Composite yarns and moisture management fabrics made therefrom

Abstract

 A composite textile yarn and a moisture management fabric made therefrom, the yarn comprising hydrophilic fibers embedded at the yarn center within a matrix of hydrophobic fibers such that the hydrophobic fibers are concentrated at the periphery of the yarn, a transition area between the center hydrophilic fibers and the peripheral hydrophobic yarns in which both fiber types are present.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates in general to a class of composite textile yarns for use in forming moisture management structures. More specifically, it relates to improved moisture management textile composite yarns comprising hydrophilic fibers embedded within a matrix of one or more hydrophobic fibers, in which there is a gradual transition between fiber types. The transition begins at the center of the composite yarn where hydrophilic fibers are concentrated and progresses to the outermost layer where hydrophobic fibers predominate. Further, this invention relates to improved moisture management fabrics and garments produced by the use of the aforementioned composite textile yarns alone or in combination with other yarns.

[0002] In recent years, "structured fabrics" (also referred to as "engineered fabrics") have become very popular in many application areas of commercial interest. A particularly important class of such structured fabrics is referred to commonly as "moisture management" fabrics. In general, fabrics of this type utilize two or more fiber types in layered structures that are formed so that the two sides of the fabrics are distinctly different in character. In particular, each side of the fabric exhibits different performance characteristics and properties with regard to water and water vapor. The innermost layer, or the fabric side that comes into contact with the body of the wearer, is comprised substantially of hydrophobic fibers, while the outer layer is made up substantially of hydrophilic fibers.

[0003] Lightweight, two-sided fabrics for use in moisture management applications also are produced by the use of "plate" knitting techniques. In plate knitting such fabrics, both hydrophobic and hydrophilic yarns are fed to a single set of knitting needles so that two disparate yarns pass through each single needle of the set. With careful control of the feed and positioning of the hydrophobic and hydrophilic yarns, the resulting "plated" fabric will show only hydrophobic yarns on one side and hydrophilic yarns on the opposite side.

[0004] The principal end use application areas for moisture management fabrics are, without limitation, in active sportswear garments, work clothing, intimate apparel, exercise garments, and footwear. In uses in garments that contact the body of a physically active wearer, the moisture management fabrics act to prevent, or minimize, the collection of perspiration as a liquid against the body and in the fabric layer next to the body of the wearer. The perspiration, in liquid or vapor form, leaves the skin surface and diffuses, or wicks, through the hydrophobic fibers and is absorbed by the hydrophilic fibers in the outer fabric layer. The perspiration that passes from the skin surface through the hydrophobic fibers is absorbed by the outer layer of hydrophilic fibers and, then, evaporated into the ambient atmosphere away from the body. The transport of moisture from the body of the wearer to the atmosphere in this manner increases the comfort level of the garment to the wearer by preventing or minimizing the formation of wet areas at the skin surface or in the fabric layer nearest the skin. Further, by avoiding the collection of liquid perspiration at the body surface and in the fabric next to the body, the insulating value of the garment is improved so that it feels warmer at low temperatures and cooler, due to an evaporative cooling effect, at higher ambient temperatures to the wearer.

[0005] The driving force, which causes the transport of water from perspiration as liquid and vapor by the process described in the foregoing, is sometimes referred to as a "push-pull" effect. That is to say, perspiration is repelled by the layer of hydrophobic fibers and "pushed", or "wicked", into the layer of hydrophilic fibers, where it is absorbed or "pulled" away. Actually, the movement of moisture from the skin to the outer atmosphere is driven by the large difference in humidity between the inner layer against the skin of the wearer and the ambient atmosphere. Further, the movement is facilitated and directed away from the body by the structured arrangement of hydrophobic and hydrophilic fibers.

