Patent Description:
<CIT> discloses bladders for articles of footwear.

Sole structures generally include a layered arrangement extending between a ground surface and the upper. One layer of the sole structure includes an outsole that provides abrasion-resistance and traction with the ground surface. The outsole may be formed from rubber or other materials that impart durability and wear-resistance, as well as enhance traction with the ground surface. Another layer of the sole structure includes a midsole disposed between the outsole and the upper. The midsole provides cushioning for the foot and may be partially formed from a polymer foam material that compresses resiliently under an applied load to cushion the foot by attenuating ground-reaction forces. The midsole may additionally or alternatively incorporate a fluid-filled bladder to increase durability of the sole structure, as well as to provide cushioning to the foot by compressing resiliently under an applied load to attenuate ground-reaction forces. Sole structures may also include a comfort-enhancing insole or a sockliner located within a void proximate to the bottom portion of the upper and a strobel attached to the upper and disposed between the midsole and the insole or sockliner.

Midsoles employing bladders typically include a bladder formed from two barrier layers of polymer material that are sealed or bonded together. The bladders may contain air, and may incorporate tensile members within the bladder to retain the shape of the bladder when compressed resiliently under applied loads, such as during athletic movements. Generally, bladders are designed with an emphasis on balancing support for the foot and cushioning characteristics that relate to responsiveness as the bladder resiliently compresses under an applied load
SI-Unit:
<NUM> atmosphere = <NUM> kPa.

Aspects of the disclosure may include one or more of the following optional features.

In some examples, the peripheral wall defines an anterior end of the support chamber having one or more lobes extending from the top wall to the bottom wall. In some implementations, the one or more lobes includes a first lobe disposed adjacent to a first side of the support chamber and a second lobe disposed adjacent to a second side of the support chamber, the first side being disposed on an opposite side of the support chamber than the second side. In some configurations, the peripheral wall defines a recess disposed between the first lobe and the second lobe.

In some examples, the peripheral wall defines a posterior end of the support chamber having one or more lobes extending from the top wall to the bottom wall. The one or more lobes may include a third lobe disposed adjacent to a first side of the support chamber and a fourth lobe disposed adjacent to a second side of the support chamber, the first side being disposed on an opposite side of the support chamber than the second side. Here, the expansion chamber may be disposed between the third lobe and the fourth lobe.

The expansion chamber includes a flat upper wall and a curved lower wall. The lower wall projects outwardly from the peripheral wall of the support chamber between the top wall and the bottom wall. The lower wall is cupped and the top wall is planar.

The support chamber and the expansion chamber cooperate to define an interior void of the bladder. Optionally, the interior void is filled with a compressible fluid at atmospheric pressure.

In some configurations, the bladder further includes one or more valves in fluid communication with the support chamber.

In some implementations, the top wall defines a recess and the bottom wall is planar.

In some examples, a thickness of the expansion chamber tapers along at least one of a width and a length of the expansion chamber.

In another example not in accordance with the claimed invention, a bladder for an article of footwear is provided. The bladder includes a support chamber defining a first portion of an interior void. The support chamber includes a first lobe and a second lobe disposed at a first end. The bladder further includes an expansion chamber disposed between the first lobe and the second lobe at the first end of the support chamber. The expansion chamber defines a second portion of the interior void, and is in fluid communication with the first portion. The interior void contains a compressible fluid at a first pressure.

Examples of the disclosure may include one or more of the following optional features.

In some examples, the first pressure is atmospheric pressure.

In some implementations, each of the first lobe and the second lobe protrudes from the first end.

In some configurations, each of the first lobe and the second lobe is rounded.

In some examples, each of the first lobe and the second lobe is cylindrical.

In some implementations, the first end of the support chamber includes a curved central portion disposed between the first lobe and the second lobe. Here, the central portion may be cylindrical. In some examples, the expansion chamber protrudes from the central portion.

In some implementations, the support chamber includes a planar bottom wall and a top wall disposed on an opposite side of the bladder from the bottom wall, the top wall defining a recess.

In some configurations, the support chamber includes a third lobe and a fourth lobe disposed at a second end of the support chamber. Optionally, each of the third lobe and the fourth lobe protrudes from the first end. In some examples, each of the third lobe and the fourth lobe is rounded. In some implementations, each of the third lobe and the fourth lobe is cylindrical.

