Antimicrobial footwear, formulations, and method of manufacture

Abstract

Foamed footwear articles, formulations, and methods of making the same are disclosed. A formulation comprises a base polymer composition including a polymer and an elastomer, an additive mixture with a filler, blowing agent, activator, cross-linking agent, and pigment, an antimicrobial compound, and a curing masterbatch comprising a polymer carrier and a peroxide cross-linking agent. A degradation additive may also be included. Methods include kneading one or more mixtures of the base polymer composition and blowing agent, pelletizing the mixture(s), blending pellets with the antimicrobial compound and curing masterbatch, and injection molding under conditions sufficient to decompose the blowing agent and effect cross-linking. In certain embodiments, two mixtures with differing blowing agent contents are prepared and pelletized separately, then blended to provide tunability of expansion ratio, hardness, density, and related properties. The molded articles include embedded public health messaging and exhibit favorable physical properties despite antimicrobial and biodegradable additives.

Description

Attorney Docket No.: 1559 / 2 PCTANTIMICROBIAL FOOTWEAR, FORMULATIONS, AND METHOD OF MANUFACTURETECHNICAL FIELD

[0001] The present disclosure relates generally to polymer foams and, more particularly, to formulations, methods, and articles involving foamed polymeric materials suitable for use in footwear. The disclosure is directed to polymer compositions incorporating antimicrobial and biodegradable additives, processes for producing foamed footwear articles using single-batch and tunable dual-batch pelletized blending approaches, and footwear articles formed thereby.BACKGROUND

[0002] Intestinal parasitic infections (IPIs) are among the most critical public health problems worldwide. Patients infected with these parasites suffer significant morbidity and mortality. The intestinal parasites are broadly classified into protozoa and helminths. According to the World Health Organization (WHO), approximately 1.5 billion people, or about 24% of the global population, are infected with IPIs, mainly the soil-transmitted helminths (geohelminths) Ascaris lumbricoid.es (roundworm), Trichuris Irichiura (whipworm), Ancylosloma duodenale, and Necator americanus (hookworms). Of this, about 576 to 740 million people are infected by hookworms worldwide. In particular, ancylostomiasis is a hookworm infection caused by Ancylostoma duodenale, Necator americanus, and Ancylosloma ceylanicum, and is common in developing countries with tropical and subtropical climates, particularly in sandy, moist soils and rural areas with poor sanitation.

[0003] The life cycle of hookworms begins when thousands of eggs are excreted in human feces into the soil. Rhabditiform larvae emerge from the eggs within 1 to 2 days in warm, moist, shaded soil. These larvae molt twice to become infective filariform larvae (L3) within 5 to 10 days. Humans become infected when L3 larvae penetrate the skin of bare feet (Ancylostoma duodenale and Necator americanus) or, in some cases, when larvae are ingested (Ancylostoma duodenale). The larvae migrate through the vascular system to the heart and lungs, causing immunological reactions during migration, and ultimately mature into adult worms in the jejunum. Adult worms attach to the intestinal walls and consume blood, leading to iron deficiency anemia.Attorney Docket No.: 1559 / 2 PCT

[0004] Measures to control IPIs include improved personal hygiene, environmental sanitation, access to potable water, and health education. Wearing footwear is an especially important intervention to prevent the cutaneous penetration of infective larvae. However, conventional foam footwear formulations are sensitive systems: introducing antimicrobial agents and / or degradable additives can disrupt peroxide-initiated cross-linking, alter gas evolution from blowing agents, and interfere with filler-polymer interactions. As a result, direct incorporation of such components can depress expansion ratio (increase density), shift hardness outside target ranges, reduce tensile strength and elongation, increase compression set, and worsen dimensional stability / shrinkage. These adverse effects can be formulation- and process-dependent and are not readily predictable, which has discouraged incorporation of public-health-oriented additives into footwear foams despite their potential benefits.

[0005] Accordingly, there is a need for footwear articles that reduce the risk of hookworm infection through the feet, while also addressing durability, comfort, and sustainability. There is a further need for footwear formulations that incorporate antimicrobial agents to suppress surface pathogens, optional degradable additives to support environmental breakdown, and curing systems that offset cure inhibition associated with such additives. In addition, footwear that incorporates embedded public health messaging directly into the article provides an opportunity to promote hygiene practices and encourage the wearing of protective footwear. The present disclosure provides formulations, methods, and articles that address these needs, including dual-batch blending processes that enable tunability of foam properties.BRIEF SUMMARY

[0006] This summary is provided to introduce in a simplified form concepts that are further described in the following detailed descriptions. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it to be construed as limiting the scope of the claimed subject matter.

[0007] The present disclosure provides formulations, methods, and articles directed to foamed footwear that incorporate antimicrobial and optional degradable additives while maintaining desirable physical properties.

[0008] In certain aspects, a method of producing a foamed footwear article is provided. The method includes preparing and kneading one or more mixtures of a base polymer compositionAttorney Docket No.: 1559 / 2 PCT and a blowing agent, pelletizing the kneaded mixture(s), blending the resulting pellets with an antimicrobial compound and a curing masterbatch, and injection molding the blended pellet composition under conditions sufficient to decompose the blowing agent and effect cross-linking. In certain embodiments, a degradation additive is further blended with the pellets, antimicrobial compound, and curing masterbatch. In further embodiments, two material mixtures with different amounts of blowing agent are prepared, pelletized separately, and blended in selected proportions to provide tunability of expansion ratio, hardness, density, and related properties.

[0009] In other aspects, formulations for producing foamed footwear articles are provided. A formulation includes a base polymer composition comprising a polymer and an elastomer, an additive mixture including a filler, a blowing agent, a blowing agent activator, a cross-linking agent, and a pigment, an antimicrobial compound, and a curing masterbatch comprising a polymer carrier and a peroxide cross-linking agent. In some embodiments, a degradation additive is further included, with the curing masterbatch offsetting cure inhibition that would otherwise be associated with such additives.

[0010] In still other aspects, foamed footwear articles produced according to the present disclosure are provided. The articles incorporate embedded public health messaging formed during molding and exhibit favorable physical properties including expansion ratio, hardness, tensile strength, elongation, compression set, resilience, tear strength, and dimensional stability despite the inclusion of antimicrobial and biodegradable additives.Attorney Docket No.: 1559 / 2 PCTBRIEF DESCRIPTION OF THE DRAWINGS

[0011] The foregoing, as well as the following Detailed Description, is better understood when read in conjunction with the appended Figures. For the purposes of illustration, there is shown in the figures certain exemplary embodiments; however, the presently disclosed subject matter is not limited to the specific methods and instrumentalities disclosed.

[0012] The embodiments illustrated, described, and discussed herein are illustrative of the present invention. As these embodiments of the present invention are described with reference to illustrations, various modifications or adaptations of the methods and or specific structures described may become apparent to those skilled in the art. It will be appreciated that modifications and variations are covered by the above teachings and within the scope of the appended claims without departing from the spirit and intended scope thereof. All such modifications, adaptations, or variations that rely upon the teachings of the present invention, and through which these teachings have advanced the art, are considered to be within the spirit and scope of the present invention. Hcncc, these descriptions and drawings should not be considered in a limiting sense, as it is understood that the present invention is in no way limited to only the embodiments illustrated.

[0013] Embodiments of the present invention are shown with reference to the following drawings introduced as follows:

[0014] FIG. 1 is a process flow diagram illustrating an exemplary general method of producing antimicrobial footwear article according to one or more embodiments herein;

[0015] FIG. 2 is a schematic diagram showing kneading, pelletizing, and blending in a dualbatch process to form a composition for molding according to one or more embodiments herein;

[0016] FIG. 3 is a schematic diagram showing kneading, pelletizing, and blending in a singlebatch process to form a composition for molding according to one or more embodiments herein;

[0017] FIG. 4 is a schematic diagram showing molding of the composition from FIGS. 2 or 3 to produce a footwear article according to one or more embodiments herein; and

[0018] FIG. 5 is a top plan view of an article of footwear having an embedded image segment according to one or more embodiments herein.Attorney Docket No.: 1559 / 2 PCTDETAILED DESCRIPTION

[0019] Footwear is a critical line of defense against soil-transmitted helminths and other intestinal parasitic infections that enter through the feet. In many endemic regions, populations walk barefoot on sandy, moist soils that harbor infective larvae, making footwear an essential public health intervention. At the same time, foam footwear materials are favored for affordability, light weight, and comfort.

[0020] Conventional foam footwear formulations, typically based on ethylene-vinyl acetate (EVA) blends, offer mechanical resilience and processability but were not developed with public health imperatives in mind. Such articles provide a physical barrier but lack antimicrobial protection, are not typically designed to degrade readily, and fail to communicate health messages to promote consistent usage. Accordingly, there remains an unmet need for footwear that integrates protective, environmental, and behavioral reinforcement features.

[0021] Incorporating antimicrobial agents into foam formulations is generally expected to suppress microbial growth on and within footwear surfaces. Incorporating degradation additives is expected to provide pathways for controlled environmental breakdown at end of life. Incorporating embedded public health messaging into the molded article presents an avenue to reinforce protective behaviors directly to the wearer and community. Together, these innovations provide a holistic solution that addresses infection risk, environmental sustainability, and health education.

[0022] Despite these potential benefits, conventional polymer-foam systems are sensitive to formulation balance. Incorporation of antimicrobial agents and degradation additives may influence peroxide-initiated curing, alter gas evolution from blowing agents, or affect filler— polymer interactions. Such changes can contribute to undesirable performance metrics, including reduced expansion ratio (increased density), hardness values outside target ranges, lower tensile strength or elongation, increased compression set, or unstable dimensions. Because these outcomes are formulation- and process-dependent, they are not readily predictable in advance. As a result, attempts to formulate foam footwear with such additives generally require significant amounts of trial and error.

[0023] The present disclosure provides formulations, methods, and articles that incorporate antimicrobial compounds, optional degradation additives, and embedded public -health messagingAttorney Docket No.: 1559 / 2 PCT while preserving desirable foam performance metrics. In particular, the use of a curing masterbatch comprising a polymer carrier and a peroxide cross-linking agent can mitigate cure inhibition that might otherwise be associated with antimicrobial and degradable components. In certain embodiments, dual-batch blending of pellets with different blowing-agent contents provides tunability of expansion ratio, hardness, and density while maintaining other performance properties. The resulting articles are designed to exhibit robust physical performance, maintain comfort and affordability, and provide integrated public -health reinforcement directly in the footwear’.Definitions and Notes

[0024] The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Certain terms that are used to describe the disclosure are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the disclosure. It will be appreciated that same thing can be said in more than one way.

