JP7597810B2 - Footwear articles including circular knit structures - Google Patents

Description

FIELD OF THE DISCLOSURE The present disclosure relates to footwear articles that include circular knit constructions and methods of making such footwear articles.
Background Art

A conventional footwear article has a sole and an upper attached to the sole. Footwear manufacturing has historically been a labor-intensive cut-sew-assemble operation. Panels of upper material are cut to size and sewn together to create the upper. The sole is attached to the upper using several different techniques to create the finished footwear article. Recent developments in footwear design have used knitting techniques to form parts of the footwear, particularly the upper. In some cases, flat knitting is used to form a flat knit fabric blank. The flat knit fabric blank is formed into a specific shape so that it can be folded or wrapped into the nearly finished shoe upper. Once the upper is formed, a sole component or other durable structure is attached to the knit shoe upper, consistent with conventional footwear manufacturing techniques. While some sewing is required to create a shoe upper using flat knitting, fewer sewing steps are required compared to conventional shoe manufacturing. Although flat knitting can increase material utilization, there are design limitations and production inefficiencies inherent in flat knitting, as cutting of fabric is minimized.

One embodiment of the present disclosure is a footwear article, a knit blank, and a method for manufacturing the footwear article and the knit blank. The footwear article includes a dual-layer knit upper having a midsole, an upper portion continuous with the midsole, an ankle opening, and an inner void for receiving a wearer's foot. The dual-layer knit upper has an outer knit layer that defines an outer surface of the dual-layer knit upper. The dual-layer knit upper also has an inner knit layer monolithically knitted to the outer knit layer. The inner knit layer has a plurality of inner knit regions that spatially correspond to the plurality of outer knit regions of the outer knit layer. The outer knit layer and the inner knit layer substantially define the midsole and the upper portion of the dual-layer knit upper.

FIG. 1 is a side view of an article of footwear according to one embodiment of the disclosure. 2 is an exploded view of the article of footwear shown in FIG. 1. 3 is a cross-sectional view of the article of footwear taken along line 3-3 of FIG. 1. FIG. 4 is a side view of a knit blank used to form components of the article of footwear shown in FIGS. 1-3. FIG. 3 is a side view of the interior of a knit blank used to form a component of the article of footwear shown in FIGS. 1 and 2, showing a portion of the knit blank that has been removed to create the ankle portion of the article of footwear. FIG. 5 is a side view of a dual layer knitted footwear component formed from the knit blank shown in FIG. 1 illustrates an article of footwear according to one embodiment of the present disclosure. 1 illustrates an article of footwear including a wing system according to one embodiment of the disclosure. 1 illustrates an article of footwear including a collar according to one embodiment of the disclosure. 1 illustrates an article of footwear including a number of features according to one embodiment of the present disclosure. 1 illustrates an article of footwear including a number of features according to one embodiment of the present disclosure. 1 illustrates an article of footwear including a wing system according to one embodiment of the disclosure. 1 illustrates an article of footwear including a wing system according to one embodiment of the disclosure. 1 illustrates an exemplary article of footwear including a functional layer according to one embodiment of the disclosure.

Embodiments of the present disclosure include an article of footwear that includes a circular knit fabric formed into a dual layer knit upper of the article of footwear 10. The article of footwear 10 is disclosed as having a configuration suitable for walking or running. The concepts related to footwear may also be applied to various other types of athletic footwear, such as, for example, baseball shoes, basketball shoes, cross training shoes, cycling shoes, football shoes, tennis shoes, soccer shoes, sprint shoes, hiking boots, etc. The concepts may also be applied to types of footwear that are generally considered non-athletic, such as dress shoes, loafers, sandals, work boots, etc. The concepts disclosed in this application apply to a wide variety of footwear.

1-3, the footwear article 10 includes a sole component 20 and an upper knitted component 30. For reference, the footwear article 10 can be divided into three general regions: a forefoot region 11, a midfoot region 12 behind the forefoot region, and a heel region 13. The forefoot region 11 generally includes the portion of the footwear article 10 corresponding to the toes and the joints connecting the metatarsals to the phalanges. The midfoot region 12 generally includes the portion of the footwear article 10 corresponding to the arch region of the foot. The heel region 13 generally corresponds to the rear of the foot. The footwear article 10 also includes a medial side 14 and a lateral side 15, which extend through each of the regions 11-13 and correspond to opposite sides of the footwear article 10. The lateral side 15 corresponds to the lateral side of the foot, i.e., the surface facing away from the other foot, and the medial side 14 corresponds to the medial side of the foot, i.e., the surface facing toward the other foot. Regions 11-13 and sides 14-15 are intended to represent the general regions of footwear article 10. In addition to footwear article 10, regions 11-13 and sides 14-15 may also apply to sole component 20 and/or upper knitted component 30.

With continued reference to Figures 1-3, the sole component 20 is secured to the upper knitted component 30 and extends between the foot and the ground when the article of footwear 10 is worn. The sole component 20 may include a midsole, an outsole, and a liner (not shown). The midsole is secured to the upper knitted component 30 as further described below. The midsole may be formed from a compressible polymeric foam element, such as polyurethane or ethyl vinyl acetate foam, which attenuates ground reaction forces and provides cushioning when compressed between the foot and the ground during walking, running, or other ambulatory activities. The outsole is secured to a lower surface of the midsole and may be formed from a wear-resistant rubber material that is textured to provide traction. The structure and features of the sole component 20 or any sole component utilized with the upper knitted component 30 may vary considerably.

The footwear article 10 includes a plurality of tabs 22a-22d extending upwardly from the sole component 20 along the medial side 14 and lateral side 15 of the footwear article 10. The plurality of tabs 22a-22d include fastening members 24a-24d in the form of openings, slots, and/or hooks that receive the cord 18.

With continued reference to Figures 1-3, the upper knitted component 30 forms an interior void 31 within the article of footwear 10 for receiving and securing the foot relative to the sole component 20. The void 31 is shaped to accommodate the foot and extends along the lateral side of the foot, along the medial side of the foot, over the foot, around the heel, and under the foot. Access to the void is provided by an ankle opening 32 located at least in the heel region 13. The cord 18, as described above, extends through portions of the upper knitted component 30, allowing the wearer to alter the dimensions of the upper knitted component 30 to fit the proportions of the foot. The cord 18 allows the wearer to tighten the upper knitted component 30 around the foot, and the cord 18 allows the wearer to loosen the upper knitted component 30 to facilitate the movement of the foot in and out of the void 31 through the ankle opening 32.

