具体实施方式：
[0019]The present disclosure is directed to a foam article which includes a first component, i.e., a thermoplastic foam component compositionally comprising a foamed first thermoplastic composition. In other words, the foamed first thermoplastic composition retains its thermoplastic properties, and can be recycled by melting the foamed first thermoplastic composition, and re-forming the first thermoplastic composition it into a new foamed article or a new solid (i.e., unfoamed) article. The first component is a foam component that includes a foamed first thermoplastic composition having a multicellular foam structure. In some aspects, the multicellular foam structure is an open-cell foam structure. In other aspects, the multicellular foam structure is a closed-cell foam structure. In some aspects, the foamed first thermoplastic composition comprises one or more copolyesters, such as, for example, one or more copolyester elastomers. In some aspects, the first thermoplastic composition further comprises one or more non-polymeric ingredients, such as a filler or a nucleating agent or a pigment. The one or more non-polymeric ingredients can comprise 5 weight percent or less of the first thermoplastic composition based on the total weight of the first thermoplastic composition. It has been found, for thermoplastic foams, particularly thermoplastic foams compositionally comprising at least one thermoplastic copolyester elastomer, that including low levels (e.g., 5 weight percent or less) of non-polymeric ingredients such as fillers, nucleating agents and pigments can improve the consistency of the sizes of the cells in the multicellular thermoplastic foam. In addition to improving the cell structure, including low levels of non-polymeric ingredients in the first thermoplastic composition can also increase recyclability of the first thermoplastic composition, due to the high polymeric content of these thermoplastic compositions. The first thermoplastic composition can be free of or essentially free of fillers. The first thermoplastic composition can be free of or essentially free of nucleating agents. The first thermoplastic composition can be free or essentially free of pigments. The first thermoplastic composition can be free of or essentially free of fillers and nucleating agents, or can be free or essentially free of fillers, nucleating agents, and pigments. The first thermoplastic composition can be free of or essentially free of non-polymeric ingredients. The foam article is particularly useful as a cushioning element.
[0020]In some aspects, the disclosed foam article also includes a second component comprising a second thermoplastic composition. In such aspects, the second component can be disposed on or in at least a portion of the first component. The second component can comprise a polymeric layer disposed on at least a portion of an external surface of the foamed first thermoplastic composition of the first component. The second component comprises a second thermoplastic composition which retains its thermoplastic properties and can be recycled by melting the second thermoplastic composition, and re-forming the second thermoplastic composition it into a new foamed article or a new solid (i.e., unfoamed) article. As both the first component and the second component are formed of thermoplastic compositions, the first and the second components need not be separated before being recycled. For example, the foam article can be recycled by grinding or shredding the entire article and forming a molten polymeric composition which is a mixture of both the first thermoplastic composition and the second thermoplastic composition. The second thermoplastic composition can comprise a thermoplastic elastomer or a thermoplastic vulcanizate material. The second thermoplastic composition can comprise a one or more thermoplastic styrene copolymer elastomers, including styrene-ethylene-butene-styrene (SEBS) copolymer elastomers. The second thermoplastic composition can comprise one or more thermoplastic polyurethane elastomers, alone or blended with other polymers such as, for example, an ethylene-vinyl alcohol copolymer, or a styrene copolymer elastomer. Second thermoplastic compositions which comprise a thermoplastic copolyester elastomer, or a thermoplastic polyurethane elastomer, or a thermoplastic styrene copolymer elastomer, or a thermoplastic vulcanizate material, have been found to form strong thermal bonds with foamed first thermoplastic compositions comprising one or more thermoplastic copolyester elastomers. The foam article disclosed herein is particularly useful as a cushioning element. The foam article including the first component and the second component is particularly useful as a cushioning element for an article of footwear, apparel or sporting equipment. For example, the first component of the foam article can be a midsole or a midsole component. The second component of the foam article can be a ground contacting component such as an outsole, or a protective element such as a rand, on an article of footwear, which provides a greater level of abrasion resistance or provides better traction or which provides both, as compared to the first foam component alone. The second component of the foam article can be a protective or reinforcing layer or a containment layer on the first foam component, such as when the first foam component is a cushioning element, or in other applications. In some aspects, when the first component has an open-cell foam structure, the second component can be a water-resistant barrier to reduce or prevent water uptake by the open cell structure of the foam.