[0025] Alternative language and synonyms may be used for any one or more of the terms discussed herein. No special significance is to be placed upon whether a term is elaborated on or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification, including examples of any terms discussed herein, is illustrative only, and is not intended to further limit the scope and meaning of the disclosure or of any exemplified term. Likewise, the disclosure is not limited to various embodiments given in this specification.

[0026] Reference within the specification to “embodiment(s)” or the like means that a particular material, feature, structure and / or characteristic described in connection with the embodiment is included in at least one embodiment, optionally a number of embodiments, but it does not mean that all embodiments incorporate the material, feature, structure, and / or characteristic described. Furthermore, materials, features, structures and / or characteristics may be combined in any suitable manner across different embodiments, and materials, features, structures and / or characteristics may be omitted or substituted from what is described. Thus, embodiments and aspects described herein may comprise or be combinable with elements or components ofAttorney Docket No.: 1559 / 2 PCT other embodiments and / or aspects despite not being expressly exemplified in combination, unless otherwise stated or an incompatibility is stated.

[0027] All ingredient percentages described herein are by weight of the specified composition or subcomposition, unless specifically stated otherwise, and may be designated as “wt%.” All ratios are weight ratios, unless specifically stated otherwise. All such percentages or weights as they pertain to listed ingredients are based on the active level and, therefore, do not include carriers or by-products that may be included in commercially available materials. The number of significant digits conveys neither a limitation on the indicated amounts nor on the accuracy of the measurements. Unless otherwise indicated, all measurements are understood to be made at approximately 21 °C and at ambient conditions, where “ambient conditions” means conditions under about 1 atmosphere of pressure and at about 50% relative humidity. All ranges are inclusive and combinable. For example, all numeric ranges are inclusive of narrower ranges, and delineated upper and lower range limits are interchangeable to create further ranges not explicitly delineated.

[0028] The compositions of the present invention can comprise, consist essentially of, or consist of, the essential components as well as optional ingredients described herein. As used herein, “consisting essentially of’ means that the composition or component may include additional ingredients, but only if the additional ingredients do not materially alter the basic and novel characteristics of the claimed compositions or methods. As used in the description and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0029] As used herein, the term “about” modifies a particular value by referring to a range of plus or minus 20% or less of the stated value (e.g., plus or minus 15% or less, 10% or less, 5% or less, or even 3% or less).

[0030] The term “base polymer composition” refers to the polymeric portion of the foamable formulation, and may comprise a polymer, an elastomer, and optionally other polymers, elastomers, or additives. In some embodiments, the base polymer composition comprises ethylenevinyl acetate (EVA), a polyolefin elastomer (POE), and optionally an olefin block copolymer (OBC).

[0031] The term “additive mixture” refers to one or more compounds combined with the base polymer composition to impart functionality to the foam. Examples include fillers, blowing agents, blowing agent activators, cross-linking agents, and pigments.Attorney Docket No.: 1559 / 2 PCT

[0032] The term “blowing agent” refers to a compound that decomposes or volatilizes under processing conditions to release a gas that generates cells or voids in the polymer matrix. A nonlimiting example is azodicarbonamide. The term “blowing agent activator” refers to a compound that facilitates or modifies decomposition of the blowing agent, such as zinc oxide or zinc stearate.

[0033] The term “cross-linking agent” refers to a compound that promotes covalent bonding between polymer chains, thereby strengthening the foam structure. Examples include peroxides such as dicumyl peroxide (DCP) and l,4-bis-(t-butylperoxyisopropyl)benzene (BIPB).

[0034] The term “curing masterbatch” refers to a mixture comprising a polymer carrier and a peroxide cross-linking agent, formulated for addition to a polymer composition to promote curing. In some embodiments, the curing masterbatch can mitigate cure inhibition that may otherwise occur when antimicrobial or degradable additives arc incorporated.

[0035] The term “antimicrobial compound” refers to a compound that can suppress, inhibit, or reduce microbial growth on or within the footwear. Non-limiting examples include oyster shell powder, calcium carbonate derivatives, metal oxides, zinc salts, and natural extracts.

[0036] The term “degradation additive” refers to a compound included to promote or accelerate environmental breakdown of the article at end-of-life. Examples include chemoattractants, glutaric acid or derivatives, carboxylic acids, swelling agents, and microbes.

[0037] The term “public health messaging” refers to indicia, images, symbols, logos, or text incorporated into the molded footwear article for the purpose of communicating a message that encourages hygienic practices or footwear usage. Such messaging can be embedded by molding against an engraved or raised mold insert.

[0038] The term “foamed footwear article” refers to an article formed from a polymer composition that has undergone expansion by a blowing agent and cross-linking by a curing agent, such as sandals, midsoles, slippers, or related footwear products.

[0039] The term “homogeneous blended dough” refers to a kneaded mass in which the polymer, elastomer, and additives are substantially uniformly dispersed, without visible agglomerates, and in which the blowing agent remains substantially undecomposed prior to molding.

[0040] The term “pellet” refers to a discrete, typically cylindrical, spherical, or irregularly granulated piece of kneaded dough, formed by pelletizing or cutting, and suitable for subsequentAttorney Docket No.: 1559 / 2 PCT blending and molding. A “pellet batch” refers to a plurality of pellets obtained from kneading and pelletizing a given material mixture.

[0041] The term “dual-batch process” refers to a process in which two or more material mixtures are prepared with differing amounts of blowing agent, kneaded and pelletized separately, and then blended together to form a tunable composition. The term “single-batch process” refers to a process in which a single material mixture containing a uniform amount of blowing agent is kneaded, pelletized, and subsequently molded.

[0042] The term “tunability” refers to the ability to adjust one or more physical properties of the foamed footwear article, including but not limited to expansion ratio, hardness, density, tensile strength, elongation, compression set, resilience, tear strength, and dimensional stability, by varying the relative proportions of pellet batches or formulation parameters.

[0043] The term “expansion ratio” refers to the ratio of the density of the unfoamed composition to the density of the foamed footwear article, as determined by ASTM D3575 or ISO 845, or equivalent standardized methods.

[0044] The term “resilience” refers to rebound resilience, typically expressed as a percentage, as measured according to ASTM D2632 or equivalent standardized methods.

[0045] The term “tear strength” refers to resistance to tearing as determined according to ASTM D624 (Die C). The term “split tear strength” refers to resistance to tearing along a split interface as determined according to BS5131.

[0046] The term “dimensional stability” refers to the maintenance of target article dimensions within a defined tolerance following molding, and may be confirmed by measuring shrinkage or dimensional change at about 30 minutes and about 24 hours post-molding.

[0047] Without intent to limit the scope of the disclosure, examples of instruments, apparatus, methods, and their related results according to the embodiments of the present disclosure are given below. Note that titles or subtitles may be used in the examples for convenience of a reader, which in no way should limit the scope of the disclosure.FOOTWEAR ARTICLES, FORMULATION, AND METHOD GENERALLY

[0048] The present disclosure is directed to foamed footwear articles 46, formulations for producing such articles, and methods of manufacture 100. The footwear articles 46 are designedAttorney Docket No.: 1559 / 2 PCT to address public health challenges associated with soil-transmitted helminth infections while maintaining the performance, comfort, and affordability expected of foam-based footwear.

[0049] In certain embodiments, the footwear articles 46 are formed from a polymeric foam composition 40 that includes a base polymer composition, an additive mixture, an antimicrobial compound 34, and a curing masterbatch 36. In some embodiments, a degradation additive 38 is also incorporated. In specific embodiments, the resulting foams exhibit desirable combinations of density, hardness, tensile strength, elongation, resilience, compression set, and dimensional stability.

[0050] In further embodiments, the footwear articles 46 incorporate an embedded image segment 48 that conveys public health messaging as in FIG. 5. The image segment 48 may include text, logos, pictograms, or other indicia and is formed integrally with the article during molding. In this manner, the footwear articles 46 not only provide a physical barrier to parasite entry but also serve as communication tools to encourage hygienic practices and reinforce the benefits of consistent footwear use.

[0051] In certain embodiments, the footwear articles 46 are produced by a dual-batch process, such as in FIG. 2, wherein two pellet batches 26, 28 with component formulations, such as different amounts of blowing-agent components, are blended and molded together. This approach allows tunability of performance characteristics such as expansion ratio, hardness, density, and compression set. In other embodiments, a single-batch process is employed, as in FIG. 3, wherein a uniform formulation 14 is pelletized and molded. Both approaches enable incorporation of antimicrobial 34 and degradable additives 38, while the dual-batch approach further permits property optimization across a range of performance characteristics.

[0052] The articles 46 produced according to the present disclosure are intended to combine protective function, durability, and sustainability with public health impact. The integration of antimicrobial activity, optional degradability, and embedded messaging distinguishes the present footwear from conventional foam footwear, while the formulations and methods disclosed herein preserve the performance metrics required for consumer adoption.FORMULATION ELEMENTS - GENERALLY

[0053] While various features and elements have been described in reference to particular embodiments and variations above, it is to be understood that no limitation of the scope of thisAttorney Docket No.: 1559 / 2 PCT disclosure is hereby intended. Thereby, elements and features might be utilized in any combination and for any embodiment to which it is particularly useful. To further promote understanding of the principles of the present disclosure, additional discussion related to particular elements of the present discussion is provided below.

[0054] The foamed footwear articles 46 described herein are produced from formulations that balance structural performance, comfort, and manufacturability with antimicrobial function, optional degradability, and embedded public-health messaging. The formulations 10, 12, and 14 (FIGS. 2 and 3) generally comprise a base polymer composition providing mechanical resilience and processability, an additive mixture that includes fillers, pigments, a blowing agent, a blowingagent activator, and a cross-linking agent, and additional components selected to address the identified needs. An antimicrobial compound 34 is incorporated to suppress microbial growth on or within the footwear. A curing masterbatch 36, comprising a polymer carrier and a peroxide cross-linking agent, is included to promote cross-linking and to mitigate cure inhibition that may otherwise occur in the presence of antimicrobial or degradable additives. In some embodiments, a degradation additive 38 is included to facilitate controlled environmental breakdown of the article at end-of-life. Together, these formulation elements enable footwear articles 46 that preserve desirable foam performance metrics while also addressing infection risk, sustainability, and health education.Base Polymer Composition

[0055] The formulations 10, 12, and 14 described herein can include a base polymer composition that provides the structural and mechanical foundation of the foamed footwear articles 46. The base polymer composition generally may comprise a polymer / elastomeric matrix of one or more polymers, one or more elastomers, and optionally composite copolymer blends. These components may be combined with additives such as fillers, pigments, cross-linking agents, and blowing agent activators. The selection and relative amounts of these components can be varied to achieve a balance of expansion, hardness, density, tensile strength, elongation, compression set, resilience, and dimensional stability.Polymer / Elastomeric Matrix

[0056] In certain embodiments, the polymer can comprise an ethylene-vinyl acetate (EVA) copolymer. EVA may provide softness, resilience, and favorable foaming characteristics. In some embodiments, the EVA can be TAISOX® 7470M as manufactured by Formosa PlasticsAttorney Docket No.: 1559 / 2 PCTCorporation. In other embodiments, the polymer may include one or more of polyethylene (PE), polypropylene (PP), polyolefin elastomers (POEs), olefin block copolymers (OBCs), thermoplastic polyurethanes (TPUs), styrene-butadiene rubber (SBR), styrene-ethylene-butylene- styrene (SEBS), natural rubber, synthetic rubbers, or other thermoplastic elastomers (TPEs).

