CN1436253A - Bilobal cross-section fibers and fabrics prepared therefrom - Google Patents

Abstract

The present invention is directed to a multifilament yarn formed at least in part from filaments having cross-sectional bilobal S-shapes or Z-shapes. The yarns preferably have a denier per filament in the range of about 0.1 to about 4.0. In addition, fabrics made using the yarns of the present invention are disclosed. The fabrics have high moisture wicking, soft hand, and a silk-like lustrous appearance.

Description

Bilobal cross-section fiber and fabric prepared from it

technical field

The present invention relates to a multifilament yarn formed from S-shaped or Z-shaped oriented filaments having a bilobal cross-sectional shape. The filaments produced according to the invention are particularly suitable for producing garment fabrics with comprehensive properties such as high moisture absorption capacity, soft hand feeling and lustrous appearance like real silk. The present invention also relates to hydrophilic agents useful for imparting superior wicking properties to fibers and articles.

Background technique

A wide variety of cross-sections are used in synthetic filaments for apparel, including round, trilobal, ribbon, dog-bone, Y-shaped, and combinations thereof. Various cross-sections have been developed to increase the ability of the filament to absorb or wick moisture. Moisture absorption, which refers to the capillary movement of water through or along fibers, is considered a desirable property of apparel fabrics because it improves wearer comfort by drawing moisture away from the skin for faster evaporation. In addition, combinations of different cross-sections, denier per filament, and filament and fabric finishing agents have been developed to increase the ability of the filament to absorb or wick moisture.

"Two-sided" fabrics have also been developed to facilitate the movement of moisture from the inner surface of the fabric to the outer surface by virtue of its surface chemistry. Typically, "two-face" fabrics have finer denier per filament (dpf) filaments, predominantly on the outer surface, and heavier denier per filament (dpf), predominantly on the inner surface. Although, such "two-faced" fabrics are easily achieved in weft knitted fabrics by knitting structures, there is still potential for further improvement of wicking through optimal shape of the monofilaments. Additionally, warp knitted and woven fabrics are difficult and costly to create with certain filaments predominantly on one side or the other. Therefore, there is a need for a filament that provides excellent moisture absorption to improve the comfort of the wearer, especially in competitive sportswear, especially in woven and warp knitted fabrics. There continues to be a need to provide a multifilament synthetic yarn that provides apparel fabrics with both a soft hand and a silky sheen while having enhanced absorbency properties.

Contents of the invention

In accordance with the above needs, the present invention provides a multifilament yarn comprising filaments having a bilobal S-shaped or Z-shaped cross-section, wherein the S- or Z-shaped cross-section comprises a rectangular central section with substantially straight sides, having two opposite ends; and an arm extending from each opposite end of the central section with substantially straight sides having a curved tip portion, wherein the central section is substantially the same width as each arm, and the central section is as wide as each arm. and wherein the angle formed between the arms and the central section is from about 105° to about 165°, and wherein the denier per filament of the filament is from about 0.1 to about 4.0.

In another embodiment, the present invention is directed to a filament having a bilobal S- or Z-shape in cross-section, wherein the cross-section of each filament comprises a substantially straight-sided rectangular central section with two opposing ends, and having substantially straight-sided arms with curved tip portions extending from each opposite end of a central segment, wherein the central segment is substantially the same width as each arm, and the central segment is substantially the same length as each arm , wherein the angle formed between the arms and the central section is from about 105° to about 165°, and wherein the denier per filament of the filament is from about 0.1 to about 4.0.

The invention also relates to a fabric which at least partially consists of filaments and yarns produced according to the invention. In one embodiment, the present invention relates to a double-faced fabric comprising on one side a multifilament yarn at least partially composed of filaments having a bilobal S-shaped or Z-shaped cross-section, wherein each The cross-section of the root filament comprises a substantially straight-sided rectangular central section having two opposite ends and having substantially straight-sided arms extending from each opposite end of the central section with curved tip portions, wherein the central section and Each arm has substantially the same width, and the central section is approximately the same length as each arm, wherein the angle formed between the arms and the central section is from about 105° to about 165°, and wherein the filaments have a denier per filament between From about 0.1 to about 4.0.

The present invention also provides a hydrophilic finish useful for imparting wicking properties to filaments, yarns or fabrics, such as those of the present invention, comprising polyhexamethylene adipamide-poly[poly(oxyethylene)hexane Diamide] copolymer solution in water and propylene glycol.

Brief description of the drawings

Figure 1A depicts a front view of a spinhole comprising three interconnected slits for filaments having a Z-shaped orientation.

Figure 1B depicts a Z-shaped cross-sectional view of a filament spun through the spin hole of Figure 1A.

Figure 2A depicts a front view of a spinhole comprising three interconnected slits for filaments having an S-shaped orientation.

Figure 2B depicts an S-shaped cross-sectional view of a filament spun through the spin hole of Figure 2A.

Figures 3A, 3B and 3C show cross-sectional views of the multifilament yarns of the present invention. Figure 3A depicts the cross-section of a multifilament yarn with 50% S-shaped filaments and 50% Z-shaped filaments. Figure 3B depicts a section with 100% Z-shaped filaments. Figure 3C depicts a section with 100% S-shaped filaments.

