Patent Publication Number: US-6910288-B2

Title: Footwear incorporating a textile with fusible filaments and fibers

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to footwear. The invention concerns, more particularly, footwear wherein a textile incorporated into the footwear includes filaments and fibers formed of a fusible material. 
     2. Description of Background Art 
     Conventional articles of footwear generally include an upper and a sole structure attached to the upper. The materials selected for the upper vary significantly between different styles of footwear, but generally include a textile material. Athletic footwear, for example, often includes an upper having textiles that are stitched or adhesively bonded to a thermoset foam layer. Similarly, hiking boots and work boots often include a durable outer shell formed of leather and an inner lining formed of a textile joined with foam materials. 
     A textile may be defined as any manufacture from fibers, filaments, or yarns characterized by flexibility, fineness, and a high ratio of length to thickness. Textiles generally fall into two categories. The first category includes textiles produced directly from webs of filaments or fibers by randomly interlocking to construct non-woven fabrics and felts. The second category includes textiles formed through a mechanical manipulation of yarn, thereby producing a woven fabric, for example. 
     Yarn is the raw material utilized to form textiles in the second category. In general, yarn is defined as an assembly having a substantial length and relatively small cross-section that is formed of at least one filament or a plurality of fibers. Fibers have a relatively short length and require spinning or twisting processes to produce a yarn of suitable length for use in textiles. Common examples of fibers are cotton and wool. Filaments, however, have an indefinite length and may merely be combined with other filaments to produce a yarn suitable for use in textiles. Modem filaments include a plurality of synthetic materials such as rayon, nylon, polyester, and polyacrylic, with silk being the primary, naturally-occurring exception. Yam may be formed of a single filament, which is conventionally referred to as a monofilament yarn, or a plurality of individual filaments grouped together. Yam may also include separate filaments formed of different materials, or the yarn may include filaments that are each formed of two or more different materials. Similar concepts also apply to yarns formed from fibers. Accordingly, yarns may have a variety of configurations that generally conform to the definition provided above. 
     The various techniques for mechanically manipulating yarn into a textile include interweaving, intertwining and twisting, and interlooping. Interweaving is the intersection of two yarns that cross and interweave at right angles to each other. The yarns utilized in interweaving are conventionally referred to as warp and weft. Intertwining and twisting encompasses procedures such as braiding and knotting where yarns intertwine with each other to form a textile. Interlooping involves the formation of a plurality of columns of intermeshed loops, with knitting being the most common method of interlooping. 
     The textiles utilized in footwear uppers generally provide a lightweight, air-permeable structure that is flexible and comfortably receives the foot. In order to impart other properties to the footwear, including durability and stretch-resistance, additional materials are commonly combined with the textile, including leather, synthetic leather, or rubber, for example. With regard to durability, U.S. Pat. No. 4,447,967 to Zaino discloses an upper formed of a textile material that has a polymer material injected into specific zones to reinforce the zones against abrasion or other forms of wear. Regarding stretch resistance, U.S. Pat. Nos. 4,813,158 to Brown and 4,756,098 to Boggia both disclose a substantially inextensible material that is secured to the upper, thereby limiting the degree of stretch in specific portions of the upper. 
     From the perspective of manufacturing, utilizing multiple materials to impart different properties to an article of footwear is an inefficient practice. For example, the various materials utilized in a conventional upper are not generally obtained from a single supplier. Accordingly, a manufacturing facility must coordinate the receipt of specific quantities of materials with multiple suppliers that may have distinct business practices or may be located in different countries. The various materials may also require additional machinery or assembly line techniques to cut or otherwise prepare the material. In addition, incorporating separate materials into an upper may involve a plurality of distinct manufacturing steps requiring multiple individuals. 
     Employing multiple materials, in addition to textiles, may also detract from the breathability of footwear. Leather, synthetic leather, or rubber, for example, are not generally permeable to air. Accordingly, positioning leather, synthetic leather, or rubber on the exterior of the upper may inhibit air flow through the upper, thereby increasing the amount of perspiration, water vapor, and heat trapped within the upper and around the foot. 
