RECYCLED CUTOUTS FOR COMPACT ENGINEERED MATERIALS

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims the benefit of Indian Application No. 202231055874, filed on, September 29, 2022, the contents of which are hereby incorporated by reference for all purposes in its entirety.

FIELD

[002] The present invention generally relates to composite materials, and more specifically, to composite structures formed using recycled materials for sound and/or thermal insulation.

BACKGROUND

[003] Various industries are frequently seeking new or improved materials to incorporate sound and noise reduction in a variety of applications. To reduce sound and/or noise in applications, industries may frequently incorporate materials that exhibit improved sound absorption characteristics. For example, industrial applications, commercial applications, residential applications, or a combination thereof may often desire improved sound absorption materials to reduce the overall noise of machinery, engines, tools, vehicles, or the like.

[004] Certain industries, such as the automotive industry and/or the construction industry, may often require materials that provide thermal insulation, sound absorption, reduction in air leakage, structural integrity, other structural properties, or a combination thereof. Industry may require a lightweight material. Depending on where the materials are being implemented, the material properties may often need to meet extremely demanding requirements. For example, materials being used within a passenger cabin of a vehicle may often require heightened sound attenuation requirements to ensure a quieter driving experience for a user.

[005] One particular application may be in passenger vehicles that include a heating, ventilation, and air conditioning (HVAC) system. Such HVAC units may be provided to heat and/or cool a cabin of the passenger vehicle by forcing conditioned air through one or more air ducts into the cabin. However, conventional air ducts may frequently be made from molded (e.g., injection molded, blow molded, or both) materials. Such conventional molded materials may frequently be heavy and structurally rigid. As a result, the air ducts may be prone to rattling, squeaking, vibrating, or other unwanted movements and/or sounds that create an undesirable level of noise permeating from the air ducts during use of the HVAC system. [006] To combat such issues, other conventional HVAC systems may incorporate a textilebased air duct into the system. However, these textile-based air ducts may frequently experience significant air leakage through the material used, thereby significantly decreasing the amount of air reaching the cabin being temperature-controlled. Similarly, such textile-based air ducts may often lack the necessary structural integrity needed to maintain an overall shape during operation of the vehicle, operation of the HVAC system, or both. Examples of other types of air duct materials can be found in US Publication Nos. 2021/0162702 and 2020/0230909, both of which are incorporated herein in their entirety for all purposes.

[007] To meet the above requirements, composite structures may be formed and shaped into various geometries. Such composite structures may then be installed in a given application to improve sound insulation, thermal insulation, structural integrity, other structural properties, to provide a lightweight material, to reduce air leakage, or a combination thereof. These types of structures may incorporate a variety of materials to form a plurality of layers within the composite structure. As a result, the composite structure may be tuned to meet certain application requirements utilizing a variety of materials if needed. The composite structure may then be cut into the final shape for installation.

[008] Unfortunately, when such composite structures are formed, various cutouts are often left as scrap. That is, when the final shape of a composite structure is cut from an overall piece of the composite material, the leftover portions of the composite material are scrapped. As a result, especially depending on the shape of the composite structure being formed, significant scrap rates may exist during manufacturing. Therefore, the overall manufacturing process may incur significantly increased material costs.

[009] Based on the above, there remains a need for a material having improved acoustic attenuation of a desired area. What is needed is a fibrous composite material having improved sound insulation characteristics. There also remains a need for a sound insulation material having an optimized manufacturing process that decreases overall manufacturing costs. As such, what is needed is a composite structure manufactured using recycled scrap materials. Furthermore, there remains a need for a composite material that facilitates incorporation of ground recycled materials without a decrease in material performance. Thus, what is needed is a composite structure having one or more substrates formed or otherwise secured to the recycled material to form the composite structure. [0010] What is also needed is a simplified method for using these recycled materials to form a composite structure. Efforts to recycle materials are shown, for example, in in U.S. Publication No. 2015/0330001, incorporated by reference in its entirety for all purposes. However, there remains a need for a simplified process and/or a process using different and/or less machinery. For example, there is a need for a process that is free of a shredder, a blending station, a recyclate separator, a recyclate spreader, a pre-formed web of material and/or a step of forming a web, a short fiber web, bi-component fibers, a compacting step, or a combination thereof.

[0011] As to air ducts, it would be attractive to have an air duct that provides improved sound and/or noise attenuation. What is needed is an air duct made from noise-absorbing materials to significantly quiet any unwanted noise during operation of an HVAC system. Additionally, it would be attractive to have an air duct that decreases permeability through the air duct materials, yet still maintains a quieter operating level for passengers within a vehicle. What is needed is an air duct made from a composite material utilized one or more nonwoven materials, one or more compressed materials, or both. Additionally, it would be attractive to have an air duct that may decrease overall noise yet maintain or improve structural integrity. Therefore, what is needed is a composite air duct material that utilizes compressed fibers that maintain a structural shape of the air duct yet provide improved sound absorption.