Detailed Description of Preferred Embodiments of the Invention

The cross-sectional shape of the filament of the present invention is a distinct bilobal S-shape or Z-shape. Referring to FIG. 1B , a section 100 has substantially straight sides, a rectangular-shaped central section 110 , and arms or lobes 120 attached to the central section. The lobes 120 have a curved shape protruding from the central section 110 so that an angle of about 105° to 165° is formed between each lobe 120 and the central section 110 . The "Z-shaped" section is drawn in Figure IB; the "S-shaped" section is drawn in Figure 2B.

Yarns formed from the filaments of the present invention may have any proportion of S-shaped or Z-shaped cross-sectional orientation. In one embodiment of the invention, the yarn consists of a mixture of filaments having S-shaped and Z-shaped cross-sections. Figure 3A depicts a mixture of filaments with S-shaped and Z-shaped cross-sections. Specifically, the S-shaped cross section can account for at least about 25% of the total number of filaments in the multifilament yarn, such as at least about 50%, such as at least about 60%, such as at least about 75%, and in some embodiments Program, about 100%. The Z-shaped cross section can account for at least about 25%, for example, at least about 50%, for example, at least about 60%, for example, at least about 75%, and in certain embodiments, about 100%.

In another embodiment of the invention, the filaments of the yarn have a uniform orientation. The term "uniformly oriented" is used herein to mean that the orientation of the cross-sections of the filaments is substantially the same. For example, the filaments may all be in the same S-shaped orientation, such as that drawn in Figure 3C. Alternatively, the filaments may all be in the same Z-shaped orientation, such as that drawn in Figure 3B.

The filaments of the present invention are composed of any thermoplastic polymer. The filaments of the present invention may be composed of homopolymers, copolymers and/or terpolymers of monomers capable of forming melt-spinnable polymers. Melt-spinnable polymers include polyamides such as polyhexamethylene adipamide (nylon 6,6); polycaprolactam (nylon 6); polyheptamide (nylon 7); nylon 10; 12); polybutylene adipamide (nylon 4,6); polyhexamethylene sebacamide homopolymer (nylon 6,10); n-dodecanedioic acid and (1,6-)hexamethylenediamine Homopolymer polyamides (nylon 6,12); and polyamides of (1,12-) dodecanediamine and n-dodecanedioic acid (nylon 12,12); polyesters such as polyterephthalmic Ethylene glycol formate (“2-GT”), poly(1,3-)trimethylene terephthalate (“3-GT”), polybutylene terephthalate (“4-GT”) , polytrimethylene terephthalate, and polyethylene naphthalate; polyolefins, such as polypropylene, polyethylene, and polyurethane; and combinations thereof. Methods of making homopolymers, copolymers and terpolymers used in the present invention are known in the art and may include the use of catalysts, co-catalysts and chain branching agents to form copolymers and terpolymers, as is known in the art known. Preferably, the fiber-forming polymer is at least one polyamide, since polyamides are generally softer based on their lower modulus, and they are more hydrophilic due to their own polymer surface chemistry. More preferably, the polymer is nylon 6, nylon 6,6 or combinations thereof. Most preferably, the polyamide is nylon 6,6.

The polymers and their filaments, yarns and articles used in the present invention may contain conventional additives which may be added during the polymerization process or added to the formed polymer or article and which may contribute to the improvement of the properties of the polymer or fiber. contribute. Examples of these additives include antistatic agents, antioxidants, antibacterial agents, flame retardants, dyes, light stabilizers, polymerization catalysts and auxiliaries, tackifiers, matting agents such as titanium dioxide, matting agents, organic phosphates and their combinations.

The polymers and their filaments, yarns and articles used in the present invention may have permanent or semi-permanent hydrophilic treatments or finishes applied to their surfaces. These treatments improve the hygroscopic properties of the article.

Wicking treatments suitable for use in the present invention include hydrophilic polymer compositions, e.g., polyamides made with hydrophilic segments, e.g., poly(hexamethylene adipamide)-poly[poly(oxyethylene) Adipamide] copolymers [Chemical Abstracts Service No. (CAS No.) 92717-79-8], for example, described in U.S. Patent 4,468,505, the entire contents of which are hereby incorporated by reference; Emulsions, such as "Sandotor HV Liquid," marketed by the company Clariant; hydrophilic copolyesters, such as those containing both polyoxyethylene diester and alkylene diester segments; and certain nonionic surfactants agents such as those disclosed in Canadian Patent 1,234,656.

These wicking treatments vary in their ability to improve water absorption, and in their washfastness or durability. This change in performance depends on several factors, including the composition of the fiber being treated, the amount of wicking treatment applied to the fiber, and the washfastness of the treatment.

Poly(hexamethylene adipamide)-poly[poly(oxyethylene) adipamide] copolymers have been found to be particularly suitable for treating articles of the present invention. The polymer is composed of polyoxyethylene adipamide segment and poly(hexamethylene adipamide) segment. The poly(oxyethylene) adipamide segments are formed by the reaction between poly(oxyethylene) diamine [CAS No. 65605-36-9] and adipic acid. The poly(oxyethylene)diamine may include small amounts, such as less than 25 mole percent, of oxypropylene groups, as well as oxyethylene groups.

