3D printed sound dampening materials

Abstract

An additively manufactured sound dampening part (102) comprising a boundary element (HOB) comprising a first coreactive composition; and an infill element (115B) comprising a second coreactive composition, wherein the boundary element substantially encloses the infill element, and the sound dampening part provides a sound transmission loss of at least 30 dB(A) for a 125Hz to 8kHz sound passing through the sound dampening part.

Description

3D PRINTED SOUND DAMPENING MATERIALSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 63 / 553,177 entitled “3D PRINTED SOUND DAMPENING MATERIALS”, filed on February 14th, 2024, which is incorporated by reference in its entirety.GOVERNMENT LICENSE RIGHTS

[0002] This invention was made with government support under Government Contract No. W91 INF-17-2-0227 (Army Research Laboratory, US ARMY). The government may have certain rights in the invention.FIELD

[0003] The present disclosure relates to 3D printed sound dampening materials for noise reduction, and methods for making and using the same.BACKGROUND

[0004] A variety of industries such as aircraft, aircraft engines, audio equipment, mining, agriculture, automotive, household appliances, heating ventilation and air conditioning, and the like involve noise generation at a broad range of audible frequencies. Since these applications involve close proximity to humans, sound-dampening materials are desired because exposure to high noise levels may contribute to hearing loss, increased stress, difficulty communicating, and / or tiredness.SUMMARY

[0005] Described herein is an additively manufactured sound dampening part comprising a boundary element comprising a first coreactive composition and an infill element comprising a second coreactive composition, wherein the boundary element substantially encloses the infill element, and the sound dampening part provides a sound transmission loss of at least 30 dB(A) for a 125Hz to 8kHz sound passing through the sound dampening part.

[0006] Another embodiment disclosed herein is a method of additively manufacturing a sound dampening part comprising depositing a boundary element in a first geometric configuration, the boundary element imparting a first sound dampening effect to the sound dampening part and depositing an infill element in a second geometric configuration different from the first geometric configuration, the infill element imparting a second sound dampening effect to the sound dampening part different from the first sound dampening effect, and wherein the boundary element and the infill element react and cure under ambient conditions to form the sound dampening part.

[0007] In yet another embodiment disclosed herein is a multi-layer sound dampening part comprising a first sound dampening component comprising a boundary element comprising a plurality of internal structures each comprising a void, an infill element configured within the voids of the plurality of internal structures, and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the first sound dampening component. The multi-layer sound dampening part may further comprise a second sound dampening component comprising a boundary element comprising a plurality of internal structures each comprising a void, an infill element configured within the voids of the plurality of internal structures, and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the second sound dampening component, wherein the first sound dampening component comprises a first layer of the multi-layer sound dampening part and the second sound dampening component comprises a second layer of the multi-layer sound dampening part, the first sound dampening element imparting a first sound dampening effect to the multi-layer sound dampening part and the second sound dampening component imparting a second sound dampening effect to the multi-layer sound dampening part different from the first sound dampening effect.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1A illustrates a first exemplary embodiment of a sound dampening part.

[0009] FIG IB. illustrates a second exemplary embodiment of a sound dampening part without a structural element.

[0010] FIG. 2A illustrates a third exemplary embodiment of a sound dampening part manufactured onto an optional substrate.

[0011] FIG. 2B illustrates a fourth exemplary embodiment of a sound dampening part without a structural element, manufactured onto an optional substrate.

[0012] FIG. 3 illustrates an exemplary embodiment of a multi-layer sound dampening part.DETAILED DESCRIPTIONI. Definitions

[0013] For purposes of the following detailed description, it is to be understood that the disclosure may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." For example, numerical ranges provided for weight percentages of components or amounts of components added should be construed as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0014] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0015] Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of " 1 to 10" is intended to include all sub-ranges from (and including) the recited minimum value of 1 to the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10.

[0016] The use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, the use of "or" means "and / or" unless specifically stated otherwise, even though "and / or" may be explicitly used in certain instances.

[0017] Ambient conditions” or “room temperature” are used herein to describes temperature values as low as 20 °C, 23 °C, or 25 °C, as high as 27 °C, 29 °C, or 30 °C, or between any of the foregoing values used as endpoints, such as between 20 °C and 30 °C , or 23 C and 27 °C; pressure values as low as 0.85 atm, 0.90 atm, or as high as 1.0 atm, 1.02 atm, or 1.05 atm, or between any of the foregoing values used as endpoints, such as between 0.85 atm and 1.05 atm, or 0.95 atm and 1.05 atm; and relative humidity values as low as 25% RH, 35% RH or 50% RH, as high as 75% RH, 85% RH, 90% RH, or 95% RH, or between any of the foregoing values used as endpoints, such as between 25% RH and 95% RH or between 50% RH and 75% RH.

[0018] “Coreactive composition” refer to the reaction product produced from the chemical interaction and reaction between at least two coreactive components (e.g., a first coreactive component, a second coreactive component, etc.).

[0019] “Coreactive component” refers to a compound containing at least one reactive functional group, that when physically combined with a second reactive functional group, interacts and reacts with the second reactive functional group to form a coreactive composition.II. Ambient Cured Coreactive Additive Manufacturing.

[0020] Additive manufacturing using coreactive compositions, also referred to as ambient reactive extrusion or ARE type three-dimensional printing, typically utilizes at least two components that react with each other (that is, are coreactive). A first coreactive component (sometimes referred to herein as a first reactant group, a first reactive functional group, part A) and at least one second coreactive component (sometimes referred to herein as a second reactant group, second reactive functional group, part B), when extruded in combination and / or succession, chemically react with one another to form a coreactive composition. The coreactive composition may thereafter cure under ambient conditions or, depending on the chemistry of the reaction, with the assistance of, for example, heat, actinic radiation, catalysts, addition of curing agents-post extrusion, etc. to form an article, or a portion of an article, comprising a thermosetting polymer (sometimes referred to as athermoset), a thermoplastic polymer, or combinations thereof. At least the first coreactive component and the second coreactive component are chosen by one skilled in the art to result in the desired final product (e.g., thermoset, thermoplastic, etc.).

[0021] Three dimensional articles formed from coreactive compositions are additively manufactured by extruding the coreactive composition, which may be in an at least partially reacted state, onto a surface, such as a build platform. The coreactive composition may be in an at least partially reacted state at the time of extrusion and thereafter fully react and cure to form a layer of the coreactive composition. Successive layers of the same and / or different coreactive compositions can be deposited, forming additional layers of material. The combination of layers forms the article. The coreactive composition may be at least partially react when the coreactive components come together, such as in a mixing volume, just prior to extrusion. Alternatively, the two coreactive components could be premixed before extrusion and treated in a way to arrest the reaction between the coreactive components, such as by freezing the composition upon mixing.

[0022] It may be desirable to select the chemistry of each layer of the deposited coreactive composition such that covalent bonds between successive layers are formed. Different portions of the article can be additively manufactured from different coreactive compositions (e.g., a first coreactive composition printed to form a first portion of the article such as a base portion, an internal structure, etc., and a second coreactive composition printed to form a second portion of the article), and, depending on the chemical reactivity between the different coreactive compositions, covalent bonds might also form between different materials.

[0023] An article may be additively manufactured so as to have a rigid portion and a flexible portion, a rigid portion and a foam-like portion, a tactile portion and a rigid and / or flexible portion, two or more portions comprising different densities, one or more conductive portions, one or more thermally / electrically conductive portions, two or more different colors, two or more different rheological profiles, two or more different materials comprising different affinities for water and / or solvent(s), and the like. The article may also be printed such that the coreactive compositions are deposited onto existing articles (e.g., other thermosets and / or thermoplastics, metals, woods, composite materials, ceramics, etc.) resulting in an article comprising both coreactive and non-coreactive compositions.