[0006] Although moisture management fabrics can be produced on weaving looms, most commercially interesting fabrics of this type are knits that are produced on warp or circular knitting equipment. The hydrophobic fibers of choice generally are melt-spun from polyester, nylon, or polypropylene polymers. These fibers may be in the form of staple yarns, flat continuous multifilaments, or texturized continuous multifilaments. For the hydrophilic side of the fabrics, the most popular fibers in use are based on modified nylon polymers. In general, such nylon polymers are provided with a hydrophilic nature by causing chemical modifications to the nylon polymer chain during the polymerization step. This is accomplished by the chemical addition of hydrophilic sites as segments within the nylon polymer chain or by the chemical attachment of hydrophilic sites as branches to the nylon polymer chain. Alternatively, nylon fibers may be made topically hydrophilic by subjecting the fibers to chemical reactions that serve to attach hydrophilic sites to the nylon polymer at the surface, or very near to the surface, of the fibers. Other less popular hydrophilic fibers are produced from modified polyvinylalcohol, acrylic, and cellulose acetate polymers. Here again, the hydrophilic fibers may be in the form of staple yarns, flat continuous multifilaments, or texturized continuous multifilaments. In some cases, cotton and modified cotton yarns also are used as the hydrophilic component.

[0007] Even though the structured fabrics of the prior art have been well received in the marketplace, they have a number of disadvantages, which limit their utility in certain applications. One of the more important problem areas involves the need to use a minimum of two yarns with knitting or weaving equipment that is capable of producing fabrics with two distinct sides. The use of such equipment results in products that are rather high in cost. Examples of other problem areas are summarized in the paragraphs that follow.

[0008] In most cases, there are significant differences in dyeability and dye fastness properties between the hydrophilic and hydrophobic fibers that are used in a particular moisture management structure. Due to such differences, it can be difficult and, at times, even impossible to produce a dyed fabric of uniform color. Often, two or more dye types, as well as multiple dyeing cycles, must be employed in order to obtain acceptable results. This can increase substantially the dyeing and finishing costs for moisture management fabrics.

[0009] As aforementioned, moisture management fabrics based on the prior art are formed so that the fabric side, which is in contact with the skin surface of the wearer, is hydrophobic, while the outer fabric surface contains the hydrophilic fibers. This creates a serious problem in certain important applications for moisture management fabrics. It is a problem particularly in the area of active sportswear and promotional items where the outer garment surfaces often are screen or transfer printed with names, logos, and other bold design features. Serious problems can occur because the preferred hydrophilic fibers based on modified nylon polymers perform very poorly as substrates for the commonly used screen and transfer printing dyes and inks. As a result, it is either impossible or costly to print a broad range of bright colorful designs onto moisture management fabrics based on the prior art technology. Sandwich-plate knitting techniques, in which a hydrophilic yarn is sandwiched between two hydrophobic yarns and fed to a single set of knitting needles, can ameliorate printing problems, to a certain extent, by forming a sandwich-plated outer fabric surface or by forming both fabric sides by such knitting techniques. Although this approach does position hydrophobic fibers in the outer fabric surface so that it is receptive to screen and transfer prints, it is a difficult technique in practice, since three yarns must be fed to each single needle in a fixed order. Further, the disparate yarns easily can slip out of register in production and usage. This lack of precise register of the sandwiched yarn structure leads to blurred prints.

[0010] Mechanical properties, including abrasion resistance, normally are lower for the preferred hydrophilic fibers based on modified nylon polymers than they are for the most commonly used hydrophobic fibers, such as polyester and polypropylene. This can complicate knitting and limit application areas in which the structures can be used successfully.

[0011] The tactile properties of the commonly used hydrophobic and hydrophilic fibers often are quite different. Although it is not a problem with the less used sandwich-plated knit fabrics, the two sides of the more commonly used moisture management fabrics exhibit a very different "hand" or "feel", depending on the fabric surface that is touched. This can be a serious disadvantage in certain applications, such as intimate apparel.

[0012] In the process of cutting and sewing moisture management fabrics with two sides having very different properties into garments, footwear, and other end use items, great care must be taken to maintain proper orientation and placement of the fabric surfaces. Should the sides be reversed in making the finished item, the resulting product cannot manage moisture effectively.