[0021]Conventionally, vulcanized and peroxide-cured natural and synthetic rubbers such as isoprene and polybutadiene rubbers have been used to form durable, abrasion-resistant outer protective layers for a wide variety of articles, including outsoles for articles of footwear. Rubber formulations used for outsoles also typically provide traction. One disadvantage of using conventional rubber materials is that these materials are highly crosslinked during the curing process, rendering the cured rubber a thermoset material and making it difficult to recycle or reuse the cured rubber. Also, it can be difficult to bond other materials to the cured rubber. Both the rubber materials and foam materials typically used in a wide variety of consumer good are highly crosslinked materials, which are formed and cured separately and then adhered to each other using an adhesive system. These adhesive systems require several manually-intensive processing steps, such as cleaning the surfaces, priming the surfaces, applying adhesive to the surfaces, and pressing the surfaces together to bond them.
[0022]It has been found that thermoplastic compositions (e.g., thermoplastic compositions comprising one or more thermoplastic copolyester elastomer) can be used to form multicellular foams having advantageous properties for use in consumer articles such as cushioning elements. When foamed as described herein, these foams retain thermoplastic properties, making it possible to readily recycle and reuse the thermoplastic compositions. Additionally, it has been found that these foams can be directly molded and foamed onto other polymeric materials (i.e., onto second thermoplastic compositions as described herein), which bonds the foam securely to the second thermoplastic composition with a thermal bond without the need for additional adhesives, or the manual process steps of applying an adhesive system. The second thermoplastic composition which is bonded to the thermoplastic foam can be a thermoplastic elastomeric material, such as a second thermoplastic composition as described herein. Examples of both second thermoplastic compositions which, when used either in solid form or in a lightly foamed form (e.g., having a specific gravity of 0.85 or greater) have been found which both bond well to the thermoplastic copolyester-based foam during a molding and foaming process, and which also provide high levels of abrasion resistance and traction under wet and dry conditions, are described herein. When the second thermoplastic composition comprises a second thermoplastic copolyester, the fact that the foam comprises a first thermoplastic copolyester and that the polymeric layer comprises a second thermoplastic copolyester composition provides the advantage that the entire article can easily be melted down and the combined material can be recycled. In this scenario, the second copolyester composition can each individually include one or more of the same individual copolyesters present in the first thermoplastic copolyester composition, either in the same proportions or in different proportions. Alternatively, the first and second copolyester compositions can each individually comprise different copolyesters.
[0023]The foam components disclosed herein are formed by foaming thermoplastic compositions comprising one or more thermoplastic elastomer into a multicellular foam having an open-cell or closed-cell foam structure. In some examples, the one or more thermoplastic elastomer can comprise or consist essentially of a thermoplastic copolyester elastomer. Examples of thermoplastic copolyester elastomers include polymers which have one or more carboxylic acid moieties present in the polymeric backbone, on one or more side chains, or both in the polymeric backbone and on one or more side chains. The one or more carboxylic acid moieties of the thermoplastic copolyester can include a free carboxylic acid, a salt of a carboxylic acid, or an anhydride of a carboxylic acid. In particular examples, the carboxylic acid moiety can be an acrylic acid moiety or a methacrylic acid moiety. The foam articles comprising a multicellular open-cell or closed-cell thermoplastic foam and a polymeric layer of the present disclosure are suitable for use in a variety of articles including for athletic equipment and apparel, particularly footwear (e.g., athletic footwear midsoles/outsoles). As discussed below, the multicellular open-cell or closed-cell thermoplastic foam exhibits a unique balance of properties such as high energy efficiency or energy return, and low specific gravity. In some examples, the multicellular foam also exhibits a high split tear and low compression set. The presence of the polymeric layer on at least a portion of the exterior surface of the foam can reduce or prevent liquid uptake by the multicellular foams, particularly multicellular open-cell foams, increasing their performance when used under conditions where the foam come into contact with liquids. Furthermore, the thermoplastic foam can also be reprocessed with minimal loss in physical properties (e.g., for recycling), providing a solution for materials sustainability.
[0024]The second thermoplastic composition of the polymeric layer can be selected to allow the entire foam article to be recycled in a single step, without the need to remove or separate the polymeric layer from the foam. For example, the second thermoplastic composition can comprise one or more thermoplastic copolyesters.