[0024] Additive manufacturing as described herein may result in an article having higher strength, particularly along the Z (e.g., vertical) axis, as compared to other extruded orprinted parts due to the covalent bonding between the printed layers. Strong intralayer and interlayer covalent bonding results in not only stronger parts, but also in more uniform part geometries; that is, less print lines and / or portion differentials. The ability to form, in one process, articles having multiple substrates and / or portions comprising different coreactive or non-coreactive compositions is a further advantage.

[0025] Table 1 describes suitable coreactive compositions and the coreactive components from which they can be formed. These coreactive compositions can be printed by any of the methods described herein, either alone or in combination, to form three dimensional articles.

[0026] Another advantage of additive manufacturing using coreactive compositions may be that the coreactive compositions can be additive manufactured at relatively low viscosity (“ viscosity” may refer to a value determined at 25 °C and ambient pressure, and reflects a fluid’s resistance to flow when subjected to a shear stress and / or a shear strain). Therefore, relatively large amounts (e.g., high relative weight percent) of additives and / or fillers can be included with the coreactive components while maintaining a printable viscosity. Both the type and / or the amount of additives can be selected or “tuned” to result in desirable chemical and / or physical properties of the printed article. Coreactive compositions can be tuned with the addition of additives and / or fillers for desired mechanical performance (e.g., strength, elasticity, rigidity, sag resistance, etc.), surface features (e.g., hardness, texturing, smoothness, etc.), chemical resistance (e.g., solvent resistance, etc.), thermal resistance (including fire retardancy, etc.) or conductivity, and / or electrical insulation or conductivity. Coreactive compositions can also be tuned with the addition of one or more catalytic / activator / accelerant additives in any of the coreactive components to result in desirable reaction kinetics, such as rate of reaction.

[0027] Table 2 describes additives that can be included with any coreactive compositions, such as those described in Table 1. The additives can be included in either or both of the first and second coreactive components depending on the desired chemical and / or physical properties of the resulting article. In this case, Table 2 describes specific additives and fillers that may be suitable for ambient reactive extrusion-based three-dimensional printing, however, Table 2 is non-limiting. Therefore, other additives may be included withthe coreactive composition(s), such as additives known to those skilled in the coatings, extrusion, and thermoplastic areas.

[0028] Any suitable combination of coreactive composition(s) and optionally additive(s) / filler(s), can be printed by a three-dimensional printing system adapted for mixing and extruding feedstocks. Two or more volumetric metering pumps (e.g., positive displacement pumps, progressive cavity pumps, etc.) may each respectively discharge, in combination or succession, the two coreactive components associated with a coreactive composition (e.g., the first reactive component discharged by the first metering pump and the second coreactive component discharged by the second metering pump into a mixing volume). In some cases, the mixing volume can include mechanical (e.g., driven) mixing features. Upon entering the mixing volume, the first and second coreactive components begin to mix and react, and thereafter, are extruded through an extrusion print nozzle in an at least partially reacted state. Once extruded, the two coreactive components further react and cure, which, as described above, may be under ambient conditions, to form either a thermoset, a thermoplastic material, or combinations thereof.III. Sound dampening Parts Additively Manufactured from Coreactive Compositions.

[0029] The present disclosure relates to sound dampening part(s) additively manufactured (e.g., 3D printed) from ambiently -cured coreactive compositions, such as those described in Section II. The physical and / or chemical characteristics of the sound dampening parts may be tuned and / or optimized to result in a targeted overall sound dampening effect. That is, each element of the sound dampening part, to be described in further detail herein, may be formed from coreactive compositions which are tuned / optimized to impart sound dampening properties to each element, resulting in an overall sound dampening effect of the sound dampening part. The sound dampening part may be printed in-place, such as additively manufactured onto an existing structure / substrate, or additively manufactured and applied to the structural component / substrate thereafter (e.g., applied in place). Multi-layer sound dampening parts can also be additively manufactured to dampen sound across a wide range of frequencies.

[0030] Sound dampening parts find applications in a wide variety of industries including the automotive industry (e.g., sound dampening structures applied to engine bays, fire walls, wheel wells, and / or interior structures of the vehicle), the aerospace industry (e.g., sound dampening structures applied to the walls of the cabins and / or cockpits of an aircraft), the consumer goods industry (e.g., the housings of dishwashers, washers, dryers, and / or other consumer goods that benefit from noise / vibration reduction) and the architectural industry (e.g., sound dampening structures applied to the interior or exterior of walls and / or room partitions).

[0031] The sound dampening parts can be additively manufactured such that any one of an overall sound dampening effect (e.g., dampening of one or more desired frequencies of sound), weight, and / or size of the sound dampening part are targeted and / or optimized, which can be in combination, to achieve a desired effect. For instance, any one of the weight and size may be optimized, either alone or in combination, to result in the smallest and lightest part that imparts the targeted noise reduction for a given frequency band.

[0032] FIG.s 1A and IB depict illustrative embodiments of sound dampening parts 101 and 102, that although shown as comprising a certain rectangular geometry, may be additively manufactured into any desired shape. Therefore, FIGs 1A and IB are meant to be illustrative only, and not to limit the size, shape, geometry, or position of the sound dampening part(s). Furthermore, it should be appreciated that for like elements, the same reference numbering is used, which may be designated as A, B, C in some contexts.

[0033] Sound dampening part 101 may comprise three basic elements: a structural element 105 which may serve as a base structure of sound dampening part 101; a boundary element 110 additively manufactured atop a surface of the structural element 105 and including one or more internal structures 112 and perimeter 114; and an infill material 115 additively manufactured, or otherwise applied inside the voids of the internal structures 112 of boundary element 110.

[0034] Here a first coreactive composition, such as a Michael addition-based coreactive composition as described in Section I previously, may be additively manufactured as a structural element 105. The structural element 105 may serve as a base structural layer, upon which one or more additional elements of the sound dampening part 101 is / are built. Structural element 105 may impart a first sound dampening effect, such as a vibration dampening (e.g., sound blocking) effect to sound dampening part 101. A second coreactive composition, such as a polyurea-based coreactive composition, may be additivelymanufactured as boundary element 110 onto an upper surface of structural element 105. Boundary element 105 may form the perimeter of the sound dampening part 101 (e.g., the side walls / exterior boundary) and may also include one or more internal structures 112. Internal structures 112 may be formed as substantially or completely hollow structures which comprise a predetermined structural size and shape (e.g., a cellular structure, a lattice structure, etc.). Boundary element 110 may impart a second sound dampening effect to the sound dampening part 101, such as a sound blocking / deadening effect. Boundary element 110 may also provide additional structural support and rigidity to the sound dampening part. A third coreactive composition, such as a polyurethane-based coreactive composition may be additively manufactured, or otherwise infilled into the voids of the one or more internal structures 112 of boundary element 110, forming infill material 115. Infill material 115 may comprise a foam-like material imparting a third sound dampening effect, such as a sound absorbing effect to sound dampening part 101.

[0035] The physical and / or chemical characteristics of, such as the thickness of, size of, geometry of, composition of, and relative proportions of (or any combination of the foregoing of) structural element 105, boundary element 110, and infill material 115 can be tuned or otherwise adjusted, either alone or in combination, such that a small, thin sound dampening part is formed with high sound blocking / absorbing characteristics for a given frequency range. For example, it is possible to modify any of the physical and / or chemical properties of any of the elements of sound dampening part 101 to form the smallest and thinnest part that meets or exceeds a desired sound dampening effect. Specifically, it may be possible to modify any of the physical and / or chemical properties of any of the elements of sound dampening part 101 in order for the overall thickness of the sound dampening part 101 to comprise less than 5 inches in thickness, such as in the 0.1 inch to 5 inch range, and more particularly in the 0.25 inch to 2 inch range, and more particularly in the 0.25 inch to 1 inch range.