In some implementations, the first end of the support chamber includes a curved central portion disposed between the first lobe and the second lobe.

In some examples, the bladder includes one or more valves in fluid communication with the support chamber.

In another example, a sole structure for an article of footwear including the bladder of any of the preceding paragraphs is provided. In some examples, the sole structure includes a cushioning element extending from a first end to a second end and including (i) a top surface, (ii) a bottom surface formed on an opposite side of the cushioning element from the top surface, and (iii) a recess formed in the top surface and configured to receive the bladder therein.

In some implementations, the bladder and the top surface of the cushioning element cooperate to define a footbed of the sole structure.

Optionally, the cushioning element includes a foam material.

In another aspect of the disclosure, an article of footwear includes the sole structure described above.

Referring to <FIG>, an article of footwear <NUM> includes a sole structure <NUM> and an upper <NUM> attached to the sole structure <NUM>. The article of footwear <NUM> may be divided into one or more regions. The regions may include a forefoot region <NUM>, a mid-foot region <NUM>, and a heel region <NUM>. The mid-foot region <NUM> may correspond with an arch area of the foot, and the heel region <NUM> may correspond with rear portions of the foot, including a calcaneus bone. The footwear <NUM> may further include an anterior end <NUM> associated with a forward-most point of the forefoot region <NUM>, and a posterior end <NUM> corresponding to a rearward-most point of the heel region <NUM>. A longitudinal axis A<NUM> of the footwear <NUM> extends along a length of the footwear <NUM> from the anterior end <NUM> to the posterior end <NUM>, and generally divides the footwear <NUM> into a medial side <NUM> and a lateral side <NUM>, as shown in <FIG>. Accordingly, the medial side <NUM> and the lateral side <NUM> respectively correspond with opposite sides of the footwear <NUM> and extend through the regions <NUM>, <NUM>, <NUM>.

With reference to <FIG>, the sole structure <NUM> includes a bladder <NUM> and a cushioning element <NUM> within which the bladder <NUM> is disposed. Accordingly, the bladder <NUM> and the cushioning element <NUM> cooperate to define a footbed for supporting the upper <NUM>. Particularly, the bladder <NUM> is disposed within the heel region <NUM> of the cushioning element <NUM> to provide the heel region <NUM> of the sole structure <NUM> with different cushioning characteristics than the forefoot region <NUM> and the mid-foot region <NUM>.

As shown in the cross-sectional views of <FIG> and <FIG>, the bladder <NUM> may be formed by a barrier layer <NUM>, which can be j oined at discrete locations to define a geometry of the bladder <NUM>. As used herein, the term "barrier layer" (e.g., barrier layer <NUM>) encompasses both monolayer and multilayer films. In some embodiments, the barrier layer <NUM> is produced (e.g., thermoformed or blow molded) from a monolayer film (a single layer). In other embodiments, the barrier layer <NUM> is produced (e.g., thermoformed or blow molded) from a multilayer film (multiple sublayers). In either aspect, the barrier layer <NUM> can have a film thickness ranging from about <NUM> micrometers to about be about <NUM> millimeter. In further embodiments, the film thickness for the barrier layer <NUM> can range from about <NUM> micrometers to about <NUM> micrometers. In yet further embodiments, the film thickness for the barrier layer <NUM> can range from about <NUM> micrometer to about <NUM> micrometers.

The barrier layer <NUM> can be transparent, translucent, and/or opaque. As used herein, the term "transparent" for a barrier layer and/or a fluid-filled chamber 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.

The barrier layer <NUM> can 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.

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 <NUM>,<NUM>-diisocyanate (NDI), <NUM>,<NUM>-tetrahydronaphthalene diisocyanate, para-phenylene diisocyanate (PPDI), <NUM>,<NUM>' - dimethyldipheny1-<NUM>, <NUM>' -diisocyanate (DDDI), <NUM>,<NUM> '-dibenzyl diisocyanate (DBDI), <NUM>-chloro-<NUM>,<NUM>-phenylene diisocyanate, and combinations thereof. In some embodiments, the copolymer chains are substantially free of aromatic groups.

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.