     SUMMARY OF THE INVENTION 
     The present invention is an article of footwear having a sole structure and an upper secured to the sole structure. The upper includes a textile that is at least partially formed from a plurality of first strands and a plurality of second strands, which may be filaments, fibers, or yarns that incorporate filaments or fibers, for example. The first strands are formed of a thermoplastic polymer material, and the textile includes a fused area wherein the first strands are fused to the second strands. The fused area may have increased stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness, for example, when compared to areas of the textile that are unfused. 
     The textile may be a non-woven material that includes the strands, or the textile may be formed from a mechanically manipulated yarn that includes the strands. Accordingly, a wide range of textiles are suitable for forming the upper. The strands may also be formed to have various configurations. For example, the first strands may be monocomponent strands that only include the thermoplastic polymer material. The first strands may also be bicomponent strands that include two or more thermoplastic polymer materials, perhaps in a core-sheath relationship. With regard to bicomponent strands, the two or more thermoplastic polymer materials may be selected to have different melting temperatures, for example. 
     The invention also embraces a method of manufacturing the upper that includes the steps of providing a plurality of strands, at least a first portion of the strands including at least one thermoplastic polymer material; incorporating the strands into a textile that forms a portion of the upper; and forming a fused area of the textile by fusing at least the first portion of the strands to a second portion of the strands. This method may be applied to uppers that are formed to have the general structure of a conventional upper that incorporates fusible strands, or may be applied to knit uppers that incorporate fusible strands. 
     The advantages and features of novelty characterizing the present invention are pointed out with particularity in the appended claims. To gain an improved understanding of the advantages and features of novelty, however, reference may be made to the following descriptive matter and accompanying drawings that describe and illustrate various embodiments and concepts related to the invention. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing Summary of the Invention, as well as the following Detailed Description of the Invention, will be better understood when read in conjunction with the accompanying drawings. 
         FIG. 1  is a perspective view of an article of footwear incorporating a textile with fusible strands in accordance with the present invention. 
         FIG. 2A  is a perspective view of a monocomponent strand. 
         FIG. 2B  is a perspective view of a bicomponent strand. 
         FIG. 3A  is a plan view of a portion of the textile, which is formed to have a non-woven structure. 
         FIG. 3B  is a plan view of a portion of the textile, which is formed through an interweaving process. 
         FIG. 3C  is a plan view of a portion of the textile, which is formed through an intertwining and twisting process. 
         FIG. 3D  is a plan view of a portion of the textile, which is formed through an interlooping process. 
         FIG. 4A  is a perspective view of a yarn formed of monocomponent strands. 
         FIG. 4B  is a perspective view of a yarn formed of bicomponent strands. 
         FIG. 4C  is a perspective view of a yarn formed of monocomponent strands and bicomponent strands. 
         FIG. 4D  is a perspective view of a yarn formed of monocomponent strands and neutral strands. 
         FIG. 5  is a perspective view of another article of footwear incorporating a textile with fusible strands in accordance with the present invention. 
         FIG. 6A  is a first perspective view of yet another article of footwear incorporating a textile with fusible strands in accordance with the present invention. 
         FIG. 6B  is a second perspective view of the article of footwear depicted in FIG.  6 A. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following discussion and accompanying figures disclose articles of footwear formed of a textile that includes fusible filaments or fibers. For purposes of the present discussion, filaments and fibers may be referred to individually or collectively as strands. In general, the fusible strands may be fused to other strands, whether fusible or non-fusible, in selected areas of the footwear to increase stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness, for example. Advantageously, these benefits may be achieved without significantly inhibiting the air-permeability of the textile or increasing the weight of the footwear. 
     An article of footwear  100  is disclosed in FIG.  1  and includes a textile with fusible strands. Footwear  100  is depicted as an article of athletic footwear, particularly a running shoe. The concepts disclosed with respect to footwear  100  may, however, be applied to a variety of footwear styles, including other types of athletic footwear, dress shoes, boots, and sandals, for example. The present invention, therefore, is not limited to a specific type of footwear that incorporates the textile of the present invention, but applies generally to a wide range of footwear styles. 
     The primary elements of footwear  100 , as depicted in  FIG. 1 , are a sole structure  110  and an upper  120 . Sole structure  110  generally extends between the foot and the ground, whereas upper  120  is configured to receive the foot and comfortably secure the position of the foot relative to sole structure  110 . 