[0036] Specifically, the physical and / or chemical properties of any of the elements of sound dampening part 101 can be designed, tuned, or adjusted, either alone or in combination, to provide a sound absorbing and / or dampening effect in the form of a sound transmission loss for sound waves passing through sound dampening part 101. The sound may have a frequency of 125Hz to 8kHz and the sound transmission loss may be as low as 10 db(A), 15 db(A), 20 db(A), 25 db(A), 30 db(A), 35 db(A), or as high as 40 db(A), 45 db(A), 50 db(A), 55 db(A), 60 db(A), 65 db(A), 70 db(A), or within any range encompassed by anytwo of the foregoing values as endpoints. For example, the sound transmission loss may be from 10 db(A) to 70 db(A), from 15 db(A) to 65 db(A), from 20 db(A) to 60 db(A), from 25 db(A) to 55 db(A), from 30 db(A) to 50 db(A), or from 35 db(A) to 45 db(A).

[0037] As will be described in further detail herein, multiple layers of sound dampening part(s) 101 can be formed in successive layers, as illustrated in FIG. 3, where each layer targets sound reduction for a given frequency band / range (which may be different frequency bands / ranges). The resulting multi-layer sound dampening part can absorb and / or block sound over a wider frequency range than a single-layer sound dampening part.

[0038] In any of the foregoing cases, the coreactive compositions may be reactive with one another at ambient conditions (e.g., ambient pressure and temperature). Curing of the coreactive composition may also occur under similar ambient conditions. In any of the foregoing cases, curing of the co-reactive components may be accomplished in the absence of special condition(s) such as UV light, heat, catalysts, or chemical initiators required to promote the curing process. a. Structural Element of the Sound Dampening Part

[0039] Sound dampening part 101 can include structural element 105. Structural element 105 can be a rigid or semi-rigid structural element 105 upon which the additional elements of sound dampening part 101 are formed. ARE type three-dimensional printing technology, as described in Section II, allows for covalent bonding to form between successive layers of coreactive compositions deposited atop one another. Here, structural element 110 and / or infill element 115 may be applied to structural element 105 during the additive manufacturing process, and covalent bonding can form between elements, resulting in a congruent object that cures substantially at the same time.

[0040] In some cases, structural element 105 may be additively manufactured from a first coreactive composition, such as an Michael addition-based coreactive composition, and particularly, an Aza-Michael addition based coreactive composition. The Aza-Michael addition-based coreactive composition chemistry may be advantageous for the composition of structural element 105 due to the vibration dampening effect of Aza-Michael additionbased coreactive compositions. However, as described previously, structural element 105 may be additively manufactured from any other coreactive composition described in Section I, as based upon a desired effect (e.g., sound blocking characteristics, flexibility, rigidity, etc.). Moreover, the selected coreactive composition may be adjusted with the inclusion of any one of the additives and / or fillers described in Section II to result in the desired effect.

[0041] Structural element 105 may be designed to have suitable rigidity to support additional elements of sound dampening part 101, while minimizing the thickness of the structural element 105 to save on mass (e.g., avoiding an unnecessarily heavy structural element 105, contributing to a higher-weight sound dampening part 101). However, in some cases, structural element 105 may be absent (e.g., FIG. 2B), such as if a light and thin part is desired (e.g., removing structural element 105 may result in a lighter acoustically damping part 101).

[0042] Structural element 105 may have a relatively higher flexural modulus than the other elements of sound dampening part 101, as measured by a flexural test such as ISO 178, such as between 2358 Mpa and 1552 MPa. In addition to providing structural support, structural element 105 contributes to vibration dampening and acts as a sound blocking portion of sound dampening part 101. Specifically, structural element 105 may block sound in the 100 Hz and 9000 Hz (i.e., 9kHz) range frequency range.

[0043] The dimensions and composition of structural element 105 can be adjusted, either alone or in combination with the other elements of the sound dampening part 101, to achieve the desired sound dampening performance for each application. For instance, the thickness of structural element 105 may be adjusted in order for the overall thickness of the sound dampening part 101 to comprise less than 5 inches in thickness, such as in the 0.1 inch to 5 inch range, and more particularly in the 0.25 inch to 2 inch range, and still more particularly in the 0.25 inch to 1 inch range. Moreover, although represented as a planar quadrilateral shape in each of FIGs 1A and IB, structural element 105 can be additively manufactured into any suitable shape, which can include irregular exterior boundaries, and / or non-planar surfaces.

[0044] As described previously, structural element 105 is an optional element of sound dampening part 101, which may or may not be present in different embodiments of the present invention. For instance, in the case where a light / thin part is affixed to a suitably rigid substrate (e.g., either directly 3D printed on the substrate or applied later), as will be discussed in relation to FIG. 3 herein, structural element 105 may not be present (e.g., is not necessary to provide structural rigidity). Additionally or alternatively, there may be a case where the lightest sound dampening part 101 is desired, and therefore, structural element 105 may not be present to save weight. Furthermore, there may be a scenario where the sound blocking characteristics of sound dampening part 101 do not require blocking the sound of the frequency range provided by structural element 105, and therefore, structural element 105may not be present. In any of the foregoing cases, the additive manufacturing process may utilize a secondary substrate, upon which the additional element (e.g., boundary element 110 and / or infill material 115) are applied and / or printed, and the secondary substrate may be removed / discarded (e.g., similar to support materials utilized in traditional three-dimensional printing) such that structural element 105 is not a required base component of the sound dampening part 101, as will be described in further detail with reference to FIG 2B. Furthermore, although illustrated as comprising the entire bottom portion of sound dampening part 101, structural element 105 may comprise only a portion of, or a segment of the bottom surface of sound dampening part 101, such that portions of both structural element 105 and boundary element 110 comprise the bottom surface of acoustical component 101 in combination. b. Boundary Element of the Sound Dampening Part

[0045] Sound dampening part 101 includes boundary element 110. Boundary element 110 can be a rigid or semi-rigid element additively manufactured to include one or more internal structures 112 and a perimeter 114.

[0046] Boundary element 110 may be additively manufactured from a second coreactive composition, which may be based on a same or a different coreactive composition to each of structural element 105 and / or infill element 115. For instance, boundary element 110 may comprise a polyurea-based coreactive composition. The polyurea-based coreactive composition chemistry may be advantageous for the composition of boundary element 110 due to the sound / vibration dampening effect of polyurea-based coreactive compositions, as well as for the strength and rigidity that polyurea based compositions provide to physical structures (e.g., a relatively thin and strong material that can be printed in complex geometries). Similar to structural element 105, in some instances, boundary element 110 may be additively manufactured from any other coreactive composition described in Section II, as based upon a desired effect, and the selected coreactive composition may be adjusted with the inclusion of any one of the additives and / or fillers described in Section II to result in the desired effect.

[0047] In any of the foregoing cases, covalent bonding forms between individual elements printed utilizing ARE type three-dimensional printing. Here, covalent bonds may form between boundary element 110 and infill material 115 filled into the voids of boundary layer 110, and may also form between the bottom surfaces of boundary element 110 and an upper surface of structural element 105 (if present).

[0048] Boundary element 110 may be additively manufactured to include each of perimeter 114 and structural elements 112. Specifically, perimeter 114 may form the outer walls / surfaces of boundary element 110, which provides the overall shape of boundary element 110. As with structural element 105, although each of FIG.s 1A and IB illustrate perimeter 114 of boundary element 110 as a planar quadrilateral shape, perimeter 114 can be additively manufactured into any suitable shape, which can include irregular exterior boundaries, and / or non-planar surfaces.

