BLADDER FOR AN ARTICLE OF FOOTWEAR

Abstract

A bladder for an article of footwear includes a first barrier layer, a second barrier layer coupled to the first barrier layer at a peripheral seam, a chamber defined between the first barrier layer and the second barrier layer and defining an interior void, and a knit infill material disposed within the interior void of the chamber between the first barrier layer and the second barrier layer and including a first material and a second material, the first material comprising a fusible yarn.

Claims

1. A bladder for an article of footwear, the bladder comprising: a first barrier layer; a second barrier layer coupled to the first barrier layer at a peripheral seam; a chamber defined between the first barrier layer and the second barrier layer and defining an interior void; and a knit infill material disposed within the interior void of the chamber between the first barrier layer and the second barrier layer and including a first material and a second material, the first material comprising a fusible yarn.

2. The bladder of claim 1, wherein the second material comprises polyester yarn.

3. The bladder of claim 1, wherein the first material comprises nylon.

4. The bladder of claim 1, wherein the first material comprises a polyamide material.

5. The bladder of claim 1, wherein the knit infill material includes a series of alternating peaks and valleys.

6. The bladder of claim 5, wherein the knit infill material is moveable between an expanded state and a compressed state, apexes of adjacent peaks moving toward one another when the knit infill material is moved into the compressed state.

7. The bladder of claim 6, wherein the knit infill material is moved into the compressed state in response to fluid being removed from the interior void.

8. The bladder of claim 6, wherein the knit infill material is biased into the expanded state.

9. The bladder of claim 1, wherein the knit infill material is attached to at least one of the first barrier layer and the second barrier layer.

10. An article of footwear incorporating the bladder of claim 1.

11. A method comprising: coupling a first barrier layer to a second barrier layer at a peripheral seam to define a chamber between the first barrier layer and the second barrier layer, the chamber including an interior void; and positioning a knit infill material within the interior void of the chamber between the first barrier layer and the second barrier layer, the knit infill material including a first material comprising a fusible yarn and a second material.

12. The method of claim 11, wherein the second material comprises polyester yarn.

13. The method of claim 11, wherein the first material comprises nylon.

14. The method of claim 11, wherein the first material comprises a polyamide material.

15. The method of claim 11, further comprising providing the knit infill material with a series of alternating peaks and valleys.

16. The method of claim 15, wherein positioning a knit infill material within the interior void of the chamber includes positioning a knit infill material that is moveable between an expanded state and a compressed state, apexes of adjacent peaks moving toward one another when the knit infill material is moved into the compressed state.

17. The method of claim 16, further comprising removing fluid from the interior void to move the knit infill material into the compressed state.

18. The method of claim 16, further comprising biasing the knit infill material into the expanded state.

19. The method of claim 15, further comprising causing the first material to flow when forming the series of alternating peaks and valleys.

20. The method of claim 19, further comprising cooling the first material after formation of the series of alternating peaks and valleys.

Description

DRAWINGS

[0007] The drawings described herein are for illustrative purposes only of selected configurations and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0008] FIG. 1A is a perspective view of an example article of footwear with an upper including a bladder in a relaxed state according to the present disclosure;

[0009] FIG. 1B is a perspective view of article of footwear of FIG. 1A with the bladder in a constricted state;

[0010] FIG. 2A is a perspective view of an example mold assembly according to the present disclosure shown in conjunction with a knit infill material;

[0011] FIG. 2B is a perspective view of an example press with a mold assembly and a knit infill material according to the present disclosure;

[0012] FIG. 3 is a cross-sectional view of a mold assembly and a knit infill material according to the present disclosure;

[0013] FIG. 4 is a perspective view of a molded knit infill material according to the present disclosure;

[0014] FIG. 5A is a perspective view of a bladder according to the present disclosure, the bladder including the molded knit infill material in a relaxed state;

[0015] FIG. 5B is a perspective view of the bladder of FIG. 5A with the molded knit infill material in a constricted state;

[0016] FIG. 6 is an enlarged view of a knit infill material according to the present disclosure;

[0017] FIG. 7 is an example cross-sectional schematic of a knit infill material according to the present disclosure;

[0018] FIG. 8A is a perspective view of an example article of footwear with an upper including a bladder in a relaxed state according to the present disclosure; and

[0019] FIG. 8B is a perspective view of the article of footwear of FIG. 8A with the bladder in a constricted state.