With continued reference to Figures 1-3, the upper knitted component 30 is a double layer knitted upper having a substantially monolithic circular knitted fabric structure. The double layer knitted upper has a midsole 41, a toe portion 42, a midfoot portion 44 (sometimes referred to as upper portion 44) that is continuous with the toe portion 42, a heel portion 46 that is adjacent and continuous with the midfoot portion 44, and an ankle portion 48 that defines the ankle opening 32. The midsole 41 extends from the toe portion 42 along the midfoot portion 44 to the heel portion 46. The sole component 20 is attached to the midsole 41. In an alternative embodiment, a liner (not shown) is disposed within the double layer knitted upper along the midsole 41. The toe portion 42, midfoot portion 44, heel portion 46, ankle portion 48, and midsole 41 generally refer to regions of the upper knitted component 30.

2 and 3, the double layer knit upper has an outer knit layer 60 and an inner knit layer 80. The outer knit layer 60 and the inner knit layer 80 together form the toe portion 42, the midfoot portion 44, the heel portion 46, and the ankle portion 48 of the double layer knit upper. However, the outer knit layer 60 defines the outer surface 50 of the double layer knit upper, and the inner knit layer defines the inner surface 52 of the double layer knit upper. Thus, it can be said that the outer knit layer 60 forms the outward facing surfaces (not numbered) of the toe portion 42, the midfoot portion 44, the heel portion 46, and the ankle portion 48. Conversely, the inner knit layer 80 defines the inward facing surfaces (not numbered) of the toe portion 42, the midfoot portion 44, the heel portion 46, and the ankle portion 48. Furthermore, both the outer knit layer 60 and the inner knit layer 80 substantially define the midsole 41 of the double layer knit upper. The outer knit layer 60 and the inner knit layer 80 may define an edge 51 along the ankle opening 32. An optional binding 54 may be positioned along the edge 51 of the ankle opening 32.

The dual layer knit upper includes at least one attachment member that integrates the outer knit layer 60 with the inner knit layer 80, thereby forming the dual layer knit upper. The attachment member can be any material that fuses the outer knit layer 60 and the inner knit layer 80 together. Because the outer and inner knit layers are of circular knit construction, each layer has float yarns on the sides due to the different knit structures formed in the knit regions described below. When the dual layer knit upper is formed, the floats from the outer knit layer 60 face the floats from the inner knit layer 80. If the floats are pulled or the layers are deformed for another reason, the floats can create snags and distort the knit structure. The attachment member addresses this problem by integrating the outer knit layer with the inner knit layer. In particular, the attachment member bonds the yarns from the outer knit layer 60 to the yarns from the inner knit layer 80. This adhesion minimizes distortion of the knit structure created during use. The attachment member bonds the outer and inner knit layers to prevent the two layers from sliding relative to each other. The attachment members provide stability to the dual layer knit upper. In one example, the attachment members may include a bonding yarn. The bonding yarn may comprise part of the knit stitch and may be woven or incorporated into the weave. When the bonding yarn is exposed to a desired temperature (above the glass transition temperature), the bonding yarn melts, thereby integrating the outer and inner knit layers 60, 80. The bonding yarn may be a thermoplastic polyurethane yarn. In another example, the bonding yarn is a low melting point thermoplastic yarn having a lower melting temperature than the yarns used to form the outer and inner knit layers 60, 80. In an alternative embodiment, the attachment members may be a low melting point adhesive film, a low melting point adhesive nonwoven web, or an adhesive coating. In yet another alternative embodiment, the attachment members may be a bonding yarn that adheres the outer and inner layers together.

The outer knit layer 60 has a plurality of outer knit regions 62a-62f, and the inner knit layer 80 has a plurality of inner knit regions 82a-82g. The outer and inner knit regions include selected textile structural elements. The selected textile structural elements may include the presence of a particular knit stitch and/or a particular yarn. Additionally, the selected textile structural elements may include the absence of a particular knit stitch and/or yarn. One or more of the outer knit regions 62a-62f of the outer knit layer 60 may spatially correspond to one or more of the inner knit regions 82a-82g. In embodiments in which the inner knit regions spatially correspond to the outer knit regions, the inner knit regions are fully or partially under the outer knit regions. For example, each of the inner knit regions 82a-82e is under a respective outer knit region 62a-62d. However, the outer knit layer 60 and the inner knit layer 80 may include different knit regions in different locations than the others.

2 illustrates a number of lateral knit regions 62a-62f. As illustrated, the number of lateral knit regions includes a first lateral knit region 62a along the toe portion 42 and a portion of the insole 41. The first lateral knit region 62a may be referred to as a forward toe knit region. The second lateral knit region 62b extends across the top of the toe portion 42. The second lateral knit region 62b may be referred to as an upper toe knit region. The third lateral knit region 62c extends across the top of the midfoot portion 44 and rearward of the toe portion 42. The third lateral knit region 62c may be referred to as an upper midsole knit region. The fourth lateral knit region 62d extends across the heel portion 46. The fourth region 62d may be referred to as a lateral heel region. The fifth lateral knit region 62e forms the remaining region of the lateral knit layer. The sixth lateral knit region 62f is disposed along the ankle portion 48 above the lateral heel portion 46. Each lateral knit region 62a-62f may have different textile construction elements with respect to knit construction and/or yarns. Alternatively, each lateral knit region 62a-62f may have a similar knit construction with respect to knit construction and/or yarns. In one example, the upper midsole knit region 62c may include a bonding yarn. The bonding yarn may be, for example, a thermoplastic polyurethane yarn. The bonding yarn may facilitate integrating the lateral and medial knit layers 60, 80.