SUMMARY

[0012] The present teachings meet one or more of the present needs by providing a composite structure comprising: (a) a nonwoven layer; (b) a core material that includes one or more layers including ground fibers formed from recycled cutouts of a previously manufactured composite structure; and (c) optionally a film layer; wherein the composite structure is adapted to attenuate noise and/or sound.

[0013] The composite structure may include a core material sandwiched between opposing nonwoven layers. The recycled cutouts may be ground into a powder to form at least a portion of the core material. The composite structure may include a non-porous film formed from low- density polyethylene (LDPE), high-density polyethylene (HDPE), or both. The non-porous film may be disposed along one or more outer surfaces of the composite structure. The material formed from the recycled cutouts may include polyethylene terephthalate (PET) fibers. The material formed from the recycled cutouts may include polypropylene fibers. The ground recycled cutouts may include binder previously present in the previously manufactured composite structure.

[0014] The core material or one or more layers of the core material may include a binder that binds the material formed from the recycled cutouts to form the core material or one or more layers of the core material. The binder may be distributed as another layer of the core material. The binder may be added separately from the ground recycled cutouts, offal, or off-cuts. The binder may be thermoplastic, thermosetting, or both. The core material or one or more layers of the core material may include about 15 wt% to about 45 wt% of the binder.

[0015] The nonwoven layer may have a weight of about 50 grams per square meter to about 400 grams per square meter. Similarly, the composite structure may have a thickness of about 1 mm to about 50 mm.

[0016] The nonwoven layer may include silica fibers, polyester (PET), polyacrylonitrile (PAN), oxidized polyacrylonitrile (Ox-PAN, OPAN, or PANOX), aramid, olefin, polyamide, imide, polyetherketone (PEK), polyetheretherketone (PEEK), polyethylene succinate) (PES), mineral, ceramic, natural, other inorganic fibers, other polymeric fibers, or a combination thereof. [0017] The nonwoven layer may be a lofted, fibrous material; a needlepunched material; a spunbond material; a melt blown (M) material; a spunbond and meltblown (SM) material; a spunbond + meltblown + spunbond (SMS) material; a cross-laid material; a compressed air laid material; a spunlaced material; a direct laid material; a wet laid material; a dry laid material; or a combination thereof. The composite structure may be thermoformable. The composite structure may include a film layer adhered to the nonwoven layer.

[0018] The core material, the film layer, or both, may include low-density polyethylene (LDPE), high-density polyethylene (HDPE), or both. Low density polyethylene and/or high density polyethylene may be supplied as a film, as a powder, or both. The core material or one or more layers of the core material may include about 55 wt% to about 85 wt% of the material formed from the recycled cutouts.

[0019] The composite structure may be shaped to form an air duct, such as an air duct for heating, ventilation, and air conditioning (HVAC) system of a vehicle. The composite structure may be adapted to attenuate noise and/or sound caused by the HVAC system when forcing air through the air duct into a cabin of the vehicle. The air duct may include an outer surface and an inner surface. The inner surface may define the cavity of the air duct through which air travels. The inner surface may be formed from the core material, a nonwoven layer, or one or more films or foils. The outer surface may be formed from the core material, a nonwoven layer, or one or more films or foils. The air duct may be formed from one or more thermoformed sheets of the composite structure. The thermoformed sheet(s) may be secured along one or more flanges to form the air duct.

[0020] The present teachings may meet one or more of the present needs by providing a composite structure formed from a method comprising grinding the recycled cutouts into a powder and disposing the powder along a surface of the nonwoven layer such that the nonwoven layer may act as a substrate during forming of the composite structure. The core material may be formed by depositing separate layers of powder, synthetic fibers, natural fibers, one or more binders, or a combination thereof. A second nonwoven layer may be disposed on an opposing surface of the core material after formation of the core material.

[0021] Furthermore, the present teachings may meet one or more of the present needs by providing: a material having improved acoustic attenuation of a desired area; a fibrous composite material having improved sound insulation characteristics; a sound insulation material having an optimized manufacturing process that decreases overall manufacturing costs; a composite structure manufactured using recycled scrap materials; a composite material that facilitates incorporation of ground recycled materials without a decrease in material performance; a composite structure having one or more substrates formed or otherwise secured to the recycled material to form the composite structure; or a combination thereof.

DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a close-up view of a ground recycled material for composite structures in accordance with the present teachings.

[0023] FIG. 2 is a close-up view of a composite structure in accordance with the present teachings.

[0024] FIG. 3 is a cross-sectional view of a composite structure in accordance with the present teachings.

[0025] FIG. 4 is a cross-sectional view of a composite structure in accordance with the present teachings. [0026] FTG. 5 is a cross-sectional view of a composite structure in accordance with the present teachings.

[0027] FIG. 6 is a flow-chart of a manufacturing process for a composite structure in accordance with the present teachings.