[0025]The foam article or foam component comprising the thermoplastic c foam can be formed by injection molding and foaming the thermoplastic composition as described herein, or by injection molding and foaming the thermoplastic composition as described herein into a foam preform and subsequently compression molding the foam-preform into a finished foam. The second thermoplastic composition can be disposed onto an exterior surface of the foam component during an injection molding and foaming process, in which the first thermoplastic composition is injected into a mold which includes the second thermoplastic composition, and the second thermoplastic composition bonds to the foam during the molding process. Alternatively or additionally, the second thermoplastic composition can be disposed onto the exterior surface of the foam component during a compression molding step, in which the foam component is compression molded in a mold which includes the second thermoplastic composition, and the second thermoplastic composition bonds to the foam during the molding process. Alternatively or additionally, the second thermoplastic composition can be disposed onto the foam component after the foam component has been formed, such as, for example, by vacuum forming a film comprising the second thermoplastic composition to the foam component.
Articles Manufactured Using the Disclosed Foams.
[0026]Footwear 10 is an exemplary article of athletic footwear that includes the thermoplastic foam of the present disclosure. While illustrated as a running shoe, footwear 10 may alternatively be configured for any suitable athletic performance, such as baseball shoes, basketball shoes, soccer/global football shoes, American football shoes, running shoes, cross-trainer shoes, cheerleading shoes, golf shoes, and the like. While an athletic shoe is exemplified in FIG. 1, it will be readily understood that some of the terminology employed will also apply to other articles of footwear or to other styles of shoe. Footwear 10 includes an upper 12 and a sole component 14 secured to upper 12. Sole component 14 can be secured to upper 12 by adhesive or any other suitable means. As used herein, the sole component 14 can be a monolithic component formed entirely of the thermoplastic foam material as described herein, or a multi-component assembly formed of a plurality of monolithic components, where at least one of the monolithic components is formed entirely of the thermoplastic foam material as described herein.
[0027]Footwear 10 has a medial, or inner, side 16 and a lateral, or outer, side 18. For ease of discussion, footwear 10 can be divided into three portions: a forefoot portion 20, a midfoot portion 22, and a heel portion 24. Portions 20, 22, and 24 are not intended to demarcate precise areas of footwear 10. Rather, portions 20, 22, and 24 are intended to represent respective areas of footwear 10 that provide a frame of reference during the following discussion. Unless indicated otherwise, directional terms used herein, such as rearwardly, forwardly, top, bottom, inwardly, downwardly, upwardly, etc., refer to directions relative to footwear 10 itself. Footwear 10 is shown in FIG. 1 in a substantially horizontal orientation, as it would be positioned on a horizontal surface when worn by a wearer. However, it is to be appreciated that footwear 10 need not be limited to such an orientation. Thus, in FIG. 1, rearwardly is toward heel portion 24 (to the right as seen in FIG. 1), forwardly is toward forefoot portion 20 (to the left as seen in FIG. 1), and downwardly is toward the bottom of the page as seen in FIG. 1. Top refers to elements toward the top of the view in FIG. 1, while bottom refers to elements toward the bottom of the view in FIG. 1. Inwardly is toward the center of footwear 10, and outwardly is toward the outer peripheral edge of footwear 10.
[0028]The component can be a sole component, such as a sole component 14 depicted in FIGS. 1-5, that includes a thermoplastic foam, including a thermoplastic copolyester foam, as described herein. The component can be an insert such as insert 36 or insert 60 depicted in FIGS. 4-5 that includes a thermoplastic foam described herein. The sole components and inserts for sole components can be made partially or entirely of a thermoplastic foam described herein. Any portion of a sole component or an insert for a sole component can be made of a thermoplastic foam described herein. For example, first portion 26 of the sole component (optionally including the ground engaging lower surface 44, such as the plurality of projections 46 and/or the groove 48 surrounding the projections), the entire insert 36, portions 62 or 64 of insert 60, a separate outsole component, or any combination thereof, can include a thermoplastic foam as described herein. The sole components and inserts can be made by foaming thermoplastic compositions as described herein, for example by injection molding or by injection molding, optionally followed by compression molding, as described herein. In some aspects, the thermoplastic foams can be formed by physical foaming of the thermoplastic compositions. The thermoplastic foams and components can demonstrate improved physical properties including one or more of an enhanced energy efficiency or energy return, an enhanced split tear, a decreased specific gravity, or a combination thereof.