     Sole structure  110  has a conventional configuration that includes an insole (not depicted), a midsole  111 , and an outsole  112 . The insole is a relatively thin, cushioning member located within upper  120  and adjacent to the foot for enhancing the comfort of footwear  100 . Midsole  111  is attached to a lower portion of upper  120  and is formed of a cushioning foam material, such as ethylvinylacetate or polyurethane. Accordingly, midsole  111  attenuates ground reaction forces and absorbs energy associated with running or walking. To enhance the force attenuation and energy absorption characteristics of sole structure  110 , midsole  111  may incorporate a fluid-filled bladder, as disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy. Alternately, midsole  111  may incorporate a plurality of columnar support elements, as disclosed in U.S. Pat. Nos. 5,353,523 and 5,343,639 to Kilgore et al. Outsole  112 , which may be formed from carbon black rubber compound, is attached to a lower surface of midsole  111  to provide a durable, wear-resistant surface for engaging the ground. In addition, outsole  112  may incorporate a textured lower surface to enhance the traction characteristics of footwear  100 . 
     Sole structure  110  is described above as having the elements of a conventional sole structure for a running shoe. Other types of athletic footwear, including basketball shoes, tennis shoes, soccer shoes, and cross-training shoes, for example, will generally have a sole structure with a similar configuration. Dress shoes, boots, and sandals, however, may have other types of conventional sole structures specifically tailored for use with the respective types of footwear. Accordingly, the particular configuration of sole structure  110  may vary significantly within the scope of the present invention to include a wide range of configurations. 
     Upper  120  forms a void within footwear  100  for receiving the foot. Access to the void is provided by an ankle opening  121 , located primarily in a heel region of footwear  100 . The volume of the void within upper  120  may be adjusted by a lacing system extending across the top of upper  120  and through a midfoot region and a forefoot region of footwear  100  (i.e., the lacing system extends along the instep area of footwear  100 ). The lacing system includes a lace  122  that is threaded through a plurality of apertures  123  and across a space formed between a medial edge  124   a  and lateral edge  124   b  formed in upper  120 . In general, lace  122  may be utilized to modify the size of the space between medial and lateral edges  124 , as is well known in the art, thereby adjusting the volume of the void within upper  120 . A tongue  125  is positioned below medial edge  124   a  and lateral edge  124   b  to enhance the comfort of the area around the lacing system. 
     A textile  130  is positioned on an exterior of upper  120 , and additional materials such as foam and other textiles may be positioned within upper  120 . The general structure of upper  120  is similar, therefore, to the structure of a conventional upper for an article of athletic footwear. In contrast with the conventional upper, however, textile  120  includes unfused areas  131  and fused areas  132 - 136 . In general, textile  130  is manufactured from yarn that is produced from a plurality of strands. At least a portion of the strands are formed from a thermoplastic material, and the application of heat to specific areas of textile  130 , which later become fused areas  132 - 136 , causes the thermoplastic strands to melt. Following the melting of individual thermoplastic strands, molten material either surrounds unmolten strands or intermingles with molten material from other thermoplastic strands. The temperature is then reduced and the molten material solidifies, thereby forming fused areas  132 - 136 . 
     Based upon the above discussion, textile  130  may generally have a plurality of unfused areas  131  and a plurality of fused areas  132 - 136 . Unfused areas  131  have an appearance of conventional textiles, and the properties of unfused areas  131  may be similar to the properties of conventional textiles. In comparison with unfused areas  131 , fused areas  132 - 136  generally have greater stiffness and stretch-resistance, enhanced abrasion-resistance, and increased durability. In addition, fused areas  132 - 136  may provide support and stability to specific areas of footwear  100 . Accordingly, a footwear manufacturer may select specific portions of upper  120  that would benefit from the inherent textile qualities of unfused areas  131  and the fused qualities of the plurality of fused areas  132 - 136 . 
     In determining the areas of an upper that should remain unfused, or become fused, one skilled in the art may determine the qualities that the material forming a specific portion of the upper should possess. In some areas of an upper, the stretch of an unfused textile would provide greater benefits than the abrasion-resistance of a fused textile. In other portions, however, the durability of a fused textile would provide greater benefits than the flexibility of an unfused textile. Accordingly, each area of an upper may be examined to determine whether fusing would enhance the quality, performance, or comfort, for example, of the footwear. 