[0057] The elastomeric portion of the base polymer composition can comprise a polyolefin elastomer (POE). In one embodiment, the POE can be an ethylene-octene random copolymer such as Engage® 8200, commercially available from Dow Chemical Company. According to the International Union of Pure and Applied Chemistry (IUPAC), an elastomer is a polymer that displays rubber-like elasticity, with polymer chains held together by relatively weak intermolecular bonds that permit stretching in response to macroscopic stresses. The elastomer may be thermoset or thermoplastic. Inclusion of an elastomer can provide elasticity, toughness, and rebound to the foamed article.

[0058] In certain embodiments, the base polymer composition may also include an olefin block copolymer (OBC). One example is Infuse® 9500, available from Dow Chemical Company. OBCs may comprise alternating amorphous soft blocks of ethylene-octene elastomer and more crystalline hard blocks of medium-density polyethylene (MDPE). Such architectures can impart improvements in heat resistance, abrasion resistance, and compression set performance at both high and low temperatures, and may support faster processing. In foam applications including EVA, OBCs can contribute to lower compression set, lighter weight, and improved sealing properties.

[0059] In some embodiments, the base polymer composition may further comprise a copolymer composite such as FY-36, produced by Feng Yang Industrial Development Company (Taiwan). FY-36 is a formulated blend that includes about 60% ethylene-octene copolymer elastomer, about 25% EVA copolymer, about 10% hydrogenated styrene-butadiene copolymer, and about 5% calcium carbonate. Such composites can enhance beneficial physical properties of the base material mixture and the formulation overall. Potential improvements may include enhanced compression set, improved split tear' strength, improved slip resistance, and increased resilience of the finished product. FY-36 is considered part of the polymer / elastomer matrix, rather than a separately added bulk filler.Filler AdditiveAttorney Docket No.: 1559 / 2 PCT

[0060] Additional fillers may also be incorporated into the base polymer composition. Fillers may enhance mechanical performance, dimensional stability, and foam morphology, while also reducing material cost and weight relative to the neat polymer. Non-limiting examples of fillers can include glass fibers, carbon fibers, talc, ceramics, and other inorganic and organic substances. In specific embodiments, the filler can comprise one or more of calcium carbonate, talcum powder, precipitated silica, pre-reacted glass ionomer, magnesium carbonate, magnesium silicate, clay, mica, barium sulfate, magnesium hydroxide, basalt fiber, or a zeolite. Zeolites can refer to crystalline aluminosilicate materials with regular pore structures, suitable for use as mineral fillers in polymer matrices. Pre-reacted glass ionomer fillers can be formed through acid-base reactions between fluoroaluminosilicate glass and polyacrylic acid, and may additionally impart antimicrobial effects. In some embodiments, the filler can comprise polymeric rubbers in minor amounts, such as ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, or styrene-butadiene rubber, to modify mechanical behavior. Fillers may also provide secondary benefits such as color, flame retardancy, UV stabilization, antistatic properties, lubrication, or release behavior. For example, calcium carbonate and magnesium hydroxide may contribute to flame retardancy, while pre-reacted glass ionomer may act as an antimicrobial.Pigment Additives

[0061] Pigments may be incorporated to impart color or visual properties to the foamed footwear article. The pigment compound can be organic or inorganic, a dye, or a combination thereof. Exemplary inorganic pigments include metal oxides such as titanium dioxide (TiCF) and iron oxides, metal compounds such as strontium chromate or barium sulfate, and metallic pigments such as aluminum flakes. Complex inorganic colored pigments can include copper chromite, copper magnesium chromite, iron chromite, bismuth manganese, and manganese ferrite. Other exemplary pigments include carbon black and talc. Organic pigments may include perylenes, phthalocyanine derivatives such as copper phthalocyanine, indanthrones, benzimidazolones, quinacridones, perinones, and azomethine derivatives. In certain embodiments, it can be desirable to avoid pigments containing lead, cadmium, or chromium (VI). In other embodiments, the pigment may comprise a black color concentrate in an EVA carrier resin. Pigment compounds may be selected to enhance consumer appeal of the footwear, and in some embodiments to accentuate the visibility of embedded public health messaging.Blowing Agent Activator AdditivesAttomey Docket No.: 1559 / 2 PCT

[0062] A blowing agent activator can also be included in the additive mixture of the base polymer composition. Blowing agent activators may function to lower the decomposition temperature of the selected blowing agent, thereby ensuring timely gas release and formation of air pockets within the polymer during processing. Suitable blowing agent activator compounds can include zinc white, zinc oxide, zinc stearate, zinc nitrate, zinc phthalate, zinc carbonate, phosphorous trichloride salts, tribasic zinc sulfate, and other inorganic salts; zinc fatty acid soaps, lead fatty acid soaps, cadmium fatty acid soaps, and other metal soaps; boric acid, oxalic acid, succinic acid, adipic acid, and other acids; and organic compounds such as urea, ethanolamine, glucose, and glycerin.

[0063] In certain embodiments, the activator can be zinc stearate, which may additionally act as a release agent to improve ejection from molds, a lubricant to reduce friction with processing equipment, and an antistatic additive to minimize static buildup. In other embodiments, the activator can be zinc oxide, used alone or in combination with zinc stearate. Zinc oxide may also serve as a filler to improve strength and elasticity, act synergistically with cross-linking agents during curing, and provide antimicrobial effects.

[0064] Other blowing agent activator compounds may be selected or interchanged to account for overlapping functions or to impart additional desirable properties. The particular activator, or combination of activators, can be tailored to coordinate with the decomposition profile of the blowing agent and the kinetics of the cross-linking system, thereby promoting uniform foam cell structure and target physical properties.Cross-Linking Agent Additives

[0065] The base polymer composition may also include one or more cross-linking agents. Under processing temperature conditions, cross-linking agent compounds can be activated to begin the process of crosslinking by extracting a hydrogen atom from the polymer backbone and providing reactive sites for crosslinking. Crosslinking in this way during the foaming operation may lead to polymer materials with improved physical properties. In embodiments, the crosslinking agent compound can be a free-radical initiator. Suitable radical initiators can generate free radicals through thermal cleavage or UV radiation. Non-limiting examples of radical initiators include peroxides, sulfurs, and sulfides. Exemplary peroxides include dicumyl peroxide (DCP), l,4-bis-(t-butylperoxyisopropyl)-benzene (BIPB), dibenzoyl peroxide, 2,5-dimethyl-2,5- di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(butylperoxy)-3-hexyne, 2,5-bis-(t-butylperoxy)-Attorney Docket No.: 1559 / 2 PCT2,5-dimethyl hexane, n-butyl-4,4-bis(t-butylperoxyl)valerate, tert-butyl peroxybenzoate, 1 ,1-bis- (t-butylpcroxy)-3,3,5-trimcthylcyclohcxanc, and di(2,4-dichlorobcnzoyl). These materials may be provided as neat liquids or powders, or formulated with carriers such as calcium carbonate, clay, silica, cellulose, or polymers including polypropylene. In some embodiments, peroxides may be formulated with silicone oils or provided as solutions in water or organic solvents. The type and level of the cross-linking agent can be selected to provide suitable foaming and curing behavior in conjunction with the selected blowing agent and activator.Relative Proportions

[0066] The relative proportions of EVA, POE, OBC, copolymer composites such as FY-36, fillers, pigments, blowing agent activators, and cross-linking agents can be varied within the ranges provided in the claims to achieve desired combinations of softness, durability, foaming behavior, and physical strength. In exemplary embodiments, the base polymer composition can comprise the amounts summarized in Table A below, each percentage being expressed relative to the weight of the base polymer composition.

[0067] It should be understood that the broad ranges, narrower ranges, and specific examples provided in Table A are illustrative only, and that additional combinations and sub-ranges within the disclosed values may be employedAttorney Docket No.: 1559 / 2 PCTBlowing Agent

[0068] The foamed footwear articles described herein can be produced by incorporating a blowing agent system into the base polymer composition. The blowing agent system may include one or more blowing agent compounds, and in some embodiments one or more blowing agent activators as described above. Together, these components can generate and regulate gas evolution during molding, thereby producing a cellular structure within the polymer matrix.

[0069] A blowing agent compound can initiate a chemical reaction that creates air pockets within the polymer during processing. This results in a foamed structure that reduces material consumption, lowers the weight of the material, and minimizes sink marks while preserving desirable physical properties. In embodiments, the blowing agent compound decomposes under the temperature conditions of injection molding to form gas bubbles and voids.

[0070] Suitable blowing agent compounds are not particularly limited, provided they decompose at the molding temperatures used. Non-limiting examples include azodicarbonamide (ADC); azo compounds such as 2,2'-azobisisobutyronitrile and azohexahydrobenzonitrile; hydrazides such as diazodiaminobenzene, benzenesulfonylhydrazide, benzene- 1,3- sulfonylhydrazide, diphenylsulfone-3, 3 '-disulfonylhydrazide, diphenyloxide-4,4'- disulfonylhydrazide, 4,4'-oxybis(benzenesulfonyl hydrazide), and p-toluenesulfonylhydrazide; azide compounds such as terephthalazide and p-t-butylbenzazide; and carbonate compounds such as sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate.

[0071] In certain embodiments, the blowing agent compound may comprise azodicarbonamide(ADC), which decomposes within the temperature range of about 200-206 °C and can be readily controlled due to the narrowness of its decomposition profile. In some embodiments, the azodicarbonamide may be AC-3000F, available from Union Chemical Industry Company (Taipei City, Taiwan).