[0013] U.S. patent 4,621,489 to Hozuma Okada discloses a textile fabric utilizing cored yarns, which fabric is said to be breathable such that the outer fibers which contact the skin of the wearer can be kept substantially dry at all times even though water vapor from perspiration is wicked. The core yarns comprise a thread wadding composed by a bundle of inner hydrophilic fibers, and a thread sheath composed of a plurality of outer hydrophobic fibers arranged exteriorly of the thread wadding so as to substantially completely enclose the inner fibers.

SUMMARY OF THE INVENTION

[0014] The principal objective of this invention is to provide a structured composite yarn with both hydrophilic and hydrophobic properties that can be used alone or in combination with other hydrophobic yarns to produce highly efficient moisture management fabrics. A further objective is to employ a composite yarn comprising a hydrophilic fiber imbedded within a matrix of a hydrophobic fiber, either alone or in combination with one or more hydrophobic yarns, to form knit and woven moisture management fabrics. The resulting moisture management fabrics, while managing moisture as well as, or better than, prior art fabrics, substantially overcome the aforementioned deficiencies that limit the utility of moisture management yarns and fabrics, which are based on the prior art.

[0015] The present invention satisfies the foregoing objectives by employing air entanglement texturing equipment to form a composite yarn by inserting a multifilament hydrophilic yarn into an air jet entanglement or texturing device along with a multifilament hydrophobic yarn. By carefully controlling feed rates, air pressures, and the relative feed tensions of the two disparate yarns entering the air jet, the composite yarn exiting the air entanglement machine has hydrophilic fibers concentrated substantially at its core, while the hydrophobic fibers are concentrated substantially at its periphery. There is no sharp demarcation area separating the hydrophobic surface fibers from the hydrophilic core fibers in the resulting composite yarn. Rather, the outer surface of the composite yarn is made up substantially of hydrophobic fibers, while hydrophilic fibers are concentrated at the center of the composite. A transition layer, comprising a mixture of hydrophilic and hydrophobic fibers, lies between the center and the outer surface of the composite yarn.

[0016] It has been found that the presence of intimately commingled hydrophobic and hydrophilic filaments within the cross-section of the composite yarn cross section leads to a more rapid transference of moisture through the peripheral hydrophobic fibers and into the centrally concentrated hydrophilic fibers as compared to conventional sheath/core composite yarns prepared, for example, according to the teachings of the abovementioned Okada patent. In like manner, the area of intimate commingling of hydrophilic and hydrophobic fibers accelerates the transfer of moisture in the vapor form from the inner hydrophilic fibers through the hydrophobic fibers and into the atmosphere.

[0017] The area within the yarn cross-section wherein hydrophilic and hydrophobic fibers commingle is critically important to the superior performance in moisture management fabrics of the composite yarns of the invention. This can be understood by a comparison with the sheath/core moisture composite yarns of the prior art in which the hydrophilic core yarn is tightly wrapped by hydrophobic fibers. In such yarns, the interface between hydrophobic fibers and hydrophilic fibers is proportional to the square of the radius of the hydrophilic bundle of fibers at the core. For the composite yarns of the invention, commingling of the individual filaments of hydrophobic and hydrophilic fibers results in a substantially larger interface area. This increase occurs because the interface within the commingling area of the composite yarn is proportional to the square of the radii of the much finer individual filaments of the hydrophobic and hydrophilic yarns. An increase in the area of the interface between hydrophobic and hydrophilic components does not increase the total amount of moisture that can be taken up by the composite yarn. An increase in interface, however, increases the kinetics of absorption so that moisture transfer becomes more rapid and effective in the moisture management fabric.

[0018] When in a garment against the skin surface of a wearer, this unique composite yarn structure leads to an efficient and rapid wicking effect of perspiration moisture from the outer hydrophobic fibers in contact with the skin surface to the inner hydrophilic fibers of the yarn. On the garment surface away from the body of the wearer, the moisture evaporates from the inner hydrophilic fibers and passes through the outer hydrophobic fibers to the atmosphere.