     Fused areas  132 - 136  of footwear  100  will now be examined to demonstrate one suitable configuration of fused and unfused areas. Depending upon the intended use for the footwear and the desired aesthetics of the footwear, other articles of footwear may include fused and unfused areas that are located in other portions of an upper. With respect to footwear  100 , however, fused area  132  circumscribes ankle opening  121  and provides stretch-resistance in the area of ankle opening  121 . As the individual walks or runs, the ankle presses against ankle opening  121 , thereby tending to stretch the portion of footwear  100  that forms ankle opening  121 . Fused area  141  is located, therefore, to prevent significant enlargement of ankle opening  121 . 
     Fused area  133  extends around the heel portion of upper  120  and effectively surrounds a heel of the wearer. Fused area  133  is similar to a heel counter that is often utilized in athletic footwear to limit movement of the heel, thereby providing stability and support in the heel area of footwear  100 . Textile  130  may be fused in the heel area, therefore, to provide the benefits of a heel counter without the necessity of incorporating additional components into footwear  100 . 
     Fused area  134  is generally elongate strips that extend horizontally or longitudinally along the lateral side of upper  120 . Fused area  134  limits horizontal stretch on the lateral side of footwear  100 , therefore, but permits lateral stretch of unfused areas  131  in the vertical direction. A similar fused area may be located on the medial side of footwear  100  to limit vertical stretch on the medial side. As the individual walks or runs, the foot may press against upper  120 , thereby tending to stretch upper  120  longitudinally. Accordingly, fused area  134  is located to prevent the stretch, thereby limiting movement of the foot relative to footwear  100 . As an alternative, fused area  134  may cover a greater area of the lateral side, or may extend vertically or diagonally, for example. 
     Fused area  135  is positioned in a toe region of upper  120  and provides a high degree of abrasion-resistance and durability to the toe region. In general, the toe regions of footwear often contact abrasive surfaces, such as rocks, concrete, or trees, that may wear away or otherwise degrade the strength of the upper. By fusing the various strands in fused area  135 , however, the abrasion-resistance and durability of this portion of upper  120  may be enhanced. 
     Fused area  136  extends along medial edge  124   a  and lateral edge  124   b  and provides two primary benefits to the lacing system. As discussed above, the lacing system includes lace  122  that is threaded through apertures  123  and across a space formed between medial edge  124   a  and lateral edge  124   b . In general, lace  122  may be utilized to modify the size of the space between medial edge  124   a  and lateral edge  124   b , thereby adjusting the volume of the void within upper  120 . In adjusting laces  122 , the individual generally pulls on ends of laces  122 , thereby inducing tension in laces  122  and drawing medial edge  124   a  and lateral edge  124   b  toward each other. Fused area  136  increases the stiffness of medial edge  124   a  and lateral edge  124   b , thereby ensuring that medial edge  124   a  and lateral edge  124   b  are uniformly drawn toward each other. A further benefit of fused area  136  relates to the construction of apertures  123 . In conventional articles of footwear, the lacing apertures include grommets to limit unraveling of the textile that forms the aperture. In footwear  100 , however, the grommets are not necessary to prevent unraveling due to the fused nature of textile  130 . 
     Fused areas  132 - 136  are intended to provide examples of the manner in which portions of textile  130  may be fused in order to impart differing characteristics to footwear  100 . As discussed, fused areas  132 - 136  have the potential to provide greater stiffness, stretch-resistance, abrasion-resistance, and durability, and fused areas  132 - 136  may provide enhanced support and stability. Accordingly, one skilled in the relevant art may select specific areas of a textile to fuse in order to impart various properties to the areas, regardless of the type of footwear or the intended use of the footwear. 
     The stretch-resistance imparted by fused areas  132  and  134 , the stability and support provided by fused area  133 , the abrasion-resistance and durability of fused area  135 , and the stiffness of fused area  136  may be imparted to upper  120  through an alternate procedure, namely the provision of additional elements. For example, leather elements may be secured around ankle opening  121  to increase stretch-resistance, a polymer heel counter may be incorporated into the heel area to provide stability, and rubber elements may be adhered to the surface of upper  120  in the toe region to provide abrasion-resistance. Although the additional elements may impart the required properties to upper  120 , the additional elements would also increase the expense of manufacturing upper  120  and add weight to upper  120 . In contrast, fused areas  132 - 136  beneficially-utilize the preexisting textile  130  to impart the desired properties without utilizing additional elements or increasing the weight of footwear  100 . Furthermore, the additional elements are generally formed of materials that are not air-permeable, thereby limiting the overall air-permeability of the footwear. Fused areas  132 - 136  retain a substantial portion of the air-permeability of unfused areas  131 . 