The barrier layer <NUM> may include two or more sublayers (multilayer film) such as shown in <CIT> and <CIT>. In embodiments where the barrier layer <NUM> includes two or more sublayers, examples of suitable multilayer films include microlayer films, such as those disclosed in <CIT>. In further embodiments, the barrier layer <NUM> may include alternating sublayers of one or more TPU copolymer materials and one or more EVOH copolymer materials, where the total number of sublayers in the barrier layer <NUM> includes at least four (<NUM>) sublayers, at least ten (<NUM>) sublayers, at least twenty (<NUM>) sublayers, at least forty (<NUM>) sublayers, and/or at least sixty (<NUM>) sublayers.

The bladder <NUM> can be produced from the barrier layer <NUM> 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 layer <NUM> can be produced by co-extrusion followed by vacuum thermoforming to form the profile of the bladder <NUM>, which can optionally include one or more valves (e.g., one way valves) that allow the bladder <NUM> to be filled with the fluid (e.g., gas).

The bladder <NUM> desirably has a low gas transmission rate to preserve its retained gas pressure. In some embodiments, the bladder <NUM> has a gas transmission rate for nitrogen gas that is at least about ten (<NUM>) times lower than a nitrogen gas transmission rate for a butyl rubber layer of substantially the same dimensions. In an aspect, bladder <NUM> has a nitrogen gas transmission rate of <NUM> cubic-centimeter/square-meter•atmosphere•day (cm<NUM>/m<NUM>•atm•day) or less for an average film thickness of <NUM> micrometers (based on thicknesses of barrier layer <NUM>). In further aspects, the transmission rate is <NUM><NUM>/m<NUM>•atm•day or less, <NUM><NUM>/m<NUM>•atm•day or less, or <NUM><NUM>/m<NUM>•atm•day or less.

In the illustrated example, the barrier layer <NUM> encloses an interior void <NUM> of the bladder <NUM>. The interior void <NUM> can be provided in a fluid-filled or in an unfilled state. The interior void <NUM> can be filled to include any suitable fluid, such as a gas or liquid. In an aspect, the gas can include air, nitrogen (N<NUM>), or any other suitable gas. The fluid provided to the interior void <NUM> can be at atmospheric pressure such that the bladder <NUM> is not pressurized but, rather, simply contains a volume of the fluid at atmospheric pressure. In other aspects, the interior void <NUM> can alternatively include other compressible media, such as pellets, beads, ground recycled material, and the like (e.g., foamed beads and/or rubber beads).

With reference to <FIG>, the bladder <NUM> includes a support chamber <NUM> configured to provide cushioning to the heel of a foot. The support chamber <NUM> includes a top wall <NUM>, a bottom wall <NUM> formed on an opposite side of the bladder <NUM> from the top wall <NUM>, and a peripheral wall <NUM> extending from the top wall <NUM> to the bottom wall <NUM> and defining an outer peripheral profile of the bladder <NUM>. The support chamber <NUM> is further described as extending along a longitudinal axis A<NUM> from an anterior end <NUM> to a posterior end <NUM> formed at an opposite end from the anterior end <NUM>. A medial side <NUM> extends from the anterior end <NUM> to the posterior end <NUM> on a first side of the support chamber <NUM> and a lateral side <NUM> extends from the anterior end <NUM> to the posterior end <NUM> on an opposite side of the support chamber <NUM> from the medial side <NUM>.

As shown, the bottom wall <NUM> of the support chamber <NUM> is substantially planar from the anterior end <NUM> to the posterior end <NUM> and from the medial side <NUM> to the lateral side <NUM>, thereby providing a bottom portion of the bladder <NUM> with a planar support surface. The top wall <NUM>, however, may have a substantially planar interior portion and curve away from the bottom wall <NUM> adjacent to each of the medial side <NUM> and the lateral side <NUM>. Thus, the top wall <NUM> defines a slight recess <NUM> that extends continuously from the anterior end <NUM> to the posterior end <NUM> for receiving a heel portion of the foot.