[0072] The type and level of the blowing agent can be selected to tune the expansion ratio, density, hardness, and cell morphology of the foamed footwear article. In certain embodiments, aAttorney Docket No.: 1559 / 2 PCT dual-batch process is employed, as in FTG. 2, wherein a first material mixture 10 comprises a higher amount of blowing agent and a second material mixture 12 comprises a lower amount, thereby allowing tunability when the two pellet batches 26, 28 are blended together. In other embodiments, a single-batch process is employed, as in FIG. 3, wherein a uniform formulation 14 is pelletized and molded. Table B below illustrates broad ranges, narrower ranges, and specific examples for blowing agent incorporation in both dual-batch and single-batch processes. All blowing agent percentages in Table B are expressed relative to the weight of the base polymer composition prior to incorporation of antimicrobial, curing masterbatch, or degradation additives, unless otherwise specified.

[0073] To further illustrate, values in Table C are expressed relative to the total weight of the base polymer composition plus the respective amount of blowing agent for the first batch 10, second batch 12, or single batch 14, and do not include additional antimicrobial 34, curing masterbatch 36, or degradation additives 38.

[0074] Without wishing to be bound by theory, the decomposition profile of the blowing agent may be influenced by the selected activator and cross-linking agent system. Proper balancing of these components can promote uniform foam cell structure, target hardness values, and expansion ratios while minimizing collapse, shrinkage, or off-gassing.Attorney Docket No.: 1559 / 2 PCTAntimicrobial Compound

[0075] The formulations described herein can include an antimicrobial compound 34 to suppress or inhibit microbial growth on or within the foamed footwear article 46. By limiting microbial colonization, antimicrobial compounds may improve hygiene, reduce odor, and contribute to lowering infection risks associated with soil-transmitted parasites. In some embodiments, the antimicrobial compound 34 may further serve to extend product usability in humid or high-contact environments where microbial load is elevated.

[0076] In various embodiments, the antimicrobial compound 34 may be configured to broadly inhibit bacteria and fungi, or to selectively inhibit certain microorganisms while permitting others. Selectivity may be useful, for example, where the formulation additionally incorporates a degradation additive 38, allowing microbes associated with biodegradation to act at end-of-life while still preventing pathogenic colonization during use. In other embodiments, the antimicrobial compound 34 may be designed to wear off gradually, thereby balancing antimicrobial protection during use with eventual biodegradability of the article in the environment.Attorney Docket No.: 1559 / 2 PCT

[0077] Suitable antimicrobial compounds 34 may include, but are not limited to, one or more of a biocide, peptide, antibiotic, or fungicide. In further embodiments, the antimicrobial compound 34 may comprise one or more of: sulfonium salts, quaternary ammonium compounds, benzimidazoles, N-halamines, imidazoles, thiabendazole, chitosan, silver-containing compounds, zinc-containing compounds, or zeolites carrying silver, zinc, or copper ions. In still further embodiments, the antimicrobial compound 34 may comprise oyster shell powder. In certain cases, a substance otherwise present in the formulation may also contribute antimicrobial functionality, such as pre -reacted glass ionomer or calcium carbonate nanoparticles.

[0078] The antimicrobial compound 34 may be present in the blended pellet composition in an amount of about 1-10 wt% relative to the base polymer composition, such as about 3-7 wt% or about 5 wt% in specific embodiments. Because antimicrobial compounds 34 can interfere with peroxide-initiated curing, foaming, and filler-polymer interactions, inclusion levels are carefully balanced. In this regard, the antimicrobial compound 34 is preferably incorporated after pelletization, during the blending stage, to ensure compatibility and to minimize premature interaction with other formulation components. The use of a curing masterbatch 36 comprising a polymer carrier and a peroxide cross-linking agent can offset cure inhibition associated with antimicrobial additives 34, thereby preserving desirable performance metrics.Degradation Additive

[0079] The formulations described herein may optionally include a degradation additive 38 to promote controlled breakdown of the foamed footwear article 46 at end of life. Such additives may facilitate microbial attack, hydrolysis, or other degradation pathways, thereby supporting environmental sustainability while maintaining functionality during use.

[0080] In various embodiments, the degradation additive 38 can comprise one or more of a chemoattractant, glutaric acid or a derivative thereof, a carboxylic acid, a swelling agent, or a microbe. In additional embodiments, the degradation additive 38 may comprise adipic acid as a less expensive alternative to glutaric acid, or aldaric acids as more efficient dicarboxylic acids. The carboxylic acid compound can include a carbon backbone of about 2 to about 36 carbons, optionally functionalized at one or both ends with aromatic, ester, amide, alkyl, alkene, or alkyne groups. Swelling agents may include natural fibers, cultured colloids, organoleptic compounds, or cyclodextrins, which may promote expansion of the polymer structure to pennit microbial ingress.Attorney Docket No.: 1559 / 2 PCTAll of the foregoing are considered exemplary embodiments of the “degradation additive” as recited in the claims.

[0081] In some embodiments, the degradation additive 38 may be included at levels of about 0.5-3 wt% relative to the base polymer composition, such as about 1 wt% in specific embodiments, as described in the claims. These levels may be sufficient to trigger degradation over an intended timeframe without compromising mechanical properties during the product’s usable life.

[0082] Certain degradation additives 38 may overlap in function with other components of the formulation. For example, calcium carbonate can serve as a filler while also enhancing degradation under acidic or microbial conditions. Similarly, specific bioactive fillers such as pre-reacted glass ionomer may contribute both antimicrobial and degradable effects.

[0083] Degradation additives 38, like antimicrobial compounds 34, may unpredictably alter curing kinetics, foaming behavior, and physical performance metrics. Effects can include depressed expansion ratio, off-target hardness, or unstable dimensions. Accordingly, degradation additives 38 are preferably incorporated after pelletization, during blending, at controlled levels. In some embodiments, the curing masterbatch 36 offsets potential cure inhibition associated with degradation additives 38, thereby preserving target expansion ratio, tensile strength, compression set, and dimensional stability.

[0084] In further embodiments, degradation additives 38 may include chemoattractant compounds configured to draw microorganisms toward the polymer surface, such as furanones or sugars (e.g., galactose, succinate, malate, serine, or ribose) that may not themselves be metabolized but induce microbial chemotaxis. In some cases, such compounds may be encapsulated with microbes to facilitate controlled release during environmental exposure.

[0085] Microorganisms capable of enzymatic degradation may include bacteria and fungi that produce hydrolases, such as Pseudomonas aeruginosa, Rhodococcus species, or fungal strains of Aspergillus or Penicillium. In practice, biodegradation may be carried out by microbial consortia, where multiple species participate in different steps of polymer breakdown.

[0086] In some embodiments, compatibilizing additives such as polymeric surfactants may be incorporated together with the degradation additive 38 to improve dispersion in the base polymer composition. Compatibilizers may function by lowering surface tension, enhancing interfacial adhesion, and stabilizing otherwise incompatible blends, thereby ensuring uniform performance.Curing MasterbatchAttorney Docket No.: 1559 / 2 PCT

[0087] The formulations described herein can include a curing masterbatch 36 to promote cross-linking of the base polymer composition during molding and foaming. The curing masterbatch 36 may comprise a polymer carrier, such as ethylene- vinyl acetate (EVA), in which one or more peroxide cross-linking agents are dispersed. In exemplary embodiments, the peroxide cross-linking agents comprise dicumyl peroxide (DCP) and l,4-bis-(t- butylperoxyisopropyl)benzene (BIPB).

[0088] Under processing conditions, the peroxide cross-linking agents decompose to generate free radicals, which abstract hydrogen atoms from the polymer backbone and initiate covalent cross-linking reactions. Such cross-linking may improve tensile strength, compression set resistance, and dimensional stability of the foamed footwear article. The polymer carrier in the masterbatch facilitates safe handling and uniform dispersion of the peroxide components in the pellet blends.

[0089] In certain embodiments, the curing masterbatch 36 may be added at levels of about 0.5-5 wt% relative to the base polymer composition, such as about 1-3 wt%, or about 1-2 wt% in specific embodiments, as described in the claims. The proportions of peroxide cross-linking agents within the curing masterbatch may vary depending on supplier and product grade. In exemplary embodiments, incorporation of the curing masterbatch into the base polymer composition corresponds to an effective level of about 0.5 wt% each of DCP and BIPB relative to the base polymer composition in specific examples.

[0090] The curing masterbatch 36 is preferably incorporated after pelletization, during the blending stage, together with the antimicrobial compound 34 and, in some embodiments, a degradation additive 38. This timing may reduce premature interaction with the base polymer composition and improve uniform distribution in the blended pellet composition 40. The curing masterbatch 36 may also serve an important role in offsetting potential cure inhibition associated with incorporation of antimicrobial compounds 34 or degradation additives 38. Without sufficient cross-linking support, these additives may depress expansion ratio, increase density, or lead to unstable dimensions. By incorporating the curing masterbatch 36 during blending, the formulations disclosed herein may achieve robust curing and foaming behavior while preserving targeted performance metrics, as recited in the claims.MANUFACTURING METHOD - GENERALLYAttorney Docket No.: 1559 / 2 PCT

[0091] The methods described herein provide for the manufacture of foamed footwear articles 46 that integrate antimicrobial protection, optional degradability, and embedded public -health messaging while maintaining desirable foam performance metrics. As shown in FIG. 1, the process 100 generally includes kneading 104, pelletizing 106, blending 108, injection molding 110, and stabilization / cooling 112, with each stage configured to balance material compatibility, curing kinetics, and foam morphology. The sequence of steps is designed to prevent premature decomposition of blowing agents, maintain cross-linking efficiency in the presence of antimicrobial 34 or degradable additives 38, and yield foams with uniform cell structure and reproducible properties. In certain embodiments, the process can be implemented as either a dualbatch method, as in FIG. 2, wherein multiple material mixtures 10, 12 are separately kneaded and pelletized, or a single-batch method, as in FIG. 3, wherein a single mixture is prepared and pelletized. Each approach may provide advantages depending on whether tunability or simplicity is prioritized. The methods are compatible with a range of mixing, pelletizing, and molding equipment, and may be scaled from laboratory to industrial production. Optional steps such as pellet drying, mold preheating, surface finishing, or packaging may be incorporated as appropriate.Material Preparation and Kneading

[0092] In embodiments, the process of producing foamed footwear articles can begin with preparation 102 of one or more material mixtures comprising the base polymer composition and a blowing agent. In a dual-batch process, as in FIG. 2, the base polymer composition can be divided into two portions, each combined with different amounts of blowing agent to form a high-loading batch 10 and a low-loading batch 12. In a single-batch process, as in FIG. 3, the base polymer composition can be combined with a uniform amount of blowing agent, forming a single batch 14. In both cases, optional pigments, fillers, blowing-agent activators, and cross-linking agents can be incorporated at this stage.