     Textile  130  may be formed through a variety of conventional textile manufacturing techniques, including randomly interlocking strands to construct a non-woven fabric. Textile  130  may also be formed by mechanically manipulating yarn through interweaving, intertwining and twisting, or interlooping. In either scenario, textile  130  includes a plurality of fusible strands formed of a thermoplastic polymer material, such as polyurethane, nylon, polyester, and polyolefin. In addition, the fusible strands may be any of the strands that are incorporated into the thermo-fusible yarns produced by Luxilon Industries N.V. of Wijnegum, Belgium under the THERMOLUX trademark. Such strands are available in a variety of melting temperatures, including 60, 90, 105, 108, 130, and 150 degrees Celsius. Other suitable fusible strands are available from EMS-Griltech, a division of EMS-Chemie AG of Ems, Switzerland, and marketed under the trademarks of GRILON, which is a polyamide and copolyamide bicomponent fiber, GRILAMID, which is a polyamide fiber, and GRILENE, which is a copolyester fiber. 
     The fusible strands may have a variety of configurations within the scope of the present invention.  FIG. 2A  depicts a monocomponent strand  141  formed of a single thermoplastic polymer material  142 . The act of raising the temperature of strand  141  above a melting temperature of material  142  causes strand  141  to become molten and permits strand  141  to fuse with other strands. In contrast,  FIG. 2B  depicts a bicomponent strand  143  formed of two thermoplastic polymer materials  144  and  145  arranged in a core-sheath relationship. That is, material  144  forms a central portion of strand  143  and material  145  surrounds the central portion. Materials  144  and  145  may be selected to such that material  144  has a higher melting temperature than material  145 . Raising the temperature of strand  143  to a point above the melting temperature of material  145 , but below the melting temperature of material  144 , will cause melting in only material  145 . This may be desirable, for example, when only a relatively small degree of fusing between the various strands is required. Further raising the temperature of strand  143  above the melting temperature of material  144  will cause melting in both materials  144  and  145 . This may be desirable when a greater degree of fusing is required. Accordingly, strands having various combinations of thermoplastic polymer materials may be utilized within the scope of the present invention. 
     Monocomponent strand  141  is formed of a single material  142  with substantially similar properties throughout. In contrast, bicomponent strand  143  is formed of two thermoplastic polymer materials  144  and  145  arranged in a core-sheath relationship. Materials  144  and  145  may both be polyester, for example, with different melting temperatures. Alternately, material  144  may be nylon and material  145  may be polyurethane, for example. Accordingly, bicomponent strand  143  is formed to have materials with different properties. In addition to the core-sheath relationship in bicomponent strand  143 , materials  144  and  145  may be arranged in a side-by-side configuration, or any other configuration wherein different distinct areas of strand  143  includes materials  144  and  145 . 
     As discussed above, textile  130  may be formed through a variety of conventional textile manufacturing techniques. With reference to  FIG. 3A , a non-woven textile  130   a  formed of randomly interlocked monocomponent strands  141  and bicomponent strands  143  are depicted. By selecting material  142  of strands  141  to have a melting temperature that is different than both materials  144  and  145  of strands  143  provides further variation in the manner in which temperatures affect the degree of fusing that occurs. In further embodiments, however, textile  130   a  may be formed of only monocomponent strands, or only bicomponent strands, for example. Similarly, a non-woven textile may be formed of monocomponent strands, bicomponent strands, or a combination of monocomponent and bicomponent strands. 
