Patent Publication Number: US-2020291550-A1

Title: Antimicrobial fiber blends

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/818,009, filed Mar. 13, 2019 and titled “Antimicrobial Fiber Blends,” the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to antimicrobial fiber blends. More particularly, the present embodiments relate to antimicrobial fiber blends, yarns, and textiles including chitosan-based fibers. 
     BACKGROUND 
     Microorganisms, such as bacteria and fungi, can be carried and can grow on textiles. Bacteria growing on a textile can produce an unpleasant odor. Some textiles include fibers treated with an antimicrobial powder or coating to inhibit growth of microorganisms. Such powders and coatings are not integral to the fiber, may wear off easily, and/or may become less effective with time (e.g., due to wear and/or washing). 
     SUMMARY 
     The present disclosure generally relates to antimicrobial fiber blends that include a chitosan-based fiber. Chitosan-based fibers can provide a more environmentally sustainable route to antimicrobial textiles than some metal particles and synthetic antimicrobial agents. For example, chitosan-based fibers can be obtained from renewable natural sources and can be biodegradable, both of which can reduce their environmental impacts as compared to some conventional antimicrobial agents. In addition, yarns, textiles, and articles including the antimicrobial fiber blends disclosed herein can have a more durable antimicrobial property than yarns, textiles, and articles including fibers or textiles including chitosan coatings or powders. 
     For example, the disclosure provides a fiber blend having an antimicrobial property. The antimicrobial property may be an antibacterial property and the antibacterial property may provide resistance to or reduction of a bacterial odor. The fiber blend may comprise a mixture of a chitosan-based fiber in an amount of at least 1% by weight and an organic fiber different from the chitosan-based fiber. In some embodiments, the fiber blend comprises at least 5% by weight of the chitosan-based fiber. The fiber blends described herein can have an antimicrobial property even with relatively small amounts of the chitosan-based fiber, such as less than 10% by weight or even 5% or less by weight. 
     The organic fiber may be a fiber of plant origin or a fiber of animal origin. For example, the organic fiber may be a wool fiber, a cashmere fiber, a silk fiber, a cotton fiber, a linen fiber, a lyocell fiber, a rayon fiber, another type of regenerated cellulose-based fiber, or a combination thereof. In some embodiments, the fiber blend may also include one or more synthetic fibers. 
     In some cases, the fiber blend comprises a chitosan-based fiber, a regenerated cellulose fiber, and a wool fiber. For example, the fiber blend may comprise a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a regenerated cellulose fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. The amount of the regenerated cellulose fiber and the amount of the wool fiber together may make up at least 90% by weight of the fiber blend. The chitosan-based fiber, the regenerated cellulose fiber, and the wool fiber may be intimately blended. In some examples, the regenerated cellulose fiber is a lyocell fiber. 
     The chitosan-based fiber may be dyed. The dyed chitosan-based fiber described herein is typically dyed using a process which substantially preserves the antimicrobial property of the chitosan-based fiber. For example, the process for dyeing the chitosan-based fiber may use neutral or mild alkaline conditions and a dye such as a reactive or a direct dye. The regenerated cellulose fiber may also be dyed and in some cases may be dyed in the same process as the chitosan-based fiber. The chitosan-based fiber and/or the regenerated cellulose fiber may be dyed in the form of loose fibers or in the form of aggregated fibers (e.g., as a roving). 
     The wool fiber may be dyed or may be substantially free from dye. When the wool fiber is dyed, it may be dyed in a process separate from the process for dyeing the chitosan-based fiber in order to preserve the antimicrobial property of the chitosan-based fiber. For example, the process for dyeing the wool fiber may use acidic conditions and an acid dye. The wool fiber may be dyed in the form of loose fibers or in the form of aggregated fibers (e.g., as a roving or top). 
     When the wool fiber is substantially free from dye, it may be undyed and combined with previously dyed fibers. In additional cases the wool fiber may be combined with the chitosan-based fiber and any other fibers of the blend prior to the dyeing process, but the dyeing process conditions may not substantially dye the wool fibers. For example, a roving, a yarn, a textile, or an article including both the wool fiber and chitosan-based fiber may be dyed under dyeing process conditions (e.g., dye composition, pH) which do not substantially dye the wool fiber. 
     The disclosure also provides antimicrobial yarns based on the fiber blends described herein. When the wool fiber is dyed in a separate process from the chitosan-based fiber and the regenerated cellulose fiber, the yarn may comprise a chitosan-based fiber and a regenerated cellulose fiber dyed using a first dye and wool fiber dyed using a second dye different than the first dye. 
     In some cases, the yarn comprises a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a regenerated cellulose fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. The amount of the regenerated cellulose fiber and the amount of the wool fiber together may make up at least 90% by weight of the yarn. The chitosan-based fiber, the regenerated cellulose fiber, and the wool fiber may be intimately blended in the yarn. In some examples, the regenerated cellulose fiber is a lyocell fiber. 
