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[0058]Inventive three-dimensionally printed (3D-printed) articles for use in footwear or other applications, and associated methods, are generally described herein. In some embodiments, the 3D-printed article may comprise one or more features that are challenging or impossible to obtain in articles manufactured by other techniques. As an example, the 3D-printed article may be a single integrated material which comprises a gradient in one or more properties (e.g., average pore size, density, stiffness, stiffness of solid components of the article, Shore A hardness, degree of cross-linking, chemical composition, color, abrasion resistance, thermal conductivity, electrical conductivity, stiffness anisotropy, elastic modulus, flexural modulus, filler content, opacity, conductivity, breathability) between two or more portions of the material. This may be achieved using a 3D printing process by printing the 3D-printed article using an ink that can be dynamically changed as the article is printed (by, e.g., changing the ratios of different components that make up the ink, changing the temperature of the ink, and the like). In some embodiments, the 3D-printed article may have one or more features that are preferred by users of the 3D-printed article or footwear of which the 3D-printed article is one component. For example, the 3D-printed article may be a single integrated material and/or may lack seams, adhesives, and other features that are typically used to join two or more materials together. These and other 3D-printed articles may be more comfortable for users, and/or may be less subject to degradation or damage during normal usage of the article.
[0059]It should be understood that references herein to 3D-printed articles may encompass articles that include more than one layer (e.g., articles that comprise multiple layers printed on top of each other) and/or may encompass articles that include a single layer (e.g., articles in which a single layer of material has been printed). 3D-printed articles may encompass articles printed from 3D-printers and/or articles that extend macroscopically in three dimensions (e.g., with a minimal extent in each dimension of 50 microns, 100 microns, 200 microns, 500 microns, or 1 mm). Similarly, 3D-printing may encompass printing articles that include more than one layer and/or printing articles that include a single layer. 3D-printing may encompass printing articles on 3D-printers, printing articles extend macroscopically in three dimensions (e.g., with a minimal extent in each dimension of 50 microns, 100 microns, 200 microns, 500 microns, or 1 mm).
[0060]It should also be understood that articles other than 3D-printed articles and printing methods other than 3D-printing are also contemplated. For example, some embodiments relate to articles that have one or more of the features of the 3D-printed articles described herein (e.g., a gradient in one or more properties) but are not 3D-printed articles. Some articles may include both one or more 3D-printed components and one or more non-3D-printed components. Similarly, some embodiments relate to methods that have one or more features of the methods described herein (e.g., may comprise employing a multi-axis deposition system) but which do not include a 3D-printing step. Some methods may include both one or more 3D-printing steps and one or more non-3D-printing steps.
[0061]Certain methods (e.g., methods including exclusively 3D-printing steps, methods including exclusively non-3D printing steps, methods including both 3D-printing steps and non-3D-printing steps) comprise depositing one or more film(s) onto a 3D-surface. Some or all of the films, if more than one are deposited, may be thin film(s).
[0062]Certain methods (e.g., methods including exclusively 3D-printing steps, methods including exclusively non-3D printing steps, methods including both 3D-printing steps and non-3D-printing steps) comprise depositing a material that does not form a film on a substrate. For instance, a material may be deposited onto a substrate into which it infiltrates. As an example, a material may be deposited onto a porous substrate (e.g., a porous textile) and then infiltrate into at least a portion of the pores of the porous substrate. After it has been deposited onto the porous substrate, it may fill a portion of the pores of the porous substrate. The material may enhance the mechanical properties of the substrate. In some embodiments, a material deposited onto a substrate into which it infiltrates, such as a porous substrate, does not extend an appreciable distance (or at all) beyond the surface of the porous substrate.