     A variety of textiles  130   b - 130   d  that are formed by mechanically manipulating a yarn  146  are depicted in  FIGS. 3B-3D . In contrast with textile  130   a , which is formed of randomly interlocked strands, the various strands of textiles  130   b - 130   d  are organized into yarn  146 . Textile  130   b  is depicted in FIG.  3 B and is formed through the interweaving manufacturing process. Textile  130   c  is depicted in FIG.  3 C and is formed through the intertwining and twisting manufacturing process. Similarly, textile  130   d  is depicted in FIG.  3 D and is formed through the interlooping manufacturing process. The various configurations of textiles  130   b - 130   d  are intended to provide an example of the many techniques that may be utilized to mechanically manipulate yarn  146  into a textile. Other techniques for mechanically manipulate yarn  146  into a textile, or variations upon the general techniques discussed above, are also intended to fall within the scope of the invention. 
     The yarn that is suitable for use in textiles  130   b - 130   d  may have a variety of configurations within the scope of the present invention. As discussed below, various yarns  151 ,  153 ,  155 , and  156  are formed of various strands  152 ,  154 , and  157 .  FIG. 4A  depicts a yarn  151  that is formed of only monocomponent strands  152 , and  FIG. 4B  depicts a yarn  153  formed of bicomponent strands  154 . If a greater range of fusibility is desired, textiles  130   b - 130   d  may incorporate a yarn  155  having both monocomponent strands  152  and bicomponent strands  154 , as depicted in FIG.  4 C. In some circumstances, however, a yarn may be utilized that incorporates strands that are not fusible, hereafter referred to as neutral strands. The neutral strands may be formed of non-melting materials, such as a thermoset polymer, cotton, or wool, for example. Accordingly, textiles  130   b - 130   d  may also include a yarn  146  that includes monocomponent strands  152  and neutral strands  157 , as depicted in FIG.  4 D. Each of yarns  151 ,  153 ,  155 , and  156  are suitable for use in textiles  130   b - 130   d . In further embodiments, textiles  130   b - 130   d  may include combinations of yarns  151 ,  153 ,  155 , and  156 , or a portion of the strands utilized in yarns  151 ,  153 ,  155 , and  156  may be formed solely of neutral strands. 
     Based upon the preceding discussion, textiles  130   b - 130   d  may incorporate various types of yarn  146 , which may be similar in composition to yarns  151 ,  153 ,  155 , and  156 , for example. In addition, a portion of the yarns  146  that form textiles  130   b - 130   d  may be formed entirely of neutral strands. Accordingly, the textile configurations falling within the scope of the present invention may include varying types and proportions of fusible strands and neutral strands. 
     Footwear  100  is depicted as having a configuration that is similar to the configuration of conventional articles of athletic footwear. In contrast, however, footwear  100  includes a textile  130  that incorporates fusible materials, and footwear  100  includes various areas where the fusible materials are fused to impart properties that include stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness, for example. An article of footwear  200  that is formed to have a non-conventional, textile upper is depicted in FIG.  5 . 
     Footwear  200  includes a sole structure  210  and an upper  220 . Sole structure  210  may be similar in configuration to upper  110  of footwear  100 . Upper  220 , however, is primarily a textile that is formed of mechanically manipulated yarn. A conventional circular knitting machine, for example, may be utilized to manufacture upper  220 . In general, circular knitting machines form a tube-like structure from a plurality of yarns. Upper  220 , therefore, also has a tube-like structure with openings at opposite ends of the tube. An ankle opening  221  forms a first opening for extending around the ankle and providing access to the interior of upper  220 , and an aperture (not depicted) in the lower surface of upper  220  forms a second opening. The aperture is analogous to the seam that extends over the toes in a conventional sock that is also manufactured on a circular knitting machine. 
     Upper  220  is formed of a textile  230 , which has a knitted structure that is similar to textile  130   d , as disclosed in  FIG. 3D  above. Accordingly, textile  230  includes yarns with fusible strands. Following the manufacture of upper  220  on a circular knitting machine, for example, specific areas of upper  220  may be fused to modify the properties of upper  220 . Upper  220  will include, therefore, a plurality of unfused areas  231  and a plurality of fused areas  232 - 235 . Various procedures for forming fused areas  232 - 235  will be discussed in greater detail below. 
     Textile  230  may be formed to include yarns with fusible strands that extend throughout textile  230  or only through the portions of textile  230  that are fused to form fused areas  232 - 235 . When the yarns with fusible strands extend throughout textile  230 , only select areas are heated to form fused areas  232 - 235 . When the yarns with fusible strands are located only in the portions of textile  230  that are fused to form fused areas  232 - 235 , however, then the entirety of textile  230  may be heated to form fused areas  232 - 235 . 