The polyoxyethylene adipamide segment has high hydrophilicity and imparts hydrophilic properties to the copolymer, thereby imparting hydrophilic properties to the treated fiber, while the poly(hexamethylene adipamide) segment has low water solubility, thereby imparting the treatment The durability of the agent on the fiber. These adipamide copolymers are especially useful when the polymer used in the substrate being treated is nylon 6, nylon 6,6 or combinations thereof, most useful when the polyamide substrate is nylon 6,6.

The polyoxyethylene adipamide and poly(hexamethylene adipamide) segments can each vary in length. Increasing the length of the polyoxyethylene adipamide segment will increase the water absorption performance of the treatment agent, but at the same time increase its water solubility and thus reduce its wash durability. Increasing the length of the poly(hexamethylene adipamide) segment will decrease its water solubility and thereby increase the wash durability of the treatment.

The suitable length of the polyoxyethylene adipamide segment also depends to some extent on the commercial availability of poly(oxyethylene)diamine. Poly(oxyethylene)diamines of molecular weight 600, 900 and 2000 are commercially available from Huntsman and are therefore particularly useful. Their trade names are XTJ-500, XTJ-501 and XTJ-502, respectively.

The relative amounts of each of these segments to each other in the treatment composition may also be varied in any desired proportion. Increasing the proportion of polyoxyethylene adipamide segments will increase the water absorption performance of the treatment agent, but at the same time increase its water solubility and thereby reduce its washing durability. Conversely, increasing the proportion of poly(hexamethylene adipamide) segments will decrease its water solubility and thus increase its wash durability. The relative amounts of polyoxyethylene adipamide and poly(hexamethylene adipamide) segments in the copolymer should be balanced to maximize absorbency while maintaining appropriate fastness to repeated washing. The preferred copolymers of the present invention employ poly(oxyethylene)diamine having a molecular weight of about 900 to about 2000, while the weight percent of nylon 6,6 is about 18 to 22%. The polymer can be prepared as described in US Patent 4,468,505.

Such copolymers, when used in the present invention, may be dissolved in any suitable solution. A preferred system was found to be a solution of 1,2-propanediol and water. This combination provides a solution which can be applied to the fabric by itself or in combination with other processing agents as described below. The amount of poly(hexamethylene adipamide)-poly[poly(oxyethylene) adipamide] copolymer in the solution ranges from about 0.1% to about 40% by weight. The most preferred range is from about 8% to about 15%. At higher percentages of copolymer, the solution will have a tendency to gel. Lower percentages are acceptable but less economical. For application to fabrics, the solution may be further diluted with water to facilitate application of just the desired amount of finish without overapplication.

1,2-Propanediol was used to promote dissolution of the copolymer in water. The preferred amount of 1,2-propanediol is approximately equal to the weight of the hydrophilic polyamide copolymer. More 1,2-propanediol may be used (eg, 1.5 times the weight of copolymer), but may prolong the drying time required during application. Lower amounts of 1,2-propanediol (eg, 0.5 times the weight of the hydrophilic polyamide copolymer) can be used but will reduce the solubility of the hydrophilic polyamide copolymer. The use of 1,2-propanediol is preferred over ethanol, as disclosed in U.S. Patent 4,468,505, because it is non-flammable, it is less toxic, less carcinogenic, needs to be used in smaller amounts, and because it has a higher boiling point and therefore out less.

Hydrophilic copolyesters are also useful in the present invention as hydrophilic agents. Hydrophilic copolyesters include copolyesters containing both polyoxyethylene diester and alkylene diester segments. They may be simple copolyesters, that is, they may contain only polyoxyethylene diester and polyalkylene diester segments, that is, the copolyesters are composed of a single polyethylene oxide, diester and derived from diols. Various amounts of polyethylene oxide, dimethyl terephthalate, and ethylene glycol are the most common raw materials for this copolymer, mainly for reasons of cost and availability. Various variations on the comonomers used to prepare such simple hydrophilic copolyesters are also possible. Such copolymers are disclosed in US Patent 3,416,952, the entire contents of which are hereby incorporated by reference. Examples of such copolymers include "ZELCON" 5126 [CAS No. 9074-67-3], commercially available from Stepan Company; and "MILEASE" T [CAS No. 9016-88-0], available from Imperial Chemical Industries (London , UK), "ZELCON" 5126 and "MILEASE" T are both sold as aqueous dispersions containing up to 85% water.

These previously disclosed permanent or semi-permanent hydrophilic treatment compositions may be applied to fabrics or fibers by any suitable means, eg, knife coating, brushing, dipping, foaming, nip feeding, spraying or other means. Typical minimum application levels of the composition are at least 0.1 wt% solids, preferably at least 0.5 wt% solids, of the fibers to achieve water absorption and fastness. Higher application rates will improve the hydrophilic properties. After drying or driving off the solvent, a durable, hydrophilic coating remains on the surface of the fabric or fiber. The coating will cause water placed on the surface to quickly wet the fabric and move along the fiber length and through the fabric layers.

Other additives may also be applied to the fibers, for example, during the spinning and/or drawing process, including antistatic agents, slip agents, tackifiers, antioxidants, antimicrobial agents, flame retardants, lubricants or combinations thereof combination. Additionally, these additional additives can be added at various process steps, as is known in the art.