[0093] The prepared mixtures 10, 12, 14 may then be introduced into kneading equipment 22 configured to form homogeneous blended doughs 16, 18, 20 while avoiding premature decomposition of blowing or cross-linking agents. Kneading 104 is a critical stage of the process, as it can ensure that the polymers, elastomers, fillers, pigments, and additives are uniformly distributed throughout the mixture. Uniform dispersion can prevent localized concentrations of additives, reduce the likelihood of weak points in the final foam structure, and promote predictable decomposition of the blowing agent. Proper kneading 104 may also contribute to consistent foamAttorney Docket No.: 1559 / 2 PCT morphology, improved mechanical performance, and reproducible physical properties across production batches. Without sufficient kneading 104, the resulting dough 16, 18, 20 may contain agglomerates, voids, or non-uniform dispersion of agents, which can translate into uneven expansion, variable hardness, or premature failure of the foamed footwear article 46.

[0094] In embodiments, kneading 104 can be carried out in kneading equipment 22, including an internal mixer (also known as a dispersion kneader), such as a Banbury mixer, a Haake Rheomix, or other industrial kneader equipped with rotors. Rotor speeds may range from about 20 to about 60 rpm, and jacketed mixing chambers may provide controlled heating and cooling to maintain temperatures of about 80 °C to about 120 °C. Kneading times can range from about 5 to about 15 minutes, with shorter times promoting throughput and longer times allowing for complete dispersion of ingredients.

[0095] In some embodiments, monitoring systems such as torque sensors or infrared thermocouples can be employed to ensure that the material mixture achieves homogeneity without triggering blowing-agent decomposition. The kneaded doughs 16, 18, 20 can be discharged once the polymer, elastomer, fillers, pigments, and other additives appear substantially uniformly dispersed. In the dual-batch process, as in FIG. 2, two distinct doughs — one with a higher proportion of blowing agent 16 and one with a lower proportion 18 — may be prepared under comparable conditions. Preparing two doughs 16, 18 in this manner can allow later blending of their resulting pellets to tune properties such as expansion ratio, hardness, density, and compression set, without requiring reformulation of the base polymer composition.

[0096] The kneading stage 104 can be configured to balance shear and thermal input. Excessive shear or overheating may prematurely activate the blowing agent, while insufficient mixing may lead to agglomerates and poor foam morphology. Accordingly, the kneading parameters can be optimized to achieve a dough that is plastically workable, dimensionally uniform, and ready for the next step, pelletizing.Pelletizing

[0097] Following kneading 104, the blended dough 16, 18, 20 can be pelletized 106 to form discrete, manageable units for subsequent processing 26, 28, 30. Pelletizing 106 may be accomplished using equipment 24 including a strand cutter, die-face cutter, underwater pelletizer, or other commercially available pelletizing equipment. In at least one embodiment, a twin screw extruder with a die-face cutter is utilized to prepare pellets. Cutting conditions can be adjusted toAttorney Docket No.: 1559 / 2 PCT yield pellets of substantially uniform size, or pellets of variable size may be produced depending on the desired downstream processing characteristics. The pellets may be cylindrical, spherical, or irregular in shape, and their dimensions can be tailored to the hopper and screw design of the injection-molding equipment used in subsequent steps.

[0098] Pelletizing 106 can provide several functional benefits. In embodiments, pelletizing 106 may help homogenize the feed into an injection-molding machine 42, ensuring smoother throughput and reducing surges or uneven melting. Pelletizing 106 can also reduce agglomeration risk during handling compared to bulk dough storage. In dual-batch systems (FIG. 2), pelletizing 106 may preserve the identity of the first 26 and second batches of pellets 28 (e.g., higher vs. lower blowing-agent content), which allows controlled blending 108 prior to molding 110 and provides tunability of properties such as expansion ratio, hardness, density, and compression set. Even in single-batch systems (FIG. 3), pelletizing 106 provides an easy to handle and precisely controllable input 30 for subsequent steps, such as blending 108.

[0099] In further embodiments, pelletizing 106 may facilitate stability and storage of the composition. Pellets 26, 28, 30 can be packaged in moisture-controlled bags, bins, or silos to reduce premature reaction of blowing agents or cross-linking agents. Pellets 26, 28, 30 may be stored for extended periods, provided that temperature and humidity are controlled (for example, below about 30 °C and under about 60% relative humidity). This intermediate form may allow transport between facilities, flexible scheduling of downstream molding operations, and consistent dosing of antimicrobial compounds, degradation additives, and curing masterbatch at the later blending stage.Blending

[0100] In embodiments, pelletized material 26, 28, 30 can be blended 108 to form a blended pellet composition 40 suitable for molding 110. In a dual-batch process (FIG. 2), pellets 26, 28 from the first batch 10 (higher blowing-agent content) and the second batch 12 (lower blowingagent content) can be combined in selected proportions to tune properties such as expansion ratio, hardness, density, and compression set without reformulating the base polymer composition. However, in both single-batch and dual-batch processes, a blending 108 may be utilized to uniformly incorporate post-pelletization additives. In fact, in a single-batch process (FIG. 3), a single pellet stream 30 may be blended primarily to uniformly incorporate post-pelletization additives.Attorney Docket No.: 1559 / 2 PCT

[0101] Indeed, in embodiments, the blending stage 108 may also comprise incorporating an antimicrobial compound 34, a curing masterbatch 36 (e.g., a polymer carrier with peroxide crosslinking agents), and, in some embodiments, a degradation additive 38. Introducing these components after pelletization 106 can reduce premature interaction with the base polymer composition and help preserve foaming and cure behavior during molding.

[0102] Blending 108 can be performed in commercially available equipment 32 such as tumble blenders, ribbon blenders, V-blenders, or drum mixers. In at least one embodiment, a gravimetric blender (such as the Gravimax G14 from Wittmann Group) is utilized to combine the pellet streams and post-pelletization additives. In other embodiments, gravimetric dosing systems and loss-in- weight feeders may meter each pellet stream and additive into a continuous blender or directly to the molding feed hopper. Residence time can be sufficient to achieve visual and mass-based homogeneity while avoiding unnecessary heat input.

[0103] In embodiments, the order of addition can be selected to promote uniformity and minimize dusting or segregation. For example, pellets 26, 28, 30 may be charged first, followed by antimicrobial compound 34 and degradation additive 38 (if used), and finally the curing masterbatch 36 to help “lock in” distribution. Alternatively, the curing masterbatch 36 can be premixed with a small slip-stream of pellets to form a pre-concentrate that is then back-blended into the bulk.

[0104] The relative proportion of first-batch pellets 26 to second-batch pellets 28 may be varied to target a desired property window. By way of illustration and without limitation, ratios between about 20:80 and 80:20 (high-BA : low-BA) can be used to span a practical tuning range. In one embodiment, the proportion is equal (50:50), or near-equal (e.g., about 40:60 to 60:40), which may balance expansion and hardness for many articles. Selection of a ratio can be confirmed by downstream property measurements (see Performance Metrics section).

[0105] In further embodiments, the antimicrobial compound 34 can be present at about 1-10 wt% relative to the base polymer composition (e.g., about 3-7 wt% or about 5 wt% in specific embodiments), the curing masterbatch 36 at about 0.5-5 wt% (e.g., about 1-3 wt% or about 1-2 wt%), and the optional degradation additive 38 at about 0.5-3 wt% (e.g., about 1 wt%). Levels may be selected to provide antimicrobial functionality and / or end-of-life degradability while the curing masterbatch 36 offsets potential cure inhibition associated with these additives.Attorney Docket No.: 1559 / 2 PCT

[0106] Blending conditions can include ambient temperature operation, antistatic control, and dust management. In embodiments, additives may be pre-dusted onto pellets or supplied as granular masterbatches to enhance flowability and distribution. Optional sieving or screening can remove oversize agglomerates before molding.

[0107] Blending uniformity may be verified by mass balance checks, spot sampling, or color tracer distribution where appropriate. In some embodiments, statistical sampling of pellet aliquots can confirm that the antimicrobial compound, curing masterbatch, and any degradation additive fall within target inclusion tolerances (e.g., ±10% of setpoint), thereby supporting reproducible molding outcomes.

[0108] Without wishing to be bound by theory, post-pelletization blending 108 can help maintain foaming predictability (by preserving the undecomposed state of the blowing agent) and cure efficiency (by staging the peroxide system closer to the molding step). This sequencing may reduce risks of depressed expansion ratios, off-target hardness, or dimensional instability otherwise associated with early introduction of antimicrobial or degradable components.

[0109] The blended pellet composition 40 may be conveyed directly to the injection-molding machine 42 or stored briefly in moisture-controlled containers. In embodiments, storage below about 30 °C and <60% RH can be used to preserve stability prior to molding.Injection Molding

[0110] Following blending 108, the pellet composition 40 can be introduced into an injection molding machine 42 configured to shape the foamed footwear article 46. Injection molding may simultaneously induce decomposition of the blowing agent, promote cross-linking through the curing masterbatch 36, and form the article 46 against a mold 44 surface bearing a public health messaging insert 48, as in FIG. 4. In this manner, both the structural foam and embedded indicia can be produced in a single integrated step.

[0111] In embodiments, molding 110 can be carried out at temperatures sufficient to trigger foaming and curing while avoiding scorching or collapse. For example, injection temperatures may be maintained between about 95 °C and 105 °C, mold temperatures between about 170 °C and 180 °C, and curing times between about 400 and 600 seconds. In some embodiments, molding may be performed under an injection pressure of about 110 bar. These parameters can be varied depending on mold design, pellet formulation, and desired footwear geometry.Attorney Docket No.: 1559 / 2 PCT

[0112] In at least one embodiment, molding 110 is conducted using a commercially available injection press 42 equipped with precision temperature and pressure controls, such as those provided by King Steel Machinery. The machine 42 may include multiple hoppers to allow direct feeding of blended pellets and optional additives, as well as integrated mold temperature control units to regulate cycle times.

[0113] During injection 110, the blowing agent decomposes to release gas, forming a cellular foam structure within the polymer matrix, while the peroxide curing agents initiate cross-linking. Proper coordination of gas evolution and cross-linking can promote a uniform foam cell structure, target density, and mechanical resilience. The embedded public health messaging image segment 48 may be created by molding 110 against an engraved, raised, or textured mold 44 insert, thereby producing text, logos, or pictograms directly on the footwear surface.