As shown in <FIG>, the anterior end <NUM> of the support chamber <NUM> includes a pair of anterior lobes 124a, 124b extending from the top wall <NUM> to the bottom wall <NUM> on opposite sides of the longitudinal axis A<NUM>. Particularly, the anterior lobes 124a, 124b include a medial anterior lobe 124a formed at the anterior end <NUM> adjacent to the medial side <NUM> of the bladder <NUM> and a lateral anterior lobe 124b formed at the anterior end <NUM> adjacent to the lateral side <NUM> of the bladder <NUM>. Generally, the lobes 124a, 124b respectively form a protruding portion of the bladder <NUM> at the medial and lateral sides <NUM>, <NUM> of the support chamber <NUM>, while a central portion <NUM> (i.e., adjacent to the longitudinal axis A<NUM>) of the anterior end <NUM> forms an anterior recess <NUM> between the anterior lobes 124a, 124b.

With continued reference to <FIG>, each of the anterior lobes 124a, 124b protrudes from the anterior end <NUM> along a direction of the longitudinal axis A<NUM> to a respective anterior distal end 130a, 130b facing outwardly from the bladder <NUM>. When incorporated into the sole structure <NUM>, the anterior distal ends 130a, 130b face the anterior end <NUM> of the article of footwear <NUM>. As shown, the anterior distal ends 130a, 130b are formed by a convex portion of the peripheral wall <NUM>. Here, the peripheral wall <NUM> is cylindrical and has a radius R<NUM> extending from the respective side <NUM>, <NUM> and around the distal end 130a, 130b to the central portion <NUM>. In the central portion <NUM>, the peripheral wall <NUM> is concave and has a second radius R<NUM>. In some examples, the radius R<NUM> of each of the distal ends 130a, 130b may be the same as the radius R<NUM> of the central portion <NUM>. Here, the central portion <NUM> may also be cylindrical. In some instances, the peripheral wall <NUM> may include straight transition portions connecting the radius R<NUM> of the distal ends 130a, 130b and the radius R<NUM> of the central portion <NUM>.

Referring still to <FIG>, the posterior end <NUM> of the support chamber <NUM> includes a pair of posterior lobes 132a, 132b extending from the top wall <NUM> to the bottom wall <NUM> on opposite sides of the longitudinal axis A<NUM>. Particularly, the posterior lobes 132a, 132b include a medial posterior lobe 132a formed at the posterior end <NUM> adjacent to the medial side <NUM> of the support chamber <NUM> and a lateral posterior lobe 132b formed at the posterior end <NUM> adjacent to the lateral side <NUM> of the support chamber <NUM>. Generally, the posterior lobes 132a, 132b respectively form a protruding portion of the support chamber <NUM> at the medial and lateral sides <NUM>, <NUM> of the support chamber <NUM>, while a central portion <NUM> (i.e., adjacent to the longitudinal axis A<NUM>) of the posterior end <NUM> forms a posterior recess <NUM> between the posterior lobes 132a, 132b.

With continued reference to <FIG>, each of the posterior lobes 132a, 132b protrudes from the posterior end <NUM> along a direction of the longitudinal axis A<NUM> to a respective posterior distal end 138a, 138b facing outwardly from the bladder <NUM>. When incorporated into the sole structure <NUM>, the posterior distal ends 138a, 138b face the posterior end <NUM> of the article of footwear <NUM>. As shown, the posterior distal ends 138a, 138b are formed by a convex portion of the peripheral wall <NUM>. Here, the peripheral wall <NUM> has a third radius R<NUM> extending from the respective sides <NUM>, <NUM> and around the distal end 130a, 130b to the central portion <NUM>. In the central portion <NUM>, the peripheral wall <NUM> is concave and has a fourth radius R<NUM>. In some examples, the radius R<NUM> of each of the distal ends 138a, 138b may be the same as the radius R<NUM> of the central portion <NUM>. In some instances, the peripheral wall <NUM> may include straight transition portions connecting the radii R<NUM> of the posterior distal ends 138a, 138b and the radius R<NUM> of the central portion <NUM>.

The posterior end <NUM> of the support chamber <NUM> further includes an expansion chamber <NUM> formed between the posterior lobes 132a, 132b. As shown, the expansion chamber <NUM> may be described as including a lower wall <NUM> (<FIG>) extending from the peripheral wall <NUM> and an upper wall <NUM> (<FIG>) extending from the top wall <NUM>. In other words, the lower wall <NUM> of the expansion chamber <NUM> is formed by a portion of the barrier layer <NUM> that projects outwardly from an intermediate portion of the peripheral wall <NUM> between the top wall <NUM> and the bottom wall <NUM>, while the upper wall <NUM> is substantially continuously formed with the top wall <NUM>. Accordingly, the interior void <NUM> of the bladder <NUM> extends into the expansion chamber <NUM>, as shown in <FIG>.