[0028] FIG. 7 is a flow diagram of a manufacturing process for a composite structure in accordance with the present teachings.

[0029] FIG. 8 is a perspective view of an air duct in accordance with the present teachings.

[0030] FIG. 9 is cross-section 2-2 of the air duct of FIG. 8.

[0031] FIG. 10 is a graph illustrating the sound absorption coefficient for composite structure samples.

[0032] FIG. 11 is a graph illustrating the sound transmission loss for composite structure samples.

[0033] FIG. 12 is a graph illustrating the sound transmission loss for composite structure samples having different thicknesses.

DETAILED DESCRIPTION

[0034] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. The specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference herein in their entirety for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference in their entirety into this written description.

[0035] Insulation materials, structural materials, acoustic absorption materials, or a combination thereof may have a wide range of applications, such as in automotive applications, aviation applications, commercial vehicle engine compartments, in-cab areas, construction equipment, agricultural applications, flooring, floormate underlayments, and heating, ventilation and air conditioning (HVAC) applications. These materials may also be used for machinery and equipment insulation, motor vehicle insulation, domestic appliance insulation, and commercial wall and ceiling panel insulation. For example, insulation materials may be used in an engine cavity or along a floor of a vehicle cabin. These materials may also provide other benefits, such as sound absorption, compression resiliency, stiffness, desired structural properties, protection (e.g., to an item around which the insulation material is located), or a combination thereof. These materials may also serve as a sound attenuation material in an aircraft or a vehicle.

[0036] For example, the material as described herein may at least partially or substantially form one or more air ducts of an HVAC system. The HVAC system may be a commercial or residential HVAC system for a building. However, it is envisioned that the composite material may be well suited for vehicle HVAC systems. While the type of vehicle is not limited, air ducts formed from the composite material may help attenuate or prevent sound originating from the HVAC system that ultimately reaches a cabin of the vehicle, whereby one or more passengers may be present to hear the noise.

[0037] The air ducts may function to direct air of a HVAC system throughout one or more locations with the vehicle. The air ducts may direct the air through the HVAC system and into a cabin of the vehicle to control a temperature therein. To regulate the temperature within the cabin, the HVAC system may include one or more components (e.g., a fan, impeller, etc.) that may force the air into and through the air ducts to reach the cabin of the vehicle. As a result, conventional air ducts may frequently be prone to vibration or movement due to the force of the air being directed through the air duct. Beneficially, the present teachings may provide a composite material to form the air ducts that may be more resistant to the vibration and/or forces created by the forced air being promulgated through the air ducts into the cabin of the vehicle. That is, the composite material may be vibration damping, sound absorbing, or both, yet still provide sufficient sealing to ensure the forced air may reach a desired end point without permeating through the composite material.

[0038] The present teachings envision the use of a fibrous material for providing insulation, acoustic absorption, structural reinforcement, or a combination thereof. In particular, it is envisioned that a plurality of layers may be formed using one or more fibrous materials to form a composite structure. The composite structure may include a plurality of layers, including any combination of woven layers, nonwoven layers, recycled material layers, films, foils, fiber matrix layers, the like, or a combination thereof. For example, the composite structure may be formed as a sheet material that may be incorporated into a variety of applications, such as forming or reinforcement one or more vehicle components (e.g., HVAC ducts, vehicle side and rear panels and/or headliner, engine firewall insulation and/or reinforcement, etc.). As such, the composite structure may be shaped or otherwise formed into a variety of geometries based on a desired application, shape, size, or a combination thereof. That is, the sheet formed as a composite material may include one or more planar portions, one or more contoured portions, one or more bends, one or more angles, one or more edges, one or more cutouts, one or more channels, one or more undulations, one or more linear segments, one or more ribs, one or more supporting portions, one or more flanges, or a combination thereof to form the composite structure. As such, the composite structure may advantageously be shaped to meet a desired packaging space. However, in certain instances it may be desired to form a more simplified planar sheet material, whereby various shaped may be cut from the composite structure formed as a sheet. Examples of such thermoacoustic and/or structural composite structures can be found in International Patent Application No. PCT/US2022/023248, all of which is incorporated herein in its entirety for all purposes.

[0039] Air ducts, for example, formed from the composite structure herein may be shaped to meet a desired shape, size, and/or packaging constraints of a given vehicle. The composite structure may be formed into the desired shape without negatively impacting the performance of the composite structure. Any desired shape (e.g., bends, angles, steps, flanges, etc.) may be formed by the composite structure without decreasing the noise attenuation characteristics of the composite structure.