[0049] Boundary element 110 may be additively manufactured to include one or more internal structures 112. Internal structures 112 may be structures that are hollow, or otherwise comprise a void, which are arranged in any regular or irregular configuration about the interior of perimeter 114 of boundary element 110. Illustratively, FIG.s 1A and IB depict internal structures 112 as comprising hollow hexagonal cells arranged in a lattice (e.g., repeat units of similar geometry). This orientation may be referred to as a honeycomb lattice-type structure and may be particularly suitable to accepting infill element 115, to be discussed further herein, while providing relatively high strength and rigidity to the overall structure of sound dampening part 101. However, as with perimeter 114, the illustrative embodiments are nonlimiting, and therefore the shape, size, and orientation / organization of internal structures 112 may be selected based upon any suitable configuration. For instance, internal structures 112 may comprise any combination of different uniform shapes (e.g., squares, circles, rectangles, pentagons, triangles, etc.) and / or irregular shapes / patterns (waves, lines, etc.) and can be arranged symmetrically (e.g., in a lattice-type configuration) or asymmetrically (e.g., randomly arranged) about boundary element 110, as based upon desired structural and / or sound absorbing effects.

[0050] Boundary element 110 may have a relatively low flexural modulus, as compared with other elements of sound dampening part 101, as measured by a flexural test such as ISO 178, such as between 108 MPa and 50 MPa. The relatively low flexural modulus contributes to the relatively high rigidity and strength of boundary element 110, as has been described previously. Furthermore, in addition to providing structural rigidity, boundary element 110 also contributes to sound / vibration dampening, and also acts as a sound blocking portion of sound dampening part 101. Specifically, boundary element 110 may block sound in the 100 Hz and 9000 Hz (i.e., 9kHz) frequency range.

[0051] The dimensions and composition of boundary element 110 can be adjusted, either alone or in combination, with the other elements of the acoustically dampening part101 to achieve the desired sound dampening performance for a given application. For instance, the size and shape of the internal structures 112 of boundary element 110 may be selected based upon a desired amount of infill material 115, as will be discussed in further detail herein. Additionally, the thickness of the walls of either the internal structures 112 or the outer perimeter 114 may be adjusted to result in a strong and rigid structure while minimizing weight. Moreover, and as with structural element 105, the size of boundary element 110 may be adjusted in order for the overall thickness of the acoustically damping part 101 to comprise less than 5 inches in thickness, such as in the 0. 1 inch to 5 inch range, and more particularly in the 0.25 inch to 2 inch range, and still more particularly in the 0.25 inch to 1 inch range. c. Infill Element of the Sound Dampening Part

[0052] Sound dampening part 101 may include infill element 115. Infill element 115 may act as a sound absorbing infill such as a colloidal or semi-colloidal mixture (e.g., a foam or foam-like material), that is additively manufactured or otherwise applied into the voids of the internal structures 112 of boundary element 110.

[0053] Infill element 115 may be additively manufactured, or otherwise formed from a third coreactive composition, which may be based on a same or a different coreactive composition to each of structural element 105 and / or boundary element 110. For instance, infill element 115 may comprise a polyurethane-based coreactive composition. The polyurethane-based coreactive composition chemistry may be advantageous to use as the composition of infill element 115 due to the sound absorbing effect of polyurea-based coreactive compositions. Specifically, polyurethane-based coreactive compositions may be advantageous in forming colloidal solutions / mixtures, whereas gasses (e.g., air, or other suitable gases) and / or additional materials can be suspended within the polyurethane-based coreactive composition forming a foam or foamlike material. Similar to structural element 105 and boundary element 110, infill element 115 may be additively manufactured from any other coreactive composition described in Section II, as based upon a desired effect.

[0054] Moreover, the selected coreactive composition may be adjusted with the inclusion of any one of the additives and / or fillers described in Section II to result in a desired effect. For instance, infill element 115 may include microcapsules, microspheres (e.g., such as Expancel™ microspheres, commercially available from Nouryon), microballoons, and / or glass beads, that assist in creating a colloidal infill element 115. Here, the microspheres (e.g., micro-balloon, microcapsule, etc.) enclose a gas that, once heated, expands, increasing thevolume of the microsphere. Once cured, the colloidal coreactive composition can have a targeted and / or desired density, as based upon the inclusion of the microspheres. For instance, a base coreactive composition, such as polyurea, may include the microspheres (e.g., Expancel ™), and is 3D printed as the infill element 115 of sound dampening part 101. Once printed, sound dampening part 101 may be allowed to cure under ambient conditions for a given time. After initially curing, sound dampening part 101 including infill material 115 containing the microspheres may be cured for a second time, and at a higher temperature range, in order to activate the expansion of the microspheres. For instance, the second curing temperature may be between 80°C and 133°C. Once activated, the microspheres increase in diameter by as much as 400%, such as from about 10 pm to 40 pm, increasing the overall volume of the infill element 115 by up to approximately 6500%. The volumetric expansion of the microspheres may be regarded as controllable, in that the expansion rate of the microspheres is temperature dependent and can be controlled as based upon the activation temperature and / or curing time. For instance, the sound dampening part 101 including infill material 115 containing the microspheres may be allowed to post-cure for anywhere between approximately 2 hours and 15 hours, in order to allow for the expansion of the microspheres to a desired volume. Therefore, inclusion of the microspheres in infill material 115 can provide enhanced controllability over infill materials 115 not containing the microspheres.

[0055] In any of the foregoing cases, covalent bonding forms between the individual elements of sound dampening part 101 printed utilizing ARE type three-dimensional printing. For instance, covalent bonds may form between infill element 115 and each boundary element 110 (e.g., the walls of internal structures 112 and / or perimeter 114) and, if present, an upper surface of structural element 105. Accordingly, once applied, boundary element 110 and infill element 115 (and if present, structural element 105) may react and cure under ambient conditions to form a contiguous sound damping part 101.

[0056] As described previously, internal structures 112 of boundary element 110 may be structures that are hollow, or otherwise comprise a void, which are arranged in any regular or irregular configuration about the interior of perimeter 114 of boundary element 110. Here, infill element 115 may be additively manufactured, or otherwise applied (e.g., by pouring and leveling, smearing in by hand, or spraying) into the voids of internal structures 112 of boundary element 110. When infill element 115 comprises a colloidal material, such material my flow and either partially or completely fill the voids of internal structures 112. FIG. 1 illustrates each of internal structures 112 filled within infill element 115, however, not everyinternal structure 112 need be filled with infill element 115, as based upon a desired acoustical effect. Furthermore, although internal structures 112 are illustrated as comprising hollow hexagonal cells arranged in a lattice (e.g., a honeycomb lattice) and internal element 112 applied therein, as described previously, internal structures 112 may comprise any combination of different uniform shapes (e.g., squares, circles, rectangles, pentagons, triangles, etc.) and / or irregular shapes / patterns (waves, lines, etc.) and be arranged symmetrically (e.g., in a lattice-type configuration) or asymmetrically (e.g., randomly arranged) about boundary element 110. In any of the foregoing cases, infill element 115 may completely or partially fill the voids created by any of the foregoing configurations of internal structures 112.

[0057] Also as described previously, the design, shape, and or organization of structural elements 112 may be based not only upon structural integrity / strength, but also an overall sound absorbing / deadening effect. Specifically, any of the shape, size, number, distribution, and / or organization of structural elements 112 may be based upon sound absorbing characteristics provided by infill materials 115. Here, infill element 115 may absorb sound (as compared to the sound deadening and blocking of each of structural element 105 and boundary element 110), in the 100 Hz and 9000 Hz (i.e., 9kHz) frequency range.