The filaments of the present invention may also be formed from two polymers, eg, two nylons, or two polyesters, formed into so-called "bicomponent" filaments. Also, filaments of the present invention having bilobal cross-sections, including those formed as bicomponents, can be blended with filaments of other cross-sections and/or polymers to form yarns.

The filaments of the present invention are formed by any suitable spinning method, which may vary depending on the type of polymer used, as is known in the art. Generally, the melt-spinnable polymer is melted and extruded through a spin orifice having a pattern corresponding to the bilobal cross-section required by the present invention. The extruded fibers are then quenched or solidified with a suitable medium, such as air, to remove heat from the fibers as they exit the spin orifice. After quenching, the filaments are bundled, interlaced and wound into multifilament bundles.

The spinholes used to produce the filaments of the present invention may be any suitable spinholes that produce the bilobal cross-section described above. A suitable spinnerette is described, for example, in US Patent No. 5,447,771, the entire contents of which are hereby incorporated by reference. Specifically and as shown in Figures 1A and 2A herein, the spinneret comprises a plate having upper and lower surfaces connected by segmented capillaries. The segmented capillary comprises a central portion and two radial arms, wherein each arm has a rectangular shape. As shown in Figures A1, 1B and 2B, the angle (C1 or C2) is the angle between one arm and the central part. Angle C1 typically ranges from about 105° to about 165°. Angle C2 typically ranges from about 105° to about 165°. The angles C1 and C2 of the section may be the same or different. Preferably, the two corners are substantially identical. Preferably, in the case of an S-shaped cross-section, the angles C1 and C2 of each arm (as shown in Figure 2B) are between about 105° and about 165°, most preferably between about 120° and about 135°. Preferably, in the case of a Z-shaped cross-section, the angles C1 and C2 of each arm (as shown in FIG. 1B ) are between about 105° and about 165°, most preferably between about 120° and about 135°.

Additionally, referring to FIG. 2A, the slits may have any length (A1 and A2), for example, between about 0.005 to about 0.050 inches, preferably between about 0.010 to about 0.020 inches, and any width (B1 and B2), for example, From about 0.001 to about 0.015 inches, preferably from 0.003 to about 0.005 inches. The central portion 110 can have any length (D), for example, between about 0.005 inches to about 0.025 inches, preferably about 0.012 inches to about 0.020 inches, and any width (E), for example, between about 0.001 inches to about 0.015 inches, preferably about 0.003 inches to About 0.005 inches. Figure 1A may have similar dimensions.

In a preferred embodiment, the size of each slit is further specified by the following ratio:

1.5<A1/B1<10, where A1 is the length of the slit and B1 is the width of the slit. The formula for the second arm would be 1.5<A2/B2<10, where A2 is the length of the other slit and B2 is the width of that slit. Generally, the spinholes should have the dimensions described above to produce the filaments of the present invention. However, it is to be understood that specific dimensions and ratios within the above ranges may vary with factors such as polymer type, viscosity and quenching medium. It should also be appreciated that the shape of the slits can be modified, for example, as shown in Figure 1A, where the tip portions of the radial slits are slightly curved. Preferably, each radial slit is substantially the same size and shape as one another.

The spin orifice through which the molten polymer is extruded is shaped to produce the cross-section required by the present invention. Figures 1A and 2A show front views of the spinholes forming the filaments. The spin holes or spinneret holes may be machined by any suitable method, for example, laser cutting, as described in U.S. Patent 5,168,143, which is hereby incorporated by reference in its entirety, drilling, electrical discharge machining (EDM), and punching. holes, as known in the art. Preferably, the spinning holes are machined with a laser beam. The spin holes can be of any suitable size and can be formed as continuous or non-continuous slits. Discontinuous capillary pores can be obtained by drilling many small holes in a pattern that collapses the polymer and forms the bilobal cross-section of the present invention.

The filaments can be formed into any type of yarn, eg fully drawn yarn or partially oriented yarn, eg feed yarn for texturing. Accordingly, in one embodiment, the filaments are spun into a fully drawn yarn, for example, a yarn having a degree of orientation having an elongation at break of about 35 to about 50%, which is directly usable in the manufacture of an article. Optionally, however, the filaments of the invention may be textured according to known methods, also known as "bulked" or "crimped" yarns. In such embodiments of the invention, the filaments can be drawn into partially oriented yarns, e.g., yarns having a degree of orientation of from about 55 to about 75% elongation at break, by any means such as draft-false twist texturing, air jet Deformation processing is carried out by techniques such as deformation and gear curling.

The filaments of the present invention can be processed into multifilament fibers or yarns having any desired denier, filament count and dpf (denier per filament). The total denier of the yarns formed from the filaments of this invention generally ranges from about 10 to about 300 denier, preferably from about 15 to about 250 denier, and most preferably from about 20 to about 150 denier. The denier per filament of the filaments of the present invention is from about 0.1 to about 4 dpf, preferably from about 0.8 to about 3.5 dpf, most preferably from about 0.9 to about 3.0. In one embodiment, the dpf is less than about 2.9, or less than about 2.5. The bilobal filaments may be blended with other filaments, for example with filaments having a dpf above or below about 4.