With continued reference to <FIG>, the expansion chamber <NUM> extends from a proximal end <NUM> at the peripheral wall <NUM> of the support chamber <NUM>, to a distal end <NUM> formed at an opposite end of the expansion chamber <NUM> and facing away from the peripheral wall <NUM>. Regardless of the shape of the lower wall <NUM>, a width W<NUM> (<FIG>) and/or a thickness T<NUM> (<FIG>) of the expansion chamber <NUM> may taper along a direction from the proximal end <NUM> to the distal end <NUM>.

As shown in <FIG>, the lower wall <NUM> of the expansion chamber <NUM> is curved, and have a radius R<NUM>, while the upper wall <NUM> is substantially flat or planar. The lower wall <NUM> has a semi-spherical curvature, such that the lower wall <NUM> curves both about and along the longitudinal axis A<NUM> of the support chamber <NUM>. As shown, this semi-spherical curvature results in the lower wall <NUM> curving towards the upper wall <NUM> along a direction from the proximal end <NUM> to the distal end <NUM> and along a direction laterally-outwardly from the longitudinal axis A<NUM>. In other examples not in accordance with the claimed invention, the lower wall <NUM> may be substantially straight along the direction of the longitudinal axis A<NUM>, and curve about the longitudinal axis A<NUM> such that the lower wall <NUM> has a frustoconical shape.

By forming the expansion chamber <NUM> with a tapering width W<NUM> and thickness T<NUM>, the expansion chamber <NUM> is configured to accommodate changes in pressure associated with compression of the support chamber <NUM>. For example, in use, the top wall <NUM> and the bottom wall <NUM> of the support chamber <NUM> will be compressed towards each other when the heel of the sole structure strikes a ground surface, thereby compressing the fluid contained within the interior void <NUM> of the bladder <NUM>. As the compression increases, the fluid applies an outwardly-biasing pressure force to the barrier layer <NUM> and, more particularly, to the portions of the barrier layer <NUM> forming the peripheral wall <NUM> and the expansion chamber <NUM>. The geometry of the expansion chamber <NUM> dampens the pressure increase by deforming within the cushioning element <NUM>. Particularly, the tapered shape of the expansion provides progressive dampening, whereby the curved lower wall <NUM> is configured to deform at a desired rate relative to an increase in pressure within the interior void.

Optionally, the bladder <NUM> may include one or more valves <NUM> for controlling the pressure of the fluid inserted into the interior void during manufacturing of the bladder <NUM>. In the illustrated example, the bladder includes a first one of the valves <NUM> extending from the central portion <NUM> of the peripheral wall <NUM> at the anterior end <NUM>, and a second of the valves <NUM> extending from the distal end <NUM> of the expansion chamber <NUM>. These valves <NUM> are sealed once manufacturing of the bladder <NUM> is complete.

Referring now to <FIG> and <FIG>, the cushioning element <NUM> extends continuously from the anterior end <NUM> to the posterior end <NUM> of the article of footwear <NUM> and forms a ground-engaging surface <NUM> of the article of footwear <NUM>. As shown in <FIG>, the cushioning element <NUM> includes a top surface <NUM> that defines a portion of a footbed of the article of footwear <NUM>, a bottom surface <NUM> formed on an opposite side of the cushioning element <NUM> from the top surface <NUM> and defining the ground-engaging surface <NUM>, and an outer peripheral side surface <NUM> extending between the top surface <NUM> and the bottom surface <NUM> and defining an outer peripheral profile of the cushioning element <NUM>.