[0114] Injection molding 110 can be adapted to different footwear styles, including sandals, midsoles, slippers, and closed-toe designs. Multi-cavity molds may allow simultaneous production of multiple articles, while interchangeable inserts may enable rapid modification of messaging or sizing.Stabilization and Cooling

[0115] Following injection molding 110, the foamed footwear article 46 can be subjected to a stabilization and cooling stage 112 to ensure dimensional accuracy and reproducibility of physical properties. This stage allows the molded article 46 to release residual heat, complete cross-linking reactions, and equilibrate internal stresses that may arise from foaming.

[0116] In embodiments, stabilization and cooling 112 may involve reducing the temperature of the molded article 46 to below about 40 °C prior to dimensional measurement. Cooling may occur in ambient air, through forced convection using cooling fans, or within a temperature- controlled chamber. Water-cooled or air-cooled conveyors may also be employed for continuous processing environments.

[0117] In embodiments, dimensions may be measured approximately 30 minutes after molding 110 to provide an initial indicator of expansion ratio and shrinkage behavior. Table D below illustrates exemplary target size ranges for various footwear sizes measured at 30 minutes post-molding 110. These ranges may be used as reference standards to confirm early-stage dimensional conformity.Attorney Docket No.: 1559 / 2 PCT

[0118] In further embodiments, dimensions may also be measured approximately 24 hours after molding 110 to confirm long-term dimensional stability. Measurements at this timepoint account for additional shrinkage, relaxation, or stabilization of the foam structure. Table E below illustrates exemplary target size ranges for various footwear sizes measured at 24 hours postmolding.Attorney Docket No.: 1559 / 2 PCT

[0119] In certain embodiments, footwear articles 46 can be certified as dimensionally stable if they remain within the target ranges of Tables D and E after both the 30-minute and 24-hour evaluations. These dimensional stability checks align directly with claim 22 and demonstrate how the disclosed formulations and processes may achieve the claimed performance characteristics. Deviations outside the listed ranges may indicate under- or over-expansion, shrinkage, or incomplete stabilization, prompting adjustment of processing parameters or formulation balance.

[0120] Stabilization 112 may also permit evaluation of other physical properties, including expansion ratio, hardness, and compression set, under conditions where the foam has reached equilibrium. The stabilization and cooling stage 112 can additionally prevent premature packaging of hot articles, which may otherwise trap residual volatiles, distort embedded image segments, or reduce mechanical performance. In at least one embodiment, articles are staged on perforated trays or racks that allow airflow and prevent deformation during cooling.

[0121] Where industrial throughput is desired, stabilization may be incorporated as part of an in-line quality -control workflow, permitting articles to be sorted, inspected, and tested before packaging.PERFORMANCE METRICS

[0122] The foamed footwear articles 46 described herein can be characterized using standardized test methods to confirm that target physical properties are achieved and maintained. Unless otherwise indicated, testing may be conducted at approximately 21 °C and about 50% relative humidity, after articles have undergone stabilization and cooling 112 as described above. Results can be used to guide process adjustments (e.g., pellet-blend ratios, molding conditions) and to demonstrate conformity with the performance features recited in the claims.

[0123] In embodiments, each metric may be measured according to the industry standards identified below, using calibrated equipment and standard specimen preparations. UnlessAttorney Docket No.: 1559 / 2 PCT otherwise stated, measurements may be taken on molded articles 46 (e.g., finished sandals or midsoles) or on test plaques cut from molded stock, provided that the sampling location and preparation are documented. For each lot, testing can include at least triplicate measurements per metric, with results reported as mean ± standard deviation and the individual readings archived.

[0124] Density (or specific gravity) can be measured in accordance with ASTM D297 (or ISO 845 for density by volume). In embodiments, the articles exhibit a specific gravity of about 0.26.

[0125] Expansion ratio may be determined as the ratio of the density of the unfoamed composition to the density of the foamed article, in accordance with ASTM D3575 or ISO 845. In some embodiments, ER is > about 140. In practice, ER can be tuned by adjusting the relative proportions of first-batch and second-batch pellets (dual-batch process) or by adjusting blowingagent level and molding conditions (single-batch process).

[0126] Hardness may be measured per ASTM D2240 (Shore C). In embodiments, articles exhibit a hardness of about 40-60 Shore C. For consistency, readings can be taken at multiple locations on a flat region of the article with a dwell time of about 1 s, and averaged.

[0127] Tensile properties can be measured per ASTM D412 using Type C dumbbells cut from molded stock or an equivalent specimen geometry feasible for the article. In embodiments, the article exhibits tensile strength > about 30 MPa and elongation at rupture > about 300%.

[0128] Compression set can be measured according to ASTM D395 (Method B unless otherwise specified), using representative specimens taken from molded parts or molded plaques fabricated with identical conditions. In embodiments, the article exhibits a compression set of less than about 50%. Test temperature and deflection history may be recorded, and post-test recovery time standardized (e.g., 30 min) before final readings.

[0129] Rebound resilience can be measured per ASTM D2632. In embodiments, articles exhibit resilience > about 50%. Measurements may be averaged over at least three impacts per test location.

[0130] Tear resistance may be measured per ASTM D624 (Die C) on specimens taken from molded stock where feasible. In embodiments, Die C tear strength > about 16 kN / m.

[0131] Split-tear may be determined in accordance with BS 5131 (appropriate section), reporting > about 3 kg / cm in embodiments. Specimen orientation and cut direction may be documented.Attorney Docket No.: 1559 / 2 PCT

[0132] Dimensional stability can be assessed by measuring a defined linear dimension (e.g., overall length) at ~30 minutes and ~24 hours post-molding, after cooling below about 40 °C. Target ranges are illustrated in Table D (30 minutes) and Table E (24 hours). In embodiments, articles are dimensionally stable if they remain within the target bands at both time points.

[0133] In embodiments, the article exhibits shrinkage at 24 hours within about ±2 mm of a target dimension. Where applicable, mold offsets may be adjusted to center articles within the target bands.

[0134] In embodiments, testing may follow the sequence: (i) 30-minute dimensional check; (ii) density / specific gravity; (iii) hardness; (iv) tensile / elongation; (v) compression set; (vi) resilience; (vii) tear / split-tear; (viii) 24-hour dimensional check. For production lots, a sampling plan can include N>5 pairs per size per lot (or equivalent plaque sets), with acceptance based on the metrics and thresholds disclosed herein.

[0135] In embodiments, one or more metrics (e.g., expansion ratio, density, hardness, compression set, resilience) may be tuned by adjusting: (a) the blend ratio of first-batch (higher BA) pellets 26 and second-batch (lower BA) pellets 28; (b) molding parameters (e.g., melt temperature, mold temperature, cure time / pressure); and / or (c) additive levels (e.g., antimicrobial 34, curing masterbatch 36, optional degradation additive 38) within the disclosed ranges. Without wishing to be bound by theory, the curing masterbatch 36 may offset cure inhibition that can otherwise arise from antimicrobial 34 or degradable components 38, thereby helping maintain the targeted property set.TEST METHODS

[0136] Unless otherwise indicated, physical properties described herein may be measured using standardized procedures published by ASTM International, the International Organization for Standardization (ISO), or the British Standards Institution (BSI). Equivalent or successor methods are considered within the scope of this disclosure. Specimens may be cut from finished footwear articles or molded plaques prepared under identical conditions. Where numerical thresholds are provided, they correspond to measurements obtained under ambient conditions (about 21 °C, about 50% relative humidity), unless stated otherwise.EXAMPLES

[0137] The following examples are provided to further illustrate embodiments of the present disclosure. These examples are not intended to limit the scope of the disclosure, but rather toAttorney Docket No.: 1559 / 2 PCT demonstrate representative formulations, methods, and resulting physical properties of foamed footwear articles.Example 1 - Dual-Batch Formulation

[0138] A dual-batch formulation was prepared by dividing the base polymer composition into two material mixtures, one containing a higher level of blowing agent (first batch 10) and one containing a lower level of blowing agent (second batch 12). Each material mixture was kneaded, pelletized, and then blended together in near-equal proportions, together with antimicrobial compound 34, curing masterbatch 36, and degradation additive 38 as specified.Example 2 - Single-Batch Formulation

[0139] A single-batch formulation was prepared by incorporating a uniform level of blowing agent into the base polymer composition, kneading the material mixture 14 into a homogeneous blended dough 20, pelletizing, and then blending with antimicrobial compound 34, curing masterbatch 36, and degradation additive 38.Attorney Docket No.: 1559 / 2 PCTExample 3 - Performance Metrics

[0140] Foamed footwear articles 46 produced from the formulations of Examples 1 and 2 were tested in accordance with ASTM, ISO, and BS methods as described herein. Representative performance metrics are summarized in Table H. Results indicate that the disclosed formulations achieve desirable balance of expansion, density, mechanical strength, and dimensional stability while incorporating antimicrobial and degradable additives.Attorney Docket No.: 1559 / 2 PCTADDITIONAL NOTES

[0141] One skilled in the art will readily appreciate that the present disclosure is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. The present disclosure is representative of embodiments, which are exemplary, and are not intended as limitations on the scope of the present disclosure. Changes and other uses will occur to those skilled in the art which are encompassed within the spirit of the present disclosure as defined by the scope of the claims.

[0142] No admission is made that any reference, including any non-patent or patent document cited in this specification, constitutes prior art. It will be understood that, unless otherwise stated, reference to any document herein does not constitute an admission that any of these documents forms part of the common general knowledge in the art in the United States or in any other country. Any discussion of the references states what their authors assert, and the applicant reserves the right to challenge the accuracy and pertinence of any of the documents cited herein. All references cited herein are fully incorporated by reference, unless explicitly indicated otherwise. The present disclosure shall control in the event there are any disparities between any definitions and / or description found in the cited references.

Claims

1. Attorney Docket No.: 1559 / 2 PCTCLAIMS1. A method of producing a foamed footwear article, the method comprising: preparing a first material mixture comprising a base polymer composition and a first amount of a blowing agent; preparing a second material mixture comprising the base polymer composition and a second amount of the blowing agent, the first amount being greater than the second amount; kneading the first material mixture under conditions sufficient to form a homogeneous first blended dough while preventing premature decomposition of components of the base polymer composition; kneading the second material mixture under conditions sufficient to form a homogeneous second blended dough while preventing premature decomposition of components of the base polymer composition; pelletizing the first blended dough to form a first batch of pellets and pelletizing the second blended dough to form a second batch of pellets; blending the first batch of pellets, the second batch of pellets, an antimicrobial compound, and a curing masterbatch to form a blended pellet composition, wherein the curing masterbatch comprises a polymer carrier and a peroxide cross-linking agent; injection molding the blended pellet composition in a mold bearing a public health messaging image segment, under conditions sufficient to decompose the blowing agent and effect cross-linking of the base polymer composition to form a foamed footwear article; and stabilizing and cooling the foamed footwear article following molding.