     Fused areas  232  extend vertically around ankle opening  221  and may be utilized to limit vertical stretch in the area of ankle opening  221 , while permitting horizontal stretch. The amount of stretch in ankle opening  221  may be modified by increasing or decreasing the degree of fusing that occurs between the various strands. Fused area  233  is located around the heel portion of upper  220  and may be utilized to stabilizes the heel. Fused areas  234  extend horizontally along the longitudinal length of the medial and lateral sides of upper  220  to limit longitudinal stretch, while permitting stretch in the girth of upper  220 . Finally, fused area  235  may be located in the toe region of upper  220  to increase the abrasion-resistance and durability of footwear  100 . 
     The preceding discussion disclosed articles of footwear  100  and  200 , which are formed of textiles that include fusible strands. In order to increase stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness, for example, the fusible strands may be bonded to other strands in selected areas of footwear  100  and  200 . Advantageously, these benefits may be achieved without significantly inhibiting the air-permeability of the textile or increasing the weight of the footwear. 
     Footwear  100  and footwear  200  may be manufactured through a variety of procedures. With regard to footwear  100  specifically, textile  130  may be manufactured on any of a variety of conventional textile manufacturing machines. Fusible strands may be incorporated into textile  130  by replacing one or more of the conventional neutral strands that characterize many conventional textiles. Following the manufacture of textile  130  in bulk form, three general procedures for forming fused areas  132 - 136  may be utilized. In the first procedure, fused areas  132 - 136  are formed with a hot die, steam, hot air, or radio frequency heating, for example, in specific portions of a relatively large section of textile  130 . Individual elements of textile  130  may then be cut from the relatively large section and incorporated into upper  120 . In the second procedure, the individual elements of textile  130  are cut and fused areas  132 - 136  are formed prior to incorporating the individual elements into upper  120 . In the third procedure, the individual elements of textile  130  are cut and incorporated into upper  120 , and fused areas  132 - 136  are subsequently formed. With regard to the third procedure, a last may be inserted into upper  120  to provide support and fused areas  132 - 136  may be formed with a hot die, for example, that contacts the exterior of upper  120 . Accordingly, the manner in which individual strands are melted to form fused areas  132 - 136  may vary significantly within the scope of the present invention. 
     With regard to footwear  200 , textile  230  may be formed with a circular knitting machine to have the structure generally described above. An example of a suitable, commercially available circular knitting machine that may be utilized to form textile  230  is sold by Sangiocomo S.p.A. of Italy under the X-MACHINE trademark. The X-MACHINE has been used to produce argyle-style socks where multiple colored yarns form argyle and other complex patterns. In manufacturing textile  230 , for example, the X-MACHINE may be selected to have a 4 inch cylinder with 160 needles. Through proper programming of such a circular knitting machine, textile  230  may be formed to have a variety of configurations. For example, textile  230  may have fusible strands that are located throughout upper  220 . That is, the fusible strands may be distributed in a substantially uniform manner in almost all portions of upper  220 . In this configuration, select areas may be heated to form fused areas  232 - 235 . A last may be placed within upper  220  to provide support when the various areas are being fused. Alternately the circular knitting machine may be programmed to place fusible strands in only selected areas of upper  220 . That is, the fusible strands may be located only in the areas of upper  220  that are intended to form fused areas  232 - 235 . In this configuration, all of upper  220  may be heated uniformly, but only the areas having fusible strands will form fused areas  232 - 235 . Following the manufacture of textile  230  using the circular knitting machine, textile  230  may be placed within a dying bath to impart color. The dying bath may be heated to a temperature that exceeds the melting temperature of the fusible strands. When the fusible strands are located only in select areas, the use of a heated dying bath may be an effective an efficient and effective manner of forming fused areas  232 - 235 . Alternately, textile  230  may be immersed in hot steam or air, for example, to form fused areas  232 - 235 . 
     Footwear  100  and footwear  200  are disclosed above as having discrete fused and unfused areas. More particularly, footwear  100  has unfused areas  131  and separate fused areas  132 - 136 . Similarly, footwear  200  includes unfused areas  231  and fused areas  232 - 234 . In both embodiments, the fused areas are in specific portions of footwear  100  and footwear  200  in order to impart specific properties to the fused areas. As discussed above, specific fused areas may be achieved through two different general methods of manufacture. According to a first method, a yarn with fusible strands may be incorporated into all of the upper and only select areas may be heated to achieve fusing of the fusible strands. According to a second method, a yarn with fusible strands may be incorporated into selected areas of the upper and the entire upper may be heated so as to achieve fusing in only the selected areas, which then become fused areas. 