[0063]In one set of embodiments, one or more methods for manufacturing 3D-printed articles as described herein may be advantageous in comparison to other methods for making articles for use in footwear. For example, a footwear manufacturer employing a method as described herein may be able to use fewer processes to create the article than would be employed in other comparable processes (e.g., the manufacturer may use a three-dimensional printer (3D printer) in a single process to make a component that would otherwise be made by a combination of several processes such as injection molding, lamination, and the like). This may allow for more rapid and/or more facile manufacturing. As another example, one or more of the methods described herein may not necessarily require the use equipment that is expensive to manufacture and whose cost is typically recovered only after repeated use (e.g., molds). Some of the methods described herein may instead employ a 3D printer to create articles whose design can be modified as desired with little or no added cost. In some embodiments, it may be economical for methods as described herein to create small batches of 3D-printed articles (e.g., batches of less than 100, less than 50, or less than 10). It is thus possible for manufacturers to employ some of the methods described herein to respond to changing market conditions, to create articles for use in footwear that are designed for individual users or groups of users, etc. In some embodiments, it may be advantageous to use one or more of the methods described herein to fabricate a 3D-printed article at the point of sale and/or to avoid long distance shipping.
[0064]As explained above, certain methods of manufacturing an article as described herein may include both 3D-printing steps and non-3D-printing steps. For example, additive manufacturing (e.g., 3D-printing) may be utilized to manufacture one or more components that may be subsequently used in one or more 3D-printing steps and/or non-3D-printing steps to produce an article for use in footwear or other applications. Certain embodiments described herein relate to a digital molding process. In some embodiments, for example, an additive manufacturing process may be used to manufacture a first mold (e.g., a master mold). The first mold may be used, in some embodiments, to provide a second mold (e.g., a secondary mold) by, for example, casting an elastomer into the first mold. According to certain embodiments, the second mold may then be digitally filled by dispensing a curable liquid into the second mold and at least partially curing the curable liquid in the second mold. The at least partially cured liquid may be transferred, in some embodiments, from the second mold to a receiving substrate (e.g., a textile) as the at least partially cured liquid becomes fully cured, thereby providing an article (e.g., footwear).
[0065]The digital molding process may advantageously be used to manufacture designs (e.g., computer-aided designs) with finer features and increased production speed while requiring less material as compared to conventional manufacturing processes and/or 3D-printing processes, therefore significantly reducing manufacturing and labor costs. In some embodiments, for example, automated digital filling of the 3D-fabricated mold (e.g., master mold), as explained above, may be used to provide an article comprising a number of high-resolution features that may have desirable properties. In some embodiments, for example, the features have zonally variable material properties, such as variable optical properties (e.g., multi-colored) and/or variable mechanical properties (e.g., stiffness).
[0066]As used herein, the term “master mold” generally refers to a mold that has at least some sections that substantially resemble the configuration (e.g., shape and/or size) of a part that will be produced from a secondary mold that is created from the master mold. The master mold may have a neutral surface that contacts the transfer medium. The master mold may be a positive master mold or a negative master mold. In the case of a positive master mold, for example, the neutral surface is the lowest upward facing surface. Alternatively, in the case of a negative master mold, the neutral surface is the highest upward facing surface. In certain non-limiting embodiments, for example, a first mold (e.g., a positive master mold) may be manufactured by additive manufacturing. The positive master mold may, in some embodiments, be used to provide a second mold (e.g., a negative secondary mold) by, for example, casting an elastomer into the positive master mold. In some such embodiments, the features that protrude above the neutral surface in the positive master mold form cavities in the negative secondary mold via casting the elastomer, as explained herein in further detail.
[0067]The term “curable liquid” as used herein is given its ordinary meaning in the art and generally refers to a flowable liquid that can undergo a change in one or more properties to become a solid material. In some embodiments, for example, in the case of a curable liquid comprising a thermoset material, the change may occur through one or more chemical reactions (e.g., crosslinking). In other embodiments, for example, in the case of a curable liquid comprising a dispersion, polymer solution, and/or an emulsion, the change may occur through evaporation of water or a solvent.
[0068]A non-limiting example of a 3D-printed article for use in footwear is shown in FIG. 1A. In this figure, 3D-printed article 100 comprises first portion 110 and second portion 120. As used herein, a portion of an article may refer to any collection of points within the article (i.e., points that are within the portion of space bounded by the external surfaces of the article). Portions of the article are typically, but not always, volumes of space within the article (in some embodiments, a portion may be a surface within an article, a line within an article, or a point within an article). Portions of the article may be continuous (i.e., each point within the portion may be connected by a pathway that does not pass through any points external to the portion) or may be discontinuous (i.e., the portion may comprise at least one point that cannot be connected to at least one other point within the article by a pathway that does not pass through any points external to the portion). Portions of an article may be substantially homogeneous with respect to one or more properties (e.g., one or more properties of the portion may vary with a standard deviation of less than or equal to 1%, 2%, 5%, or 10% throughout the portion), and/or may be heterogeneous with respect to one or more properties (e.g., one or more properties of the portion may vary with a standard deviation of greater than or equal to 1%, 2%, 5%, or 10% throughout the portion).