2. The method of claim 1, wherein the base polymer mixture comprises a polymer and an elastomer and an additive mixture comprising a filler compound, a blowing agent activator, a cross-linking agent, and a pigment compound.

3. The method of claim 2, wherein the polymer comprises ethylene-vinyl acetate (EVA), the elastomer comprises a polyolefin elastomer (POE) and optionally an olefin blockAttomey Docket No.: 1559 / 2 PCT copolymer, the filler compound comprises calcium carbonate, the blowing agent compound comprises azodicarbonamidc, the blowing agent activator comprises zinc oxide and zinc stearate, the cross-linking agent comprises dicumyl peroxide and l,4-bis-(t- butylperoxyisopropyl)benzene, and the pigment compound comprises carbon black, a chromite, a ferrite, or a pigment concentrate in an EVA carrier.

4. The method of claim 3, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 30 to about 40 wt% EVA, about 10 to about 20 wt% POE, about 5 to about 15 wt% olefin block copolymer, about 15 to about 25 wt% FY-36 composite, about 5 to about 20 wt% calcium carbonate, about 3 to about 8 wt% pigment, about 0.5 to about 2 wt% zinc oxide, about 0.5 to about 2 wt% zinc stearate, and about 0.5 to about 1.5 wt% total cross-linking agents; and wherein the first amount of the blowing agent is about 1.5 to about 2.5 wt% based on the weight of the base polymer composition and the second amount of the blowing agent is about 0.8 to about 1.5 wt% based on the weight of the base polymer composition.

5. The method of claim 4, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 35 to about 38 wt% EVA, about 13 to about 16 wt% POE, about 8 to about 10 wt% olefin block copolymer, about 18 to about 22 wt% FY-36 composite, about 10 to about 13 wt% calcium carbonate, about 5 to about 7 wt% pigment, about 1.0 to about 1.2 wt% zinc oxide, about 0.5 to about 0.7 wt% zinc stearate, and about 0.5 wt% each dicumyl peroxide and l,4-bis-(t-butylperoxyisopropyl)benzene; and wherein the first amount of the blowing agent is about 2.0 to about 2.3 wt% based on the weight of the base polymer composition and the second amount of the blowing agent is about 1.0 to about 1.2 wt% based on the weight of the base polymer composition.

6. The method of claim 5, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 36.8 wt% EVA, about 14.1 wt% POE, about 9.0 wt% olefin block copolymer, about 20.3 wt% FY-36 composite, about 11.3 wt% calcium carbonate, about 5.7 wt% pigment, about 1.1 wt% zinc oxide, about 0.6 wt% zinc stearate, about 0.5 wt% dicumyl peroxide, and about 0.5 wt% l,4-bis-(t-Attorney Docket No.: 1559 / 2 PCT butylperoxyisopropyl)benzene; and wherein the first amount of the blowing agent is about 2.22 wt% based on the weight of the base polymer composition and the second amount of the blowing agent is about 1.13 wt% based on the weight of the base polymer composition.

7. The method of claim 1, wherein the antimicrobial compound is present in an amount of about 1 to about 10 wt% based on the weight of the base polymer composition.

8. The method of claim 7, wherein the antimicrobial compound is present in an amount of about 3 to about 7 wt% based on the weight of the base polymer composition.

9. The method of claim 8, wherein the antimicrobial compound is present in an amount of about 5 wt% based on the weight of the base polymer composition.

10. The method of claim 1, wherein the curing masterbatch is present in an amount of about 0.5 to about 5 wt% based on the weight of the base polymer composition.

11. The method of claim 10, wherein the curing masterbatch is present in an amount of about 1 to about 3 wt% based on the weight of the base polymer composition.

12. The method of claim 11, wherein the curing masterbatch is present in an amount of about 1 to about 2 wt% based on the weight of the base polymer composition.

13. The method of claim 1, further comprising incorporating into the blended pellet composition a degradation additive in an amount of about 0.5 to about 3 wt% based on the weight of the base polymer composition.

14. The method of claim 13, wherein the degradation additive is present in an amount of about 1 wt% based on the weight of the base polymer composition.Attorney Docket No.: 1559 / 2 PCT15. The method of claim 13, wherein the degradation additive comprises one or more of a chemoattractant, glutaric acid or a derivative thereof, a carboxylic acid, a swelling agent, or a microbe.

16. The method of claim 13, wherein the curing masterbatch offsets cure inhibition associated with inclusion of the degradation additive.

17. The method of claim 13, wherein the curing masterbatch offsets cure inhibition associated with inclusion of the antimicrobial compound.

18. The method of claim 1, wherein the conditions sufficient to form a homogeneous first blended dough comprise a temperature of about 80 °C to about 120 °C, a time of about 5 to about 15 minutes, and a rotor speed of about 20 to about 60 revolutions per minute.

19. The method of claim 1, wherein the conditions sufficient to decompose the blowing agent and effect cross-linking of the base polymer composition comprise an injection temperature of about 95 °C to about 105 °C, a mold temperature of about 170 °C to about 180 °C, and a curing time of about 400 to about 600 seconds.

20. The method of claim 19, wherein the conditions comprise performing the injection molding under a pressure of about 110 bar.

21. The method of claim 1, wherein the stabilizing and cooling comprises reducing the temperature of the molded footwear article to below about 40 °C prior to dimensional measurement.

22. The method of claim 1, wherein the stabilizing and cooling further comprises measuring the dimensions of the foamed footwear article about 30 minutes and about 24 hours after molding to confirm dimensional stability.Attorney Docket No.: 1559 / 2 PCT23. The method of claim 1 , wherein the foamed footwear article formed under the conditions of claim 1 exhibits an expansion ratio of at least about 140, as determined by density measurement in accordance with ASTM D3575 or ISO 845.

24. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a hardness of about 40 to about 60 Shore C, as determined in accordance with ASTM D2240.

25. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a tensile strength of at least about 30 MPa and an elongation at rupture of at least about 300 percent, as determined in accordance with ASTM D412.

26. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a compression set of less than about 50 percent, as determined in accordance with ASTM D395.

27. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits shrinkage at 24 hours within about ±2 millimeters of a target dimension.

28. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a specific gravity of about 0.26 as determined by ASTM D297.

29. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a resilience of at least about 50% as determined by ASTM D2632.

30. The method of claim 1, wherein the foamed footwear article formed under the conditions of claim 1 exhibits a Die C tear strength of at least about 16 kN / m as determined by ASTM D624 and a split tear strength of at least about 3 kg / cm as determined by BS5131.

31. The method of claim 1 , wherein the relative proportions of the first batch of pellets and the second batch of pellets are selected to tune one or more properties comprising at least oneAttomey Docket No.: 1559 / 2 PCT of expansion ratio, specific gravity (density), hardness (Shore C), tensile strength, elongation at break, compression set, resilience (rebound), tear strength (ASTM D624, Die C), split-tear strength (BS 5131), and dimensional stability / shrinkage.

32. A foamed footwear article produced according to the method of claim 1.

33. A method of producing a foamed footwear article, the method comprising: preparing a material mixture comprising a base polymer composition and a blowing agent; kneading the material mixture under conditions sufficient to form a homogeneous blended dough while preventing premature decomposition of components of the base polymer composition; pelletizing the blended dough to form a batch of pellets; blending the batch of pellets with an antimicrobial compound and a curing masterbatch to form a blended pellet composition, wherein the curing masterbatch comprises a polymer carrier and a peroxide cross-linking agent; injection molding the blended pellet composition in a mold bearing a public health messaging image segment, under conditions sufficient to decompose the blowing agent and effect cross-linking of the base polymer composition to form a foamed footwear article; and stabilizing and cooling the foamed footwear article following molding.

34. The method of claim 33, wherein the base polymer composition comprises a polymer and an elastomer and an additive mixture comprising a filler compound, a blowing agent activator, a cross-linking agent, and a pigment compound.

35. The method of claim 34, wherein the polymer comprises ethylene-vinyl acetate (EVA), the elastomer comprises a polyolefin elastomer (POE) and optionally an olefin block copolymer, the filler compound comprises calcium carbonate, the blowing agent comprises azodicarbonamide, the blowing agent activator comprises zinc oxide and zinc stearate, the cross-linking agent comprises dicumyl peroxide and l,4-bis-(t-Attorney Docket No.: 1559 / 2 PCT butylperoxyisopropyl)benzene, and the pigment compound comprises carbon black, a chromite, a ferrite, or a pigment concentrate in an EVA carrier.

36. The method of claim 35, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 30 to about 40 wt% EVA, about 10 to about 20 wt% POE, about 5 to about 15 wt% olefin block copolymer, about 15 to about 25 wt% FY-36 composite, about 5 to about 20 wt% calcium carbonate, about 3 to about 8 wt% pigment, about 0.5 to about 2 wt% zinc oxide, about 0.5 to about 2 wt% zinc stearate, and about 0.5 to about 1.5 wt% total cross-linking agents; and wherein the blowing agent is present at about 1.5 to about 2.5 wt% based on the weight of the base polymer composition.

37. The method of claim 36, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 35 to about 38 wt% EVA, about 13 to about 16 wt% POE, about 8 to about 10 wt% olefin block copolymer, about 18 to about 22 wt% FY-36 composite, about 10 to about 13 wt% calcium carbonate, about 5 to about 7 wt% pigment, about 1.0 to about 1.2 wt% zinc oxide, about 0.5 to about 0.7 wt% zinc stearate, and about 0.5 wt% each dicumyl peroxide and l,4-bis-(t-butylperoxyisopropyl)benzene; and wherein the blowing agent is present at about 1.6 to about 2.0 wt% based on the weight of the base polymer composition.

38. The method of claim 37, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 36.8 wt% EVA, about 14.1 wt% POE, about 9.0 wt% olefin block copolymer, about 20.3 wt% FY-36 composite, about 11.3 wt% calcium carbonate, about 5.7 wt% pigment, about 1.1 wt% zinc oxide, about 0.6 wt% zinc stearate, about 0.5 wt% dicumyl peroxide, and about 0.5 wt% l,4-bis-(t- butylperoxyisopropyl)benzene; and wherein the blowing agent is present at about 1.6 wt% based on the weight of the base polymer composition.

39. The method of claim 33, wherein the antimicrobial compound is present in an amount of about 1 to about 10 wt% based on the weight of the base polymer composition.Attorney Docket No.: 1559 / 2 PCT40. The method of claim 39, wherein the antimicrobial compound is present in an amount of about 3 to about 7 wt% based on the weight of the base polymer composition.

41. The method of claim 40, wherein the antimicrobial compound is present in an amount of about 5 wt% based on the weight of the base polymer composition.