The inventive yarns can also be constructed from a variety of different yarns with different dpf ranges. In this case, the yarn should consist of at least one filament having a multilobal cross-section according to the invention. Preferably, each filament of the yarn comprising a plurality of different filaments has the same or different dpf, and each dpf is between about 0.1 and about 4 dpf, preferably between about 0.8 and about 3.5, most preferably between About 0.9 to about 3.0.

The filaments of the invention can be used to make fabrics. Any method known to be suitable for making fabrics can be used. For example, warp knitting, circular knitting, hosiery knitting, and the method of laying ordinary short fibers into a nonwoven fabric are also suitable for fabricating. In one embodiment, a two-faced fabric is made using the filaments of the present invention on substantially one side of the fabric. Any other type of yarn can be used to form the other side of the fabric, but preferably it has a different wicking capacity. Yarns suitable for the other side of the reversible fabric may consist of polyamides, polyesters, polyolefins, natural fibers such as cotton, wool, silk, rayon, and combinations thereof. Two-face fabrics can be produced by methods known in the art. For example, the fabric may be knitted with a multifilament yarn having a bilobal cross-section according to the invention on one side and another yarn on the other side. Suitable methods of making a two-face fabric include warp knitting and plating of the yarns. The nice thing about the double sided fabric is that it wicks moisture away from the body. Generally, higher dpf fabrics are used on the inside of the garment and lower dpf fabrics are used on the outside of the garment. However, the bilobal cross-section multifilament yarns of the present invention can be used on either side of a double-faced fabric. For example, the bilobal cross-section multifilament yarns of the present invention may be applied to the outside of the fabric and treated with a finish such as the hydrophilizing agents described above. In another embodiment, a different yarn, eg, cotton, can be used on the outside of the forming fabric, with the bilobal multifilament yarn on the inside.

In another preferred embodiment, the fabric is comprised of at least about 50%, preferably at least about 80%, of the filaments of the present invention, based on the total number of filaments. In another preferred embodiment, fabrics formed from the filaments of the present invention are combined with a permanent or semi-permanent hydrophilic wetting agent as described above. The fabric can be used to make any type of garment, including swimwear, sportswear for competitions and ready-to-wear.

Any desired additives can be applied directly to the fabric. Examples of such additives include antistatic agents, antioxidants, antibacterial agents, flame retardants, dyes, light stabilizers, polymerization catalysts and auxiliaries, tackifiers, matting agents such as titanium dioxide, matting agents, organic phosphoric acids Esters, permanent or semi-permanent hydrophilic wetting agents and combinations thereof. Preferably, a suitable wetting agent is added to fabrics made from the multifilament yarns of the present invention. Wetting agents suitable for direct application to fabrics include hydrophilic agents as described above.

Fabrics made using the filaments and yarns of the present invention were found to exhibit excellent moisture absorption properties, a soft hand and a silky sheen. Multifilament yarns with high dpf filaments have been developed for use in carpets with oppositely directed bilobal cross-sections. For example, Mill et al., US Pat. No. 5,447,771, describe a multifilament yarn in which in cross-section "S" and "Z" are present in a ratio of 40:60 to 60:40. The present inventors have surprisingly discovered that the S and Z cross-section filaments can be used to make garments with excellent wicking properties, especially at a dpf of less than about 4.

The moisture absorption of the yarns of the invention is determined by known methods, for example by the Vertical Wicking Test or the Horizontal Wicking Test. The vertical wicking test may be performed by knitting the yarn into a tube, scouring or treating the tube with any desired agent, and allowing the treated tube to air dry. The tubing was then cut into strips 1 inch wide by about 8 inches long and hung vertically above the water so that 3 inches were in the water and 5 inches above the water. Observe with the naked eye the height of water sucked up along the bar within the specified time, for example, within 1 min, 5 min, 10 min and 30 min.

Mixed S-shaped and Z-shaped cross-sections having a denier per filament ranging from about 0.1 to about 4.0 were found to exhibit enhanced moisture absorption. Excellent results were also observed with multifilament yarns directed to a uniform S-shaped or Z-shaped cross-section as described herein.

The inventive yarn has a strength suitable for use in clothing. Strength was measured on an Instron (tensile testing machine) equipped with two grips holding the sample 10 inches apart. The yarn was then stretched at a strain rate of 10 inches per minute, and the data was recorded by a load cell, whereby a stress-strain curve was obtained. Tenacity is the breaking strength (grams) divided by the denier of the yarn. Both the partially oriented and fully drawn yarns of the present invention can have a tenacity of from about 2 to about 8, preferably from about 3 to about 6 g/denier.

The elongation at break of the yarn can be determined using known equipment. For example, one method involves stretch-to-break on an Instron Tester TTB (Instron Engineering Co.) equipped with a Twister Head manufactured by Alfred Suter Co., using 1-inch by 1-inch flat-jaw grips (Instron Engineering Co. ). Samples with typical dimensions of about 10 inches long were pre-applied with 2 twists per inch and stretched at a draw rate of 60% per minute in an environment of 65% relative humidity and 70°F. The elongation at break is from about 30% to about 80%, preferably from about 40% to about 60%, for both fully drawn and partially oriented yarns of the present invention.