[0019] In a two-sided moisture management fabric, the composite yarn of the invention replaces the hydrophilic yarn that would be positioned in the outer fabric surface of a moisture management fabric based on prior art technology. The resulting two-sided fabric has one side made up of hydrophobic yarn, while the opposite side contains a composite yarn of the invention alone, or in combination with, a hydrophobic yarn. In a moisture management garment, or other end use article, in contact with the body of a wearer, moisture from perspiration passes from the skin surface through the hydrophobic fibers of the inner fabric layer and, then, through the peripheral hydrophobic matrix and into the inner hydrophilic fibers of the composite yarn of the outer layer. Finally, the moisture evaporates from the hydrophilic fibers, passes through the hydrophobic peripheral fibers of the composite yarn, and into the atmosphere.

[0020] By using the uniquely structured composite hydrophilic/hydrophobic yarns of the invention in the production of moisture management fabrics and garments, the problems associated with products based on prior art technology that are described in the foregoing are avoided. The reasons for these marked improvements are summarized briefly in the following paragraphs.

[0021] With clear, dull, or neutral colored hydrophilic fibers embedded within matrices of hydrophobic fibers in composite yarns of this invention, it is possible to dye only the hydrophobic fibers and leave the hydrophilic fibers undyed, since they will be substantially concealed by the outer hydrophobic fibers. Also, if a fiber such as polyester is used as the hydrophobic component, it will be at the yarn and fabric surface where it will accept readily screen and transfer prints. For the same reason, fabric tactile properties will be dependent primarily on the hydrophobic fiber at the surface of the composite yarn. Further, mechanical properties of fabrics, such as abrasion resistance, will be controlled primarily by the hydrophobic component of the composite yarn structure.

[0022] An additional advantage for this invention over prior art technology is that the unique character of the composite yarns based thereon permits the production of moisture management fabrics from a single composite yarn. This feature of the invention makes possible the use of simpler and lower cost knitting equipment and procedures than those required when using two or more disparate yarns as required by the technology disclosed in the prior art. Depending on the knitting technique used, the two sides of the resulting moisture management fabrics may be identical. This is an important advantage for the invention, since, with fabrics having interchangeable sides, workers cannot make the mistake of using the wrong fabric side in the cutting and sewing operations required in producing the end use products. Single-yarn fabrics that are produced by using composite yarns of this invention have the same hydrophobic fibers exposed on both sides. In a garment, hydrophobic fibers are in intimate contact with the body of the wearer. Perspiration is wicked rapidly into the interstices of the composite yarn where it is absorbed by the hydrophilic fibers imbedded within the hydrophobic fiber matrix. The moisture, then, is transmitted through the hydrophilic fibers to the outer fabric surface, where it evaporates from the hydrophilic fibers and the vapor passes through the outer hydrophobic fibers to the atmosphere. This moisture transport occurs with equal efficiency irrespective of which fabric surface contacts the wearer and which is exposed to the atmosphere, as the moisture moves from the high humidity at the skin surface to the lower humidity of the atmosphere.

[0023] The composite yarns of the invention are particularly useful in the production of two-sided moisture management fabrics similar in structure to fabrics based on prior art technology. In such fabrics utilizing composite yarns of the invention, however, the composite yarn replaces the hydrophilic yarn that would be used, according to the prior art, in the outer layer of the fabric that is away from the body of the wearer in a finished garment. Depending on the effect desired in the structured moisture management fabric and the end use garment, the composite yarns of the invention may be utilized, alone or in combination with hydrophobic yarns, for both sides of the two-sided fabric. When composite yarns of the invention are used in producing two sided fabrics, hydrophobic fibers are at the surface of both the inner layer and outer layer of the finished fabric. As a result, transfer or screen printing can be done on either or both fabric sides so that prints in complex designs and bright, sharply-defined color patterns can appear on either or both surfaces of the finished garment without the complications associated with screen and transfer printing onto surfaces made up primarily of hydrophilic fibers, such as the modified nylon based fibers.