     Another article of footwear  300  is disclosed in  FIGS. 6A and 6B  and is formed of a knit structure with a circular knitting machine similar to the X-MACHINE described above. Footwear  300  includes a sole structure  310  and an upper  320 . An ankle opening  321  forms an opening in upper  320  that provides the foot with access to the interior of upper  320 . An instep portion of upper  320  includes a tongue  322  that extends under a longitudinal opening  323 . A plurality of eyelets  324  are positioned adjacent to longitudinal opening  323  to form apertures for receiving laces. Accordingly, upper  320  is a knit structure with a general configuration that is similar to a conventional upper. In contrast with conventional uppers, however, a substantial portion of upper  320  incorporates a yarn with fusible strands, as detailed below. 
     Substantially all of the textile that forms upper  320  includes a yarn with fusible strands. More particularly, the portions of upper  320  that are depicted as having a ribbed configuration, which is a majority of upper  320 , include a yarn with fusible strands. The remaining portions, which include tongue  322  and the area surrounding ankle opening  321 , are knit so as to include yarns without fusible strands. In further embodiments, however, tongue  322  and the area surrounding ankle opening  321  may incorporate a yarn with fusible strands. Although selected areas of upper  320  may be heated to form fused areas, as with footwear  100  and  200 , all of upper  320  is heated such that all of the ribbed area becomes effectively fused. In configurations wherein the various areas of upper  320  are separated by adjacent courses, rather than wales, a tuck stitch may be utilized to join the areas in a seamless manner. 
     In addition to the configurations discussed above, the portion of upper  320  that includes the yarn with fusible strands may be more limited. For example, the toe area and the heel area, although having a ribbed structure, may be formed of a yarn that does not include fusible strands in order to limit the position of the fused area to the medial side, the lateral side, and lower portions of upper  320 . In each of the embodiments related to upper  320 , however, a relatively large area of upper  320  includes a yarn with fusible strands, and the entirety of the area is fused in order to impart such characteristics as increased stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness. 
     As discussed with respect to footwear  100  and  200 , the fused areas impart desirable properties to an upper, which include increased stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness, for example, without significantly inhibiting the air-permeability of the textile or increasing the weight of the footwear. In contrast with footwear  100  and footwear  200 , wherein specific areas of the uppers are fused, substantially all of upper  320  is fused in order to take advantage of these desirable characteristics. Accordingly, it is not necessary to fuse specific, defined areas of an upper within the scope of the present invention. Instead, substantially all of the upper may be fused to impart the enhanced properties of the fused areas to a greater portion of the upper. 
     A variety of techniques may be utilized to melt the fusible strands within upper  320 . For example, upper  320  may be immersed in a dye bath that is at a greater temperature than the melting temperature of the fusible strands. Steam may also be utilized to uniformly heat upper  320 . Depending upon the materials utilized in upper  320 , microwave or other radio frequency heating techniques may also be utilized. Once upper  320  is cooled, sole structure may be secured to the lower surface with an adhesive, for example. 
     Whereas specific portions of the uppers associated with footwear  100  and  200  were fused, a majority of upper  320  is fused. The degree of heating that occurs during the manufacture of upper  320  determines the degree of fusing that occurs between adjacent fusible strands. In certain portions of upper  320  additional heat may be applied to induce greater fusing. For example, eyelets  324  may experience significant stresses when the laces are tied, and additional fusing around eyelets  324  may serve as reinforcement. Similarly, a greater degree of fusing around a heel portion of upper  320  may be utilized to provide greater stability in the heel portion. Accordingly, different degrees of fusing may be utilized in upper  320 , or in the uppers associated with footwear  100  and  200 , in order to impart varying degrees of stretch-resistance, stability, support, abrasion-resistance, durability, and stiffness. 
     The present invention is disclosed above and in the accompanying drawings with reference to a variety of embodiments. The purpose served by the disclosure, however, is to provide an example of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims.