at 2100-2400 m/min. The filaments had 12% CI, 51% CD and a linear density of 2.4 dtex per filament. To convert to staple fibers, the filaments from the cake are bundled into a tow and fed to a conventional staple tow cutter. The blade spacing was adjusted to obtain a staple length of 1.5 inches (3.8 cm).

Comparative example 4

To make samples comparative example 4A and comparative example 4B, poly (1, 3-trimethylene terephthalate)(s) were prepared, unless otherwise notedBrand, 1.00IV) was extruded uniformly at a maximum temperature of about 260 c, and polyethylene terephthalate ("pet")System ", semi-matt, fibre grade 211 from interfacial Polymers, 0.54dl/g IV) was extruded uniformly at a maximum temperature of 285 ℃.

The spin pack was heated to 280 ℃ and had 2622 circular holes, 0.4mm in diameter. In the side-by-side round cross-section fiber (about 1 to 2 dtex) obtained, 52 wt% of polyethylene terephthalate and 48 wt% of 1, 3-propylene terephthalate were contained, and the IV was 0.94 dl/g. Fibers from a plurality of spinning positions are collected in a can by a drawing roll operating at 1200-1500 m/min.

The tows from about 50 cans were combined, passed around a feed roll to a first draw roll operating below 35 ℃, through a steaming box operating at 80 ℃, and then to a second draw roll. The first draw is about 80% of the total draw to which the fiber is subjected. The drawn tow is about 800,000 denier (888, 900 dtex) to 1,000,000 denier (1, 111, 100 dtex). The drawn tow is subjected to a heat treatment by contacting a first set of four rolls operating at 110 ℃, a second set of four rolls operating at 140-160 ℃, and a third set of four rolls operating at 170 ℃. The ratio of the roll speeds between the first and second sets of rolls is about 0.91 to 0.99 (relax), the value between the second and third sets of rolls is about 0.93 to 0.99 (relax), and between the third set of rolls and the pulling/cooling rolls it is about 0.88 to 1.03, so the total relaxed let-down is 0.86 to 0.89. The final fiber was about 1.46 denier (about 1.62 dtex). The spraying amount of the oil agent is adjusted to ensure that the content of the oil agent on the filament bundle is 0.15-0.35 wt%. The drawing roll/cooling roll is operated at 35-40 ℃. The tow is then sent through a continuous forced convection dryer operating at 35 ℃ and collected in a box under essentially no tension. Additional processing conditions and fiber properties are shown in Table 3.

TABLE 3

Sample (I)	Total draw ratio	T10(cN/dtex)	Strength (cN/dtex)	Filament bundle Cl%	Tow CD%
						Comparative example 4A	3.08	1.5	4.2	24	54
Comparative example 4B	2.93	1.5	4.0	7	29

The tow samples were cut into 1.75 inch (4.4cm) staple fibers, combined with cotton by intimate blending, carded on a j.d. hollingsworth carding machine at a speed of 60 pounds (27kg) per hour, and ring spun to produce yarns of various cotton counts.

Example 2

Spun yarns were prepared comprising the bicomponent staple fiber samples prepared in example 1 and comparative examples 1, 2, 3 and 4. Cotton was Standard strong Low midrange eastern Variety, micronlness 4.3 (about 1.5 denier per fiber (1.7 dtex per fiber)), to produce a yarn using intimate blending, the cotton and polyester bicomponent staple fibers were blended by feeding them into a double feed chute feeder (from which they were fed into a Standard textile carding machine), unless otherwise indicated, the amount of bicomponent polyester staple fiber in each yarn was uniformly 60 wt%, based on the weight of the fiber, the resulting carded sliver was 70 grains/yard (about 49,500 dtex), 6 slivers were drawn together and 6.5 times in each of 2 or 3 passes (the individual slivers were appropriately combed prior to each pass), 60 grains (about 42,500 dtex) of drawn sliver were given, the latter was subsequently converted into roving, unless otherwise indicated, the total draw in the spinning process was 9.9 times, however, in the case of yarns produced using draw frame blending, the cotton and bicomponent staple fibers were each carded separately and then combined together during a sliver-roving draft step, unless otherwise indicated, the roving was ring spun on a Saco-Lowell spinning frame using a post draft of 1.35, and a total draft of 29, resulting in 22/1 cotton count (270 dtex) spun staple yarns having twist multiplier of 3.8 and 17.8 turns/inch (7.0 turns/cm). when 100% cotton was so processed, the spun staple yarns obtained had a total boil-off shrinkage of 5% the spun staple properties are as set forth in Table 4.

TABLE 4

Note:

(1) combed cotton

(2) Drawing and blending

(3) Bima cotton

(4) The yarn was spun to have a twist multiplier of 4.2 to achieve 32.5 turns/inch (12.8 turns/cm).

(5)35 wt% bicomponent staple fiber, 40 wt% cotton, 25 wt% T-40A medium strength (4.95cN/dtex)1.2dpf Dacron (R) polyethylene terephthalate staple fiber, manufactured by DAK America

(6)35 wt% bicomponent staple fiber, 40 wt% cotton, 25 wt% T-90S high strength (5.65cN/dtex)0.9dpf Dacron (R) polyethylene terephthalate staple fiber, made by DAK Amercas

(7)100 wt% bicomponent staple fiber

The data in table 4 show that the staple fibers of the present invention can be used to make very high quality spun yarns (low fine and coarse areas, low wool count, low CV and overall superior quality) while retaining high boiling water shrinkage.

Claims (10)

1. A spun yarn having a cotton count of from about 14 to about 60 and comprising bicomponent staple fiber comprising polyethylene terephthalate and poly-1, 3-trimethylene terephthalate, the spun yarn having from about 0.1 to about 150 fine domains/1000 yard, from about 0.1 to about 300 coarse domains/1000 yard, from about 0.1 to about 260 fluff/1000 yard and from about 27% to about 45% boiling water shrinkage, wherein the bicomponent staple fiber is present in an amount of from about 30% to about 100% by weight, based on the total weight of the spun yarn, and wherein the bicomponent staple fiber has a substantially elliptical cross-sectional shape having an axial to axial ratio a: B of from about 2: 1 to about 5: 1, wherein a is the length of the major axis of the fiber cross-section and B is the length of the minor axis of the fiber cross-section.

2. The spun yarn of claim 1, further comprising staple fibers selected from the group consisting of cotton, synthetic cellulosic fibers, and acrylic fibers, wherein the bicomponent is present in an amount of about 30% to about 70% by weight, based on the total weight of the spun yarn.

3. The spun yarn of claim 2 wherein the staple fiber selected is cotton and the bicomponent staple fiber has an axial to axial ratio a: B of from about 2.6: 1 to about 3.9: 1, wherein a is the length of the major axis of the fiber cross-section and B is the length of the minor axis of the fiber cross-section.

4. The spun yarn of claim 1 having a quality factor of from about 0.1 to about 650.

5. The spun yarn of claim 1, wherein the bicomponent staple fiber has a free fiber length memory of between about 40% and about 85%.

6. The spun yarn of claim 2 further comprising from about 1 wt% to about 69 wt% of a polyethylene terephthalate monocomponent staple fiber.

7. The spun yarn of claim 2 having a total boil-off shrinkage of from about 27% to about 45% and a coefficient of variation of mass of from about 10% to about 18%.

8. The spun yarn of claim 7 having a total boil-off shrinkage of from about 30% to about 45% and a coefficient of variation of mass of from about 12% to about 16%.

9. The spun yarn of claim 2 having a quality factor of from about 0.1 to about 650 and a total boil-off shrinkage of from about 27% to about 45%.

10. The spun yarn of claim 9 having a quality factor of from about 1 to about 300 and a total boil-off shrinkage of from about 30% to about 45%.