[0024] These and other objectives, features, and advantages of the present invention will become apparent upon reading the following detailed description and claims and studying the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 presents an enlarged view of a typical hydrophobic/hydrophilic fiber distribution within the composite yarn of the present invention by a sketch of a cross-section taken at a right angle to the long axis of the yarn structure.

[0026] FIG. 2 presents an enlarged view of a typical distribution of hydrophobic and hydrophilic fibers within the composite yarn of the present invention by a sketch of a side view along the long axis of the yarn structure.

[0027] FIG. 3 illustrates an enlarged view of the composite yarn of this invention plied with a yarn of hydrophobic filaments.

[0028] FIG. 4 illustrates an enlarged view of the composite yarn of this invention plied with two hydrophobic yarns.

[0029] FIG. 5 illustrates an enlarged plan view of a plain knit moisture management fabric formed by utilizing only a single hydrophobic/hydrophilic composite yarn based on this invention to produce a structure in which the two sides are substantially identical.

[0030] FIG. 6 is a representation of typical pathways for hydrophobic and hydrophilic fibers as they are processed on an air-jet texturing machine to produce the composite yarns of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention provides a composite yarn, comprising a combination of both hydrophobic and hydrophilic fibers, in which the hydrophilic fibers are concentrated in the interior of the yarn and the hydrophobic fibers are concentrated peripherally, while there is a commingling of both filament types within an intermediate area between the yarn center and its periphery. Also, the invention provides highly effective moisture management fabrics made by using only a composite yarn of the invention or by using a hydrophobic yarn for the fabric side that will contact the body of the wearer and the composite yarn of the invention for the fabric side away from the body of the wearer. Further, the invention provides highly effective moisture management fabrics made by using only a composite yarn of the invention or by using a hydrophobic yarn for the fabric side that will contact the body of the wearer and the composite yarn of the invention plied with one or more hydrophobic yarns for the fabric side away from the body of the wearer. Similarly, a composite yarn of the invention may be plied with one or more hydrophobic yarns and used without other yarns in producing moisture management fabrics.

[0032] The annular area within the composite yarn cross-section in which hydrophilic and hydrophobic fibers commingle that lies between the inner hydrophilic fiber concentration and the peripheral concentration of hydrophobic fibers is an important and unique feature of the composite yarns of the invention. In a conventional sheath core composite there is a clear transition between hydrophobic and hydrophilic fibers within the yarn cross-section. As a result, the interface through which moisture must penetrate in crossing from the hydrophobic fibers to the hydrophilic fibers is very restricted. By providing an area of commingling of hydrophobic and hydrophilic fibers within the cross-section of the composite, the composite yarns of the invention greatly increase the area per unit length of the interface through which the moisture must penetrate to be absorbed by the hydrophilic fibers. This increase in interface area per unit length acts on the kinetics of moisture transfer to increase the transfer rate and efficiency.

[0033] The hydrophilic fiber component of the composite yarn of the invention may be in the form of a continuous flat multifilament yarn, a continuous texturized multifilament yarn, or a staple fiber yarn. The hydrophobic fiber also may be in the form of a flat multifilament yarn, a texturized multifilament yarn, or a staple fiber yarn. If the hydrophobic yarn is in the form of a staple fiber yarn, however, great care must be used in forming the composite to avoid breakup of the staple fiber yarn. Further, for applications in which high abrasion resistance is required, the preferred form for the hydrophobic component is a continuous flat or texturized multifilament yarn.

[0034] FIG. 1 represents an enlarged view of a typical cross sectional profile, taken at a right angle to the longitudinal axis, of the composite yarn generally designated 3 of the invention. The hydrophilic filaments 1 are shown as shaded open circles, while the hydrophobic filaments 2 are shown as open circles without shading. As can be seen in FIG. 1, the hydrophilic filaments are concentrated near the center of the cross-section, and the hydrophobic filaments are concentrated to the periphery of the composite yarn. Hydrophilic and hydrophobic filaments can be seen clearly commingled at an intermediate area between the composite yarn center and periphery with no clear interface.

[0035] FIG. 2 represents an enlarged side view along the longitudinal axis of the composite yarn 3 of the invention and shows hydrophilic filaments 1 concentrated near the yarn core surrounded by a matrix of hydrophobic filaments 2. Similarly to FIG. 1, FIG. 2 illustrates a commingling of hydrophilic and hydrophobic fibers in an intermediate area between the composite yarn's center and its outer surface. Further, the sketch of Fig. 2 illustrates a gradual migration along the longitudinal axis of the composite yarn 3 of hydrophobic fibers 2 from the yarn periphery to the transition zone of principal commingling along and, even, into the central area where hydrophilic fibers 1 are concentrated. Similarly, hydrophilic fibers 1 migrate between the central zone of the composite yarn 3 and the periphery where hydrophobic fibers 2 are concentrated. This physical interchange of fiber positions within the yarn has the effect of accelerating the transport of moisture into the hydrophilic fibers 1 concentrated at the composite yarn center.

[0036] Depending on end use applications, the percentage of hydrophilic fibers needed for optimum mechanical and comfort performance in the moisture management fabric may vary from a low of 8 to 10 percent to a high of 60 to 75 percent by weight. Further, from an economic standpoint, it is desirable to avoid the use of more hydrophilic fibers in the fabric structure than the amount required for optimum moisture management performance, as the hydrophilic fibers cost substantially more than the hydrophobic fibers.

[0037] The hydrophilic fiber content in a moisture management fabric of the invention may be varied by adjusting the ratio of hydrophobic to hydrophilic fibers used in the preparation of the composite yarn of the invention. In practice, however, it frequently is more economical to produce a limited number of standard composite yarns of the invention with fixed hydrophilic fiber contents and, then, to adjust the hydrophilic yarn content in the finished moisture management fabric by plying composite yarns with one or more hydrophobic yarns. Fig. 3 shows an enlarged side view of the composite yarn 3 of the invention with both hydrophilic 1 and hydrophobic 2 fibers plied with a continuous multifilament hydrophobic yarn 4 comprising essentially 100 percent hydrophobic filaments. In like manner, Fig. 4 illustrates a magnified side view of a composite yarn 3 of the invention plied with two continuous multifilament hydrophobic yarns 4 and 5 each comprising essentially 100 percent hydrophobic filaments. The two hydrophobic yarns 4 and 5 may be identical or different, depending on the effect desired in the plied composite yarn and in the moisture management fabric. For example, one hydrophobic yarn could be based on polyester and the other polypropylene. Further, in order to obtain a fabric with a soft hand (i.e., a soft feel) and a high resistance to abrasion, the composite yarn of the invention could be plied with one polyester yarn comprising monofilaments of normal deniers in the range of 1.5 to 3, while the other would comprise micro monofilaments with deniers well below 1.

[0038] The hydrophilic fiber content in a moisture management fabric also can be adjusted by knitting alternate courses of the composite yarn 3 of the invention along with courses of a hydrophobic yarn.

[0039] The sketch of FIG. 5 shows an enlarged plan view representation of a plain knit fabric produced from a single composite yarn 3 of the invention containing both hydrophilic 1 and hydrophobic 2 fibers. Due to the unique structure and properties of the composite yarn of the invention, such a simple fabric structure is effective in absorbing perspiration from the high humidity atmosphere at the skin surface of a wearer and, then, evaporating the absorbed moisture from the inner hydrophilic fibers through the hydrophobic matrix fiber at the opposite fabric side into the lower humidity at ambient conditions. In marked contrast to fabrics based on the prior art, the fabric of the invention will function to transport moisture from the skin of a wearer to the atmosphere equally well, irrespective of which fabric side is in contact with the body. Further, since the outer surfaces of both fabric sides are made up substantially of hydrophobic fabric, garments based on the single composite yarn fabric readily accept screen and transfer printed designs on either or both fabric sides.

[0040] The hydrophobic fibers of most interest for use in the composite yarns of the invention have low moisture regain values. The preferred hydrophobic fibers for a majority of current end uses for moisture management fabrics and garments are derived from either polyester or nylon polymers. Other hydrophobic fibers that can be used in composite yarns of the invention include fibers based on: polypropylene, polyvinylchloride, and polyacrylonitrile polymers. Although hydrophobic fibers based on polyester and, to a lesser extent, nylon polymers are preferred for most moisture management fabrics and garments of current commercial interest, the hydrophobic fiber actually chosen for use in a particular application must be selected on the basis of economics and the needs of the end use application.

[0041] The hydrophilic fibers for use in the composite yarns of the invention must have high moisture regain values. The preferred hydrophilic fibers are based on modified 6- or 66-nylon polymers. A particularly useful modified 6-nylon fiber is supplied under the trade name "Hydrofil". The AlliedSignal Co. was the original developer and supplier of this product; but it, now, is produced and supplied by Universal Fiber Systems, LLC. Other useful products based on a modified nylon product that can be used as the hydrophilic component for the composite yarns of the invention include fibers sold under the trade names of "Quup" and "Hygra". Toray Nylon, Ltd. of Japan produces "Quup" in continuous multifilament form by melt extruding a modified 6-nylon. "Hygra" is also produced and supplied from Japan. It is a structured sheaf/core bicomponent fiber in which the outer surface of the individual continuous filaments is comprised of a hydrophobic 6-nylon, while the core is comprised of a hydrophilic modified 6-nylon. This fiber is produced and supplied by Unitika Fibers, Ltd. Other hydrophilic fibers of lesser interest include: cotton, cellulose acetate staple yarns and filaments, rayon, linen, modified acrylics, and modified polyvinylalcohols.

[0042] As aforementioned, the composite yarns of the invention comprise hydrophilic fibers embedded within a matrix of texturized hydrophobic fibers. Depending on the effect desired in the finished product, the hydrophilic fiber might be in the form of flat continuous filaments, textured continuous filaments, or staple yarn. The hydrophobic matrix component also may be in the form of a flat or textured continuous filament form; but a staple yarn form is only rarely appropriate, as air jets in the air entanglement equipment tend to disrupt a staple fiber yarn.

[0043] Although other approaches are possible, the preferred process for producing composite yarns of the invention is to pass the two fiber types together through an air jet of the type commonly used in air jet texturing equipment. The feed rates must be carefully controlled in order to assure a concentration of hydrophilic fibers toward the center and the hydrophobic fibers toward the periphery of the resulting composite yarn. This objective is accomplished by feeding the hydrophilic fibers under tension, while the hydrophobic fibers are overfed. Air jet yarn texturing machines of use in producing composite yarns of the invention are supplied by a number of textile equipment fabricators. Among these are ICBT in France, Staehle in Germany, and Menegatto in Italy. FIG 6 illustrates typical hydrophobic and hydrophilic fiber pathways in an air-jet texturing machine as supplied, for example, by the aforementioned fabricators.

[0044] In Fig. 6, a positive drive feeds the hydrophilic multifilament continuous yarn 1 at a fixed rate and controlled tension through entry guides 8 into the air-jet cavity 9 of an air-jet texturing device. An overfeed assembly pulls the hydrophobic multifilament yarn 2 over the end of the supply package and feeds it at a higher feed rate than that used for the hydrophilic yarn, through entry guides 8 into the air jet cavity 9. The relative rates by weight at which the hydrophilic and hydrophobic yarns are fed must be adjusted so that the finished composite yarn will contain a minimum of 8 percent by weight but not more than 75 percent by weight of hydrophilic fibers. To an extent, feed adjustments may be made by over-feeding the hydrophobic by up to 60 percent. Further, adjustments can be made by selecting different hydrophilic and hydrophobic yarn deniers (i.e., sizes) to produce the composite yarns. On exiting the air jet cavity 9 the composite yarn passes through a heat setting assembly 10. Finally, a winding assembly 11 takes up the composite yarn onto a bobbin 12.

[0045] As the hydrophilic 1 and hydrophobic 2 yarns pass through the violent, high-velocity air stream maintained in the air jet cavity 9, the hydrophilic filaments substantially maintain their integrity, due to the controlled tension maintained by the feed control assembly 6. The individual monofilaments of the overfed hydrophobic yarn 2 are blown about violently by the air stream in the air jet cavity. As a result, hydrophilic filaments under tension are caused to concentrate at and near the center of the composite yarn that exits the jet cavity, while the hydrophobic filaments are concentrated peripherally.

[0046] When a thermoplastic fiber is texturized in an air jet or other texturing equipment, the fiber is heat set as it exits the texturing zone of the machine. Fig. 6 shows a heat setting cavity 10 just below the air jet cavity 9. Hydrophilic fibers produced from modified nylon polymers, however, may melt if exposed to heat setting temperatures commonly used for polyester based, as well as for some other, hydrophobic fibers. Consequently, it is necessary to minimize the temperatures and dwell times used to heat set the hydrophobic fibers when producing the composite yarns of the invention. For certain combinations of hydrophobic and hydrophilic fibers, it is not possible to properly heat set the hydrophobic component of the composite yarn without damaging the hydrophilic fiber. In such cases, it is possible to produce a good quality composite yarn by, first, texturing and heat setting the hydrophobic component and, then, running the pretexturized hydrophobic and the hydrophilic fibers through the air jet texturing equipment without applying temperature to the heat setting zone. Further, depending on the performance characteristics needed in the composite yarn, it can be preferable to pass both the hydrophilic and hydrophobic yarns through the air-jet texturing machine without heat setting. This is particularly the case, if a very lightweight composite yarn is desired.

Claims

1. A composite textile yarn, comprising both hydrophilic and hydrophobic fibres with the hydrophilic fibers embedded substantially at the yarn center within a matrix of the hydrophobic fibers with the hydrophobic fibers concentrated at the periphery of the yarn, there being a transition area between the center hydrophilic fibers and the peripheral hydrophobic fibers in which both fiber types are present.

2. A composite textile yarn, comprising at least 8 percent but not more than 75 percent by weight of hydrophilic fibers embedded within a matrix of hydrophobic fibers with the hydrophilic fibers positioned substantially at the yarn center and the hydrophobic fibers positioned predominantly at the periphery, there being a transition area between the center hydrophilic fibers and the peripheral hydrophobic fibers in which both fiber types are present.

3. A composite textile yarn according to claim 1 or 2, wherein the hydrophobic fibers comprise flat or textured continuous filament yarn of polyester fibers and the hydrophilic fibers comprise flat or textured continuous filaments of a modified 6-nylon or a spun staple yarn of a modified 6-nylon.

4. A composite textile yarn according to claim 1 or 2, wherein the hydrophobic fibers comprise flat or textured continuous filament yarn of polyester fibers and the hydrophilic fibers comprise flat or textured continuous filament or spun staple yarn of a modified 66-nylon.

5. A plied textile yarn, comprising the composite textile yarn according to any of the preceding claims, and further comprising a hydrophobic yarn of essentially 100 percent hydrophobic fibers plied with the composite yarn.

6. A composite yarn according to claim 1 or 2, produced by feeding a flat or textured continuous filament hydrophilic yarn under tension at a predetermined rate into an air jet texturing device along with a flat or textured continuous filament hydrophobic yarn fed at a rate of at least 10 percent but not more than 50 percent greater than said predetermined rate.

7. A moisture management fabric made from the composite yarn according to any of claims 1 to 4.

8. A two-faced moisture management fabric for wearing apparel, comprising at least one hydrophobic yarn essentially 100 percent hydrophobic fibers, and a composite yarn according to any of claims 1 to 4, the hydrophobic yarn being concentrated in the body contacting face of the fabric, and the composite yarn being concentrated in an outer face of the fabric.

Drawing