[0058] Therefore, the amount of infill element 115 and / or the composition of infill element 115 may be selected based upon a desired sound absorbing characteristic, and any one of the characteristics of internal structures 112 may be selected based upon the desired amount or composition of infill element 115 to achieve the sound absorbing effect.Additionally, as discussed above, the size of boundary element 110 may be adjusted in order for the overall thickness of the acoustically damping part 101 to comprise less than 5 inches in thickness, such as in the 0.1 inch to 5 inch range, and more particularly in the 0.25 inch to 2 inch range, and still more particularly in the 0.25 inch to 1 inch range. The amount and / or composition of infill element 115 may also be adjusted to result in the same desired thickness.IV. Sound Dampening Parts Additively Manufactured onto Substrates

[0059] FIGs. 2A and 2B illustrate sound dampening parts 201 and 202 that may be additively manufactured onto substrates 220A and 220B respectively. Each of sound dampening part 201 may include structural element 205 A, which may be the same as structural element 105; boundary element 310 which may be the same as boundary element 110, and infill element 315A which may be the same as infill element 115. Similarly, sounddampening component 202 may comprise each of boundary element 21 OB which may be the same as boundary element 110 and / or infill element 215B which may be the same as infill element 115. Therefore, any of the foregoing embodiments discussed in relation to FIG.s 1A and / or IB may be incorporated into sound dampening parts 201 and / or 202.

[0060] As described in Section II, each element of the sound dampening part 201 may be fabricated using ARE-type three-dimensional printing. Here, the sound dampening parts can be additively manufactured onto a substrate, such as substrates 220 A and 220B. For instance, structural element 205, boundary element 210, and / or infill element 215 may be additively manufactured directly onto a substrate 220 where substrate 220 comprises any suitable material such as metal, glass, wood, plastic, and the like. Specifically, as illustrated in FIG 2 A, structural element 205 A of sound dampening part 201 may be formed directly onto substrate 220A, boundary element 210B may be formed on structural element 205A thereafter, and infill element 215B may be formed or otherwise applied into the voids of boundary element 210B. Similarly, as illustrated in FIG. 2B boundary layer 210B and infill element 215B of sound dampening component 202 may be formed directly onto substrate 220B.

[0061] In any of the foregoing cases, substrate 220 can be either a primary substrate or a secondary substrate. A primary substrate may comprise a substrate where the sound dampening part is permanently affixed. This can include the interior walls of a vehicle, the walls of an architectural structure, the interior of a fuselage of an aircraft, the interior walls of a home appliance, and the like. In these cases, the primary substrate can be any one of, or combination of suitable materials such as metal, glass, wood, plastic, and the like.

[0062] A secondary substrate may comprise a substrate whereas the sound dampening part is temporarily affixed. For instance, the secondary substrate may comprise a build material that is utilized during the additive manufacturing process, which is removed (e.g., either partially or completely) from the sound dampening part later. Thereafter, the sound dampening part may be applied to a primary substrate. For instance, as described in relation to a sound dampening part 101B which may not include a structural element 105, and as illustrated in FIG. 2B, the boundary element 210B and infill element 215B may be formed onto substrate 220B where substrate 220B is a secondary substrate. Once sound dampening part 202 has partially or fully cured, secondary substrate 220B can be removed (e.g., removing by force, by dissolving secondary substrate 220B, etc.), leaving only the sound dampening part 220B. Similarly, structural layer 205 A of sound dampening part 201 can beadditively manufactured onto a secondary substrate, and a cured sound dampening part 201 can be removed and applied to a primary substrate thereafter. In each of the above-described scenarios, the sound dampening parts can be described as being applied in place (e.g., printed onto a secondary substrate, which can be partially or completely removed, and applied to a primary substrate thereafter).

[0063] As described in Section II, additive manufacturing of the sound dampening part can be accomplished via a three-dimensional printing system adapted for mixing and extruding feedstocks. Such three-dimensional printing systems may utilize a gantry, or in other cases, may utilize a robotic arm adapted for three-dimensional printing. A robotic arm equipped with a three-dimensional printing system may be used to additively manufacture sound dampening parts directly onto primary substrates, such as the hood of an automobile. In this scenario, the robotic arm-equipped with a three-dimensional printing system can “print in place” the sound dampening part directly onto the desired primary surface. In other cases, a gantry-type printing system may be adapted for print-in-place applications of the sound dampening parts.V. Multi-layer Sound Dampening Parts

[0064] FIG. 3 illustrates a multi-layer sound dampening part 301 that includes each of first sound dampening component 350 and second sound dampening component 360. Each of sound dampening components 350 and 360 may comprise any variation of sound dampening components 101, 102, 201, or 202 as described in relation to FIG.s 1 and / or 2 previously. For instance, sound dampening component 350 may comprise each of: structural element 3O5A, which may be the same as structural element 105A and / or structural element 205 A; boundary element 310A which may be the same as boundary element 110A / B and / or boundary element 210A / B; and / or infill element 315A which may be the same as infill element 115A / B and / or infill element 215A / B. Similarly, sound dampening component 360 may comprise each of: structural element 305B, which may be the same as structural element 105 A and / or structural element 205A; boundary element 310B which may be the same as boundary element 110A / B and / or boundary element 210A / B; and / or infill element 315B which may be the same as infill element 115A / B and / or infill element 215A / B.

[0065] Each of the sound dampening components 350 and 360 of multi-layer sound dampening part 301 may be formed to target a desired overall acoustical effect. For instance, each of sound dampening components 350 and 360 may be additively manufactured to target 1a desired frequency band / range of sound, which when combined into a multi-layer sound dampening part 301 blocks or otherwise reduces sound over a larger frequency band than a single layer sound dampening part. Here, the size, proportions, compositions, and the like of each of the elements of first sound dampening component 350 and second sound dampening component 360 maybe tuned, optimized, or otherwise adjusted, either alone or in combination, to target desired sound dampening characteristics (e.g., blocking / absorbing / reducing sound over different frequency bands / ranges), and once formed into the multi-layer sound dampening part, block or otherwise reduce sound over a larger frequency band that a single-layer sound dampening part. For instance, first sound dampening component 350 may be additively manufactured to block or otherwise reduce sound over frequency range X, and second sound dampening component 360 may be additively manufactured to block or otherwise reduce sound over frequency range Y, where frequency range X may comprise at least a portion of sound waves from a different frequency than sound range Y. In this case, multi-layer sound dampening part 301 may therefore block or otherwise reduce sound over a larger frequency range (e.g., X and Y), as compared to a single layer sound dampening component (e.g., X or Y). As described previously, ARE-type three- dimensional printing allows for covalent bonding to form between the individual layers of coreactive compositions, and therefore, covalent bonding can form between the individual sound dampening components (e.g., first sound dampening component 350 and second sound dampening component 360) to form a congruent multi-layer sound dampening part 301.

[0066] Although illustrated as a two-layer multi-layer sound dampening part 301, FIG. 3 is nonlimiting. For instance, more layers of sound dampening components may be present than those illustrated in FIG. 3. Here, any number of layers of sound dampening components, which may be the same or different in features / characteristics to one another, can be additively manufactured into a multi-layer sound dampening part to target an overall sound dampening characteristic (e.g., reducing sound over many different frequency ranges, reducing sound over the same frequency range but a higher degree of sound blocking / elimination, etc.). Furthermore, although FIG. 3 illustrates multi-layer sound dampening part 301 as a rectangular prism shape comprising planar surfaces, as with sound dampening parts 101 and / or 201, multi-layer sound dampening part 301 can be additively manufactured into any suitable shape, which can include irregular exterior boundaries, and / or non-planar surfaces.ASPECTS

[0067] Aspect 1 is an additively manufactured sound dampening part comprising a boundary element comprising a first coreactive composition; and an infill element comprising a second coreactive composition, wherein: the boundary element substantially encloses the infill element, and the sound dampening part provides a sound transmission loss of at least 30 dB(A) for a 125Hz to 8kHz sound passing through the sound dampening part.

[0068] Aspect 2 is the sound dampening part of aspect 1, wherein the first coreactive composition comprises a polyurea-based coreactive composition comprising: a first coreactive component including an isocyanate-containing compound, and a second coreactive component including an amine-containing compound.

[0069] Aspect 3 is the sound dampening part of either of aspects 1 or 2, wherein the second coreactive composition comprises a polyurea-based coreactive composition comprising: a first coreactive component including a hydroxyl-containing compound, and a second coreactive component including an isocyanate-containing compound.