Referring still to <FIG>, the cushioning element <NUM> includes a cavity <NUM> formed in the top surface <NUM> and configured to receive the bladder <NUM> therein. The cavity <NUM> may be described as being defined by a recessed surface <NUM> that is spaced apart from the top surface <NUM> to define a depth D<NUM> of the cavity <NUM>, and an inner peripheral side surface <NUM> that extends from the recessed surface <NUM> to the top surface <NUM> and defines a peripheral profile of the cavity <NUM>. The depth D<NUM> of the cavity <NUM> corresponds to an overall thickness T<NUM> of the bladder <NUM> such that the top wall <NUM> of the bladder <NUM> is flush with the top surface <NUM> of the cushioning element <NUM> when the bladder <NUM> is disposed within the cavity <NUM>. Likewise, as best shown in <FIG> and <FIG>, the peripheral side surface <NUM> has a profile corresponding to the profile of the peripheral wall <NUM> and lower wall <NUM> of the bladder <NUM>, such that the bladder <NUM> experiences a snug fit within the cavity <NUM>.

Optionally, the cushioning element <NUM> may include one or more windows <NUM> extending from the outer peripheral side surface <NUM> to the inner peripheral side surface <NUM>. As shown, the cushioning element <NUM> includes a first window <NUM> on the lateral side of the cavity <NUM> and a second window <NUM> on a medial side of the cavity <NUM>, such that the windows <NUM> provide visibility of the bladder <NUM> within the cavity <NUM> when the article of footwear <NUM> is assembled. In some examples, the windows <NUM> may be configured to accommodate deformation of the peripheral wall <NUM> of the bladder <NUM> when the bladder <NUM> is compressed.

The cushioning element <NUM> is formed of a resilient polymeric material, such as foam or rubber, to impart properties of cushioning, responsiveness, and energy distribution to the foot of the wearer. Example resilient polymeric materials for cushioning element <NUM> may include those based on foaming or molding one or more polymers, such as one or more elastomers (e.g., thermoplastic elastomers (TPE)). The one or more polymers may include aliphatic polymers, aromatic polymers, or mixtures of both; and may include homopolymers, copolymers (including terpolymers), or mixtures of both.

In further aspects, the one or more polymers may include one or more polyamide copolymers (e.g., polyamide-polyether copolymers) and/or one or more polyurethanes (e.g., crosslinked polyurethanes and/or thermoplastic polyurethanes). Examples of suitable polyurethanes include those discussed above for barrier layer <NUM>. Alternatively, the one or more polymers may include one or more natural and/or synthetic rubbers, such as butadiene and isoprene.

When the resilient polymeric material is a foamed polymeric material, the foamed material may be foamed using a physical blowing agent which phase transitions to a gas based on a change in temperature and/or pressure, or a chemical blowing agent which forms a gas when heated above its activation temperature. For example, the chemical blowing agent may be an azo compound such as adodicarbonamide, sodium bicarbonate, and/or an isocyanate.

Referring now to <FIG>, the upper <NUM> is attached to the sole structure <NUM> and includes interior surfaces that define an interior void <NUM> configured to receive and secure a foot for support on the sole structure <NUM>. The upper <NUM> may be formed from one or more materials that are stitched or adhesively bonded together to form the interior void <NUM>. Suitable materials of the upper may include, but are not limited to, mesh, textiles, foam, leather, and synthetic leather. The materials may be selected and located to impart properties of durability, air-permeability, wear-resistance, flexibility, and comfort.

Claim 1:
A bladder (<NUM>) for an article of footwear (<NUM>), the bladder (<NUM>) comprising:
a support chamber (<NUM>) extending along a longitudinal axis (A<NUM>) from an anterior end (<NUM>) to a posterior end (<NUM>) formed at an opposite end from the anterior end (<NUM>) and having a top wall (<NUM>), a bottom wall (<NUM>), and a peripheral wall (<NUM>) extending between the top wall (<NUM>) and the bottom wall (<NUM>) and defining a peripheral profile of the support chamber (<NUM>); and
an expansion chamber (<NUM>) including a flat upper wall (<NUM>) and a curved lower wall (<NUM>), the expansion chamber (<NUM>) extending from the peripheral wall (<NUM>) at a first end of the bladder (<NUM>), wherein the lower wall (<NUM>) projects outwardly from the peripheral wall (<NUM>) of the support chamber (<NUM>) between the top wall (<NUM>) and the bottom wall (<NUM>), and
wherein the lower wall (<NUM>) has a semi-spherical curvature, such that the lower wall (<NUM>) curves both about and along the longitudinal axis (A<NUM>) of the support chamber (<NUM>).