[0040] The air ducts may form a channel to direct the air through the HVAC system. The channel may be a cavity formed within the air duct. The cavity may vary in size and/or shape along a length of the air duct. The cavity within the air duct may be round, oval, square rectangular, triangular, trapezoidal, or a combination thereof, at its cross-section at a portion of the air duct. The cavity may have a generally constant or consistent cross-section. The cavity may have a crosssection at one section that is different from the cross-section at another section. For example, localized regions of the air duct may have a cavity with a cross-section having a length less than or greater than another region or the remainder of the air duct. The air duct may have a varying cross-sectional diameter along a length of the air duct. Variations in cross-section of the cavity may be due to the shape of the composite structure forming the air duct. Variations in cross-section of the cavity may be due to varying thickness of the composite structure along a length of the air duct. [0041] The air duct may provide improved sound attenuation while also maintaining a temperature of the air within the air duct. The composite material may thermally insulate the air ducts so that an initial conditioned temperature of the air being forced through the air duct may reach the cabin or desired end point within the vehicle at a temperature substantially the same as the initial conditioned temperature. For example, the composite material may include a plurality of layers to improve thermal insulation, sound attenuation, structural properties, or a combination thereof. As such, the composite material may be tuned for creation of the air duct to maintain structural integrity, decrease overall noise within the HVAC system, and also maintain a temperature of the air within the air duct.

[0042] It is envisioned that the composite structure may be fire retardant, smoke retardant, may have a low toxicity (e.g., as compared to more conventional composite structures), or a combination thereof. Additionally, while thermal and/or noise characteristics of the composite material may be described in more detail herein, the composite material may also exhibit improved compression resistance, mold and/or mildew resistance, moisture resistance, or a combination thereof. As a result, the composite structure may provide a structural material better configured to withstand long-term exposure to humid environments or significant humidity and/or temperature fluctuations, such as those found in automotive vehicle operation and/or storage.

[0043] The composite structure may be molded, compressed, thermoformed, or a combination thereof to create an overall shape of the composite structure. The thermoforming may result from heating and then forming the layers of the composite material into the specific shaped thermoformed composite structure. It is envisioned that the thermoforming may be promoted by a binder (e.g., a high-temperature binder) present in one or more of the layers of the composite structure to mold fibers of the layers and form the desired shape of the composite structure. Such binder may promote bonding of various layers to each other to maintain the shape of the overall composite structure. However, it should be noted that one or more layers within the composite structure may be free of thermoforming. For example, a film layer or foil layer may be pre-formed and disposed over a thermoformed shape of the composite structure. A film layer or foil layer may be pre-formed and disposed over a thermoformed shape (e.g., a thermoformed shape of the air duct).

[0044] One or more strengthening features may be incorporated into or secured to the composite structure during or after forming. The strengthening features may be one or more ribs, gussets, channels, beads, bends, angles, embossments, perforations, flanges, or a combination thereof. The strengthening features may function to improve structural integrity of the article during use. These strengthening features may be positioned and/or tuned based upon a given application. For example, the strengthening features may be one or more flanges formed along portions of the air duct so that the portions of the air duct may be joined to each other along the flanges. Similarly, such flanges may also provide additional strength to the air duct. It should be noted that one or more layers may include a strengthening feature while one or more additional layers may be free of a strengthening feature.

[0045] The composite structure may include one or more nonwoven layers. The nonwoven layers may function to improve thermal insulation, acoustic absorption, structural support and/or protection, or a combination thereof. The nonwoven layers may function as a support layer or substrate for the core material or one or more layers of the core material during a manufacturing process, after a manufacturing process, or both. The nonwoven layers may provide structure or rigidity to the composite structure. The nonwoven layers may be molded or otherwise thermoformed. The nonwoven layers may include one or more binding agents to secure the nonwoven layers with other layers (e.g., the core material or one or more layers of the core material) within the composite structure. As a result of such forming, the nonwoven layers may form an overall or general contour of the composite structure, including any desired strengthening features, bends, undulations, steps, the like, or a combination thereof. The nonwoven layers may, for example, be molded or otherwise thermoformed into the shape of an air duct having a hollow channel or cavity for air to flow through.

[0046] The nonwoven layers may be made up of a fiber matrix. The fiber matrix may be of a relatively low weight yet still exhibit good resiliency and thickness retention. The fiber matrix, due to factors such as, but not limited to, unique fibers, facings, physical modifications to the three- dimensional structure (e.g., via processing), orientation of fibers, or a combination thereof, may exhibit good thermal insulation capabilities or thermal conductivity (e.g., lower) along with acoustic performance versus traditional insulation materials. The fiber matrix, and thus the nonwoven layers, may retard fire and/or smoke. The fiber matrix, or parts thereof, may be capable of withstanding high temperatures without degradation (e.g., temperatures up to about 1150 °C for a shorter duration and 600 to 650 °C for continuous exposure). The fiber matrix may provide structural properties or may provide physical strength to the nonwoven layers. The fiber matrix may provide insulative properties. The fiber matrix may function to provide high temperature resistance, acoustic absorption, structural support, and/or protection to one or more areas of the composite structure.