[0020] Corresponding reference numerals indicate corresponding parts throughout the drawings.

DETAILED DESCRIPTION

[0021] Example configurations will now be described more fully with reference to the accompanying drawings. Example configurations are provided so that this disclosure will be thorough, and will fully convey the scope of the disclosure to those of ordinary skill in the art. Specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of configurations of the present disclosure. It will be apparent to those of ordinary skill in the art that specific details need not be employed, that example configurations may be embodied in many different forms, and that the specific details and the example configurations should not be construed to limit the scope of the disclosure.

[0022] The terminology used herein is for the purpose of describing particular exemplary configurations only and is not intended to be limiting. As used herein, the singular articles a, an, and the may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms comprises, comprising, including, and having, are inclusive and therefore specify the presence of features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. Additional or alternative steps may be employed.

[0023] When an element or layer is referred to as being on, engaged to, connected to, attached to, or coupled to another element or layer, it may be directly on, engaged, connected, attached, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being directly on, directly engaged to, directly connected to, directly attached to, or directly coupled to another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (between versus directly between, adjacent versus directly adjacent, etc.). As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

[0024] The terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections. These elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as first, second, and other numerical terms do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example configurations.

[0025] In one configuration, a bladder for an article of footwear includes a first barrier layer, a second barrier layer coupled to the first barrier layer at a peripheral seam, a chamber defined between the first barrier layer and the second barrier layer and defining an interior void, and a knit infill material disposed within the interior void of the chamber between the first barrier layer and the second barrier layer and including a first material and a second material, the first material comprising a fusible yarn.

[0026] The bladder may include one or more of the following optional features. For example, the second material may comprise polyester yarn. Additionally or alternatively, the first material may comprise nylon and/or a polyamide material.

[0027] In one configuration, the knit infill material may include a series of alternating peaks and valleys. The knit infill material may be moveable between an expanded state and a compressed state, apexes of adjacent peaks moving toward one another when the knit infill material is moved into the compressed state. In this configuration, the knit infill material may be moved into the compressed state in response to fluid being removed from the interior void. Additionally or alternatively, the knit infill material may be biased into the expanded state.

[0028] The knit infill material may be attached to at least one of the first barrier layer and the second barrier layer. An article of footwear may incorporate the bladder.

[0029] In another configuration, a method is provided and includes coupling a first barrier layer to a second barrier layer at a peripheral seam to define a chamber between the first barrier layer and the second barrier layer, the chamber including an interior void. The method also includes positioning a knit infill material within the interior void of the chamber between the first barrier layer and the second barrier layer, the knit infill material including a first material comprising a fusible yarn and a second material.

[0030] The method may include one or more of the following optional steps. For example, the second material may comprise polyester yarn. Additionally or alternatively, the first material may comprise nylon and/or a polyamide material.

[0031] In one configuration, the knit infill material may be provided with a series of alternating peaks and valleys. Positioning a knit infill material within the interior void of the chamber may include positioning a knit infill material that is moveable between an expanded state and a compressed state, apexes of adjacent peaks moving toward one another when the knit infill material is moved into the compressed state. In one configuration, fluid may be removed from the interior void to move the knit infill material into the compressed state. Additionally or alternatively, the knit infill material may be biased into the expanded state.

[0032] The first material may flow when forming the series of alternating peaks and valleys. In this configuration, the first material may be cooled after formation of the series of alternating peaks and valleys.

[0033] The details of one or more implementations of the disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description, the drawings, and the claims.

[0034] With reference to FIGS. 1A and 1B, an example of an article of footwear 10 is illustrated including a bladder 100 configured with a knit infill material 102 disposed within a throat 12 of the footwear 10. The principles of the present disclosure may be used for forming bladders 100 used in other parts of the article of footwear 10, such as in an upper 14 or a sole structure 16 of the article of footwear 10. The principles of the present disclosure may also be used for forming bladders 100 used in other articles including, but not limited to, articles of apparel.