As best shown in Figures 2 and 4, the medial knit layer 80 includes a plurality of medial knit regions 82a-82g including selected textile structural elements. Regions 82a-82g are not shown in Figure 2, but are shown in Figure 4 as part of the knit blank 130. As shown, the plurality of medial knit regions includes a first medial knit region 82a along the toe portion and a portion of the midsole. The first medial knit region 82a may be referred to as a forward toe knit region. The second medial knit region 82b extends across the top of the toe portion. The second medial knit region 82b may be referred to as an upper toe knit region. The third medial knit region 82c extends across the top of the midsole portion and rearward of the toe portion. The third medial knit region 82c may be referred to as an upper midsole knit region. The fourth medial knit region 82d extends across the heel portion. The fourth region 82d is referred to as the medial heel region. The fifth medial knit region 82e forms the remaining region of the medial knit layer 80. The sixth medial knit region 82g extends across the bottom of the midsole portion and rearward of the toe portion. The sixth medial knit region 82g may be referred to as the lower midsole knit region 82g. The seventh medial knit region 82f is disposed along the ankle portion. Each medial knit region 82a-82g may have different textile construction elements in terms of knit construction and/or yarns. Alternatively, each medial knit region 82a-82g may have a similar knit construction in terms of knit construction and/or yarns. In one example, the upper midsole knit region 82c and/or the lower midsole knit region 82g may include a bonding yarn. The bonding yarn may be a thermoplastic polyurethane yarn, as described above. The bonding yarn may facilitate integrating the outer and inner knit layers 60, 80.

The double layer knit upper can have a variety of circular knit constructions. For example, the double layer knit upper can include a single jersey knit construction, a double knit construction, a rib knit construction, a terry knit construction, or other types of weft knit constructions. Additionally, different regions of the double layer knit upper can include different knit constructions, such as float knit constructions, presser knit constructions, skip knit constructions, and other knit constructions known to those skilled in the art. In one example, the outer knit toe region 62a, 82a of the outer and/or inner layer can include a cushioned knit construction. Similarly, the heel region 62d, 82d of the outer and/or inner layer can have a cushioned knit construction. The cushioned knit construction includes knit terry loops.

The double layer knit upper can be formed from any number of yarn types, such as spun yarns or continuous filament yarns. Spun yarns can include natural fibers, synthetic fibers, or blends of natural and synthetic fibers. Natural fibers include cotton, wool, bamboo, flax, hemp, and the like. Synthetic fibers can include polyethylene terephthalate (PET), polyolefin, polyamide 6, polyamide 6,6, polylactic acid (PLA) fibers, viscose rayon, acrylic, or other fiber types. Suitable thermoplastic synthetic staple fibers can be monocomponent or bicomponent type fibers. A variety of spinning types can be used, such as ring spun, open end, air jet, and compact spun. Continuous filament yarns may include either or both monocomponent or bicomponent filament types. Continuous filament yarns can be polyethylene terephthalate, polyolefin, and/or polyamide 6, polyamide 6,6, polylactic acid filaments. Yarns used in the knit fabric can have a variety of counts. For example, in one example, the knit yarns can have a count ranging between about 50 denier and about 250 denier (or higher). The yarns are not limited to the stated range of denier. Bonding yarns are used in selected areas of the outer knit layer 60 and the inner knit layer 80 to help integrate the outer and inner layers. The bonding yarns can be yarns such as low melting thermoplastic yarns or thermoplastic polyurethane yarns.

Another embodiment of the present disclosure is a method for forming a footwear article 10. The method may include a knitting step configuration to form a circular knitted blank 130. Following the knitting step, the method may include an assembly step in which the circular knitted blank 130 is formed into an upper knitted component 30 and a sole component 20 is attached to the midsole 41 of the upper knitted component 30. With reference to FIGS. 4-6, the circular knitted blank 130 has a first knit section 160 that defines an outer knit layer 60 and a second knit section 180 that defines an inner knit layer 80. The circular knitted blank 130 is folded on itself to define a double layer knit upper such that the inner knit layer 80 forms the inner void 31 of the footwear article 10.

The knitting step utilizes a circular knitting machine (not shown) that is well known to those skilled in the art. The circular knitting machine may be a double needle machine including two cylinders. Alternatively, a circular knitting machine with a cylinder and a dial may be used. For illustration and clarity, the knitting process using a knitting machine with two cylinders is described below. It is understood that other types of knitting machines may be used. Each cylinder has a number of needles arranged around the circumference of the cylinder, with each needle housed in a moveable track. A cam assembly engages the needles along each cylinder. The rotational motion of the cam assembly (or the relative motion of the cylinders) causes the needles to move up and down the track through what is known in the art as a knitting cycle, creating a course of knit loops of interconnected yarns. The course of knit loops defines the circular knitted fabric blank 130. By modifying the knitting cycle and/or holding certain needles in place during knitting, certain stitches and/or patterns can be formed in the circular knitted blank 130. Circular knitting machines and the basic circular knitting process are well known to those skilled in the art. Various circular knitting processes may be used, such as tubular circular knitting, narrow tubular circular knitting jacquard, single knit circular knitting jacquard, and double knit circular knitting jacquard knitting.

With reference to FIG. 4, the circular knit blank 130 has a first end 132 and a second end 134. The circular knit blank 130 is formed to have a first knit section 160 that defines the first end 132 and a second knit section 180 that defines the second end 134. The circular knit blank 130 is composed of interconnected knit rows of knit loops, referred to as courses, as described above. The first "course" of the knit blank 130 is located at the first end 132. The circular knit blank 130 is formed course by course in the direction K shown in FIG. 4 until the circular knit blank 130 is completed, as shown in FIG. 4. Thus, during the knitting stage, the first knit section 160 is knit first, and then the second knit section 180 is formed into a single monolithic fabric with the first knit section 160.

Circular knitting of the knitted blank 130 begins with cylinder needles knitting the first toe portion 142 of the first knit section 160. Next, the circular knitting machine knits the midsole portion, including the first upper portion 144a and the first lower portion 144b. Next, the first heel portion 146 of the first knit section 160 is knitted adjacent to the first lower portion 144b. While knitting the first heel portion 146, the knitting machine can selectively drop needles and change knitting direction to form the desired curve of the first heel portion 146. After the first heel portion 148 is formed, the circular knitting machine knits the first ankle portion 148 of the first knit section 160 adjacent to the first heel portion 148 and the first upper portion 144a. At this point, the first knit section 160 is substantially complete. The first knit section 160 comprises the outer knit layer 60 of a dual layer knit upper, as described below. Thus, as the knitting machine forms the first knit section 160, different knit regions 62a-62f are created within the circular knit blank 130, as shown.

The knitting process continues to form the second knit section 180. During this stage of knitting, the second ankle portion 248 of the second knit section 180 is formed adjacent to the first heel portion 148. The circular knitting machine knits the second heel portion 246 adjacent to and continuous with the second ankle portion 248. The circular knitting machine knits the second upper portion 244a and the second lower portion 244b of the second knit section 180. The knitting process continues to form the second toe portion 242 of the second knit section 180 adjacent to the second upper portion 244a and the second lower portion 244b. The second toe portion 242 is formed at the end 134 to complete the circular knit blank 130. As the knitting machine forms the second knit section 180, different knit regions 82a-82g are created in each region of the circular knit blank 130. As shown, the resulting circular knit blank 130 is a tubular structure having substantially the shape of two crew cut socks connected at the ankle.