[0047] At least some of the fibers forming the fiber matrix of the nonwoven layers may be of an inorganic material. The inorganic material may be any material capable of withstanding temperatures of about 250 °C or greater, about 500 °C or greater, about 650 °C or greater, or about 1000 °C or greater. The inorganic material may be a material capable of withstanding temperatures up to about 700 °C (e.g., up to about 650 °C). The fibers of the fiber matrix may include a combination of fibers having different melting points. For example, fibers having a melting temperature of about 200 °C may be combined with fibers having a higher melting temperature, such as about 750 °C. When these fibers are heated above the melting temperature of the lower melt temperature fibers (e.g., exceeding 200 °C), the lower melt temperature fibers may melt and bind to the higher temperature fibers. The inorganic fibers may have a limiting oxygen index (LOI) via ASTM D2836 or ISO 4589-2 for example that is indicative of low flame or smoke. The LOI of the inorganic fibers may be higher than the LOI of standard binder fibers. The inorganic fibers may be present in the fiber matrix in an amount of about 10 percent by weight or greater, about 20 percent by weight or greater, about 30 percent by weight or greater, or about 40 percent by weight or greater. The inorganic fibers may be present in the fiber matrix in an amount of about 100 percent by weight or less. The inorganic fibers may be selected based on a desired stiffness. The inorganic fibers may be crimped or non-crimped. Non-crimped organic fibers may be used when a fiber with a larger bending modulus (or higher stiffness) is desired. The inorganic fibers may be ceramic fibers, silica-based fibers, glass fibers, mineral-based fibers, or a combination thereof. That is, the inorganic fibers may form a glass mesh within the nonwoven layer. Ceramic and/or silica-based fibers may be formed from polysilicic acid (e.g., Sialoxol or Sialoxid), or derivatives of such. For example, the inorganic fibers may be based on an amorphous aluminum oxide containing polysilicic acid. The fibers may include about 99% or less, about 95% or less, or about 92% or less SiO2. The remainder may include -OH (hydroxyl or hydroxy) and/or aluminum oxide groups. Siloxane, silane, and/or silanol may be added or reacted into the fiber matrix to impart additional functionality. These modifiers may include carbon-containing components. [0048] The nonwoven layers may include binder fibers. The nonwoven layers may include bicomponent fibers. The bi-component fibers may be a thermoplastic lower melt bi-component fiber. The bi-component fibers may have a lower melting temperature than the other fibers within the nonwoven layer. The bi-component fibers may allow for the fibers of the nonwoven layer to be fused in space as a network so the nonwoven layer and/or composite structure may have structure and body and can be handled, laminated, fabricated, installed as a cut or molded part, or the like to provide desired properties. The bi-component fibers may include a core material and a sheath material around the core material. The sheath material may have a lower melting point than the core material. The sheath material may have a melting point of about 90°C or greater, about 100 °C or greater, about 110°C or greater, or about 120 °C or greater. The sheath material may have a melting point of about 300°C or less, about 250°C or less, or about 200°C or less. The binder and/or bi-component fibers may provide attachment to other fibers in the nonwoven layers and/or in adjacent layers, such as the core material. The binder and/or bi-component fibers may be present in the nonwoven layer in an amount of about 5 wt% or more, about 7 wt% or more, or about 10 wt% or more. The binder and/or bi-component fibers may be present in the nonwoven layer in an amount of about 50% or less, about 40% or less, or about 35 wt% or less.

[0049] The fiber matrix may comprise one or more structural fibers. It is contemplated that the structural fibers may be included to further improve flame retardance of the article. The structural fibers may have any desired specifications based on a given application. For example, the structural fibers may have a weight of about 50 grams per square meter (GSM) or more, about 100 GSM or more, or about 500 GSM or more. The structural fibers may have a weight of about 1500 GSM or less, about 1000 GSM or less, or about 500 GSM or less. The nonwoven layers may include the structural fibers to reinforce the nonwoven layer, at least partially form the nonwoven layer, or both. As such, the structural fibers provide further flame retardance, structural integrity (e.g., impact resistance), or both to the composite structure.

[0050] The nonwoven layers may be substantially uniform or may vary depending on the application. For example, each nonwoven layer may incorporate the same type of fibers, may have a substantially similar thickness, may have a substantially similar fiber orientation (e.g., each nonwoven layer includes a similar fiber matrix orientation), may have a substantially similar weight, or a combination thereof. Alternatively, or additionally, the nonwoven layers may vary in one or more of the aforementioned properties to even further tune one or more characteristics of the composite structure.