[0035] Referring to FIGS. 2A-5B, an example mold assembly 200 for molding the knit infill material 102 of the bladder 100 is provided. The mold assembly 200 includes a first mold 202 and a second mold 204. The first mold 202 has one or more first mold projections 206, and the second mold 204 has one or more second mold projections 208 that cooperate with the first mold projections 206 to define a respective mold pattern 210 that defines a shape and surface profile of the knit infill material 102. In the illustrated example, the first mold 202 includes a first pattern 212 formed along a mold surface 214 and the second mold 204 includes a second pattern 216 formed along a second mold surface 218. The second pattern 216 cooperates with the first pattern 212 to form a configuration of the knit infill material 102, referred to as an infill geometry 104. For example, the patterns 212, 216 of the molds 202, 204 are illustrated as having a wave pattern. As described in more detail below, the knit infill material 102 is molded with the patterns 212, 216 to define the infill geometry 104 and, more particularly, to provide the infill geometry with a waveform geometry.

[0036] Prior to molding the knit infill material 102, the first mold 202 and the second mold 204 are preheated to define an even, elevated temperature along each of the first surface 214 and the second surface 218. For example, the mold assembly 200 may be preheated to approximately 160 degrees Celsius. It is also contemplated that the mold assembly 200 may be preheated to a temperature greater than or less than 160 degrees Celsius. Once the first and second molds 202, 204 are preheated, the knit infill material 102 is positioned between the first mold 202 and the second mold 204 along one of the first surface 214 and the second surface 218 and a first pressure is applied. FIG. 2B illustrates an example press system 300 in which the mold assembly 200 and the knit infill material 102 may be positioned.

[0037] The press system 300 may include an upper platen opposing the first mold 202 and a second platen opposing the second mold 204. As the platens are moved toward one another, a pressure is applied to the first mold 202 and the second mold 204, thereby causing the first mold 202 and the second mold 204 to move toward one another. In so doing, the first mold 202 and the second mold 204 compress the knit infill material 102 between the first mold 202 and the second mold 204. The press system 300 may additionally include a heating element (not shown) associated with one or more of the first platen and the second platen. The heating element may heat the first platen and/or the second platen, thereby heating the first mold 202 and the second mold 204. The applied heat may be transferred to the knit infill material 102 during compression of the knit infill material 102 between the first mold 202 and the second mold 204.

[0038] The applied heat assists in softening the knit infill material 102, which may mold to the first and second patterns 212, 216 under the applied first pressure. In some examples, the mold assembly 200 may apply the first pressure to the knit infill material 102 via the press system 300 at a temperature of approximately 160 degrees Celsius. Specifically, the applied heat is transferred to the knit infill material 102 via the molds 202, 204, thereby causing the knit infill material 102 to become softened. At the same time, pressure is applied to the knit infill material 102 via the press system 300 and the first and second molds 202, 204 to allow the first pattern 212 and the second pattern 216 to deform and shape the infill material 102 into the infill geometry 104. In some examples, the first pressure may be applied for approximately (60) seconds. In other examples, the first pressure may be applied for greater than approximately sixty (60) seconds or less than approximately sixty (60) seconds. The application of the first pressure in combination with the applied heat defines a first mold impression along the knit infill material 102.

[0039] Referring still to FIGS. 2A-5B, after the first predetermined period of time, the first pressure is removed and the mold assembly 200 and knit infill material 102 may be cooled. For example, FIG. 3 illustrates the mold assembly 200 with the knit infill material 102 disposed therein after formation of the knit infill material 102 into the infill geometry 104 (i.e., after deformation of the infill material 102 into the geometry shown in FIG. 4). As illustrated in FIG. 3, the knit infill material 102 is molded to the first and second patterns 212, 216 of the respective first and second molds 202, 204. As previously described, the first and second patterns 212, 216 of the respective molds 202, 204 include a series of alternating peaks and valleys that provide the knit infill material 102 with a waveform infill geometry 104 having a series of alternating peaks and valleys.