[0029]Sole component 14, which is generally disposed between the foot of the wearer and the ground, provides attenuation of ground reaction forces (i.e., imparting cushioning), traction, and may control foot motions, such as pronation. As with conventional articles of footwear, sole component 14 can include an insole (not shown) located within upper 12. In some aspects, the sole component is an insole or sockliner or is a multi-component assembly including an insole or sockliner, can further include an insole or sockliner located within the upper, where the insole or sockliner is formed entirely or partially of a thermoplastic foam described herein. Articles of footwear described herein can include an insole or sockliner formed entirely or partially of a thermoplastic foam described herein.
[0030]As can be seen in FIG. 2, sole component 14 consists of a first portion 26 having an upper surface 27 with a recess 28 formed therein. Upper surface 27 is secured to upper 12 with adhesive or other suitable fastening means. A plurality of substantially horizontal ribs 30 is formed on the exterior of first portion 26. In certain aspects, ribs 30 extend from a central portion of forefoot portion 20 on medial side 16 rearwardly along first portion 26, around heel portion 24 and forwardly on lateral side 18 of first portion 26 to a central portion of forefoot portion 20.
[0031]First portion 26 provides the external traction surface of sole component 14. In certain aspects it is to be appreciated that a separate outsole component could be secured to the lower surface of first portion 26. When a separate outsole component is secured to the lower surface of first portion 26, the first portion 26 is a midsole component. In some aspects, the article is a midsole component for an article of footwear. In other aspects, the article is a combination midsole-outsole component for an article of footwear.
[0032]The article can be an insert. An insert 36 can be received in recess 28. As illustrated in FIG. 2, insert 36 can provide cushioning or resiliency in the sole component. First portion 26 can provide structure and support for insert 36. In such aspects, first portion 26 can be formed of a material of higher specific gravity and/or hardness as compared to insert 36 such as, for example, non-foam materials including rubber and thermoplastic polyurethane, as well as foam materials. In certain aspects, insert 36 can be formed of a thermoplastic foam as disclosed herein.
[0033]Insert 36 has a curved rear surface 38 to mate with curved rear surface 32 of recess 28 and a transverse front surface 40 to mate with transverse front surface 34 of recess 28. An upper surface 42 of insert 36 is in contact with and secured to upper 12 with adhesive or other suitable fastening means. For example, when there is an insert 36, a recess 28 can extend from heel portion 24 to forefoot portion 20. In certain aspects, the rear surface 32 of recess 28 is curved to substantially follow the contour of the rear of heel portion 24 and the front surface 34 of recess 28 extends transversely across first portion 26.
[0034]As seen best in FIG. 3, a ground engaging lower surface 44 of first portion 26 includes a plurality of projections 46. Each projection 46 is surrounded by a groove 48. A plurality of transverse slots 50 are formed in lower surface 44, extending between adjacent projections 46. A longitudinal slot 52 extends along lower surface 44 from heel portion 26 to forefoot portion 20.
[0035]FIGS. 4 and 5 show bottom and top views of an insert 60 which can be used in a sole component as described herein. Insert 60 is similar to insert 36, but as illustrated in FIGS. 4 and 5, insert 60 is formed of two types of materials 62 and 64, where at least one of the materials is a thermoplastic foam as disclosed herein. FIG. 4 shows a bottom view of insert 60, while FIG. 5 shows a top view of insert 60 formed of two types of materials 62 and 64, with the insert placed inside a first portion 66 to form a sole component 14. Inserts with more than two types of materials, at least one of which is a thermoplastic foam as disclosed herein, can also be used. In the example illustrated in FIGS. 4 and 5, a portion of a first material 62 can be used in the heel region of the insert, and a portion of a second material 64 can be used in the toe region of the insert. A higher specific gravity material can be used to support the heel region, while a lower specific gravity material can be used to support the toe region. For example, the specific gravity of the first material can be at least 0.02 units greater than the specific gravity of the second material. The shape of the portions of the two materials 62 and 64 of the insert can be any suitable shape. For example, the heel region can be in the shape of a wedge. Inserts formed of two types of materials can be useful in running shoes, as well as in basketball shoes.