Additional yarn courses may be added to facilitate the transition to the next knit blank formed by the circular knitting machine. An optional cutting device is used to cut the finished circular knitted blank 130 from the knitting machine. The circular knitted blank 130 is discharged from the knitting machine for further processing.

The finished circular knit blank 130 may have toe openings 152 and 252 in the toe portion 142 and the toe portion 242, respectively. As shown in FIG. 5, the toe openings 152 and 252 may be closed at seams 154 and 254. In an alternative embodiment, the circular knit blank 103 may be formed to automatically close the toe openings 152 and 252 using a bridge stitch or inlay yarn, or the like.

The circular knit blank 130 may be cut to form the ankle opening 32 by removing the panel 156 from the circular knit blank 130. In an alternative embodiment, the circular knit blank 103 may be formed to define the ankle opening 32 during knitting. In such an embodiment, the circular knit blank 130 may form a welt edge along the border of the ankle opening 32 to prevent fraying and provide a location for attaching the binding 54 (FIGS. 1 and 6).

When the circular knit blank 130 is completed, the second knit section 180 is folded into the first knit section 160 to form a double layer knit upper for the article of footwear. At this stage, the double layer knit upper includes an outer knit layer 60 defined by the first knit section 160 and an inner knit layer 80 defined by the second knit section 180. In this state, at least two of the outer knit regions 62a-62d of the outer knit layer 60 spatially correspond to at least two of the inner knit regions. According to the illustrated embodiment, the inner knit regions 82a-82e are below the outer knit regions 62a-62e.

The method may include disposing a liner component along a bottom portion of the first knit section prior to folding. Thus, the liner component is disposed between the outer knit layer and the inner knit layer.

The method may include attaching a sole directly to an outer knit layer of a dual layer knit upper. Attaching the sole to the outer knit layer includes placing the dual layer knit upper over a positioning member of an injection molding apparatus (not shown). A sole component is then injection molded onto the outer knit layer of the dual layer knit upper. Additionally, the method may include injection molding a plurality of tabs 22a-22d along the medial and lateral sides of the dual layer knit upper. The injection molding process may melt the TPU yarn in certain knit areas, thereby bonding the outer knit layer to the inner knit layer to form a monolithic dual layer knit upper.

A circular knitted, double layer knit upper as described herein has several advantages. A wide range of knit structures across various regions of the upper are possible while using a single fabric construction. Specific knit structures can be designed into various regions of the footwear article as needed. Additionally, complex three-dimensional shapes that better fit the anatomy of the wearer's foot can be formed during the knitting process. Because the circular knit upper is made to fit the wearer's foot, fewer assembly steps are required before the upper can be attached to the sole to create the finished footwear article. Fewer total components in the finished footwear article reduces supply chain complexity and increases production efficiency and yield. Additionally, the circular knitted, double layer upper can be manufactured at relatively fast production rates, further increasing production efficiency.

Footwear article 300 may include multiple layers or may be continuous to form a single body. Footwear article 300 may include a first layer 301 and a second layer 302. First layer 301 and second layer 302 may include a soft material, such as a fabric. First layer 301 and second layer 302 may be generally tubular or may include other shapes. Second layer 302 may include a rigid material, such as leather or plastic. First layer 301 and second layer 302 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. Second layer 302 may be folded or inverted to be disposed adjacent to at least a portion of first layer 301. Second layer 302 may include at least a portion of the interior or exterior of footwear article 300. Footwear article 300 may include additional layers that may provide additional functionality.

As shown in FIG. 7, the footwear article 300 may include a first layer 301 and a second layer 302. The first layer 301 and the second layer 302 may include a generally tubular shape. The first layer 301 may include a waterproof, breathable material suitable for forming at least a portion of the exterior of the footwear article 300. The first layer 301 may be coated with a spray application to provide waterproofing and may also be breathable. The second layer 302 may include a soft material suitable for conforming to a wearer's foot and providing comfort. The second layer 302 may be or may include a comfort liner. When the second layer 302 is folded into the first layer 301, the second layer 302 defines an interior of the footwear article 300 and the first layer 301 defines an exterior of the footwear article 300. Although reference is made to a first layer 301 and a second layer 302, other arrangements may be used. For example, the characteristics of each layer may be switched or combined between layers.

One of the problems with traditional circular knit applications is that it is difficult to sew or glue other materials onto a circular knit upper because it is finished in a 3D shape.

As an example, most heat presses and sewing machines are optimized to process scrolls in a flat surface. When a circular knit upper has a 3D shape, normal flat surface work may not be appropriate.

As a further example, 3D direct injection can be used to add additional structure, cushioning, lacing details, etc. to a circular knit upper. This process can be implemented into a long-lasting upper and can be finished into a 3D shape.

As shown in FIG. 8, the footwear article 400 may include multiple layers or may be continuous to form a single body. The footwear article 400 may include a first layer 401 and a second layer 402. The first layer 401 and the second layer 402 may include a soft material, such as a fabric. The first layer 401 and the second layer 402 may be generally tubular or may include other shapes. The second layer 402 may include a rigid material, such as leather or plastic. The first layer 401 and the second layer 402 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 402 may be folded or inverted so as to be disposed adjacent to at least a portion of the first layer 401. The second layer 402 may include at least a portion of the interior or exterior of the footwear article 400. The footwear article 400 may include additional layers that may provide additional functionality.

As shown in FIG. 8 , the footwear article 400 may include a first layer 401, a second layer 402, and a wing system 403. The wing system 403 may include laces, eyelets, straps, hook-and-loop fasteners, or other types of fasteners. The wing system 403 may be disposed adjacent to a portion of the first layer 401, a portion of the second layer 402, or a portion of both layers 401, 402. The first layer 401 and the second layer 402 may include a generally tubular shape that may be circular knit. The second layer 402 may be folded into the first layer 401. The second layer 402 may define an inner portion of the footwear article 400, and the first layer may define an outer portion of the footwear article 400. As shown, the wing system 403 may be disposed circumferentially around the second layer 402. When the second layer 402 is folded into the first layer 401, the wing system 403 can be disposed between the first circular knit layer 401 and the second circular knit layer 402 of the footwear article 400.