[0069]Portions of an article may have any suitable size. In some embodiments, a portion may have a largest dimension and/or may comprise one or more features with a size of greater than or equal to 100 microns, greater than or equal to 200 microns, greater than or equal to 500 microns, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 5 mm, greater than or equal to 10 mm, greater than or equal to 20 mm, greater than or equal to 50 mm, greater than or equal to 1 cm, or greater than or equal to 2 cm. In some embodiments, a portion may have a largest dimension and/or may comprise one or more features with a size of less than or equal to 5 cm, less than or equal to 2 cm, less than or equal to 1 cm, less than or equal to 5 mm, less than or equal to 2 mm, less than or equal to 1 mm, less than or equal to 500 microns, or less than or equal to 200 microns. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 100 microns and less than or equal to 5 cm). Other ranges are also possible.
[0070]In some embodiments, a 3D-printed article may comprise two or more portions, where one or more properties (e.g., average pore size, density, stiffness, stiffness of solid components of the article, Shore A hardness, degree of cross-linking, chemical composition, color, abrasion resistance, thermal conductivity, electrical conductivity, stiffness anisotropy, elastic modulus, flexural modulus, filler content, opacity, conductivity, breathability) of a first portion may differ from one or more properties of a second portion. The one or more properties may be structural properties (e.g., average pore size, density, surface roughness, filler content), chemical properties (e.g., average degree of cross-linking, chemical composition), mechanical properties (e.g., average stiffness, stiffness of solid components, Shore A hardness, abrasion resistance, stiffness anisotropy, elastic modulus, flexural modulus, strength, elongation at break, tensile elastic modulus, modulus at 100% strain), optical properties (e.g., color, opacity, reflectivity), and/or other properties (e.g., average thermal conductivity, electrical conductivity, conductivity, breathability, dimensional change upon heat activation). In some embodiments, the difference in properties between the first portion and the second portion may comprise a gradient of the one or more properties (e.g., the property or properties may vary relatively smoothly from a first value in the first portion to a second value in the second portion). In other embodiments, there may be a sharp change in one or more of the properties at a boundary of one or more of the first portion and the second portion.
[0071]It should be understood that while FIG. 1A shows the second portion positioned above the first portion, other arrangements of the first portion with respect to the second portion are also contemplated. For example, the first portion may be positioned beside the second portion, the first portion may surround the second portion, the first portion and the second portion may interpenetrate (e.g., a first portion may comprise a foam that interpenetrates with a second portion that comprises an elastomer), etc. It should also be noted that while FIG. 1A shows the second portion directly adjacent the first portion, this configuration should not be understood to be limiting. In some embodiments, the first portion may be separated from the second portion by one or more intervening portions positioned between the first portion and the second portion. As used herein, a portion that is positioned “between” two portions may be directly between the two portions such that no intervening portion is present, or an intervening portion may be present.
[0072]Similarly, while FIG. 1A only depicts two portions, it should also be understood that an article may comprise three portions, four portions, or more portions. In some embodiments, portions within a 3D-printed article as described herein may also further comprise sub-portions. Each portion and/or sub-portion may differ from each other (sub-)portion in at least one way (e.g., any two (sub-)portions may comprise at least one property that is different), or one or more (sub-)portions may be substantially similar to other (sub-)portion(s) of the 3D-printed article.