[0036]In the articles comprising the foam articles or components including the thermoplastic foam, for example a thermoplastic copolyester foam having an open cell structure, and the layer of a second thermoplastic composition disposed on at least a portion of an exterior surface of the foam as described herein. Referring to FIG. 7, in an aspect, a foam component 70 can have a foam portion 72, comprising a polymeric material that comprises a thermoplastic copolyester multicellular foam having an open-cell or closed-cell foam structure. The foam portion 72 has one or more sides that, when the foam component 70 is disposed in an article such as an article of footwear, are oriented toward an exterior facing side or surface of the article (e.g. an outer peripheral edge of article of footwear 10 of FIG. 1). A polymeric layer 74 is disposed on at least a portion of an exterior facing side or surface of the foam portion 72. The polymeric layer 74 comprises a second thermoplastic composition that may be the same as or different from the first thermoplastic composition of the foam portion 72. According to aspects, the polymeric layer 74 is not a foamed material. The polymeric layer 74 can function as an outsole, for example, which can provide improved abrasion resistance on one or more surfaces of the foam portion 72.
[0037]In some aspects, the article can be something other than a sole component. For example, the article can be an upper or an upper component. An upper component refers to a piece that is stitched or otherwise joined with one or more other pieces to form an upper portion for an article of footwear. The materials in the upper generally contribute to characteristics such as breathability, conformability, weight, and suppleness or softness. A lower component refers to a piece that is joined with one or more other pieces to form the lower portion of an article of footwear. The lower can include, for example, the outsole and midsole. The choice of outsole materials and design will contribute, for instance, to the durability, traction, as well as to the pressure distribution during use. The midsole materials and design contribute to factors such as the cushioning and support. Grindery components include all of the additional components that can be attached to the upper, lower, or both. Grindery components can include, for example, eyelets, toe puffs, shanks, nails, laces, velcro, catches, backers, linings, padding, heel backings, heel foxings, toe caps, etc.
[0038]The upper can be a lasted upper. A “lasted upper,” as used herein, refers to an upper that is formed into the shoe shape prior to attachment to the sole by one or more mechanical means. The lasted upper can include a heel counter formed to shape the heel of the upper. The lasted upper can include a strobel or a strobel board attached to the upper, typically via a strobel stitch.
[0039]While the thermoplastic foams described herein, including the thermoplastic copolyester foams described herein, can be used for making any of a variety of components, including a variety of components for an article of footwear, in particular aspects the components include a midsole, an outsole, an insole, or an insert. Additional articles can include a tongue padding, a collar padding, and a combination thereof. As described above and detailed more completely below, the articles comprising the thermoplastic foams described herein can exhibit a unique balance of beneficial physical properties such as high energy efficiency or energy return, and low specific gravity. Furthermore, the thermoplastic foam can also be reprocessed with minimal loss in physical properties (e.g., for recycling), providing a solution for materials sustainability.
[0040]In some instances a disclosed article can comprise a first component comprising a foamed thermoplastic composition, such as a foamed thermoplastic copolyester composition, and a second component comprising a second thermoplastic composition. An article comprising the first component with the second thermoplastic composition can be characterized by good bonding strength between the second thermoplastic composition and the foam component. The ply adhesion strength between the second thermoplastic composition and the foam component is greater than 2.5 kg force/centimeter or greater than 3.0 kg force/centimeter, when determined using the Ply Adhesion Test method described herein.
First Components
[0041]The first component is a foam component comprising a thermoplastic composition comprising one or more thermoplastic elastomers. In one aspect, the thermoplastic composition is a thermoplastic copolyester composition comprising one or more thermoplastic copolyester elastomers. The first component can be a component such as, but not limited to, a component of a midsole or a midsole component. It is understood that the first component comprises a foamed thermoplastic composition. For example, a thermoplastic composition includes at least 90 weight percent, or at least 95 weight percent, or at least 99 weight percent of thermoplastic polymers, such as, for example, the thermoplastic copolyester disclosed herein, based on the total weight of the thermoplastic composition. In some instances, the polymeric component of the thermoplastic composition, which includes all the polymers present in the thermoplastic composition, includes or consists essentially of one or more thermoplastic elastomers, such as one or more of the disclosed thermoplastic copolyester elastomers. In other words, the only polymers present in the thermoplastic composition can be thermoplastic elastomers, or the only polymers present in the thermoplastic composition can be thermoplastic copolyester elastomers.