[0051] The nonwoven layer may be formed from a textile material. The nonwoven layer may be formed by needle-punching, alone or in combination with any of the methods of forming layers described herein or known in the art. The nonwoven layer may be compressed using one or more methods, such as with a press, laminator, set of calender rolls, or the like. The nonwoven layer may be compressed and melted in a thermoforming step. The nonwoven layer may be formed using any nonwoven technologies. For example, the nonwoven layer may be spunbond (S), melt blown (M), spunbond and meltblown (SM), spunbond + meltblown + spunbond (SMS), cross-laid, compressed air laid, spunlaced, direct laid, wet laid, dry laid, the like, or a combination thereof. The nonwoven layer may be formed from any fibers capable of being mechanically or thermally bonded to each other.

[0052] The composite structure may include a core material. The core material may include one or more core layers. The composite structure may include one or more core layers used in conjunction with the one or more nonwoven material layers. The core material or one or more layers of the core material may function to improve thermal insulation, acoustic absorption, structural support and/or protection, or a combination thereof. The core material or one or more layers of the core material may exhibit similar or different properties to that of the nonwoven layers. The core material or one or more layers of the core material may be thermoformed, molded, compressed, or a combination thereof. The core material or one or more layers of the core material may include one or more fibers.

[0053] It is contemplated that the core material or one or more layers of the core material may be adjusted based on the desired properties for a given application. The core material or one or more layers of the core material may be tuned to provide a desired weight, thickness, compression resistance, other physical attribute, or a combination thereof. For example, the core material or one or more layers of the core material may have a weight of about 100 GSM or more, about 500 GSM or more, or about 1,500 GSM or more. The core material or one or more layers of the core material may have a weight of about 4,000 GSM or less, about 3,000 GSM or less, or about 2,000 GSM or less. The core material or one or more layers of the core material may be tuned to provide a desired thermal conductivity and acoustics performance. [0054] The core material or one or more layers of the core material may be substantially uniform or may vary depending on the application. For example, each core layer of the core material may incorporate the same type of fibers, may have a substantially similar loft, may have a substantially similar fiber orientation (e.g., each core layer is vertically lapped, cross-lapped, rotary lapped, air laid, or a combination thereof), may have a substantially similar weight, or a combination thereof. Alternatively, or additionally, the core layers may vary in one or more of the aforementioned properties to further tune one or more characteristics of the air duct. One or more of the core layers may be formed by scattering fibers onto another layer. Therefore, it should be clear from the present teachings that the composite structure may be highly customizable to meet the demands of any given application.

[0055] The fibers that make up the core material or one or more layers of the core material may have an average linear mass density of about 1 denier or greater, about 4 denier or greater, or about 9 denier or greater. The fibers that make up the core material or one or more layers of the core material may have an average linear mass density of about 25 denier or less, about 20 denier or less, or about 15 denier or less. Fibers may be chosen based on considerations such as cost, resiliency, desired thermal conductivity, acoustics performance, or the like. For example, a coarser blend of fibers (e.g., a blend of fibers having an average denier of about 12 denier) may help provide resiliency to the core material or one or more layers of the core material. A finer blend may be used, for example, if thermal conductivity and acoustics are desired to be further controlled. The fibers may have a staple length of about 20 millimeters or greater, or even up to about 150 millimeters or greater (e.g., for carded fibrous webs). For example, the length of the fibers may be between about 30 millimeters and about 100 millimeters. The fibers may have an average or common length of about 50 to 75 millimeters staple length, or any length typical of those used in fiber carding processes. Short fibers may be used (e.g., alone or in combination with other fibers). Some or all of the fibers may be a powder-like consistency. Fibers of differing lengths may be combined to provide desired insulation and/or acoustic properties. The fiber length may vary depending on the application; the insulation properties desired; the acoustic properties desired; the type, dimensions and/or properties of the core material or one or more layers of the core material (e.g., density, porosity, desired air flow resistance, thickness, size, shape, and the like of the core material or one or more layers of the core material and/or any other layers of the article); or any combination thereof. The addition of shorter fibers, alone or in combination with longer fibers, may provide for more effective packing of the fibers, which may allow pore size to be more readily controlled in order to achieve desirable characteristics (e.g., acoustic and/or thermal insulation characteristics).

[0056] Advantageously, it is envisioned that the core material or one or more layers of the core material may incorporate fibers having a powder-like consistency (e.g., with a fiber length of about 6 mm or less, about 4 mm or less, about 3 mm or less, about 2 millimeters to about 3 millimeters, or even smaller, such as about 200 microns or greater or about 500 microns or greater). As a result, the core material or one or more layers of the core material may initially be disposed or deposited on one or more of the nonwoven layers in the powdered form such that the nonwoven layer may provide a substrate for the core material or one or more layers of the core material (e.g., the powder) during manufacturing. Similarly, due to disbursement along a nonwoven layer during manufacturing, fibers of the core material or one or more layers of the core material may be randomly oriented or scattered along a surface of the nonwoven layer to strengthenjoining of the core material or one or more layers of the core material to the nonwoven layer in the resultant composite structure. Additionally, the fibers of the core material or one or more layers of the core material disbursed or scattered along the nonwoven layer may at least partially penetrate an outer surface of the nonwoven layer to further join the core material or one or more layers of the core material to the nonwoven layer.