The boiling water shrinkage of yarn can be determined by any known method. For example, it can be determined by suspending a weight from a length of yarn to create a load of 0.1 g/denier on the yarn and then measuring its length (L ₀ ). Then, remove the weight, and immerse the yarn in boiling water for 30 minutes. Next, remove the yarn, load it again with the same weight, and record its new length (L _f ). Shrinkage percentage (S) is calculated according to the following formula:

Shrinkage (%) = 100(L ₀ -L _f )/L ₀ Low shrinkage is highly favored for most textile applications. The shrinkage of the yarns of the present invention is less than about 10%, preferably less than about 7%, and most preferably less than about 6%.

The invention will now be illustrated by the following non-limiting examples.

Example

Preparation of poly(hexamethylene adipamide)-poly[poly(oxyethylene) adipamide] copolymer used in the finishing agent of example 1

Polyoxyalkylene amine XTJ-501 (Huntsman, CAS 65605-36-9, molecular weight 900) 506g, adipic acid 82.1g and 277.6g nylon salt solution (hexamethylenediamine and adipic acid are in 1: 1 molar ratio in 53.2% solution in water, heated to homogeneity), combined in a 2 L resin kettle equipped with a mechanical stirrer, thermocouple, stirring blades, distillation head and nitrogen tube. Stirring was started and all air was then driven out by 3 repetitions of evacuating and releasing the vacuum with nitrogen. The mixture was a thin white slurry. The mixture was rapidly heated to a kettle temperature of 120°C to distill off water. A nitrogen purge was used to facilitate the removal of water throughout the reaction. Water reflux can be reduced by steam heating or by using a heat strip at the top of the kettle. Once the evaporation of water had slowed (approximately 130 mL was collected), the mixture was heated to a pot temperature of 200 °C for 4 h. Water continued to distill off, and the mixture was heated to 260°C within 1 h, kept at 260°C for 30 min, and then cooled to room temperature. The solid polymer is removed from the flask and chopped or ground to the required size.

Preparation of poly(hexamethylene adipamide)-poly[poly(oxyethylene) adipamide] copolymer solution

100g of 1,2-propanediol and 800g of water are combined in a mixer, and then heated to 90-95°C. Add 100 g of the poly(hexamethylene adipamide)-poly[poly(oxyethylene) adipamide] copolymer prepared above and stir rapidly for 30 min until it dissolves. The solution was filtered through a filter cloth to remove undissolved particles, and then a small amount of glutaraldehyde (670 mg) (Ucarcide 225) was added as a preservative.

Example 1

A 40 denier - 14 monofilament bilobal cross-section yarn was spun, 50% of the filaments being "S"-shaped and 50% of the filaments being "Z"-shaped. The filaments were spun at a temperature of 290°C. The yarn is spun from nylon 6,6 with a relative viscosity (RV) of 45-47. A common nylon module formulation was used, in which a spinnerette with a bilobal cross-section in a 3-head/module configuration was used. Nylon 6,6 is spun at a winding speed of 3000-3200 yards per minute and stretched at a draw ratio of 2.5-2.7 times. The tenacity of the filament was 3.6 g/denier; the elongation at break of the yarn was 42%. The cross-section of the yarn was similar to that given in Figure 3A. A general spinning/secondary spinning finish was used.

The yarn was knitted into Lawson tubes on a single end knitting machine. After being woven into a tube, each of the products in the above examples was tested by a vertical wicking test. The product is prepared in two ways: (1) extensively scoured to remove all oils, and (2) subsequently, treated with a hydrophilic hygroscopic agent and then air dried. The specific hydrophilic finish used in this test was a copolymer dispersion prepared as described above. The product was then cut into strips 1 inch wide by approximately 8 inches long and hung vertically over the water with 3 inches in the water and 5 inches above the water. The tester then visually observed the water up the strip up to a height of 5 inches. Observation was carried out at 1 min, 5 min, 10 min and 30 min. When 5 inches is reached, the test is stopped. Controls of nylon 6,6 with circular, trilobal and dog-bone cross-sections were used for comparison. Interestingly, none of these different cross-sections wick very well when scoured, and the results are quite different when treated with a hydrophilic finish. Bilobal sections benefit the most from the addition of a hydrophilic finish. The results are summarized in Table I.

Example 2

In a manner similar to Example 1, a 40 denier-14 filament bilobal cross-section yarn having a 100% S-filament cross-section and spun from nylon 6,6 was prepared. The tenacity of the filament was 4.3 g/denier; the yarn elongation at break was 41%. Also, the yarn had a boiling water shrinkage of 5.3% and was interlaced at 11 knots per meter. The yarn has a cross-section similar to that shown in Figure 3C. Subsequently, the moisture absorption capacity of the yarns was tested according to the vertical wicking test, as listed in Table 1.

Example 3

In a manner similar to Example 1, a 40 denier-14 filament bilobal cross-section yarn having a 100% Z-filament cross-section and spun from nylon 6,6 was prepared. The moisture absorption capacity of the yarns was tested according to the vertical wicking test, as listed in Table 1. The cross-section of the yarn was similar to that shown in Figure 3B. The denier, elongation, and boiling water shrinkage of this yarn were similar to the Example 1 yarn.