Second Components
[0042]The second component comprising a second thermoplastic composition can be a component such as, but not limited to, a component of an outsole or an outsole component. It is understood that the second component can be foamed, partially foamed, or essentially unfoamed. In some instances the second component is a foamed component, i.e., a second foam component. In other instances, the second component is an unfoamed component, i.e., a solid component. In some instances, the second thermoplastic composition is a disclosed thermoplastic composition, such as a thermoplastic copolyester composition. For example, a second thermoplastic composition can include at least 90 weight percent, or at least 95 weight percent, or at least 99 weight percent of thermoplastic elastomers as disclosed herein, based on the total weight of the second thermoplastic composition. In some instances, the second thermoplastic composition includes a polymeric component consisting essentially of one or more disclosed thermoplastic elastomers, including one or more disclosed copolyester elastomers. In other instances, the second thermoplastic composition can include a polymeric component which is essentially free of a thermoplastic copolyester, e.g., the polymeric component can consist essentially of a thermoplastic polyurethane elastomer or a thermoplastic vulcanizate material as disclosed herein. In still other instances, a second thermoplastic composition can include a mixture of a disclosed thermoplastic copolyester and a polymeric material that is not a disclosed thermoplastic copolyester, e.g., a thermoplastic elastomer or thermoplastic vulcanizate material.
Characteristics of Thermoplastic Copolyester Foam Components.
[0043]As discussed herein above, a first component can be foam component, i.e., a first foam component, comprising a disclosed first thermoplastic composition. In some instances, a second component can be foam component, i.e., a second foam component, comprising a disclosed second thermoplastic composition. That is, each of the first or second foam components can independently comprise a disclosed thermoplastic foam component. It is understood herein throughout that reference to a “thermoplastic foam” is inclusive of a first foam component, a second component, or both a first and a second foam components, and that each of the first and second foam components can independently comprise one or more disclosed thermoplastic compositions as disclosed herein below. A disclosed thermoplastic foam can exhibit various beneficial properties.
[0044]For example, the thermoplastic foam can exhibit a beneficial split tear, for example a high split tear for a sole component in an article of footwear. In some aspects, the thermoplastic foam can have a split tear value of greater than about 1.5 kilogram/centimeter (kg/cm), or greater than about 2.0 kg/cm, or greater than about 25 kg/cm, when determined using the Split Tear Test Method described herein. In some aspects, the thermoplastic foam can have about 1.0 kg/cm to 4.5 kg/cm, about 1.5 kg/cm to 4.0 kg/cm, about 2.0 kg/cm to 4.0 kg/cm, about 2.0 kg/cm to 3.5 kg/cm, or about 2.5 kg/cm to 3.5 kg/cm, when determined using the Split Tear Test method described herein. In some aspects, the thermoplastic foam is injection molded, or is injection molded and subsequently compression molded in a separate compression mold having different dimensions than the mold used in the injection molding step. The thermoplastic foam can have a split tear of about 0.08 kg/cm to 4.0 kg/cm, about 0.9 kg/cm to 3.0 kg/cm, about 1.0 to 2.0 kg/cm, about 1.0 kg/cm to 1.5 kg/cm, or about 2 kg/cm. In some aspects, the thermoplastic foam the thermoplastic foam is injection molded, and has have a split tear of about 0.07 kg/cm to 2.0 kg/cm, or about 0.8 kg/cm to 1.5 kg/cm, or about 0.9 to 1.2 kg/cm, about 1.5 kg/cm to 2.2 kg/cm.
[0045]The specific gravity of a disclosed thermoplastic foam is also an important physical property to consider when using a foam for in an article of footwear or athletic equipment. As discussed above, the thermoplastic foam of the present disclosure exhibits a low specific gravity, which beneficially reduces the weight of midsoles or other components containing the thermoplastic foam. The thermoplastic foams of the present disclosure can have a specific gravity of from 0.02 to 0.22, or of from 0.03 to 0.12, or of from 0.04 to 0.10, or from 0.11 to 0.12, or from 0.10 to 0.12, from 0.15 to 0.2; 0.15 to 0.30, when determined using the Specific Gravity Test Method described herein. Alternatively or in addition, the thermoplastic foam can have a specific gravity of from 0.01 to 0.10, or of from 0.02 to 0.08, or of from 0.03 to 0.06; 0.08 to 0.15; or from 0.10 to 0.12, when determined using the Specific Gravity Test Method described herein. For example, the specific gravity of the thermoplastic foam can be from or from 0.15 to 0.20, or can be from 0.10 to 0.12. The thermoplastic foam can be injection molded, or can be injection molded and subsequently compression molded. In some aspects, the thermoplastic foam has a specific gravity of about 0.7 or less, or 0.5 or less, or 0.4 or less, or 0.3 or less, when determined using the Specific Gravity Test Method described herein. In some aspects, the thermoplastic foam, including thermoplastic foam present in midsoles and midsole components, can