[0040] Additionally, the molded knit infill material 102 may have a second pressure applied thereto immediately following the application of the first pressure with or without first executing a cooling step. For example, the press system 300 and the first and second molds 202, 204 may apply a second pressure to the knit infill material 102 via the first and second molds 202, 204. The application of the second pressure may occur after allowing the molds 202, 204 and/or the molded knit infill material 102 to cool or may be applied without allowing the molds 202, 204 and/or the molded infill material 102 to cool.

[0041] In other examples, the second pressure may be applied during a cooling period. For example, a cooling step may occur simultaneously with the application of the second pressure to define the molded knit infill material 102. For example, the infill material 102 having the waveform infill geometry 104 may be removed from the first and second molds 202, 204 and may be placed in a second set of identical molds 202, 204. The second set of identical molds 202, 204 may be used in conjunction with a press system that is identical to the press system 300 to provide for application of the second pressure to the second set of identical molds 202, 204. The application of the second pressure to the molded knit infill material 102 may be identical to the process described above with respect to the application of the first pressure to the knit infill material 102 but is performed without heating the platens of the press system 300 or the molds 202, 204. For example, the second pressure may be applied at room temperature and may be applied to the mold assembly 200 and the molded knit infill material 102 for a second period of time. The second period of time may, in some examples, be approximately sixty (60) seconds. In other examples, the first pressure may be applied for greater than approximately sixty (60) seconds or less than approximately sixty (60) seconds.

[0042] With further reference to FIGS. 2A-5B, the bladder 100 includes a first film or barrier layer 110 and a second film or barrier layer 112 that cooperate to define an interior void 114. The first barrier layer 110 is coupled to the second barrier layer 112 to form the interior void 114 of the bladder 100. Interior surfaces of the barrier layers 110, 112 face each other and are joined to each other to form a chamber 116 sealed by a peripheral seam 118 that surrounds the interior void 114 of the bladder 100. As described herein, the bladder 100 may be formed via a thermoforming process. However, it is also contemplated that the bladder 100 may be formed via a blow molding process, such that the bladder 100 may be free from the peripheral seam 118.

[0043] As used herein, the term barrier layer (e.g., barrier layers 110, 112) encompasses both monolayer and multilayer films. In some embodiments, one or both of barrier layers the 110, 112 are each produced (e.g., thermoformed or blow molded) from a monolayer film (a single layer). In other embodiments, one or both of the barrier layers 110, 112 are each produced (e.g., thermoformed or blow molded) from a multilayer film (multiple sublayers). In either aspect, each layer or sublayer can have a film thickness ranging from approximately 0.2 micrometers to approximately 1 millimeter. In further embodiments, the film thickness for each layer or sublayer can range from approximately 0.5 micrometers to approximately 500 micrometers. In yet further embodiments, the film thickness for each layer or sublayer can range from approximately 1 micrometer to approximately 100 micrometers.

[0044] One or both of the barrier layers 110, 112 can independently be transparent, translucent, and/or opaque. As used herein, the term transparent for a barrier layer means that light passes through the barrier layer in substantially straight lines and a viewer can see through the barrier layer. In comparison, for an opaque barrier layer, light does not pass through the barrier layer and one cannot see clearly through the barrier layer at all. A translucent barrier layer falls between a transparent barrier layer and an opaque barrier layer, in that light passes through a translucent layer but some of the light is scattered so that a viewer cannot see clearly through the layer.

[0045] The barrier layers 110, 112 can each be produced from an elastomeric material that includes one or more thermoplastic polymers and/or one or more cross-linkable polymers. In an aspect, the elastomeric material can include one or more thermoplastic elastomeric materials, such as one or more thermoplastic polyurethane (TPU) copolymers, one or more ethylene-vinyl alcohol (EVOH) copolymers, and the like.

[0046] As used herein, polyurethane refers to a copolymer (including oligomers) that contains a urethane group (N(CO)O). These polyurethanes can contain additional groups such as ester, ether, urea, allophanate, biuret, carbodiimide, oxazolidinyl, isocynaurate, uretdione, carbonate, and the like, in addition to urethane groups. In an aspect, one or more of the polyurethanes can be produced by polymerizing one or more isocyanates with one or more polyols to produce copolymer chains having (N(CO)O) linkages.