[0070] Aspect 4 is the sound dampening part of any preceding aspect, wherein the boundary element further defines a perimeter of the sound dampening part.

[0071] Aspect 5 is the sound dampening part of any preceding aspect, wherein the boundary element comprises a plurality of internal structures, each internal structure comprising a void.

[0072] Aspect 6 is the sound dampening part of any preceding aspect, wherein the plurality of internal structures each comprise a hexagonal geometry arranged in a lattice.

[0073] Aspect 7 is the sound dampening part of any preceding aspect, wherein the infill element at least partially fills the void of at least one of the plurality of internal structures.

[0074] Aspect 8 is the sound dampening part of any one of any preceding aspect, wherein the infill element comprises a colloidal solution.

[0075] Aspect 9 is the sound dampening part of any one of any preceding aspect, wherein the infill element imparts a first sound dampening effect to the sound dampening part, and the boundary element imparts a second sound dampening effect to the sound dampening part different from the first sound dampening effect.

[0076] Aspect 10 is the sound dampening part of any one of any preceding aspect, further comprising a structural element comprising a third coreactive composition, wherein the structural element supports the boundary element and the infill element.

[0077] Aspect 11 is the sound dampening part of any preceding aspect, wherein the third coreactive composition comprises a Michael addition-based coreactive composition comprising:

[0078] a first coreactive component including a Michael donor compound, and

[0079] a second coreactive component including a Michal acceptor compound.

[0080] Aspect 12 is the sound dampening part of either of any preceding aspect, wherein the structural element comprises a base structure of the sound dampening part, the structural element comprising a first surface upon which the boundary element and infill element are formed.

[0081] Aspect 13 is the sound dampening part of any one of any preceding aspect, wherein the infill element imparts a first sound dampening effect to the sound dampening part, the boundary element imparts a second sound dampening effect to the sound dampening part, and the structural element imparts a third sound dampening effect to the sound dampening part, each of the first sound dampening effect, the second sound dampening effect, and the third sound dampening effect comprising different sound dampening effects.

[0082] Aspect 14 is a method of additively manufacturing a sound dampening part comprising: depositing a boundary element in a first geometric configuration, the boundary element imparting a first sound dampening effect to the sound dampening part; and depositing an infill element in a second geometric configuration different from the first geometric configuration, the infill element imparting a second sound dampening effect to the sound dampening part different from the first sound dampening effect, and wherein the boundary element and the infill element react and cure under ambient conditions to form the sound dampening part.

[0083] Aspect 15 is the method of aspect 14, wherein the boundary element comprises a polyurea-based coreactive composition, and the first configuration comprises a plurality of internal structures each comprising a void.

[0084] Aspect 16 is the method of aspect 15, wherein each of the plurality of internal structures comprises a hexagonal geometry, and the internal structures are arranged in a lattice.

[0085] Aspect 17 is the method of either of aspects 15 or 16, wherein the infill element comprises a polyurethane-based coreactive composition, and the second configuration comprises an infill of the voids of the plurality of internal structures.

[0086] Aspect 18 is the method of any one of aspects 14 through 17, wherein the boundary element and the infill element are deposited onto a substrate.

[0087] Aspect 19 is the method of any one of aspects 14 through 17, further comprising depositing a structural element in a third geometric configuration, the structural element imparting a third sound dampening effect to the component different from the first sound dampening effect and the second sound dampening effect, the third geometric configuration being different from the first and the second configurations, and each of the boundary element, the infill element, and the structural element react and cure under ambient conditions to form the sound dampening part.

[0088] Aspect 20 is the method of any one of aspects 14 through 19, wherein the structural element comprises a polyurethane-based coreactive composition, and the third configuration comprises a base structure of the sound dampening part.

[0089] Aspect 21 is the method of any one of aspects 14 through 20, wherein the structural element is deposited onto a substrate, and the boundary element and the infill element are deposited onto the structural element thereafter.

[0090] Aspect 22 is a multi-layer sound dampening part comprising: a first sound dampening component comprising: a boundary element comprising a plurality of internal structures each comprising a void; an infill element configured within the voids of the plurality of internal structures; and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the first sound dampening component; and a second sound dampening component comprising: a boundary element comprising a plurality of internal structures each comprising a void; an infill element configured within the voids of the plurality of internal structures; and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the second sound dampening component, wherein the first sound dampening component comprises a first layer of the multi-layer sound dampening part and the second sound dampening component comprises a second layer of the multi-layer sound dampening part, the first sound dampening element imparting a first sound dampening effect to the multi-layer sound dampening part and the second sound dampening component imparting a second sound dampening effect to the multi-layer sound dampening part different from the first sound dampening effect.

[0091] Aspect 23 is a component additively manufactured according to any one of aspects 14 through 20.

[0092] Aspect 24 is a method for additively manufacturing any one of 1 through 13.

[0093] Aspect 25 is a system for additively manufacturing a component of any one of1 through 13.

[0094] Aspect 26 is a system of additively manufacturing a component according to any one of aspects 14 through 20.EXAMPLESExample 1 - Black Polyurea Acoustic Panel

[0095] A 3D printable 2K polyurea formulation with additives and rheology modifiers was printed and tested for noise reduction. The amine and the isocyanate components were formulated using the compositions below. The amine-side composition was made from the components in Table 3.

[0096] Four curable coating compositions were prepared from the components listed in Table 3.Table 3Amine-side Composition1Desmophen NH-1220, aspartic ester di-amine, CAS# 168253-59-6, commercially available from Covestro LLC2Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot Corporation3Black Soild Pigment, pigment, product # IXS 90000, commercially available from PPG4Joncryl 584, pigment, product # HC-51-8411, commercially available from PPG5Jeffamine T5000, polyether tri-amine, CAS# 64852-22-8, commercially available from Huntsman Corporation6HXA CE-425, di-amine, commercially available from Hanson Group LLC7Byk 9077, wetting and dispersing additive, commercially available from BYK8Cyasorb UV-1164L, UV stabilizer, commercially available from Solvay9Tinuvin 292, amine light stabilizer, commercially available from BASF Corp

[0097] From Table 3, the aspartic ester di-amine, first pigment, and rheology modifier were weighed into a metal beaker and dispersed via standard Cowles grind procedure under a nitrogen blanked for thirty minutes at 185 °F. The dispersed mixture was then transferred to a Max 300L Flacktek DAC cup. The amounts of polyether tri-amine, di-amine, wetting and dispersing additive, UV light stabilizer, and amine light stabilizer listed in Table 3 above were then weighed and dispersed into the mixture via typical Speedmixer procedure.

[0098] The isocyanate-side composition was made from the components listed in Table 4.Table 4Isocyanate-side Composition1Isophorone diisocyanate IPDI, aliphatic diisocyanate, CAS# 98-4098-71-9, commercially available from Sigma Aldrich2Jeffamine D4000, polyetheramine, CAS# 9046-10-0, commercially available from Huntsman3Desmodur N3900, aliphatic polyisocyanate, CAS# 28182-81-2, commercially available from Covestro4Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot Corporation

[0099] From Table 4, the aliphatic diisocyanate, the polyetheramine, aliphatic polyisocyanate, and rheology modifier were weighed and dispersed in 300L container via an air motor mixer and via the standard Speedmixer procedure.

[0100] The amine-side and isocyanate- side compositions were transferred from their respective DAC cups to 32oz cartridges via Flacktek SpeedDisc which is optimal for 3D printing by reactive extrusion via Viscotec 2K extruders mounted to a gantry such as the 3DP. The amine and isocyanate compositions were printed at parameters listed in Table 5.Table 5Print Parameters for Black Polyurea

[0101] The formulation was printed with a 100% rectilinear infill pattern at a 45° angle to form a 13”xl3”x0.5” prism acoustic panel for noise reduction testing. Procedures for testing are documented in the test method section. The completed black flexible polyurea acoustic panel print was cured for 1 day at ambient conditions and 2 days at 140°F.Procedures for testing are documented in the test method section, but a summary of the relevant data is shown in Table 6.Table 6Noise Reduction Analysis of 3D printed acoustic panel containing the Black Polyurea FormulationExample 2 - White Aza-Michael Acoustic Panel

[0102] In this example, a 3D printable, 2K aza-michael formulation utilizing additives and rheology modifiers was printed and tested for noise reduction. The amine and the acrylate components of the formulation were formulated using the compositions below. The amine-side was made from the components in Table 7.Table 7Amine-side Composition1Epikurc Curing Agent 3381, Cyclo-aliphatic amine adduct, CAS# 285-13-2, commercially available from Westlakepoxy2l,8-Diazabicyclo[5.4.0]undec-7-ene, DBU, catalyst, CAS# 6674-22-2, commercially available from Sigma Aldrich3Wollastanite NY AD M9000, calcium silicate, commercially available from Imerys4Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot

[0103] From Table 7, the amine adduct, catalyst, and silicate were weighed and dispersed in a Max 300L Flacktek DAC cup via standard Speedmixer procedure.

[0104] The acrylate side composition was made from the components in Table 8.Table 8Acrylate-side Composition1Miramer SC9610, polyester acrylate melamine acrylate, commercially available from Miwon Specialty Chemical24’4’ methyl enebis(N,N-diglycidylaniline), epoxy, CAS# 28768-32-3, commercially available from Sigma Aldrich3Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot Corporation

[0105] From Table 8, the polyester acrylate melamine acrylate, epoxy, and rheology modifier were weighed and mixed via the standard Speedmixer procedure.

[0106] The amine-side and the acrylate-side compositions were transferred from their respective DAC cups to 32oz cartridges via Flacktek SpeedDisc which is optimal for 3D printing by reactive extrusion via Visoctec 2K extruder mounted to the gantry such as 3DP. The amine and acrylate with epoxy compositions were printed at parameters listed in Table 9.Table 9Print Parameters for White Aza-Michael

[0107] The white Aza-Michael formulation was printed with a 100% rectilinear infill pattern at a 450angle to form a 13”xl3”x0.5” prism acoustic panel for noise reduction testing. The completed white Aza-Michael acoustic panel print was cured for 1 day at ambient conditions and 2 days at 140°F. Procedures for testing are documented in the test method section, but a summary of relevant data is listed below in Table 10.Table 10Noise Reduction Analysis of 3D Printed Acoustic Panel Containing White Aza-Michael FormulationExample 3 - Multi-Material Acoustic Panels Containing Black Polyurea and White Aza-Michael

[0108] In this example, two 3D printable, 2K formulations, one polyurea and one Aza-Michael, utilizing additives and rheology modifiers were printed and tested for noise reduction. The polyurea’s amine and isocyanate components of the formulation were formulated and loaded into 32oz cartridges as described in Example 1. The Aza-Michael formulation’s amine and acrylate were formulated and loaded into 32oz cartridges as described in Example 2. The black polyurea formulation was printed at parameters described in Table 5, and the white Aza-Michael formulation was printed at parameters described in Table 9. The white Aza-Michael formulation was completely printed first at a 100% rectilinear infill pattern at a 45 ° angle to form a 13”xl3”x0.12” prism directly on the printbed. The black polyurea formulation was printed directly on top of the completed print of the white Aza-Michael material to form a 13”xl3”x0.35” prism. The infill designs for the black polyurea portion of the acoustic panel are listed below in Table 11. The percentages for infill refer to the total panel area filled when looking down on the panel from a 2 dimensional plan view.Table 11Infill Patterns of the Black Polyurea Segment of Multi-Material Acoustic Panel

[0109] The completed multi-material acoustic panel was cured for 1 day at ambient conditions and 2 days at 160°F. The procedures for testing are documented in the test method section while a summary of relevant data is listed below in Table 12.Table 12Infill Patterns of the Black Polyurea Segment of Multi-Material Acoustic PanelExample 4 - Multi-Material Acoustic Panels containing Foam, Black Polyurea and White Aza-Michael

[0110] In this example, multi-material acoustic panels were printed and tested for noise reduction. The same two formulations as used in Example 3, black polyurea and white Aza-Michael, were formulated, loaded into cartridges, printed with parameters, and printed with infill patterns in the same fashion as example 3. After these panel were cured for 1 day at ambient conditions and an additional 2 days at 160°F, a polyurea-based foa: FOAM-iT™ 8, commercially available from Hydro Systems, was mixed at proper ratio and poured into the hexagonal structures. The procedures for testing are documented in the test method section. The summary of relevant data is listed below in Table 13.Table 13Noise Reduction Analysis of 3D Printed Multi-Material Acoustic Panels Containing the Black Polyurea and White Aza-Michael CompositionExample 5 - Acoustic Testing

[0111] Several samples with the chemistries described in Examples 1-4 were prepared to test their acoustical dampening properties. The samples and their physical properties are described in Table 14 below.Table 14Physical Properties of Acoustic Dampening Sample Panels

[0112] A series of additional samples were prepared using a variety of conventional substrate materials. These samples and their physical properties are described in Table 15 below.Table 15Physical Properties of Acoustic Dampening Sample Panels with Conventional SubstratesAcoustic Test Method

[0113] An acoustic testing apparatus was used to conduct sound dampening performance testing on the 3D ARE printed panels. The apparatus consists of an aluminum rectangular enclosure with a noise source mounted at one end and a test panel mounted the other end. The noise source is a tube featuring a loudspeaker at one end and an opening at theother end. The high noise generated through the loudspeaker radiates out of the open end of the tube and into the rectangular enclosure. The other end of the rectangular enclosure is designed to accommodate mounting and dismounting of a square test sample and its acoustic insertion loss performance can be measured.

[0114] This insertion loss is measured by generating a high, broad band, noise within the enclosure, measuring its reference sound pressure levels with a microphone installed inside the enclosure, and comparing it with the sound pressure levels measured outside the enclosure by using a sound intensity probe / . Since the external sound intensity probe is traversable in X and Y axis directions, a mapping of the acoustic pressure levels over the center area of the square sample can also be performed. This entire set-up is placed within an anechoic room environment to minimize influence of other potential acoustic disturbances from room’s sound reflections. A summary of the test equipment and parameters, which conform to ISO 9614 ASTM E2249, is shown in Table 16 below.Table 16Parameters and Methodology of Acoustic Testing

[0115] FIG. 4 shows the reduction in overall sound pressure levels passing through the center subarea (of approximately 10.5 inches by 10.5 inches) of the samples in Table 14 (summed up over all l / 3rd octave bands between 125 Hz to 8 kHz). The overall sound pressure level (approximately 111 dB A) was measured by the microphone installed inside the test enclosure. The plot shows the overall sound pressure levels values in dBA units, which were measured outside the enclosure, for several different samples mounted in the apparatus. Specific samples designs are described elsewhere. The highest insertion loss, i.e., the most efficient noise isolation solution, is described by the samples that show the lowest sound pressure levels in dBA units. The sample labeled “Black flexible” shows the highest insertion loss which may be attributed to its favorable combination of structural and sound dampening materials.

[0116] FIG. 5 shows the reduction in overall sound pressure levels for the samples described in Table 15. The highest insertion loss is demonstrated by the “Lead (Pb)” sample.