[0057] When a powdered form of the core material or one or more layers of the core material is used, a blend of fibers may be used. The powdered form may include a single type of fiber. The powdered form may include a plurality of fiber types. Different types of fiber types may be applied separately or in separate layers. For example, recycled fibers may be distributed separately from synthetic fibers, natural fibers, binder fibers, or a combination thereof.

[0058] Short fibers or powdered form of fibers may be formed from recycled off-cuts or offal. The recycled off-cuts or offal may be processed into short fibers or powder via one or more grinding operations. After grinding, the fibers or powder may be sent to a feed zone of the process for forming the composite structure.

[0059] Advantageously, it is envisioned that the core material or one or more layers of the core material may be formed using recycled materials from previous manufacturing processes. Such recycling may be completed using scrap materials from manufacturing composite structures such as those taught herein or using scrap from other material manufacturing. For example, manufacturing of composite structures, nonwoven structures, thermoformed structures, or a combination thereof may frequently require cutting sheets or larger formed structures. As a result, scrap cutouts not used within the final structure formed are often trashed, thereby increasing overall manufacturing costs while also increasing the carbon footprint created from the increase of waste. Beneficially, the present teachings provide a means for recycling such scrapped cutouts to decrease overall manufacturing costs and significantly reducing the carbon footprint of manufacturing by repurposing such scrapped materials.

[0060] To allow for such recycled materials to be incorporated into the composite structure, the scrapped material may undergo preliminary processing. For example, the scrapped material may be compiled, compressed, ground, heated, or a combination thereof to form the desired powder consistency to form the core material or one or more layers of the core material (i.e., the desired powder consistency for dispersion along a nonwoven). During such processing, the scrapped material may be blended with one or more additives to improve or otherwise alter material characteristics. The one or more additives may include one or more binders. The ratio of additives to the recycled materials may vary or be tuned based upon a given application for a specified core layer. For example, the core material or one or more layers of the core material may include about 30 wt.% or more, about 50 wt.% or more, or about 75 wt.% or more of the recycled material (e.g., the recycled cutouts). The core material or one or more layers of the core material may include about 95 wt.% or less, about 80 wt.% or less, or about 65 wt.% or less of the recycled material (e.g., the recycled cutouts). The core material or one or more layers thereof may be free of additives. For example, a layer of the core material may include only ground recycled material, without additives.

[0061] The core material may include one or more binders. The binder may be incorporated into or mixed with fibers of the core material or a layer of the core material. The core material or one or more layers of the core material may be free of any binders or separately-added binder. For example, binder and/or bi-component fibers may be present in the recycled material (e.g., recycled offal or off-cuts), such that the ground recycled material may include binder and/or bi-component fibers, but it is contemplated that one or more layers may be free of added binder. Binder may be applied as a separate layer of the core material during processing. For example, powdered fibers as ground recycled materials may be distributed along a facing layer or a nonwoven layer. Binder may be applied or distributed separately from the powdered fibers or recycled materials (see, e.g., Fig. 6). Different binders may be applied or distributed separately.

[0062] The core material or one or more layers of the core material may include about 10 wt.% or more, about 25 wt.% or more, or about 40 wt.% of more of one or more binders. The core material or one or more layers of the core material layer may include about 75 wt.% or less, about 60 wt.% or less, or about 45 wt.% or less of one or more binders. For example, the final blend or final distribution of fibers forming the core material or one or more layers of the core material may be about 70 wt.% to about 65 wt.% of the recycled material and about 30 wt.% to about 35 wt.% of the one or more binders. It should also be noted that the one or more binders may be thermoplastic, thermosetting, or both.

[0063] The fibers forming the core material or one or more layers of the core material may be natural or synthetic fibers. Such fibers forming the core material or one or more layers of the core material may be recycled fibers from the scrapped materials discussed above. Suitable natural fibers may include cotton, jute, wool, cellulose, glass, silica, and ceramic fibers. Suitable synthetic fibers may include silica, polyester, polypropylene, polyethylene, nylon, aramid, imide, acrylate fibers, or a combination thereof. The fibrous layers may comprise polyester fibers, such as polyethylene terephthalate (PET), and co-polyester/polyester (CoPET/PET) adhesive bicomponent fibers. The fibers may include polyacrylonitrile (PAN), oxidized polyacrylonitrile (Ox- PAN, OP AN, or PANOX® from SGL Carbon), olefin, polyamide, polyetherketone (PEK), polyetheretherketone (PEEK), poly(ethylene succinate), polyether sulfonate (PES), or other polymeric fibers. The fibers may include glass, silica, mineral, or ceramic fibers. The fibers may be formed of any material that is capable of being ground into a powdered-like consistency for dispersion along one or more nonwoven layers. As stated above, the fibers may be virgin fibers, fibers regenerated from waste, or a combination thereof. The fibers may have or may provide improved thermal insulation properties, acoustic insulation properties, or both. The fibers may have relatively low thermal conductivity. The fibers may be flame-retardant, heat resistant, or both. The fibers may be water repellant, water resistant, or both. The fibers may be antimicrobial, antifungal, or both. The fibers may have geometries that are non-circular or non-cylindrical to alter convective flows around the fiber to reduce convective heat transfer effects within the three- dimensional structure. The core material or one or more layers of the core material may include or contain engineered aerogel structures to impart additional thermal insulating benefits. [0064] Core materials may be made of multiple layers. As a non-limiting example, a core may include a layer of recycled PET and bi-component powder (either added or part of the recycled material), and a second layer of polyethylene powder, such as low density polyethylene powder (“LD powder”).