[0047] Examples of suitable isocyanates for producing the polyurethane copolymer chains include diisocyanates, such as aromatic diisocyanates, aliphatic diisocyanates, and combinations thereof. Examples of suitable aromatic diisocyanates include toluene diisocyanate (TDI), TDI adducts with trimethyloylpropane (TMP), methylene diphenyl diisocyanate (MDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated xylene diisocyanate (HXDI), naphthalene 1,5-diisocyanate (NDI), 1,5-tetrahydronaphthalene diisocyanate, para-phenylene diisocyanate (PPDI), 3,3-dimethyldiphenyl-4,4-diisocyanate (DDDI), 4,4-dibenzyl diisocyanate (DBDI), 4-chloro-1,3-phenylene diisocyanate, and combinations thereof. In some embodiments, the copolymer chains are substantially free of aromatic groups.

[0048] In particular aspects, the polyurethane polymer chains are produced from diisocynates including HMDI, TDI, MDI, H12 aliphatics, and combinations thereof. In an aspect, the thermoplastic TPU can include polyester-based TPU, polyether-based TPU, polycaprolactone-based TPU, polycarbonate-based TPU, polysiloxane-based TPU, or combinations thereof.

[0049] In another aspect, the polymeric layer can be formed of one or more of the following: EVOH copolymers, poly(vinyl chloride), polyvinylidene polymers and copolymers (e.g., polyvinylidene chloride), polyamides (e.g., amorphous polyamides), amide-based copolymers, acrylonitrile polymers (e.g., acrylonitrile-methyl acrylate copolymers), polyethylene terephthalate, polyether imides, polyacrylic imides, and other polymeric materials known to have relatively low gas transmission rates. Blends of these materials as well as with the TPU copolymers described herein and optionally including combinations of polyimides and crystalline polymers, are also suitable.

[0050] The barrier layers 110, 112 may include two or more sublayers (multilayer film) such as shown in Mitchell et al., U.S. Pat. No. 5,713,141 and Mitchell et al., U.S. Pat. No. 5,952,065, the disclosures of which are incorporated by reference in their entirety. In embodiments where the barrier layers 110, 112 include two or more sublayers, examples of suitable multilayer films include microlayer films, such as those disclosed in Bonk et al., U.S. Pat. No. 6,582,786, which is incorporated by reference in its entirety. In further embodiments, barrier layers 110, 112 may each independently include alternating sublayers of one or more TPU copolymer materials and one or more EVOH copolymer materials, where the total number of sublayers in each of the barrier layers 110, 112 includes at least four (4) sublayers, at least ten (10) sublayers, at least twenty (20) sublayers, at least forty (40) sublayers, and/or at least sixty (60) sublayers.

[0051] The chamber 116 can be produced from the barrier layers 110, 112 using any suitable technique, such as thermoforming (e.g. vacuum thermoforming), blow molding, extrusion, injection molding, vacuum molding, rotary molding, transfer molding, pressure forming, heat sealing, casting, low-pressure casting, spin casting, reaction injection molding, radio frequency (RF) welding, and the like. In an aspect, the barrier layers 110, 112 can be produced by co-extrusion followed by vacuum thermoforming to produce the chamber 116.

[0052] In some embodiments, the chamber 116 has a gas transmission rate for nitrogen gas that is at least approximately ten (10) times lower than a nitrogen gas transmission rate for a butyl rubber layer of substantially the same dimensions. In an aspect, chamber 116 has a nitrogen gas transmission rate of 15 cubic-centimeter/square-meter.Math.atmosphere.Math.day (cm.sup.3/m.sup.2.Math.atm.Math.day) or less for an average film thickness of 500 micrometers (based on thicknesses of the barrier layers 110, 112). In further aspects, the transmission rate is 10 cm.sup.3/m.sup.2.Math.atm.Math.day or less, 5 cm.sup.3/m.sup.2.Math.atm.Math.day or less, or 1 cm.sup.3/m.sup.2.Math.atm.Math.day or less.

[0053] The barrier layers 110, 112 are bonded together at the peripheral seam 118, as mentioned above, and the molded knit infill material 102 (i.e., the knit infill material having the waveform infill geometry 104) is disposed within the chamber 116. While the barrier layers 110, 112 are bonded at the peripheral seam 118, the knit infill material 102 is generally unattached or otherwise unbonded with the barrier layers 110, 112. For example, the knit infill material 102 is positioned within the interior void 114 while being free from bonding with the barrier layers 110, 112. Thus, the bladder 100 includes the knit infill material 102 disposed within the interior void 114 of the chamber 116 between the first barrier layer 110 and the second barrier layer 112. It is contemplated that the bond along the peripheral seam 118 maintains the position of the knit infill material 102 within the chamber 116 while being free from direct bonding between the barrier layers 110, 112 and the knit infill material 102. Additionally or alternatively, in other examples, portions of the knit infill material 102 may be selectively attached to the barrier layers 110, 112.

[0054] For example, as illustrated in FIG. 4, the knit infill material 102 includes a perimeter edge 120 that is free from peaks and valleys and, thus, is substantially flat. The perimeter edge 120 may be positioned between the barrier layers 110, 112 along the peripheral seam 118 to anchor the knit infill material 102 within the chamber 116 around a majority or an entirety of the perimeter edge 120. In other examples, a portion of the peripheral seam 118 proximate to the interior void 114 may remain unbonded during manufacturing, such that the perimeter edge 120 of the knit infill material 102 may be placed between the barrier layers 110, 112 during assembly while remaining free from direct bonding with the barrier layers 110, 112. At this point, the portion of the perimeter edge 120 disposed between the barrier layers 110, 112 at the peripheral seam 118 may be joined to the barrier layers 110, 112 to fix the perimeter edge 120 for movement with the peripheral seam 118. In situations where the knit infill material 102 is not attached to the barrier layers 110, 112, the perimeter edge 120 of the knit infill material 102 may abut the bladder 100 proximate to the peripheral seam 118 to aid in fixing a position of the knit infill material 102 relative to and within the bladder 100.

[0055] Referring now to FIGS. 5A-7, the knit infill material 102 includes a first material and a second material. It is contemplated that the first material may be a fusible yarn and the second material may be a polyester yarn. In one example, the knit infill material 102 may be approximately fifty (50) percent fusible yarn and approximately fifty (50) percent polyester yarn. In other examples, the knit infill material 102 may include greater than approximately fifty (50) percent of one of the first material and/or the second material and a correspondingly adjusted ratio for the other of the first material and/or the second material. In some examples, the first material may be a nylon or polyamide material. The first material is configured to provide additional stiffness to the knit infill material 102 and, thus, the bladder 100. For example, the first material may have a larger knit denier as compared to the second material. Further, when heat is applied to the knit infill material 102, the applied heat may cause the first material to at least partially melt and flow, thereby causing the infill material 102 to conform to the geometries of the first mold 202 and the second mold 204. The material of the first material may meld with itself and, further, may fuse the material of the second material into the shape shown in FIG. 4. Accordingly, when the knit infill material 102 cools, the first material once again hardens and retains the waveform shape imparted to the knit infill material 102 by the first mold 202 and the second mold 204.

[0056] In some configurations, the first material may have a different color than the second material, such that the contrasting colors of the first and second materials provides the knit infill material 102 with a color-changing appearance. For example, the knit infill material 102 may be configured to appear to change colors between a relaxed state (FIG. 5A) and a constricted state (FIG. 5B) of the bladder 100. As the bladder 100 transitions between the relaxed state and the constricted state, the first and second materials cooperate to define a color change appearance of the knit infill material 102. As the fibers of the first and second materials are drawn together and apart, the fibers change position. In so doing, the fibers provide the infill material 102 with a change in appearance (i.e., color) when the infill material 102 is moved with the bladder 100 between the relaxed state and the constricted state.

[0057] The first and second materials may be interwoven via a mesh needle, which defines a plurality of openings 122 along the knit infill material 102. The openings 122 are configured to provide the knit infill material 102 with a degree of flexibility, while the infill geometry 104 maximizes the structural density. The plurality of openings 122 may have a generally circular shape prior to molding of the knit infill material 102 and, after the molding process, have a generally oblong or elongated shape. For example, FIG. 6 illustrates an enlarged view of a portion of the molded knit infill material 102 with individual threads 124 interspaced with the plurality of openings 122. It is contemplated that the threads 124 are formed from the interwoven first material and second material, which collectively define the openings 122. As generally mentioned above, the knit infill material 102 is molded into a waveform geometry, such that a plurality of peaks 130 and valleys 132 are defined along the knit infill material 102. The mold assembly 200 (FIG. 2A) is configured to define a large number of peaks 130 and valleys 132 along the knit infill material 102. This structure provides the molded knit infill material 102 with the ability to flex and bend while still retaining the waveform infill geometry 104 provided by the peaks 130 and valleys 132. In short, the peaks 130 and valleys 132 allow the knit infill material 102 to easily bend about a longitudinal axis of each peak 130 and valley 132, resist such bending in a direction substantially perpendicular to the longitudinal axis of each peak 130 and valley 132, and retain the overall waveform shape of the molded infill material 102.

[0058] The peaks 130 may be spaced apart in a row by approximately 2.6 millimeters to define the valleys 132. In other examples, the peaks 130 may be spaced apart by more than approximately 2.6 millimeters or less than approximately 2.6 millimeters. Each of the peaks 130 includes an apex 134 at which the knit infill material 102 is configured to flex or hinge between a relaxed state and a compressed state. For example, the peaks 130 are designed to hinge the knit material 102 about the respective apex 134 to draw sidewalls 136 of the peaks 130 together in the compressed state. The constriction of the sidewalls 136 toward one another ultimately constricts the knit infill material 102 and, thus, the bladder 100. The resilient nature of the molded infill material 102 causes the peaks 130 to be biased into the relaxed or expanded state. Accordingly, when a force exerted on the infill material 102 that causes the infill material 102 to be in the compressed state is released, the resilient nature of the infill material 102, along with the shape of each peak 130, causes the infill material 102 to automatically move into the relaxed or expanded state such that adjacent peaks 130 move away from one another.

[0059] As described herein, the bladder 100 may be integrated as a portion of an article of footwear 10 (FIGS. 1A and 1B), such that the constriction of the peaks 130 of the knit infill material 102 constricts the portion of the footwear 10 in which the knit infill material 102 and bladder 100 are incorporated. The peaks 130 of the knit infill material 102 may, in some examples, have a height H.sub.130 of approximately 10.5 millimeters. In other examples, the height H.sub.130 of the peaks 130 may be greater than approximately 10.5 millimeters or may be less than approximately 10.5 millimeters. Further, in one example, the peaks 130 may have a width W.sub.130 of approximately 10.5 millimeters and, in other examples, have a width W.sub.130 of greater than approximately 10.5 millimeters or less than approximately 10.5 millimeters.

[0060] The valleys 132 defined between each of the peaks 130 define a flexion angle 138 between adjacent peaks 130. The flexion angle 138 may include a first flexion angle corresponding to the relaxed state of the knit infill material 102 and a second flexion angle corresponding to the compressed state of the knit infill material 102. It is generally contemplated that the first flexion angle is greater than the second flexion angle, as the peaks 130 are spaced apart in the relaxed state as compared to the compressed state. A plurality of intermediate flexion angles may be defined between full relaxation of the knit infill material 102 and full constriction of the knit infill material 102, such that the peaks 130 may be angularly spaced to varying degrees depending on a vacuum drawn within the interior void 114 of the bladder 100 to constrict the knit infill material 102. In some examples, the flexion angle 138, in the relaxed state, may be approximately 31.8 degrees between adjacent peaks 130. However, it is contemplated that the flexion angle 138 may be equal to approximately 31.8 degrees or less than approximately 31.8 degrees depending on the placement of the bladder 100. Stated differently, a distance D.sub.130 between a respective apex 134 of adjacent peaks 130 may be approximately 11 millimeters. However, depending on the configuration and flexion angle 138, the distance D.sub.130 between each apex 134 may be greater than approximately 11 millimeters or may be less than approximately 11 millimeters.

[0061] The valleys 132 also include a hinge point 140 at which the peaks 130 flex or hinge between the relaxed state and the compressed state. The biasing of the apex 134 and the hinge point 140 of the valleys 132, in combination with the flexion angle, is configured to minimize elongation of the knit infill material 102 in the compressed state. The knit infill material 102 biases at the apex 134 and hinge point 140 of the peaks 130 and valleys 132, respectively, as a fluid is removed from the bladder 100 to generally define a vacuum.