As shown in FIG. 9, the footwear article 500 may include multiple layers or may be continuous to form a single body. The footwear article 500 may include a first layer 501 and a second layer 502. The first layer 501 and the second layer 502 may include a soft material, such as a fabric. The first layer 501 and the second layer 502 may be generally tubular or may include other shapes. The second layer 502 may include a rigid material, such as leather or plastic. The first layer 501 and the second layer 502 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 502 may be folded or inverted so as to be disposed adjacent to at least a portion of the first layer 501. The second layer 502 may include at least a portion of the interior or exterior of the footwear article 500. The footwear article 500 may include additional layers that may provide additional functionality.

As shown in FIG. 9, the footwear article 500 may include a first layer 501, a second layer 502, and a collar portion 504. As shown, the first layer 501 may include a generally tubular shape. The first layer 501 may be circular knit. The second layer 502 may include a planar rectangular shape. The second layer 502 may be flat knit. The second layer 502 may include one or more welded reinforcements 505 for securing the second layer 502 to the first layer 501. The second layer 502 may be configured for a flat stitching operation 506, such as flat stitching, molding, or screen printing. The second layer 502 may be configured to be folded into or around the first layer 501 to define the collar portion 504. The second layer 502 may be configured to be partially circumferentially disposed about an outer portion of the first layer 501 to define a collar portion 504. The second layer 502 may also be disposed adjacent the midfoot, ankle, or other portions of the first layer 501 to define other features.

10 illustrates that the footwear article 600 may include multiple layers or may be continuous to form a single body. The footwear article 600 may include a first layer 601 and a second layer 602. The first layer 601 and the second layer 602 may include a soft material, such as a fabric. The first layer 601 and the second layer 602 may be generally tubular or may include other shapes. The second layer 602 may include a rigid material, such as leather or plastic. The first layer 601 and the second layer 602 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 602 may be folded or inverted so that it is disposed adjacent to at least a portion of the first layer 601. The second layer 602 may include at least a portion of the interior or exterior of the footwear article 600. The footwear article 600 may include additional layers or features that may provide additional functionality.

As shown in FIG. 10, the footwear article 600 may include a first layer 601 and a second layer 602. The first layer 601 may be generally tubular. The first layer 601 may be circular knit. The second layer 602 may include a hard or rigid material, such as leather, rubber, or plastic, suitable for defining at least a portion of the exterior of the footwear article 600. The second layer 602 may be flat knit. The second layer 602 may be configured to be disposed adjacent to at least an exterior portion of the first layer 601. The second layer 602 may include a reinforcement region 610. For example, as shown, the reinforcement region 610 may define a heel cup 610a and a toe cup 610b. The second layer 602 may include apertures 608 that define a wing system 603 or other features. The aperture 608 may include an eyelet or lace configured to receive a shoe lace or strap.

Footwear article 600 may further include one or more ventilation areas 607 that provide ventilation. Ventilation areas 607 may be generally triangular or planar, or may have other shapes. As shown, first layer 601 and second layer 602 may include multiple ventilation areas 607. Ventilation areas 607 of first layer 601 may correspond to ventilation areas 607 of second layer 607 and may be configured to be adjacently positioned when inverted to form footwear article 600.

The footwear article 700 may include multiple layers or may be continuous to form a single body. The footwear article 700 may include a first layer 701 and a second layer 702. The first layer 701 and the second layer 702 may include a soft material, such as a fabric. The first layer 701 and the second layer 702 may be generally tubular or may include other shapes. The second layer 702 may include a rigid material, such as leather or plastic. The first layer 701 and the second layer 702 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 702 may be folded or inverted so as to be disposed adjacent to at least a portion of the first layer 701. The second layer 702 may include at least a portion of the interior or exterior of the footwear article 700. The footwear article 700 may include additional layers that may provide additional functionality.

11, the article of footwear 700 may include a first layer 701 and a second layer 702. The first layer 701 and the second layer 702 may be continuous to define a unitary body. The second layer 702 may be configured to invert adjacent an outer surface of the first layer 701. The first layer 701 and the second layer 702 may include one or more features. As shown, the second layer 702 may include a plurality of strips 709a, 709b, 709c. The strips 709a, 709b, 709c may include knitted materials, rigid materials, or combinations of knitted and rigid materials to define the different features. As shown, the first strip 709a may include a reinforced region 710 that may define a heel cup 710a. The second strip 709b may include an aperture 708 that may define a wing system 703.

The footwear article 800 may include multiple layers or may be continuous to form a single body. The footwear article 800 may include a first layer 801 and a second layer 802. The first layer 801 and the second layer 802 may include a soft material, such as a fabric. The first layer 801 and the second layer 802 may be generally tubular or may include other shapes. The second layer 802 may include a rigid material, such as leather or plastic. The first layer 801 and the second layer 802 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 802 may be folded or inverted so as to be disposed adjacent to at least a portion of the first layer 801. The second layer 802 may include at least a portion of the interior or exterior of the footwear article 800. The footwear article 800 may include additional layers that may provide additional functionality.

12, the footwear article 800 may include a first layer 801 and a second layer 802. The first layer 801 may be generally tubular. The first layer 801 may be circular knit. The second layer 802 may include an irregular planar shape. The second layer 802 may be flat knit. The footwear article 800 may further include a wing system 803. As shown, the second layer 802 may include a member 811 configured to extend through at least a portion of the first layer 801. The member 811 may be configured to be removably received in an aperture 808 in the first layer 801. The member 811 may include loops and hooks to define the footwear article 800 with a pull-through feature.

The footwear article 900 may include multiple layers or may be continuous to form a single body. The footwear article 900 may include a first layer 901 and a second layer 902. The first layer 901 and the second layer 902 may include a soft material, such as a fabric. The first layer 901 and the second layer 902 may be generally tubular or may include other shapes. The second layer 902 may include a rigid material, such as leather or plastic. The first layer 901 and the second layer 902 may be formed by circular knitting, flat knitting, or other manufacturing methods, or from other materials. The second layer 902 may be folded or inverted so as to be disposed adjacent to at least a portion of the first layer 901. The second layer 902 may include at least a portion of the interior or exterior of the footwear article 900. The footwear article 900 may include additional layers that may provide additional functionality.