Example 4

In a manner similar to Example 1, except that the draw ratio was reduced to 1.9 times, a 44 denier-14 monofilament bilobal partially oriented yarn was spun with 50% S-filament cross section and 50% Z-filament The section is spun from nylon 6,6. The cross-section of the yarn was similar to that shown in Figure 3A. The tenacity of the yarn was 3.1 g/denier; the elongation at break of the yarn was 59%.

Example 5

In a manner similar to that of Example 1, an 80 denier-28 filament bilobal cross-section yarn having a 50% S-filament cross-section and a 50% Z-filament cross-section and spun from nylon 6,6 . The tenacity of the filament was 4.2 g/denier; the elongation at break of the yarn was 42%. The boiling water shrinkage of the yarn was 6.0%; the yarn was interlaced at a rate of 15 knots per meter. Subsequently, the moisture absorption capacity of the yarns was tested according to the vertical wicking test, as listed in Table 1. However, since the standard test had reached a maximum of 5 inches in 30 minutes, additional tests were carried out using longer strips of the treated 80-28 yarn, and it was found that the core of the 80-28 bilobal sample Continue to rise after sucking more than 5 inches, up to 6.2 inches within 30 minutes.

Comparative example A～F

The control yarns were formed in a manner similar to Example 1 and are reported in Table 1 in denier-count and cross-section. Each yarn is made from nylon 6,6. Subsequently, the moisture absorption capacity of the yarns was tested according to the vertical wicking test, as listed in Table 1.

Table I example denier - number of roots section deal with Wicking height (inches) 1 minute 5 minutes 10 minutes 30 minutes 1 40-14 Double Lobe (50%S, 50%Z) boiled 0.3 0.35 0.45 0.65 1 40-14 Double Lobe (50%S, 50%Z) deal with 1.75 2.85 3.75 5.00 2 40-14 Double leaf shape (100%S) boiled 0.35 0.40 0.50 0.75 2 40-14 Double leaf shape (100%S) deal with 1.70 2.95 3.85 5.00 3 40-14 Double leaf (100% Z) boiled 0.30 0.35 0.55 0.70 3 40-14 Double leaf (100% Z) deal with 1.65 2.80 3.80 5.00 5 80-28 Double Lobe (50%S, 50%Z) boiled 0.30 0.35 0.45 0.65 5 80-28 Double Lobe (50%S, 50%Z) deal with 1.70 2.95 3.85 5.00 Contrast A 70-51 round boiled 0.1 0.1 0.25 0.55 Contrast A 70-51 round deal with 0.75 1.55 2.00 2.75 Contrast B 70-24 trefoil boiled 0.40 0.75 0.95 1.40 Contrast B 70-24 trefoil deal with 0.95 2.05 2.70 3.70 Contrast C 70-66 round boiled 0.20 0.50 0.75 1.55 Contrast C 70-66 round deal with 1.10 1.90 2.35 2.95 Contrast D 86-26 Dogbone boiled 0.40 0.40 0.40 1.10 Contrast D 86-26 Dogbone deal with 1.15 2.05 2.80 3.85 Contrast E 70-34 round boiled 0.40 0.50 0.55 1.30 Contrast E 70-34 round deal with 0.50 1.00 1.55 2.65 Contrast F 70-34 trefoil boiled 0.40 0.40 0.60 0.95 Contrast F 70-34 trefoil deal with 0.95 1.75 2.45 3.65

As shown in Table 1, the bilobal cross-section treated by the present invention far exceeds other cross-sections in terms of wicking capacity. For example, the bilobal cross-sections treated by the present invention each wicked to the full yarn length within 30 minutes. This is particularly surprising since the trefoil and dogbone cross-sections had better wicking performance than the bilobal when tested as scoured fabrics, but not when treated with a hydrophilic finish. Therefore, what was unexpected was the synergistic effect between the bilobal cross-section and the hydrophilic finish. It is believed that this synergistic effect may be related to the way the bilobal fibers gather together to form tiny pores between the fibers which strengthen the core once the fiber surface is wetted by the action of the hydrophilic finish suction, which does not occur in the case of the trefoil and dog-bone sections.

Example 6

The yarn of Example 1 and yarns of various cross-sections, such as dogbone and round, were spun from nylon 6,6. Each of these yarns was weft knitted into a substantially "two-faced construction" in which the second yarn was 70 denier 34 filament nylon 6,6 with 50% by weight of each yarn in the fabric. This two-sided nature of the fabric is achieved by controlling the length of the knitting loops and the feed tension of the knitting machine. These fabrics are then dyed and finished using techniques normally used with nylon. Sandator HV fluid from Clariant was applied as a hydrophilic agent.

The wicking test involves a method of determining the rate of wicking and the amount of moisture absorbed by a fabric in one test. Specifically, the test involved the use of an apparatus consisting of a 55 mm diameter perforated plate fixed to a wooden table for stability and connected to a length of non-compressible hose. The hose is placed in a 1L liquid pool, and the liquid pool is placed on an electronic balance to determine the weight of the remaining liquid in the pool. As water is wicked from the pool onto the fabric, a computer linked to the scale records the weight loss to determine the water intake. The fabric was cut into 120 mm by 130 mm samples and placed on top of a perforated plate with a cylindrical mass placed on top to facilitate contact with the wet perforated plate. The overall moisture absorption of the fabric was determined and based on this data the wicking rate was calculated. The results of this test are presented in Table 2.