[0073]In some embodiments, two or more portions may be disposed relative to each other such that they may be connected by a pathway along which the 3D-printed article lacks an interface along which one or more properties (e.g., average pore size, density, stiffness, stiffness of solid components of the article, Shore A hardness, degree of cross-linking, chemical composition, color, abrasion resistance, thermal conductivity, electrical conductivity, stiffness anisotropy, elastic modulus, flexural modulus, filler content, opacity, conductivity, breathability) undergo step changes. In other words, the property or properties may vary smoothly along the pathway. The pathway may be a straight path pathway (e.g., it may be a line segment), or it may include one or more curves or corners (e.g., it may be a meander, as described more fully below). In some embodiments, the pathway may be a pathway along which material was deposited during formation of the 3D-printed article, such as a pathway travelled by a print head (or by a substrate with respect to the print head) during 3D-printing.
[0074]When two or more portions are connected by a pathway, the pathway may have any suitable length. In some embodiments, the pathway has a length of greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 5 mm, greater than or equal to 10 mm, greater than or equal to 20 mm, greater than or equal to 50 mm, greater than or equal to 100 mm, greater than or equal to 200 mm, greater than or equal to 500 mm, greater than or equal to 1 m, greater than or equal to 2 m, or greater than or equal to 5 m. In some embodiments, the pathway has a length of less than or equal to 10 m, less than or equal to 5 m, less than or equal to 2 m, less than or equal to 1 m, less than or equal to 500 mm, less than or equal to 200 mm, less than or equal to 100 mm, less than or equal to 50 mm, less than or equal to 20 mm, less than or equal to 10 mm, less than or equal to 5 mm, less than or equal to 2 mm, or less than or equal to 1 mm. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.5 mm and less than or equal to 10 m, or greater than or equal to 0.5 mm and less than or equal to 50 mm). In some embodiments, the length of the pathway may have a certain relationship to the 3D-printed article (e.g., if the 3D-printed article is an article of footwear, the length of the pathway may be the length of the article of footwear). Other ranges are also possible.
[0075]When a first portion and a second portion are connected by a pathway, a property (e.g., average pore size, density, stiffness, stiffness of solid components of the article, Shore A hardness, degree of cross-linking, chemical composition, color, abrasion resistance, thermal conductivity, electrical conductivity, stiffness anisotropy, elastic modulus, flexural modulus, filler content, opacity, conductivity, breathability) may change along the pathway at a rate that is advantageous. The average rate of change of the property may be greater than or equal to 0.05% of the average of the property in the first portion per mm, greater than or equal to 0.1% of the average of the property in the first portion per mm, greater than or equal to 0.2% of the average of the property in the first portion per mm, greater than or equal to 0.5% of the average of the property in the first portion per mm, greater than or equal to 1% of the average of the property in the first portion per mm, or greater than or equal to 2% of the average of the property in the first portion per mm. The average rate of change of the property may be less than or equal to 5% of the average of the property in the first portion per mm, less than or equal to 2% of the average of the property in the first portion per mm, less than or equal to 1% of the average of the property in the first portion per mm, less than or equal to 0.5% of the average of the property in the first portion per mm, less than or equal to 0.2% of the average of the property in the first portion per mm, or less than or equal to 0.1% of the average of the property in the first portion per mm. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.05% and less than or equal to 5%). Other ranges are also possible. It should be understood that the average rates of changed described above may apply to pathways that straight (e.g., pathways that are line segments), or to pathways that are curved.
[0076]In some embodiments, a first portion and a second portion as described herein may be components of a 3D-printed article that is a single integrated material. As used herein, two or more portions that together form a single integrated material are not separated by a separable interface. In some embodiments, a single integrated material may not separate into discrete parts during the course of normal use, and/or may be separated into discrete parts whose morphologies would not be predictable prior to normal use and/or along interfaces that would not be predictable prior to normal use. For instance, a single integrated material may lack seams and/or lack an adhesive that bonds two or more portions together. In some cases, the 3D-printed article as a whole may lack an interface at which one or more properties (e.g., average pore size, density, stiffness, stiffness of solid components of the article, Shore A hardness, degree of cross-linking, chemical composition, color, abrasion resistance, thermal conductivity, electrical conductivity, stiffness anisotropy, elastic modulus, flexural modulus, filler content, opacity, conductivity, breathability) undergo step changes as described above. In some cases, the property or properties may vary smoothly throughout the 3D-printed article.