13, the footwear article 900 may include a first layer 901 and a second layer 902. The first layer 901 may include a generally tubular shape. The first layer 901 may be circular knit. The second layer 902 may include a planar irregular shape. The second layer 902 may be flat knit. The second layer 902 may be inverted adjacent the exterior surface of the first layer 901. The second layer 902 may include a wing system 903. As shown, the second layer 902 may include apertures 908 (e.g., eyelets) that define the wing system 903. The second layer 902 may include a reinforced region 910 that may define a heel cup 910a and a toe cup 910b that provide structure and integrity to the exterior of the footwear article 900.

FIG. 14 illustrates exemplary footwear articles 950-954 that may include functional layers 960-965. The functional layers 960-965 may include insoles, midsoles, insulation, socks, collars, and other functional features within the footwear articles 950-954. As described and shown, one or more functional layers may be interposed between two knit layers (e.g., circular knit layers), such as using a folding or other technique. The functional layer may include a waterproof material or membrane, or a breathable waterproof membrane. The functional layer may be a preformed laminate or composite. The functional layer may be a spray application. The functional layer may be 3D direct injection. The functional layer may be applied to other configurations or other surfaces. As a non-limiting example, one problem addressed by the present disclosure is that although circular knitting is fast, it can be difficult to sew or attach things to a circular knit upper because of the finished 3D shape. Most state of the art heat presses and sewing machines are optimized to process rolls in a flat surface. As an illustrative example, 3D direct injection is one way to apply additional structure, cushioning, lacing details, etc. that are optimized to work with 3D molding. This process can be implemented into a long-lasting upper as a fully finished 3D shape.

As shown, functional layer 960 may include a midsole incorporated into the midsole of footwear article 950. Functional layer 961 may include a knit midsole (e.g., padding knit) within footwear article 951. Functional layer 962 may include insulation incorporated within footwear article 952. Functional layer 963a may include a midsole trapped within footwear article 953. The midsole may include features such as outsole projections that may extend through the first and/or second layers. The projections may be configured to engage the ground. As an example, one or more of the first or second layers may include apertures to allow projections from the trapped midsole to extend therethrough. Various configurations of projections may be used, such as placement at the heel or placement at the forefoot. Functional layer 963b may include a foam collar trapped within footwear article 953. Functional layer 964 may include the entire upper and outsole within article of footwear 954. Functional layer 965 may include a custom inner sock within article of footwear 954.
Aspects

The present disclosure includes at least the following aspects:

Aspect 1: A footwear article comprising a double-layer knit upper having a midsole, an upper portion continuous with the midsole, an ankle opening, and an inner void for receiving a wearer's foot, the double-layer knit upper comprising:
a) an exterior knit layer defining an exterior surface of a dual layer knit upper, the exterior knit layer having a plurality of exterior knit regions;
b) an inner knit layer monolithically knitted to the outer knit layer and forming an inner void, the inner knit layer having a plurality of inner knit regions spatially corresponding to the plurality of outer knit regions of the outer knit layer, the outer knit layer and the inner knit layer substantially defining a midsole and an upper portion of a double layer knit upper, and a sole attached to at least the midsole of the double layer knit upper.

Aspect 2. The article of footwear of aspect 1, further comprising a midsole disposed between the outer knit layer and the inner knit layer along the midsole.

Aspect 3. The footwear article of aspect 1, wherein the outer knit layer and the inner knit layer are monolithic circular knit fabrics.

Aspect 4. The footwear article of aspect 1, wherein the outer knit layer and the inner knit layer each define a tubular knit shape.

Aspect 5. The article of footwear of aspect 1, wherein the inner knit layer is monolithically knitted to the outer knit layer around at least a portion of the ankle opening.

Aspect 6. The article of footwear of aspect 5, wherein the outer knit layer and the inner knit layer define a welt edge along at least a portion of the ankle opening.

Aspect 7. The article of footwear of aspect 1, wherein the outer knit layer and the inner knit layer include a binding along at least a portion of the ankle opening.

Aspect 8. The article of footwear of aspect 1, further comprising at least one attachment member that integrates the outer knit layer and the inner knit layer.

Aspect 9. The article of footwear of aspect 8, wherein at least one attachment member bonds the yarns of the outer knit layer to the yarns of the inner knit layer.

Aspect 10. The footwear article of aspect 8, wherein at least one attachment member is a bonding thread.

Aspect 11. The footwear article of aspect 10, wherein the bonding yarn is a thermoplastic polyurethane yarn.

Aspect 12. The footwear article of aspect 10, wherein the bonding yarn is a low melting thermoplastic yarn.

Aspect 13. The footwear article of aspect 10, wherein the outer knit layer comprises a first yarn, the inner knit layer comprises a second yarn, and the bonding yarn has a lower melting temperature than the first yarn and the second yarn.

Aspect 14. The footwear article of aspect 8, wherein at least one attachment member is an adhesive film.

Aspect 15. The footwear article of aspect 8, wherein at least one attachment member is a low melt adhesive web.

Aspect 16. The article of footwear of aspect 8, wherein at least one of the plurality of outer knit regions includes at least one attachment member.

Aspect 17. The article of footwear of aspect 16, wherein the dual layer knit upper has a toe portion, and a first of the multiple outer knit regions in the outer knit layer extends across the rear upper portion of the toe portion, and the first outer knit region includes at least one attachment member.

Aspect 18. The article of footwear of Aspect 8, wherein at least one of the plurality of inner knit regions includes at least one attachment member.

Aspect 19. The article of footwear of aspect 18, wherein a second lateral knit region of the plurality of lateral knit regions extends across the toe portion, a second medial knit region of the plurality of medial knit regions underlies the second lateral knit region, and at least one of the second lateral knit region and the second medial knit region includes at least one attachment member.

Aspect 20. The article of footwear of aspect 18, wherein the plurality of inner knit regions includes an inner central region along the insole that includes at least one attachment member.

Aspect 21. The article of footwear of aspect 1, wherein the dual layer knit upper has a heel portion that connects the insole to the ankle portion, the heel portion having a cushioned knit construction.

Aspect 22. The article of footwear of aspect 1, wherein the dual layer knit upper has a toe portion, and the toe portion has a cushioned knit construction.

Aspect 23. The footwear article of aspect 1, further comprising a plurality of tabs extending upwardly from the sole along the medial and lateral sides of the footwear article.

Aspect 24. The article of footwear of aspect 23, wherein the plurality of tabs include a fastening member configured to receive a cord.