[0117] FIG. 6 shows the sound transmission loss (dB) vs. frequency for the center area of the panels in Table 14.Example 6 - Expandable ARE Foam for Acoustic Dampening

[0118] A 3D printable 2K polyurea formulation with expandable fillers, additives, and rheology modifiers was printed for noise reduction. The amine and the isocyanate components were formulated using the compositions below. The amine-side composition was made from the components in Table 17.Table 17Amine Side Compostiion| Amine light stabilizer [8] | 1.9 | 0.1-5 |1Desmophen NH-1220, aspartic ester di-amine, CAS# 168253-59-6, commercially available from Covestro LLC2Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot Corporation3Expancel 031 DU 40, expandable filler, CAS# 75-28-5 commercially available from Sevron4Jeffamine T5000, polyether tri-amine, CAS# 64852-22-8, commercially available from Huntsman Corporation5HXA CE-425, di-amine, commercially available from Hanson Group LLC6Byk 9077, wetting and dispersing additive, commercially available from BYK7Cyasorb UV-1164L, UV stabilizer, commercially available from Solvay8Tinuvin 292, amine light stabilizer, commercially available from BASF Corp

[0119] From Table 17, the aspartic ester di-amine, polyether tri-amine, di-amine, expandable filler, wetting and dispersing additive, UV light stabilizer, amine light stabilizer, and rheology modifier listed in Table 17 above were weighed into a Max 300L Flacktek DAC cup. The components were then dispersed into the mixture via typical Speedmixer procedure.

[0120] The isocyanate-side composition was made from the components listed in Table 18.Table 18Isocyanate-side Composition1Isophorone diisocyanatc IPDI, aliphatic diisocyanatc, CAS# 98-4098-71-9, commercially available from Sigma Aldrich2Jeffamine D4000, polyetheramine, CAS# 9046-10-0, commercially available from Huntsman3Desmodur N3900, aliphatic polyisocyanate, CAS# 28182-81-2, commercially available from Covestro4Cabosil TS-720, rheology modifier, CAS# 112945-52-5, commercially available from Cabot Corporation

[0121] From Table 18, the prepolymer, aliphatic polyisocyanate, and rheology modifier were weighed and dispersed in a Max 300L Flacktek DAC cup via standard Speedmixer procedure.

[0122] The amine-side and isocyanate- side compositions were transferred from their respective DAC cups to 32oz cartridges via Flacktek SpeedDisc which is optimal for 3D printing by reactive extrusion via Viscotec 2K extruders mounted to a gantry such as the 3DP. The amine and isocyanate compositions were printed at parameters listed in Table 19.Table 19Print Parameters for Expandable ARE Foam

[0123] The completed expandable foam polyurea panel print was cured for 2 days at 160°F. Once cured the polyurea material was placed in an oven at 125°C for 40 minutes to activate the expandable filler. The polyurea sample expanded with an increase in volume up to 850 %.

[0124] The expandable polyurea foam was used to create an acoustic dampening panel both on its own and in place of the foam in Example 4. In both configurations, the expandable polyurea contributed significantly to the acoustic dampening effect of the material, especially in the high frequency region.

[0125] Whereas particular examples of this disclosure have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present disclosure may be made without departing from what is defined in the appended claims.

Claims

CLAIMSWhat is claimed is:

1. An additively manufactured sound dampening part comprising: a boundary element comprising a first coreactive composition; and an infill element comprising a second coreactive composition, wherein: the boundary element substantially encloses the infill element, and the sound dampening part provides a sound transmission loss of at least 30 dB(A) for a 125Hz to 8kHz sound passing through the sound dampening part.

2. The sound dampening part of claim 1, wherein the first coreactive composition comprises a polyurea-based coreactive composition comprising: a first coreactive component including an isocyanate-containing compound, and a second coreactive component including an amine-containing compound.

3. The sound dampening part of either of claims 1 or 2, wherein the second coreactive composition comprises a polyurea-based coreactive composition comprising: a first coreactive component including a hydroxyl-containing compound, and a second coreactive component including an isocyanate-containing compound.

4. The sound dampening part of any one of claims 1 through 3, wherein the boundary element further defines a perimeter of the sound dampening part.

5. The sound dampening part of any one of claims 1 through 4, wherein the boundary element comprises a plurality of internal structures, each internal structure comprising a void.

6. The sound dampening part of claim 5, wherein the plurality of internal structures each comprise a hexagonal geometry arranged in a lattice.

7. The sound dampening part of claim 5, wherein the infill element at least partially fills the void of at least one of the plurality of internal structures.

8. The sound dampening part of any one of claims 1 through 7, wherein the infill element comprises a colloidal solution.

9. The sound dampening part of any one of claims 1 through 8, wherein the infill element imparts a first sound dampening effect to the sound dampening part, and the boundary element imparts a second sound dampening effect to the sound dampening part different from the first sound dampening effect.

10. The sound dampening part of any one of claims 1 through 9, further comprising a structural element comprising a third coreactive composition, wherein the structural element supports the boundary element and the infill element.

11. The sound dampening part of claim 10, wherein the third coreactive composition comprises a Michael addition-based coreactive composition comprising: a first coreactive component including a Michael donor compound, and a second coreactive component including a Michal acceptor compound.

12. The sound dampening part of either of claims 10 or 11, wherein the structural element comprises a base structure of the sound dampening part, the structural element comprising a first surface upon which the boundary element and infill element are formed.

13. The sound dampening part of any one of claims 9 through 12, wherein the infill element imparts a first sound dampening effect to the sound dampening part, the boundary element imparts a second sound dampening effect to the sound dampening part, and the structural element imparts a third sound dampening effect to the sound dampening part, each of the first sound dampening effect, the second sound dampening effect, and the third sound dampening effect comprising different sound dampening effects.

14. A method of additively manufacturing a sound dampening part comprising: depositing a boundary element in a first geometric configuration, the boundary element imparting a first sound dampening effect to the sound dampening part; anddepositing an infill element in a second geometric configuration different from the first geometric configuration, the infill element imparting a second sound dampening effect to the sound dampening part different from the first sound dampening effect, and wherein the boundary element and the infill element react and cure under ambient conditions to form the sound dampening part.

15. The method of claim 14, wherein the boundary element comprises a polyurea-based coreactive composition, and the first configuration comprises a plurality of internal structures each comprising a void.

16. The method of claim 15, wherein each of the plurality of internal structures comprises a hexagonal geometry, and the internal structures are arranged in a lattice.

17. The method of either of claims 15 or 16, wherein the infill element comprises a polyurethane-based coreactive composition, and the second configuration comprises an infill of the voids of the plurality of internal structures.

18. The method of any one of claims 14 through 17, wherein the boundary element and the infill element are deposited onto a substrate.

19. The method of any one of claims 14 through 17, further comprising depositing a structural element in a third geometric configuration, the structural element imparting a third sound dampening effect to the component different from the first sound dampening effect and the second sound dampening effect, the third geometric configuration being different from the first and the second configurations, and each of the boundary element, the infill element, and the structural element react and cure under ambient conditions to form the sound dampening part.

20. The method of claim 19, wherein the structural element comprises a polyurethane- based coreactive composition, and the third configuration comprises a base structure of the sound dampening part.

21. The method of either of claims 19 or 20, wherein the structural element is deposited onto a substrate, and the boundary element and the infill element are deposited onto the structural element thereafter.

22. A multi-layer sound dampening part comprising: a first sound dampening component comprising: a boundary element comprising a plurality of internal structures each comprising a void; an infill element configured within the voids of the plurality of internal structures; and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the first sound dampening component; and a second sound dampening component comprising: a boundary element comprising a plurality of internal structures each comprising a void; an infill element configured within the voids of the plurality of internal structures; and optionally, a structural element upon which the boundary element and the infill element are formed, wherein the boundary element, the infill element, and the optional structural element react and cure under ambient conditions to form the second sound dampening component, wherein the first sound dampening component comprises a first layer of the multilayer sound dampening part and the second sound dampening component comprises a second layer of the multi-layer sound dampening part, the first sound dampening element imparting a first sound dampening effect to the multi-layer sound dampening part and the second sound dampening component imparting a second sound dampening effect to the multi-layer sound dampening part different from the first sound dampening effect.

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