[0077]In some embodiments, one or more portions may together form an 3D-printed article with one or more of the following features: macrovoids embedded within the article (e.g., a midsole) without an intersecting interface from overmolding, lamination, or ultrasonic welding; one or more open cell lattices; variations in density across geometries that would be challenging to form by molding; interpenetrating foams and elastomers that may, in some embodiments, not be separated by an interface due to molding or lamination; and/or one or more interfaces between different materials with extreme undercuts (e.g., materials with a negative draft angle, materials which cannot be injection molded using a single mold because they would be unable to slide out of the mold).
[0078]According to certain embodiments, an article may be manufactured by dispensing a curable liquid into a mold. The mold may be digitally filled with the curable liquid, according to some embodiments. In certain embodiments, for example, the curable liquid may be dispensed through a printing nozzle disposed on a robotic gantry as explained herein in greater detail. According to certain embodiments, the curable liquid may be dispensed into the mold by extrusion. In some embodiments, the curable liquid may be dispensed into the mold by additive manufacturing (e.g., 3D-printing). According to some embodiments, the curable liquid may be dispensed into the mold using one or more non-3D-printing steps. For example, in some embodiments, neither the printing nozzle nor the robotic gantry are part of or otherwise associated with an additive manufacturing device (e.g., a 3D-printer).
[0079]In some embodiments, a composition of the curable liquid may be varied between a first portion of the composition and a second portion of the composition, thereby providing a material (e.g., upon curing) comprising a variation in properties between a first portion of the material and a second portion of the material, similar to the concept described above of properties being varied in 3D-printed articles. For example, one or more properties of a first portion of the curable liquid may differ from one or more properties of a second portion of the curable liquid, resulting in a cured material with a variation in properties, including, but not limited to, pore size, density, stiffness, Shore A hardness, tensile elastic modulus, degree of cross-linking, chemical composition, color, and/or reflectivity, between a first portion of the cured material and a second portion of the cured material. The one or more properties of the cured material may be structural properties (e.g., pore size, density, etc.), chemical properties (e.g., degree of cross-linking, chemical composition, etc.), mechanical properties (e.g., stiffness, Shore A hardness, tensile elastic modulus, etc.), optical properties (e.g., color, reflectivity, etc.), and/or other properties.
[0080]As will be described in further detail below, the curable liquid may comprise a catalyst, in some embodiments. The presence of a catalyst in the curable liquid may advantageously affect the cure rate of the curable liquid, as would generally be understood by a person of ordinary skill in the art. According to some embodiments, a concentration of the catalyst in the curable liquid may be varied between a first portion of the composition and a second portion of the composition. In some such embodiments, the concentration of the catalyst may be varied by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, or more, between at least a first portion of the composition of the curable liquid and the second portion of the composition of the curable liquid.
[0081]In certain embodiments, the one or more properties of the first portion of the cured material that differ from the one or more properties of the second portion of the cured material may be a tensile elastic modulus. In certain embodiments, for example, the tensile elastic modulus of the cured material is varied by at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, or more between at least a first portion of the cured material and the second portion of the cured material.
[0082]In some embodiments, a 3D-printed article (e.g., a 3D-printed article comprising two or more portions) may be a foam (e.g., a closed cell foam). For instance, FIG. 1B shows one non-limiting embodiment of a 3D-printed article 100 which is a foam comprising pores 130. The foam may be a material comprising a matrix and pores disposed within the matrix. Pores may be randomly distributed throughout the foam, or may be positioned at regular and/or pre-determined intervals. The material present within the pores of a foam is typically of a different phase than the material forming the matrix of the foam (e.g., a foam may comprise pores that comprise gas within a matrix that comprises a liquid and/or a solid). As would be understood to one of ordinary skill in the art, in a closed-cell foam, the cells of the foam are typically isolated or separated from each other. By contrast, in an open-cell foam, the cells of the foam are interconnected with each other; for example, they may be formed in an interconnected fashion, or the cells may be ruptured or become interconnected during or after formation of the foam. These conditions are typically more violent foaming conditions than those resulting in a closed-cell foam. The foam may be formed from a variety of polymers and gases. The gases may be introduced into the foam during formation (e.g., physically), and/or generated during formation (e.g., via chemical reaction). In addition, in some cases, a gas may be introduced by providing a liquid that forms a gas, e.g., upon a decrease in pressure or an increase in temperature. For instance, a liquid such as butane may be kept under pressure and/or cooled prior to introduction into the nozzle or the mixing chamber; a change in temperature and/or pressure may cause the liquid to form a gas. Without wishing to be bound by theory, closed cell foams and open cell foams may have different properties (e.g., closed cell foams may have different values of density, stiffness, Shore A hardness, and the like than otherwise equivalent open cell foams) and may be suitable for different applications. In some embodiments, closed cell foams may have properties that are better suited to footwear applications than open cell foams. In some embodiments, a 3D-printed article or a portion thereof may comprise an enclosed open cell foam, or an open cell foam surrounded by a layer of continuous material. In some cases, an enclosed open cell foam may be suitable for use as an air cushion, and/or may have tactile properties that may be varied by varying infill density.