Aspect 25. A circular knit blank used to form an article of footwear, the circular knit blank having a first end and a second end, the first circular knit blank having a first toe portion defining the first end of the circular knit blank, a first upper portion, a first lower portion joined to the first upper portion, a first heel portion, and a first ankle portion joined to the first heel portion, the first circular knit section having a first plurality of knit regions each having a different knit structure, a second ankle portion monolithically knitted to the first ankle portion, a second heel portion joined to the second ankle portion, and a first ankle portion joined to the first ankle portion. A circular knit blank comprising: a second upper portion; a second lower portion coupled to the second upper portion and the second heel portion; and a second toe portion defining a second end of the circular knit blank opposite the first end of the circular knit blank; and a second circular knit section having a second plurality of knit regions each having a different knit structure, wherein the first plurality of knit regions correspond to the second plurality of knit regions such that the first plurality of knit regions and the second plurality of knit regions overlap when the first circular knit section is folded into the second circular knit section.

Aspect 26. The circular knit blank of aspect 25, further comprising an opening disposed where the first ankle portion and the second ankle portion are joined.

Aspect 27. The circular knit blank of aspect 25, further comprising at least one attachment member configured to adhere the first circular knit section and the second circular knit section together.

Aspect 28. A method of forming a footwear article, comprising circular knitting a tubular knit blank having a first knit section and a second knit section, wherein a) the first knit section includes a first toe portion, a first lower portion, a first upper portion, a first heel portion adjacent to the first lower portion, and a first ankle portion adjacent to the first heel portion and the first upper portion, and b) the second knit section includes a second toe portion, a second lower portion, a second upper portion, a second heel portion adjacent to the second lower portion, and a second ankle portion adjacent to the second heel portion and the second upper portion. The method includes: circular knitting a blank; folding a first knit section into a second knit section to form a double layer knit upper for an article of footwear, the double layer knit upper having an outer knit layer defined by the second knit section and an inner knit layer defined by the first knit section, the inner knit layer defining an inner void of the double layer knit upper; folding the first knit section into the second knit section; and attaching a sole directly to the outer knit layer of the double layer knit upper.

Aspect 29. Circular knitting in sequence,
a. knitting a first toe portion of a first knit section;
b. knitting a first upper portion and a first lower portion of a first knit section;
c. knitting a first heel portion of the first knit section adjacent the first lower portion;
d. knitting a first ankle portion of the first knit section adjacent the first heel portion and the first upper portion;
e. knitting a second ankle portion of the second knit section adjacent the first heel portion;
f. knitting a second heel portion adjacent the second ankle portion of the second knit section;
g. knitting a second upper portion and a second lower portion of the second knit section;
h) knitting a second toe portion of the second knit section adjacent the second upper portion and the second lower portion.

Aspect 30. The method of aspect 28, wherein attaching the sole to the outer knit layer includes positioning the dual layer knit upper over a positioning member of an injection molding apparatus, injection molding the sole to the outer knit layer of the dual layer knit upper, and injection molding a plurality of tabs along the medial and lateral sides of the dual layer knit upper, the plurality of tabs being configured to receive a cord.

Aspect 31. An article of footwear comprising a first circular knit layer defining at least a portion of an outer surface, and a second circular knit layer bonded to the first circular knit layer, the second circular knit layer configured to be positioned adjacent to at least a portion of the first circular knit layer when folded into or around the first circular knit layer.

Aspect 32. The footwear article of aspect 31, wherein the second circular knit layer extends from the first circular knit layer as a unitary body.

Aspect 33. The article of footwear of aspect 31, wherein the first circular knit layer comprises a generally tubular shape.

Aspect 34. The footwear article of aspect 31, wherein the second circular knit layer comprises a generally tubular shape.

Aspect 35. The footwear article of aspect 31, wherein the second circular knit layer comprises a planar shape.

Aspect 36. The footwear article of aspect 31, wherein the first circular knit layer comprises a waterproof, breathable material and the second circular knit layer comprises a comfort liner.

Aspect 37. The footwear article of aspect 31, further comprising a wing system disposed adjacent to at least a portion of the second circular knit layer such that when the second circular knit layer is folded into the first circular knit layer, at least a portion of the wing system is interposed between the second circular knit layer and the first circular knit layer.

Aspect 38. The article of footwear of aspect 37, wherein at least a portion of the wing system is circumferentially disposed around the second circular knit layer.

Aspect 39. The footwear article of aspect 31, wherein the first circular knit layer includes a generally tubular shape and the second circular knit layer includes a planar shape, the planar second circular knit layer being configured for planar operation prior to being folded into or around the first circular knit layer.

Aspect 40. The footwear article of aspect 39, wherein the planar work includes one or more of flat stitching, fusing, molding, or screen printing.

Aspect 41. The footwear article of aspect 39, wherein the planar second circular knit layer includes one or more welded reinforcement regions.

Aspect 42. The article of footwear of aspect 31, wherein the first circular knit layer includes a collar, and the second circular knit layer, which is planar, is configured to be at least partially circumferentially disposed around an outer surface of the first circular knit layer.

Aspect 43. The article of footwear of aspect 31, wherein the first circular knit layer includes a generally tubular shape and the second circular knit layer is configured to be folded so as to be positioned on an outer surface of the first circular knit layer adjacent one or more ankle portions or adjacent a midfoot portion of the first circular knit layer.

Aspect 44. The footwear article of aspect 43, wherein the first circular knit layer includes one or more ventilation areas, and the second circular knit layer is configured to be folded over the first circular knit layer so as to be adjacent at least a portion of the ventilation areas.

Aspect 45. The footwear article of aspect 44, wherein the second circular knit layer includes one or more features configured to be positioned adjacent a portion of the ventilation area.

Aspect 46. The article of footwear of aspect 45, wherein one or more features include an aperture.

Aspect 47. The footwear article of aspect 43, wherein the second circular knit layer includes one or more features configured to be positioned adjacent to the first circular knit layer.

Aspect 48. The article of footwear of aspect 47, wherein the one or more features include an aperture, eyelets, or heel cup, or a combination thereof.

Aspect 49. The footwear article of aspect 47, wherein the one or more features include a pull-through configured to extend through a portion of the first circular knit layer.

Aspect 50. The footwear article of aspect 31, wherein the first circular knit layer includes a generally tubular shape and the second circular knit layer is configured to be folded so as to be disposed adjacent to an outer or inner surface of the first circular knit layer.

Aspect 51. The footwear article of aspect 50, further comprising a functional layer interposed between the first and second circular knit layers when the second circular knit layer is folded into or over the first circular knit layer.