[0062] With particular reference to FIGS. 1A, 1B, 5A, and 5B, operation of the bladder 100 and associated infill material 102 will be described in detail. While the bladder 100 will be described and shown in conjunction with the footwear 10 of FIGS. 1A and 1B, the bladder 100 could be used in conjunction with an article of apparel. Further, FIGS. 8A and 8B show another example of an article of footwear 10a including the bladder 100a disposed within a throat 12a of the footwear 10a. Operation of the bladder 100a is similar to operation of the bladder 100. Accordingly, operation of the bladder 100a is foregone.

[0063] When the bladder 100 is in the relaxed state, the interior void 114 is at substantially atmospheric pressure. Accordingly, the resilient nature of the material forming the infill material 102 along with the peaks 130 and valleys 132 of the infill material 102, cause the infill material 102 to move into the expanded state. In this position, the peaks 130 move away from one another until the infill material 102 is in the relaxed or expanded state. Because the infill material 102 is either fully or partially fixed for movement with the bladder 100 or, alternatively, abuts portions of the bladder 100 (i.e., the perimeter edge 120 contacting the seam 118), movement of the infill material 102 into the expanded state likewise causes the bladder 100 to move into the relaxed or expanded state. In this position, an opening to the article of footwear 10 is increased, thereby facilitating entry of a wearer's foot into the footwear 10 or removal of a wearer's foot from the footwear 10.

[0064] The bladder 100 and, thus, the infill material 102, may be moved into the constricted state by removing fluid from the interior void 114. For example, a pump (not shown) may be used to remove fluid from the interior void 114, thereby placing the interior void 114 under a vacuum. In so doing, the barrier layers 110, 112 move toward one another and the infill material 102 is contracted. Specifically, the walls 136 of the peaks 130 move toward one another such that the peaks 134 move toward one another and the overall size of the infill material 102 is reduced (FIG. 5B). The constricted state results in the infill material 102 folding on itself along the longitudinal axis of each peak 130 and valley 132, thereby causing the barrier layers 110, 112 to take on a similar shape as the folded infill material (FIG. 5B). In so doing, the opening of the article of footwear 10 is constricted about the wearer's foot during use.

[0065] The wearer may release the vacuum pressure, thereby allowing fluid to once again enter the interior void 114 of the bladder 100. At this point, the resilient nature of the material forming the infill material 102 along with the shape of the infill material 102 cooperate to automatically move the infill material 102 into the expanded state. As described above, movement of the infill material 102 into the expanded state likewise causes movement of the bladder 100 into the expanded state. At this point, the opening to the article of footwear 10 is increased and the footwear 10 may be removed from a wearer's foot.

[0066] The knit infill material 102 may have a contraction ratio greater than or equal to approximately forty (40) percent. Further, the knit infill material 102 has a tensile force of greater than or equal to approximately twenty (20) kilogram force per square millimeter (kgf/mm.sup.2). In one example, the knit infill material 102 may have a tensile force of approximately forty-eight (48) kgf/mm.sup.2. In other examples, the bladder 100 including the knit infill material 102 may be utilized in combination with other fastening or securing features, such as laces, to further secure the portion of the footwear 10 around the foot of the wearer.

[0067] With further reference to FIGS. 5A-7, in some configurations, the bladder 100 may include one or more reinforcements 150 disposed along an exterior surface 152 of one or both of the barrier layers 110, 112. The reinforcements 150 may be formed of, in one example, a pliable, knit material to reinforce the structure of the bladder 100 while facilitating constriction of the bladder 100. The reinforcements 150 may be configured to protect the bladder 100 from exterior abrasions while providing an added degree of strength to the bladder 100. The reinforcements 150 may be positioned at various locations along the bladder 100 and/or may be disposed across the outermost barrier layer 110, 112. The reinforcements 150 may at least partially stiffen the bladder 100 as a whole and increase the tensile strength of the bladder 100.

[0068] The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular configuration are generally not limited to that particular configuration, but, where applicable, are interchangeable and can be used in a selected configuration, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.