[0083]It should also be understood that certain 3D-printed articles described herein may not be foams (i.e., they may not include any pores). For instance, certain embodiments may relate to 3D-printed articles that are not foams and that comprise one or more elastomers. In addition, in some cases, an article may be printed that can then be formed into a foam, e.g., using a chemical reaction to produce a gas within the article.
[0084]As shown in FIG. 1C, in some but not necessarily all embodiments, a 3D-printed article that is a foam (e.g., a closed-cell foam that is optionally a single integrated material) may comprise one or more portions having different properties. FIG. 1C shows 3D-printed article 100 comprising first portion 110, second portion 120, and pores 130. Although FIG. 1C depicts a 3D-printed article comprising an average pore (or cell) size in the first portion (i.e. a first average pore size) that is different from an average pore (or cell) size in the second portion (i.e., a second average pore size), in some embodiments the first portion and the second portion may have the same average pore size but may comprise differences in other properties (e.g., one or more of the density, stiffness, Shore A hardness, degree of cross-linking, chemical composition may be different in the first portion than in the second portion). Thus the pore sizes are presented here for illustrative portions only. Similarly, although FIG. 1C shows an average pore size in the first portion that is larger than the average pore size in the second portion, in some embodiments the average pore size of the first portion may be smaller than the average pore size of the second portion.
[0085]According to certain embodiments, the foam may have any of a variety of suitable properties, such as any of those described in U.S. application Ser. No. 17/188,490, entitled “System and method for maintaining a consistent temperature gradient across an electronic display,” which is incorporated by reference herein in its entirety.
[0086]In some embodiments, a 3D-printed article as described herein may be suitable for use as a component of one or more articles of footwear. In certain embodiments, a 3D-printed article as described herein may be suitable for use in manufacturing one or more articles of footwear. FIG. 2 shows one non-limiting embodiment of an article of footwear 1000. The article of footwear comprises a sole, a toe box, an upper, lacing, a heel counter, and a pull tab. It should be understood that 3D-printed articles suitable for use in footwear may form any of the components or be a portion of any or all of the components shown in FIG. 2. In some embodiments, multiple 3D-printed articles may be positioned on a single article of footwear (e.g., a single article of footwear may comprise a 3D-printed article that is disposed on a sole or is a sole and a 3D-printed article that is disposed on an upper). In some embodiments, the 3D-printed article may be a sole or a sole component, such as an outsole, a midsole, or an insole. In some embodiments, the 3D-printed article may be an article that is printed onto a sole component, such as a midsole and/or insole that is printed onto an outsole (e.g., a commercially available outsole, an outsole produced by a non-3D printing process). In some embodiments, the 3D-printed article may be an upper. In some embodiments, the 3D-printed article may be an article that is printed onto an upper, such as a toe box, a heel counter, an ankle support, an eyestay, an article comprising a logo and/or embodying a logo, an eyelet, a quarter panel, a no sew overlay feature, and/or a pull tab. The upper may be one component of a fully assembled shoe which lacks the part(s) to be printed, or it may be an upper that has not been assembled with other footwear components. In some embodiments, a 3D-printed article may be a combination of two or more footwear components that are typically provided as separate articles. For example, the 3D-printed article may be able to serve as both a midsole and an insole, or may comprise a midsole and an insole that are a singl