     In addition, the disclosure provides antimicrobial textiles and articles including the antimicrobial textiles. Textiles and articles including the antimicrobial fiber blends can have a number of beneficial properties, including antibacterial, antifungal, and anti-odor properties. For example, the textile may have a bacterial reduction of at least 95%, 97.5%, 99%, 99.5%, or 99.5% as measured with the AATCC 100 or the JIS L 1902 test. 
     In some cases, the textile comprises a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a regenerated cellulose fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. The amount of the regenerated cellulose fiber and the amount of the wool fiber together may make up at least 90% by weight of the fiber blend. The textile may have a knitted or woven structure formed at least in part from an antimicrobial yarn as described herein. In some examples, the regenerated cellulose fiber is a lyocell fiber. 
     A variety of articles can benefit from having an antimicrobial property including clothing, footwear, and accessory articles. The disclosure provides articles including the textiles, yarns, and/or fiber blends described herein. As an example, the clothing article comprises a textile or yarn comprising: a chitosan-based fiber in an amount of at least 1% by weight; and an organic fiber different from the chitosan-based fiber. As an additional example, the clothing article may include a textile comprising a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a regenerated cellulose fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. In some examples, the regenerated cellulose fiber is a lyocell fiber. The articles described herein may have resistance to bacterial odors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like elements. 
         FIG. 1  shows an example antimicrobial yarn. 
         FIG. 2A  shows an example detail view of a section of the yarn of  FIG. 1 . 
         FIG. 2B  shows an additional example detail view of a section of the yarn of  FIG. 1 . 
         FIG. 3  shows an example of a composite antimicrobial yarn, with a portion of the yarn cut away to show a core of the yarn. 
         FIG. 4  shows a further example of a composite antimicrobial yarn. 
         FIG. 5  shows a process for forming an additional example of a composite antimicrobial yarn. 
         FIG. 6  shows an example of a shoe including an antimicrobial textile. 
         FIG. 7  shows an example of a shirt including an antimicrobial textile. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred implementation. To the contrary, the described embodiments are intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the disclosure and as defined by the appended claims. 
     The following disclosure relates to antimicrobial fiber blends that include a chitosan-based fiber as an antimicrobial agent. As previously mentioned, chitosan-based fibers can provide a more environmentally sustainable route to antimicrobial textiles. Since chitosan-based fibers can be produced from the discarded shells of crabs, shrimp, and the like, processes for producing chitosan-based fibers can have a reduced environmental impact as compared to processes for producing conventional antimicrobial agents (such as metal particles). In addition, since chitosan-based fibers can be biodegradable, disposal of textiles including chitosan-based fibers can have a reduced environmental impact as compared to disposal of some conventional antimicrobial textiles. 
     Recent advances have allowed production of antimicrobial chitosan-based fibers having high levels of chitosan and a structure based largely on the structure of chitosan. Such chitosan-based fibers can be more effective against bacteria, fungi, and other microorganisms than existing chitosan-coated fibers or fibers including particles of chitosan in a matrix of another polymer material. However, yarns incorporating chitosan-based fibers can be difficult to make using some conventional yarn spinning techniques. Further, yarns incorporating chitosan-based fibers can be difficult to dye using some conventional processes. 
     In aspects, the disclosure provides fiber blends suitable for making a yarn incorporating a chitosan-based fiber. The fiber blends described herein can have an antimicrobial property even for fiber blends including relatively small amounts of the chitosan-based fiber, such as less than 10% by weight or even 5% or less by weight. The fiber blends described herein may include a high percentage of organic fibers and therefore may have environmental benefits as compared to some largely synthetic fiber blends. In addition, the fiber blends described herein may be substantially free from metal particles and/or synthetic antimicrobial agents. 
     The fiber blends may combine a chitosan-based fiber with another organic fiber, such as a fiber of plant or animal origin. For example, a fiber blend may include a wool fiber and/or a cellulose-based fiber in addition to the chitosan-based fiber. As an additional example, a fiber blend may predominantly include organic fibers, but may also include one or more synthetic fibers to modify the performance of the resulting yarn and textile. In further examples, the fiber blend may predominantly include synthetic fibers. It is to be understood that reference in the present disclosure and claims to a type of fiber in the singular form (e.g., “a chitosan-based fiber”) typically includes reference to one or more fibers of that type (e.g., multiple chitosan-based fibers in a fiber blend). 
     The disclosure also provides antimicrobial yarns including a chitosan-based fiber. In contrast to existing yarns including chitosan-coated fibers, the antimicrobial yarns disclosed herein may have improved durability with respect to wear and washing. The antimicrobial yarns may have linear densities and mechanical properties suitable for use in a variety of textiles. 
     The fiber blends and yarns disclosed herein can be used to form antimicrobial textiles. The antimicrobial properties of textiles including the chitosan-based fiber may be superior to existing textiles to which a chitosan coating is applied as a finishing step. For example, the antimicrobial textiles disclosed herein may have improved durability with respect to washing. The antimicrobial textiles may have a knitted, woven, or non-woven structure. 