42. The method of claim 33, wherein the curing masterbatch is present in an amount of about 0.5 to about 5 wt% based on the weight of the base polymer composition.

43. The method of claim 42, wherein the curing masterbatch is present in an amount of about 1 to about 3 wt% based on the weight of the base polymer composition.

44. The method of claim 43, wherein the curing masterbatch is present in an amount of about 1 to about 2 wt% based on the weight of the base polymer composition.

45. The method of claim 33, further comprising incorporating into the blended pellet composition a degradation additive in an amount of about 0.5 to about 3 wt% based on the weight of the base polymer composition.

46. The method of claim 45, wherein the degradation additive is present in an amount of about 1 wt% based on the weight of the base polymer composition.

47. The method of claim 45, wherein the degradation additive comprises one or more of a chemoattractant, glutaric acid or a derivative thereof, a carboxylic acid, a swelling agent, or a microbe.

48. The method of claim 45, wherein the curing masterbatch offsets cure inhibition associated with inclusion of the degradation additive.Attorney Docket No.: 1559 / 2 PCT49. The method of claim 33, wherein the conditions sufficient to form a homogeneous blended dough comprise a temperature of about 80 °C to about 120 °C, a time of about 5 to about 15 minutes, and a rotor speed of about 20 to about 60 revolutions per minute.

50. The method of claim 33, wherein the conditions sufficient to decompose the blowing agent and effect cross-linking of the base polymer composition comprise an injection temperature of about 95 °C to about 105 °C, a mold temperature of about 170 °C to about 180 °C, and a curing time of about 400 to about 600 seconds.

51. The method of claim 50, wherein the injection molding is performed under a pressure of about 110 bar.

52. The method of claim 33, wherein stabilizing and cooling comprises reducing the temperature of the molded footwear article to below about 40 °C prior to dimensional measurement.

53. The method of claim 33, wherein stabilizing and cooling further comprises measuring the dimensions of the foamed footwear article about 30 minutes and about 24 hours after molding to confirm dimensional stability.

54. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits an expansion ratio of at least about 140, as determined by density measurement in accordance with ASTM D3575 or ISO 845.

55. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits a hardness of about 40 to about 60 Shore C, as determined in accordance with ASTM D2240.

56. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits a tensile strength of at least about 30 MPa and an elongation at rupture of at least about 300 percent, as determined in accordance with ASTM D412.Attorney Docket No.: 1559 / 2 PCT57. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits a compression set of less than about 50 percent, as determined in accordance with ASTM D395.

58. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits shrinkage at 24 hours within about ±2 millimeters of a target dimension.

59. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits a specific gravity of about 0.26, as determined by ASTM D297.

60. The method of claim 33, wherein the foamed footwear article formed under the conditions of claim 33 exhibits a resilience of at least about 50% as determined by ASTM D2632, a Die C tear strength of at least about 16 kN / m as determined by ASTM D624, and a split tear strength of at least about 3 kg / cm as determined by BS 5131.

61. A foamed footwear article produced according to the method of claim 33.

62. The foamed footwear article of claim 61 , wherein the base polymer composition comprises a polymer and an elastomer and an additive mixture comprising a filler compound, a blowing agent activator, a cross-linking agent, and a pigment compound.

63. The foamed footwear article of claim 62, wherein the polymer comprises EVA, the elastomer comprises POE and optionally an OBC, the filler comprises CaCOr, the blowing agent comprises azodicarbonamide, the activator comprises ZnO and zinc stearate, the cross-linking agent comprises DCP and BIPB, and the pigment comprises carbon black, a chromite, a ferrite, or a pigment concentrate in an EVA carrier.Attorney Docket No.: 1559 / 2 PCT64. The foamed footwear article of claim 62, further comprising an antimicrobial compound present in an amount of about 1-10 wt% based on the weight of the base polymer composition.

65. The foamed footwear article of claim 64, wherein the antimicrobial compound is present in an amount of about 5 wt%.

66. The foamed footwear article of claim 61, further comprising a degradation additive in an amount of about 0.5-3 wt% based on the weight of the base polymer composition.

67. The foamed footwear article of claim 66, wherein the degradation additive is present in an amount of about 1 wt%.

68. The foamed footwear article of claim 61, wherein the article exhibits an expansion ratio of at least about 140, as determined by ASTM D3575 or ISO 845.

69. The foamed footwear article of claim 61, wherein the article exhibits a hardness of about 40-60 Shore C, as determined by ASTM D2240.

70. The foamed footwear article of claim 61, wherein the article exhibits a tensile strength of at least about 30 MPa and an elongation at rupture of at least about 300 percent, as determined by ASTM D412.

71. The foamed footwear article of claim 61, wherein the article exhibits a compression set of less than about 50 percent, as determined by ASTM D395.

72. The foamed footwear article of claim 61, wherein the article exhibits shrinkage at 24 hours within about ±2 millimeters of a target dimension.

73. The foamed footwear article of claim 61, wherein the article exhibits a specific gravity of about 0.26, as determined by ASTM D297.Attorney Docket No.: 1559 / 2 PCT74. The foamed footwear article of claim 61, wherein the article exhibits a resilience of at least about 50% as determined by ASTM D2632, a Die C tear strength of at least about 16 kN / m as determined by ASTM D624, and a split tear strength of at least about 3 kg / cm as determined by BS 5131.

75. The foamed footwear article of claim 61 , wherein the article comprises an embedded image segment bearing a public health message formed during injection molding.

76. A formulation for producing a foamed footwear article by injection molding, the formulation comprising: a base polymer composition comprising a polymer and an elastomer; an additive mixture comprising a filler compound, a blowing agent compound, a blowing agent activator, a cross-linking agent, and a pigment compound; an antimicrobial compound; and a curing masterbatch comprising a polymer carrier and a peroxide cross-linking agent.

77. The formulation of claim 76, wherein the polymer comprises ethylene-vinyl acetate (EVA), the elastomer comprises a polyolefin elastomer (POE) and optionally an olefin block copolymer, the filler compound comprises calcium carbonate, the blowing agent compound comprises azodicarbonamide, the blowing agent activator comprises zinc oxide and zinc stearate, the cross-linking agent comprises dicumyl peroxide and l,4-bis-(t- butylperoxyisopropyl)benzene, and the pigment compound comprises carbon black, a chromite, a ferrite, or a pigment concentrate in an EVA carrier.

78. The formulation of claim 77, wherein the base polymer composition comprises, based on the weight of the base polymer composition: about 3C -0 wt% EVA, about 10-20 wt% POE, about 5-15 wt% olefin block copolymer, about 15-25 wt% FY-36 composite, about 5-20 wt% calcium carbonate, about 3-8 wt% pigment, about 0.5-2 wt% zinc oxide, about 0.5-2 wt% zinc stearate, and about 0.5-1.5 wt% total cross-linking agents; and whereinAttorney Docket No.: 1559 / 2 PCT the blowing agent compound is present at about 1.5-2.5 wt% based on the weight of the base polymer composition.

79. The formulation of claim 78, wherein the base polymer composition comprises: about 35- 38 wt% EVA, about 13-16 wt% POE, about 8-10 wt% olefin block copolymer, about 18- 22 wt% FY-36 composite, about 10-13 wt% calcium carbonate, about 5-7 wt% pigment, about 1.0-1.2 wt% zinc oxide, about 0.5-0.7 wt% zinc stearate, and about 0.5 wt% each dicumyl peroxide and l,4-bis-(t-butylperoxyisopropyl)benzene; and wherein the blowing agent compound is present at about 1.6-2.0 wt%.

80. The formulation of claim 79, wherein the base polymer composition comprises about 36.8 wt% EVA, about 14.1 wt% POE, about 9.0 wt% olefin block copolymer, about 20.3 wt% FY-36 composite, about 11.3 wt% calcium carbonate, about 5.7 wt% pigment, about 1.1 wt% zinc oxide, about 0.6 wt% zinc stearate, about 0.5 wt% dicumyl peroxide, and about 0.5 wt% l,4-bis-(t-butylperoxyisopropyl)benzene; and wherein the blowing agent compound is present at about 1.6 wt%.

81. The formulation of claim 76, wherein the antimicrobial compound is present in an amount of about 1-10 wt% based on the weight of the base polymer composition.

82. The formulation of claim 81, wherein the antimicrobial compound is present in an amount of about 3-7 wt%.

83. The formulation of claim 82, wherein the antimicrobial compound is present in an amount of about 5 wt%.

84. The formulation of claim 76, wherein the curing masterbatch is present in an amount of about 0.5-5 wt% based on the weight of the base polymer composition.

85. The formulation of claim 84, wherein the curing masterbatch is present in an amount of about 1-3 wt%.

86. The formulation of claim 85, wherein the curing masterbatch is present in an amount of about 1-2 wt%.Attorney Docket No.: 1559 / 2 PCT87. The formulation of claim 76, further comprising a degradation additive in an amount of about 0.5-3 wt% based on the weight of the base polymer composition.

88. The formulation of claim 87, wherein the degradation additive is present in an amount of about 1 wt%.

89. The formulation of claim 87, wherein the degradation additive comprises one or more of a chemoattractant, glutaric acid or a derivative thereof, a carboxylic acid, a swelling agent, or a microbe.

90. The formulation of claim 87, wherein the curing masterbatch offsets cure inhibition associated with inclusion of the degradation additive.

91. The formulation of claim 87, wherein the curing masterbatch offsets cure inhibition associated with inclusion of the degradation additive.

92. The formulation of claim 76, wherein a foamed footwear article produced from the formulation exhibits a hardness of about 40-60 Shore C, as determined by ASTM D2240.

93. The formulation of claim 76, wherein a foamed footwear article produced from the formulation exhibits a tensile strength of at least about 30 MPa and an elongation at rupture of at least about 300 percent, as determined by ASTM D412.

94. The formulation of claim 76, wherein a foamed footwear’ article produced from the formulation exhibits a compression set of less than about 20 percent, as determined by ASTM D395.

95. The formulation of claim 76, wherein a foamed footwear article produced from the formulation exhibits shrinkage at 24 hours within about ±2 millimeters of a target dimension.

96. The formulation of claim 76, wherein a foamed footwear article produced from the formulation exhibits a specific gravity of about 0.26, as determined by ASTM D297.Attorney Docket No.: 1559 / 2 PCT97. The formulation of claim 76, wherein a foamed footwear article produced from the formulation exhibits a resilience of at least about 50% as determined by ASTM D2632, a Die C tear strength of at least about 16 kN / m as determined by ASTM D624, and a split tear strength of at least about 3 kg / cm as determined by BS 5131.

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