Table 2 Yarn cross section Wicking results Water storage capacity on the surface (g water/square meter) Water transfer rate on the surface (g water/m2/s) Double leaf section (Example 5) 565 6.14 Dogbone 417 4.81 round 377 4.09

As shown in Table 2, the bilobal cross-section of the present invention far surpasses other cross-sections in the capacity of accumulating surface water and absorbing water.

Numerous modifications will be able to be made by those skilled in the art having the benefit of the disclosure of the invention given above. Such modifications are considered to be within the scope of the invention as defined by the appended claims.

Claims (21)

1. A yarn formed at least in part from filaments having a bilobed S-shape or a Z-shape in cross section, wherein the filaments of the S-shape or Z-shape cross-section comprise a substantially straight-sided rectangle a central section having two opposite ends; and arms extending from each opposite end of the central section with substantially straight sides having curved tip portions, wherein the central section and each arm have substantially the same width, and the central section and Each arm is substantially the same length, wherein the angle formed between the arms and the central section is from about 105° to about 165°, and wherein the filaments in the yarn have a denier per filament from about 0.1 to about 4.0. 2. The yarn of claim 1, wherein said yarn comprises at least about 50% Z-shaped or S-shaped cross-sectional filaments, based on the total number of filaments. 3. The yarn of claim 2, wherein said yarn comprises at least about 90% Z-shaped or S-shaped cross-sectional filaments. 4. The yarn of claim 1 having a denier in the range of about 15 to 200 denier. 5. The yarn of claim 1, wherein each filament is formed from a homopolymer, copolymer, terpolymer, or combinations thereof of a polymer selected from the group consisting of polyamides, polyolefins, polyesters, and combinations thereof. 6. The yarn of claim 1, wherein each filament is formed from a polyamide selected from the group consisting of nylon 6, nylon 6,6, nylon 6,12, and combinations thereof. 7. The yarn of claim 5, wherein the polyamide is nylon 6,6. 8. A filament having a bilobal S- or Z-shape in cross-section, wherein the cross-section of each filament comprises a substantially straight-sided rectangular central section with two opposite ends; two arms projecting at opposite ends and having substantially straight sides with curved tip portions, wherein the central section is substantially the same width as each arm, and the central section is approximately the same length as each arm, wherein a gap is formed between the arms and the central section The angle is from about 105° to about 165°, and the denier per filament of the filament is from about 0.1 to about 4.0. 9. A yarn formed at least in part by a filament having a bilobal S-shape or a Z-shape in cross-section, wherein the cross-section of each bilobal filament comprises a substantially straight-sided rectangular central section, having two opposite ends; and an arm extending from each opposite end of the central section with a substantially straight side having a curved tip portion, wherein the central section and each arm have substantially the same width, and the central section and each arm wherein the angle formed between the arms and the central section is from about 105° to about 165°, and wherein the yarn comprises at least about 70% Z-shaped or S-shaped cross-section filaments, based on the total number of filaments The number of roots is the basis. 10. A fabric made at least in part from the multifilament yarn of claim 1. 11. A fabric made at least in part from the multifilament yarn of claim 9. 12. A fabric made at least in part from the filament of claim 8. 13. A double-sided fabric comprising on one side at least partially a multifilament yarn composed of one or more filaments having a bilobal S-shape or a Z-shape in cross-section, wherein each bilobal filament comprises a substantially straight-sided rectangular central section having two opposite ends; and substantially straight-sided arms extending from each opposite end of the central section with curved tip portions, wherein the central section and each The arms are substantially the same width, and the central section is approximately the same length as each arm, wherein the angle formed between the arms and the central section is from about 105° to about 165°, and the other side comprises another yarn. 14. The fabric of claim 13, wherein the filaments have a denier per filament of from about 0.1 to about 4.0. 15. The fabric of claim 13, wherein a wetting agent is applied to the side comprising filaments having an S- or Z-shaped cross-section. 16. The fabric of claim 15, wherein the wetting agent is selected from the group consisting of hydrophilic polyamides, hydrophilic silicones and hydrophilic polyesters. 17. The fabric of claim 14, wherein the other side of the fabric comprises polyester, polyamide, polyolefin or natural fibers. 18. The fabric of claim 10 comprising on at least one surface thereof a wetting agent selected from the group consisting of hydrophilic polyamides, hydrophilic silicones and hydrophilic polyesters. 19. The fabric of claim 12 comprising on at least one surface thereof a wetting agent selected from the group consisting of hydrophilic polyamides, hydrophilic silicones and hydrophilic polyesters. 20. A solution of polyhexamethylene adipamide-poly[poly(oxyethylene) adipamide] copolymer in water and 1,2-propylene glycol. 21. A method of increasing the wicking capacity of an article comprising forming the article from at least one filament as claimed in claim 8, wherein the filament is optionally treated with a hydrophilic wicking agent.

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