Aspect 52. The footwear article of aspect 51, wherein the functional layer includes a midsole.

Aspect 53. The footwear article of aspect 51, wherein the functional layer comprises a midsole.

Aspect 54. The footwear article of aspect 51, wherein the functional layer comprises an insulating material.

Aspect 55. The footwear article of aspect 51, wherein the functional layer includes a collar.

Aspect 56. The footwear article of aspect 50, wherein the second circular knit layer includes an aperture such that the second circular knit layer is configured to be rolled.

Aspect 57. An article of footwear, comprising:
a first circular knit layer defining at least a portion of an outer surface;
a second layer coupled to the first circular knit layer, the second layer configured to be positioned adjacent to at least a portion of the first circular knit layer when folded into or around the first circular knit layer.

Aspect 58. The footwear article of aspect 57, wherein the second layer comprises a planar shape.

Aspect 59. The footwear article of aspect 58, wherein the planar shape is configured for planar operation prior to folding into or around the first circular knit layer.

Aspect 60. The footwear article of aspect 57, wherein the second layer is flat knit.

Aspect 61. The footwear article of aspect 57, wherein the second layer includes one or more welded reinforcement regions.

Aspect 62. The article of footwear of aspect 57, wherein the first circular knit layer includes a generally tubular shape and the second layer is configured to be folded so as to be disposed adjacent an outer surface of the first circular knit layer.

Aspect 63. The article of footwear of aspect 57, wherein the first circular knit layer includes a collar, and the second layer is configured to be at least partially circumferentially disposed around an outer surface of the collar of the first circular knit layer.

Aspect 64. The footwear article of aspect 57, wherein the first circular knit layer includes one or more ventilation areas, and the second layer is configured to be folded over the first layer adjacent at least a portion of the ventilation areas.

Aspect 65. The footwear article of aspect 57, wherein the second layer includes one or more features configured to be positioned adjacent to the first circular knit layer.

Aspect 66. The article of footwear of aspect 65, wherein the one or more features include an aperture, a wing system, eyelets, or a heel cup, a toe cup, or a combination thereof.

Aspect 67. The footwear article of aspect 65, wherein the one or more features include a pull-through configured to extend through at least a portion of the first circular knit layer.

Aspect 68. The footwear article of aspect 57, further comprising a functional layer interposed between the first circular knit layer and the second layer when the second layer is folded into or over the first circular knit layer.

Aspect 69. The footwear article of aspect 68, wherein the functional layer includes a midsole.

Aspect 70. The article of footwear of claim 68, wherein the functional layer comprises a midsole.

Aspect 71. The article of footwear of claim 68, wherein the functional layer comprises an insulating material.

Aspect 71. The article of footwear of claim 68, wherein the functional layer comprises a collar.

This disclosure describes certain embodiments and their detailed structure and operation. The embodiments described herein are described for purposes of illustration only, not limitation. Those skilled in the art will recognize that there may be a range of equivalents to the exemplary embodiments described herein in light of the teachings herein. Most notably, other embodiments are possible. Changes may be made to the embodiments described herein, and there may be equivalents to the components, parts, or steps that make up the described embodiments. For clarity and brevity, specific aspects of the components or steps of certain embodiments are presented without undue detail, where such details would be apparent to one skilled in the art in light of the teachings herein and/or where such details would obscure an understanding of more pertinent aspects of the embodiments.

Claims (15)

1. An article of footwear comprising:
a first circular knit layer; and
a second circular knitted layer coupled to the first circular knitted layer, the second circular knitted layer configured to be positioned adjacent to at least a portion of the first circular knitted layer when folded into or around the first circular knitted layer;
and a functional layer interposed between the first and second circular knit layers by using a folding technique such that when the second circular knit layer is folded into or around the first circular knit layer, the functional layer is trapped between the first and second circular knit layers and comprises an insole integrated into a midsole of the footwear article, wherein the trapped midsole insole comprises outsole projections extending through the first and second circular knit layers, and the first or second circular knit layer comprises apertures allowing the outsole projections from the trapped midsole to extend therethrough. The article of footwear of claim 1, wherein the functional layer is applied to at least one surface of the first circular knit layer or the second circular knit layer using a spray application. The article of footwear of any one of claims 1 to 2, wherein the first circular knit layer defines at least a portion of an outer surface. The article of footwear of any one of claims 1 to 3, wherein the second circular knit layer extends from the first circular knit layer as a unitary body. The article of footwear of any one of claims 1 to 4, wherein the first circular knit layer comprises a generally tubular shape. The article of footwear of any one of claims 1 to 5, wherein the second circular knit layer includes a generally tubular shape. The article of footwear of any one of claims 1 to 6, wherein the first circular knit layer comprises a waterproof, breathable material and the second circular knit layer comprises a comfort liner. The article of footwear of any one of claims 1 to 7, further comprising a wing system disposed adjacent to at least a portion of the second circular knit layer such that at least a portion of the wing system is interposed between the second circular knit layer and the first circular knit layer when the second circular knit layer is folded into the first circular knit layer. The article of footwear of any one of claims 1 to 8, wherein the first circular knit layer includes a generally tubular shape, the second circular knit layer includes a planar shape, and the second circular knit layer is configured for planar operation prior to being folded into or around the first circular knit layer. The article of footwear of claim 9, wherein the second circular knit layer includes one or more fused reinforcement regions. The article of footwear of any one of claims 9 to 10, wherein the first circular knit layer includes a collar, and the second circular knit layer is configured to be at least partially circumferentially disposed around an outer surface of the first circular knit layer. The article of footwear according to any one of claims 1 to 11, wherein the first circular knit layer includes one or more ventilation areas, and the second circular knit layer is configured to be folded into or around the first circular knit layer adjacent at least a portion of the ventilation area. The article of footwear of any one of claims 1 to 12, wherein the second circular knit layer includes one or more features configured to be positioned adjacent to the first circular knit layer when the second circular knit layer is folded into or around the first circular knit layer, the one or more features including an aperture, a lacing hole, or a heel cup, or a combination thereof. The article of footwear of any one of claims 1 to 13, wherein the second circular knit layer includes one or more features configured to be positioned adjacent to the first circular knit layer when the second circular knit layer is folded into or around the first circular knit layer, and the one or more features include a pull-through configured to extend through a portion of the first circular knit layer. The article of footwear according to any one of claims 1 to 14, wherein the functional layer includes an insole, a midsole, an insulating material, or a collar.