     Surprisingly, the yarns and textiles described herein can have an antimicrobial property even when they include relatively small amounts of the chitosan-based fiber, such as less than 10% by weight or even 5% or less by weight of chitosan-based fiber. In some cases, a yarn comprising less than 10% by weight or 5% or less by weight of a chitosan-based fiber, a regenerated cellulose fiber, and a wool fiber provides an antimicrobial property to a textile formed from the yarn. The textile may also be moisture absorbing, moisture wicking, and have a soft handle. An example of a textile having an antimicrobial property comprises a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a regenerated cellulose fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. The amount of the regenerated cellulose fiber and the amount of the wool fiber together may make up at least 90% or 95% by weight of the fiber blend. In some examples, the regenerated cellulose fiber is a lyocell fiber. This textile may also be moisture absorbing, moisture wicking, and have a soft handle. 
     In addition, the chitosan-based fiber in the fiber blends, yarns, and textiles described herein may substantially retain its antimicrobial properties after dyeing of the fiber blends, yarns, or textiles. The inventors have discovered that some dyeing processes (e.g., conventional wool acid dyeing processes) can degrade the antimicrobial properties of the chitosan-based fiber. In order to substantially preserve the antimicrobial properties of a chitosan-based fiber blended with a wool fiber, the wool fiber may be substantially free from dye or may be dyed separately from the chitosan-based fiber. The yarn may be formed from the dyed chitosan-based fiber, the dyed wool fiber, and the other fiber(s) in the blend. Additional description of fiber dyeing processes is provided below. 
     These and other embodiments are discussed below with reference to  FIGS. 1-7 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  schematically shows an example yarn  100 . The yarn  100  is formed from and includes a fiber blend  110 .  FIGS. 2A and 2B  show detail view of fiber blends  210  and  220 , each of which may be an example of the fiber blend  110 . As previously described, the fiber blend  110  may be suitable for making yarn incorporating chitosan-based fibers via a spinning process and the yarn  100  may be a spun yarn. The description of spinning techniques provided with respect to  FIGS. 2A and 2B  is generally applicable herein and, for brevity, is not repeated here. 
     The yarn  100  may comprise one or more plies. For example, multiple plies may be twisted together to obtain a desired yarn thickness, linear density, and/or mechanical property. The yarn  100  may be used to form a textile by a weaving or knitting operation and the yarn properties may be adjusted for the particular weaving or knitting operation. In some embodiments, the yarn has a linear density from 50 dTex to 1000 dTex (100 Tex), from 50 dTex to 200 dTex, from 100 dTex to 500 dTex, or from 250 dTex to 1000 dTex. 
     In embodiments, the yarn  100  has an antimicrobial property due to the presence of the chitosan-based fibers. For example, the yarn  100  may have an antibacterial property, an antifungal property, or a combination of these. As previously described, the antimicrobial property of the yarn  100  may be more durable than that of a conventional yarn including chitosan-coated fibers. 
       FIG. 2A  shows a detail view of the yarn  200 , which is an example of the yarn  100  of  FIG. 1 . The yarn  200  includes a fiber blend  210 . As shown in  FIG. 2A , the fiber blend  210  includes two different types of fibers, which in this example are a chitosan-based fiber  212  and a fiber  214  that is different from the chitosan-based fiber. The chitosan-based fiber  212  and fiber  214  may each be in staple form. For example, the fibers  212  and  214  may have a length from 25 mm to 80 mm. The description of different types of fibers provided with respect to the example of  FIG. 2A  is not limited to this example but is generally applicable to the fiber blends, yarns, and textiles described herein. 
       FIG. 2B  shows a detail view of the yarn  201 , which is an additional example of the yarn  100  of  FIG. 1 . The yarn  201  includes a fiber blend  220 . As shown in  FIG. 2B , the fiber blend  220  includes three different fibers, which in this example are a chitosan-based fiber  222 , a fiber  224  and a fiber  226 . Each of the fibers  224  and  226  is different from each other and is different from the chitosan-based fiber. For example, the fiber  224  may be a regenerated cellulose fiber and the fiber  226  may be a wool fiber. As shown in  FIG. 2B , each of the chitosan-based fiber  222  and the fibers  224  and  226  may be in staple form. 
     In some embodiments, the chitosan-based fiber includes chitosan and/or a chitosan derivative in an amount of at least 50% by weight. As previously discussed, the structure of the chitosan-based fiber may be based largely on the structure of chitosan and/or a chitosan derivative. For example, the chitosan-based fiber may comprise at least 80%, 90%, or 95% by weight of chitosan and/or a chitosan derivative. As used herein, chitosan derivatives include, but are not limited to, chemically modified versions of chitosan and complexes of chitosan with other moieties, such as metal ions. 
     Chitosan is a polysaccharide polymer derived from chitin through a deacetylation process. Assemblies of chitosan polymers can be used to form a regenerated fiber. The molecular weight of the chitosan-based polymers as well as the degree of polymerization and the degree of deacetylation can influence the antimicrobial effect. The chitosan-based fiber typically has a linear density from 1 dTex to 3 dTex, but in additional examples the linear density may be greater than 3 dTex. The staple length of the chitosan-based fiber may be from 25 mm to 80 mm, or from 25 mm to 50 mm. 
     In some embodiments, the chitosan-based fiber may further include an additional polymer. The additional polymer may also be organic. For example, the chitosan-based fiber may include a cellulose-based polymer and/or a chitin polymer. Because cellulose-based polymers and chitin polymers are chemically similar to chitosan polymers, they can be combined with chitosan polymers to provide desired mechanical and/or chemical properties to the fiber. 
     In some cases, the chitosan-based fiber may be treated by a bleaching, dyeing, and/or finishing process. These processes may use neutral or mild alkaline conditions to substantially preserve the antimicrobial properties of the chitosan-based fiber. For example, these processes may use a pH of 7 to 11, greater than 7 to 11, from 7.5 to 11, from 8.5 to 11, from 7.5 to 9.5, from 7 to 8, or from greater than 7 to 8. Extended exposure of the chitosan-based fiber to acidic conditions (e.g., a pH of 6.5 or less) can lead to degradation of the fiber and reduction of its antibacterial properties. 
     The chitosan-based fiber may be dyed or substantially free of dye (e.g., undyed). The chitosan-based fiber may be dyed using a dye suitable for use at neutral or mildly alkaline pH levels, such as a direct or reactive dye. A chitosan-based fiber may be dyed with multiple dyeing agents, each of which is derived from a dye molecule and includes a chromophore (an atom or chemical group which imparts color). Each of the dyeing agents also has an affinity for (alternately, is substantive to) the chitosan-based fiber. For example, a dyeing agent derived from a reactive dye molecule may be covalently bonded to the chitosan-based fiber. As another example, a dyeing agent derived from a direct dye molecule may be substantive to the chitosan-based fiber through hydrogen bonding and/or Van der Waals intermolecular forces. 
     As referred to herein, a “dyeing agent” is a molecular entity which is derived from a dye molecule and which is substantive to a textile fiber. The type of dye can determine the way in which the dyeing agent is substantive to the textile fiber. For example, reactive dyes include one or more reactive groups which can produce covalently bonded dyeing agents. In contrast, acid dyes can produce ionically bonded dyeing agents. In some cases, different dyeing agents can be distinguished using analytical techniques such as UV-visible microspectrophotometry, Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, mass spectrometry, thin-layer chromatography, high-performance liquid chromatography, and capillary electrophoresis. For example, these analytical techniques may be used to distinguish between different chromophores, to identify functional groups present in the dyeing agent, and/or to identify the chemical nature of the dyeing agent on the textile fiber. 
     Typically, the fiber blend comprises an effective amount of chitosan-based fiber. As examples, the effective amount of the chitosan-based fiber may be from 1% to 15%, 1% to 10%, 1% to less than 10%, 1% to 5%, 1% to less than 5%, 2% to 10%, 2% to less than 10%, 2% to 5%, 2% to less than 5%, 2.5% to 7.5%, or 5% to 15% by weight of the fiber blend. Furthermore, the amount of the chitosan-based fiber may be from 1% to 15%, 1% to 10%, 1% to less than 10%, 1% to 5%, 1% to less than 5%, 2% to 10%, 2% to less than 10%, 2% to 5%, 2% to less than 5%, 2.5% to 7.5%, or 5% to 15% by weight of a yarn and/or textile produced from the fiber blend. 
     The fiber blend may comprise one or more additional organic fibers. The organic fibers may be of animal origin, such as from sheep, goats, silkworms, and the like. Fibers of animal origin include, but are not limited to, wool, cashmere, and silk fibers. The organic fibers may also be of plant origin, such as from trees (e.g., eucalyptus, beech), bamboo, cotton plants, and the like. Fibers of plant origin include, but are not limited to, cellulose-based fibers (also referred to as cellulosic fibers) such as cotton and linen and regenerated cellulose fibers. Regenerated cellulose fibers include, but are not limited to, rayon, viscose, and lyocell fibers. 
     For example, the fiber blend may include a wool fiber, such as a merino wool fiber. Fine wool fibers, such as fibers having a mean or an average diameter less than 24 microns, less than 20 microns or even less than or equal to 17.5 microns, may be used to provide a soft “handle” to the resulting textile. For example, a test method established by the International Wool Testing Organization (IWTO) or the American Society for Testing and Materials (ASTM) may be used to determine the average diameter. IWTO standards include IWTO-8-2011, IWTO-12-2012, and IWTO-47-2013. ASTM standards include D3991, D6466, and D6500. In some embodiments the wool fiber may be treated to provide an additional antimicrobial property to the fiber blend. 
     The wool fiber may be dyed or substantially free of dye (e.g., undyed). In some cases, the wool fiber is dyed under acid conditions (e.g., a pH less than 7) using a dye suitable for use at these pH levels, such as an acid dye. Therefore, the wool fiber may be dyed using a different dye than the dye used for the chitosan-based fiber and in a different dyeing process. The dye used for the wool fiber may have a different chromophore, a different functional group (e.g., a functional group that leads to affinity of the dyeing agent with the textile fiber), or both. A dyed wool fiber comprises multiple dyeing agents each of which includes a chromophore and has an affinity for (alternately, is substantive to) the wool fiber. A dyeing agent derived from an acid dye molecule may be ionically bonded to the wool fiber. 
     As an additional example, the fiber blend may include a regenerated cellulose fiber such as a lyocell fiber. Lyocell fibers are regenerated cellulose fibers produced using the lyocell process. The lyocell process allows the use of a non-toxic solvent to dissolve the source material (e.g., wood) and the solvent can be recycled at high efficiency. The lyocell process can also produce fibers of higher strength than some other processes for making regenerated cellulose fibers. In some embodiments, the lyocell fibers have a linear density from 1 dTex to 3 dTex. A standard method test method, such as an ASTM test method or an ISO test method (e.g., ISO 1973:1995), may be used to determine the linear density of the fibers and the yarns described herein. 
     The regenerated cellulose fiber may be dyed or substantially free of dye (e.g., undyed). In some cases, a lyocell fiber is dyed under neutral or mildly alkaline conditions using a dye suitable for use at these pH levels, such as a direct or a reactive dye. A dyed regenerated cellulose fiber comprises multiple dyeing agents each of which includes a chromophore. Each of the dyeing agents has an affinity for (alternately, is substantive to) the lyocell fiber and may be derived from a direct or a reactive dye. The lyocell fiber may be dyed together with the chitosan-based fiber using the same dye(s) and process conditions. In some cases, the regenerated cellulose fiber may uptake the reactive dye to a greater extent than the chitosan-based fiber, so that a density of the dyeing agents substantive to the regenerated cellulose fiber is greater than a density of the dyeing agents substantive to the chitosan-based fiber. 
     In some embodiments, the fiber blend may predominantly include organic fibers. The amount of the chitosan-based fiber and the amount of the other organic fiber(s) together may make up greater than 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even up to 100% by weight of the fiber blend or yarn. As an example, the amount of the chitosan-based fiber and the amount of the wool fiber together make up greater than 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even up to 100% by weight of the fiber blend or yarn. As another example, the amount of the chitosan-based fiber and the amount of a regenerated cellulose fiber together make up greater than 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even up to 100% by weight of the fiber blend or yarn. In some examples, the regenerated cellulose fiber is a lyocell fiber. The amount of the chitosan fiber may be as previously described. 
     As a further example, the amount of the chitosan-based fiber, the amount of the wool fiber, and the amount of the regenerated cellulose fiber together make up greater than 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even up to 100% by weight of the fiber blend or yarn. The amount of the wool fiber in the fiber blend or yarn may be from 10% to 90%, 40% to 80%, 40% to 60%, or 50% to 70% by weight of the total amount of wool fiber and regenerated cellulose fiber. In some cases, the amount of the wool fiber in the fiber blend may be from 25% to 45%, 25% to 40%, or 30 to 40%. The amount of the regenerated cellulose fiber in the fiber blend may be from 50% to 70%, 55% to 70%, or 60% to 70%. In some examples, the regenerated cellulose fiber is a lyocell fiber. The amount of the chitosan fiber may be as previously described. 
     In some cases, the fiber blend comprises a chitosan-based fiber, a lyocell fiber, and a wool fiber. For example, the fiber blend may comprise a chitosan-based fiber in an amount of at least 1% and less than 10% by weight, a lyocell fiber in an amount from 50% to 70% by weight, and a wool fiber in an amount of from 25% to 45% by weight. The amount of the lyocell fiber and the amount of the wool fiber together may make up at least 90% by weight of the fiber blend. 
     In some cases, the fiber blend includes a dyed chitosan-based fiber, a dyed lyocell fiber, and a dyed wool fiber. As previously mentioned, the wool fiber may be dyed during a different dyeing process than the chitosan-based fiber in order to better preserve the anti-microbial activity of the chitosan-based fiber. The chitosan-based fiber and/or the lyocell fiber may be dyed in the form of loose fibers or in the form of aggregated fibers. Similarly, the wool fiber may be dyed in the form of loose fibers or in the form of aggregated fibers. A yarn may be formed from the blend of the dyed chitosan-based fiber, the dyed lyocell fiber, and the dyed wool fiber. 
     Methods used in the art to determine antimicrobial activity of fiber or yarn specimens include American Society for Testing and Materials (ASTM) standard E3151: 2018 and turbidity measurements. Alternately, the chitosan-based fiber can be assessed prior to and following dyeing using analytical techniques to detect the chemical groups in the chitosan-based fiber which contribute to anti-microbial activity. 
     As previously discussed, the fiber blend may also include a synthetic fiber in combination with the chitosan-based fiber and the other organic fiber. For example, the synthetic fiber may include one or more of nylon, polyester, acrylic, and the like. The synthetic fiber may be in staple form. The amount of the synthetic fiber may be less than or equal to 50%, less than or equal to 40%, less than or equal to 30%, less than or equal to 20%, less than or equal to 10%, or less than or equal to 5% by weight of the weight of the fiber blend or yarn. 
     Further, in some embodiments the fiber blend may predominantly include one or more synthetic fibers in combination with the chitosan-based fiber. For example, the synthetic fiber may include one or more of nylon, polyester, acrylic, and the like. The amount of the chitosan-based fiber and the amount of the synthetic fiber(s) together may make up greater than 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or even up to 100% by weight of the fiber blend or yarn. 
     As schematically shown in  FIG. 2A , the fibers  212  and  214  of the fiber blend  210  are intimately mixed. In addition, at least some of the fibers  212  and  214  of the fiber blend  210  are interlocked, such as through a spinning process to form the yarn  200 . Similarly, the fibers  222 ,  224 , and  226  of the fiber blend  220  of  FIG. 2B  may be intimately mixed and interlocked. The fibers may be blended together to form a roving and then the yarn made by spinning the roving. Techniques such as ring-spinning, rotor spinning, friction spinning, and air jet spinning, vortex spinning, parallel spinning, siro spinning and the like may be used to form the yarn. 
       FIG. 3  shows another example of a yarn  300  having a core  320  at least partly surrounded by a sheath  340 . A portion of the sheath  340  is cut away to better show the core  320 . As shown in  FIG. 3 , the sheath  340  comprises a fiber blend  310 . In some embodiments, the yarn has a linear density from 50 dTex to 1000 dTex (100 Tex), from 50 dTex to 200 dTex, from 100 dTex to 500 dTex, or from 250 dTex to 1000 dTex. 
     The core  320  may comprise one or more fibers in filament form. In some embodiments, the filament fibers of the core  320  may have a linear density greater than that of the staple fibers in the sheath  340 . As examples, the filament fibers may have a linear density from 1 dTex to 10 dTex, from 5 dTex to 25 dTex, from 10 dTex to 30 dTex, or 10 dTex to 50 dTex. 
     For example, the core may comprise one or more synthetic elastomer fibers, such as spandex or elastane filament fibers. The elastomer fiber may be a polyurethane elastomer (e.g., a segmented polyurethane elastomer), a cross-linked polyacrylate, or a combination of a polyurethane elastomer with another polymer, such as nylon. In some cases, the spandex fiber may be a bio-based spandex or a post-industrial recycled spandex. The amount of the elastomer filament may be from 1% to less than 10% by weight, from 1% to 8% by weight, or from 2% to 7% by weight. 
     As an additional example, the core may comprise a regenerated cellulose filament, such as a lyocell filament. The regenerated cellulose filament may have a linear density from 5 dTex to 25 dTex, from 10 dTex to 30 dTex, or from 10 dTex to 50 dTex. The regenerated cellulose filament may have a linear density greater than that of one or more staple fibers present in the fiber blend, such as any regenerated cellulose fibers in the fiber blend. 
     Typically, the fiber blend  310  of the sheath  340  comprises a mixture of fibers in staple form. As previously described with respect to the fiber blend  210  of  FIG. 2A  and the fiber blend  220  of  FIG. 2B , the fibers of the fiber blend  310  may be intimately mixed and interlocked. The sheath may be formed around the core using a core spinning technique, such as a ring spinning technique, a rotor spinning technique, a friction spinning technique, an air jet technique, a vortex technique, and the like. 
     The fibers of the core  320  may provide at least 2% and up to 5%, 10%, or 15% of the yarn. The fiber blend  310  may make up the remainder of the yarn or the fibers of the core and the fiber blend  310  together may form 95% or 90% by weight of the yarn. For example, the amount of the chitosan-based fiber in the fiber blend  310  may be from 1% to 15%, 1% to 10%, 2% to 10%, or 5% to 15% by weight of the yarn and the amount of any additional fibers in the fiber blend  310  may form the balance of the yarn. By the way of example, a yarn may include elastane in the core and include chitosan-based fibers in combination with cotton, nylon, and/or polyester in the sheath. The yarn may include approximately 5% elastane and approximately 95% of the combination of chitosan-based fibers with cotton, nylon, and/or polyester. More generally, the fibers of fiber blend  310  may be any of those previously described for the fiber blend  210  or the fiber blend  220 . 
       FIG. 4  shows an example of a yarn  400  including multiple filament fibers  418  wrapped around a core  420  formed from a fiber blend  410 . The yarn  400  may also be described as having a wrapped structure in which the multiple filament fibers  418  and the fiber blend  410  alternate at the surface of the yarn. As schematically illustrated in  FIG. 4 , the fiber blend may comprise a fiber  412  and a fiber  416 . The fiber  412  may be a chitosan-based fiber and the fiber  416  may be a fiber other than the chitosan-based fiber, such as a wool fiber. In some cases, a filament fiber  418  may be a cellulose-based filament fiber, such as a lyocell filament fiber, or a synthetic fiber, such as nylon or polyester. The regenerated cellulose filament may have a linear density from 5 dTex to 25 dTex, from 10 dTex to 30 dTex, or from 10 dTex to 50 dTex. The regenerated cellulose filament may have a linear density greater than that of one or more staple fibers present in the fiber blend, such as any regenerated cellulose fibers in the fiber blend. In some cases, the amount of the filament fiber  418  is from 2% to 5%, from 2% to 10%, from 2% to 15%, or from 5% to 20% by weight of the yarn. In addition, the fiber blend  410  may form the balance of the yarn or the filament fiber  418  and the fiber blend  410  together may form 95% or 90% by weight of the yarn composition. The example of  FIG. 4  is not limiting and the fiber blend  410  may be any of the fiber blends described herein, including those described with respect to  FIGS. 2A and 2B . For brevity, that description is not repeated here. 
       FIG. 5  schematically illustrates a process for making another yarn  500  including multiple filament fibers  518  combined with a fiber blend  510 . As shown in  FIG. 5 , strands of the filament fiber  518  and the fiber blend  510  are twisted to form a filament strand  519  and a fiber blend strand  511 . The filament strand  519  and the fiber blend strand  511  are then combined to form a reinforced strand  520 . Two of the reinforced strands  520  are twisted together to form the yarn  500 . The dotted line  550  schematically illustrates the nip line. The process illustrated in  FIG. 5  may be referred to as a siro-fil or embeddable and locatable spinning process. The fiber blend  510  may include a chitosan-based fiber and a fiber other than the chitosan-based fiber, such as a wool fiber. Each of the filament fibers  518  may be a cellulose-based filament fiber, such as a lyocell filament fiber, or a synthetic fiber, such as nylon or polyester, or combinations thereof. The regenerated cellulose filament may have a linear density from 5 dTex to 25 dTex, from 10 dTex to 30 dTex, or from 10 dTex to 50 dTex. The regenerated cellulose filament may have a linear density greater than that of one or more staple fibers present in the fiber blend, such as any regenerated cellulose fibers in the fiber blend. In some cases, the amount of the filament fiber  518  is from 2% to 5%, from 2% to 10%, from 2% to 15%, or from 5% to 20% by weight of the yarn. In addition, the fiber blend  510  may form the balance of the yarn or the filament fiber  518  and the fiber blend  510  together may form 95% or 90% by weight of the yarn composition. This example is not limiting and the fiber blend  510  may be any of the fiber blends described herein, including those described with respect to  FIGS. 2A and 2B . For brevity, that description is not repeated here. 
     Some embodiments take the form of antimicrobial textiles formed from the antimicrobial fiber blends and antimicrobial yarns described herein. These chitosan-based textiles include a chitosan-based fiber as described herein. An antimicrobial textile may have a woven or knitted structure formed at least in part from an antimicrobial yarn as described herein. An antimicrobial textile may also have a nonwoven structure, such as felted textile, formed from an antimicrobial fiber blend as described herein. The composition of the antimicrobial yarn or textile may be substantially the same as a fiber blend composition previously described and, for brevity, that description is not repeated here. 
     Knitted or woven antimicrobial textiles may be formed by weaving or knitting antimicrobial yarns, alone or in combination with other yarns. In some embodiments, the woven or knitted antimicrobial textiles may further include one or more yarns including or formed from a synthetic fiber. For example, a knitted antimicrobial textile may include a synthetic elastomer yarn to provide stretch. 
     The antimicrobial or antibacterial activity of the textiles provided herein may be assessed using standard test methods. For example, standard test methods are available from the American Association of Textile Chemists (e.g., AATCC 100), the Japanese Industrial Standards (e.g., JIS L 1902), the International Standards Organization (e.g., ISO 20743), and ASTM (e.g., ASTM E2149). Several of these test methods measure microbial concentrations at “time zero” and after a specified contact time. The difference between results for test and control fabrics are used as the basis for determining antimicrobial activity level (e.g., % reduction in growth for a particular microorganism and/or microorganism killing ability). Common test microorganisms include, but are not limited to,  Staphylococcus aureus  and  Klebsiella pneumoniae . In some cases, a textile provided herein containing at least 1% and less than 10% by weight of a chitosan-based fiber has at least a 99.9%, 99.5%, 99.0%, 98%, 97%, 96%, 95%, 90%, or 85% reduction in microbial growth. For example, a textile containing at least 1% and less than 10% by weight of a chitosan-based fiber, 50% to 70% by weight of a lyocell fiber, and 25% to 45% by weight of a wool fiber, has at least a 99.9%, 99.5%, 99.0%, 98%, 97%, 96%, 95%, 90%, or 85% reduction in microbial growth. 
     In addition to their antimicrobial properties, the textiles described herein may provide other benefits. For example, the textiles may provide a desirable “feel” or “handle” to a user. In embodiments, the textiles may provide a soft tactile sensation that is due at least in part to the fibers included in the blend. The textiles may also be moisture absorbing and/or moisture wicking. 
     The yarn or textile may be dyed or undyed. When the yarn or textile is dyed, all of the fibers in the yarn or textile may be dyed or some of the fibers may be less than fully dyed. In some cases, the dye may be absorbed by some of the fibers but not fully absorbed by the chitosan-based fibers, which may have clear or at least partly translucent appearance. The resulting yarn or textile may be at least partly translucent. In other cases, the chitosan-based fibers may be dyed as described above. 
     The disclosure also provides articles including antimicrobial textiles. For example, an antimicrobial textile may be included in a clothing article. A clothing article may be a garment such as a shirt, a pair of pants, a sweatshirt, a jacket, socks, and the like. A clothing article may also be an undergarment such as a pair of underwear or a bra. Clothing articles such as garments or undergarments may be suitable for use as activewear or sportswear. The antimicrobial textile may also be included in a footwear article, such as a shoe. 
     The antimicrobial textiles disclosed herein may also be included in other types of articles. For example, an antimicrobial textile may be included in an accessory article, such as a tote bag, handbag, or drawstring bag. Further, an antimicrobial textile may be included in a household good, such as a sheet, a bath towel, a dish towel, a tablecloth, an upholstered furniture article, and the like. 
     The articles described herein may be textile articles comprising the antibacterial textile. For example, a textile article may be a garment or undergarment. Further, an article may include a material in addition to the antibacterial textile. For example, the article may be a shoe comprising the antimicrobial textile as well as a molded polymer sole. The antimicrobial property may be provided over a portion or the whole of the article. 
       FIG. 6  shows an example of a shoe  600  including an antimicrobial textile  660  in the upper  610  of the shoe. As shown in  FIG. 6 , the shoe  600  also includes a sole  620 , a tongue  630 , eyelets  640 , a lace  650 , and a liner  670 . Alternately or in addition to including an antimicrobial textile  660  in the upper  610  of the shoe, an antimicrobial textile may be included in another portion of shoe  600 , such as the tongue  630 , or an insole. 
     In some embodiments, an upper  610  of the shoe  600  may be knit, woven, or otherwise form a chitosan-based textile, as may the tongue  630 . The upper  610  and/or tongue  630  textile may be chitosan-based either in whole or in part. The chitosan-based textile may reduce odor, prevent microorganisms from growing in or on the shoe, and otherwise provide benefits as described herein. The chitosan-based textile of the shoe  600  generally includes chitosan-based fibers in its structure rather than fibers coated, dusted, powdered, sprayed, or otherwise deposited with chitosan. Insofar as the chitosan-based fiber is an integral part of the yarn forming the textile, the chitosan textile of the upper  610  and/or the tongue  630  may maintain its antimicrobial and/or anti-odor properties over an extended period of time as compared to an upper or tongue incorporating fibers on which chitosan has been deposited. 
     In some embodiments, a liner  670  of the shoe may be may be knit, woven, or otherwise formed from a chitosan-based textile. In some embodiments, a chitosan-based textile may line an interior portion of the shoe while another textile may form an exterior portion of the shoe. The chitosan-based textile of the liner  670  may reduce odor, prevent microorganisms from growing in or on the shoe, and otherwise provide benefits as described herein while the other textile forming the exterior portion of the shoe may provide wear resistance. 
     In some embodiments, an insole of the shoe may be knit, woven, or otherwise formed from a chitosan-based textile. The insole of the shoe can be a removable insole, and therefore easily replaceable. The chitosan-based textile included in the insole may be oriented to face the foot of a wearer. 
     In some embodiments, the concentration of the chitosan-based fiber within an article may vary in order to provide a greater antimicrobial effect in certain regions or zones of the article. For example, an article may define a first region having a first percentage of the chitosan-based fiber and a second region having a second percentage of the chitosan-based fiber.  FIG. 7  shows an example of a shirt  700  which has different amounts of chitosan-based fiber in different regions of the shirt. As shown in  FIG. 7 , the shirt  700  comprises different regions  701 ,  702 ,  703 , and  704 . 
     Chitosan-based fiber may be allocated to each of the regions  701  through  704  in different concentrations. For example, region  703 , which is located in an underarm area of the shirt  700 , may include a higher amount or percentage of chitosan-based fiber than region  701 , which includes the front of the shirt  700 . Similarly, the region  702  and/or the region  704  may include a lesser amount or percentage of chitosan-based fiber than the region  703 , but a different amount or percentage of chitosan-based fiber than the region  701 . Some of the regions may be free of chitosan-based fiber. In additional examples, the article may include a lesser or a greater number of regions than shown in  FIG. 7 . As an additional example the chitosan-based fiber may be distributed substantially uniformly over the article. 
     In some embodiments, a region of the article having a lesser amount or percentage of the chitosan-based fiber may include a higher amount or percentage of other fibers to provide properties such as moisture wicking and/or durability. For example, while the region  703  of the shirt  700  includes a relatively high percentage of chitosan-based fiber, another region, such as the region  704 , may be configured to provide a greater amount of moisture wicking than the region  703 . 
     A knitting process may use yarns with different chitosan-based fiber concentrations to form the shirt  700 . A yarn with a higher chitosan-based fiber concentration may be used to provide a greater amount or percentage of chitosan-based fiber in a particular region of the shirt  700 , such as the region  703 . Similarly, a yarn with a lesser chitosan-based fiber concentration or even a yarn free of chitosan-based fiber may be used to form another region of the shirt  700 . In addition, one or more additional yarns may be included in a particular region of the shirt to further tailor the properties of the region. 
     As used herein, the term “substantially” is used to account for relatively small variations, such as a variation of +/−10%, +/−5%, +/−2%, or +/−1%. For example, the term “substantially retain(s)” or “substantially preserve(s)” may indicate a decrease of 10% or less, 5% or less, 2% or less, or 1% or less from a reference value. The term “substantially free” may indicate an amount of 10% or less, 5% or less, 2% or less, or 1% or less of the element specified. In addition, the singular forms “a,” “an,” and “the” include the plural form unless the context dictates otherwise. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.