[0065] As another non-limiting example, a core material may include a layer of natural fibers, a layer of recycled PET and bi-component powder (either added or part of the recycled material), and a layer of LD powder. The core may include LD powder in an amount of about 10 wt% or greater, about 15 wt% or greater, or about 20 wt% or greater. The core may include LD powder in an amount of about 50 wt% or less, about 45 wt% or less, or about 40 wt% or less. The core may include natural fibers in an amount of 50 wt% or less, about 45 wt% or less, or about 40 wt% or less. The core may be free of natural fibers. For example, the core may include natural fibers in an amount of about 0% to about 40 wt%. The core may include recycled PET and bi-component powder in an amount of about 10 wt% or greater, about 15 wt% or greater, or about 20 wt% or greater. The core may include recycled PET and bi-component powder in an amount of about 90 wt% or less, about 85 wt% or less, or about 80 wt% or less.

[0066] The core material or one or more layers of the core material and the nonwoven layers may be secured to one another to form the composite structure. Layers of the composite structure, such as the core material, the core material and one or more additional layers (e.g., nonwoven layers), or a combination thereof, may be attached to each other by one or more lamination processes, one or more adhesives, heat sealing, sonic and/or vibration welding, pressure welding, additional mechanical connection (e.g., stitching, needle-punching, etc.), or a combination thereof. For example, layers of the composite structure may be needle-punched together to mechanically connect the layers and form the composite structure. After and/or before needle-punching, one or more binders located within the nonwoven layers, the core material or one or more layers of the core material, or a combination thereof may be activated (e.g., heated) to bond the layers to one another. In another example, an adhesive fdm may be located between other layers to connect the layers.

[0067] The composite structure may include a foil layer. The foil layer may be an interior layer, an exterior layer, an intermediate layer, or a combination thereof of the composite structure. The foil layer may be reflective to reflect heat. The foil layer may be formed by a coating applied to one or more surfaces so that the coating may have high infrared reflectance or low emissivity. The foil layer may be an extension of, attached to, or part of the core material or one or more layers of the core material, the nonwoven layers, or both. For example, fibers along an outer surface of the nonwoven layers may form the foil layer or may act as a surface for which the foil layer may be applied.

[0068] Fibers of the composite structure or one or more layers thereof may be metallic or metallized in addition to or instead of a foil layer. At least some of the surfaces of the core material or one or more layers of the core material, the nonwoven layers, or a combination thereof may be metallized to provide infrared (IR) radiant heat reflection. To provide heat reflective properties to protect the article, one or more layers may be metalized. For example, fibers of the nonwoven layers may be aluminized. The fibers themselves may be infrared reflective (e.g., so that an additional metallization or aluminization step may not be necessary). Metallization or aluminization processes can be performed by depositing metal atoms onto the fibers of the layers. As an example, aluminization may be established by applying a layer of aluminum atoms to one or more of the layers.

[0069] A foil layer may be a separate layer disposed on top of one or more exterior surfaces of the composite structure. The foil layer may be adhered to an exterior surface of the composite structure, such as adherence to an outer surface of the nonwoven layers. The foil layer may be fastened to the composite structure (e.g., stitched and/or adhered to the composite structure). The foil layer may be a foil, film, or both. The foil layer may be metallic. For example, the foil layer may be an aluminum foil, an aluminum laminated glass cloth, a tin foil, bronze foil, stainless steel (e.g., SS-304, SS-316, SS-430), other metals, or a combination thereof.

[0070] The foil layer may be perforated or have one or more openings to provide permeability in one or more areas. The foil may be non-perforated. The foil may be impermeable. The foil layer may be micro-perforated, embossed, or both. The micro-perforation of the foil layer may further improve acoustic performance of the article by allowing some air flow through the material. Micro-perforation may facilitate thinner foil layers being utilized, thereby decreasing the overall weight of the air duct while maintaining performance. The micro-perforation of the foil layer may be in any desired pattern. As such, the micro-perforation may be uniform or nonuniform. The micro-perforation may also include perforations of any desired dimension. Similarly, substantially all or only a portion of the foil layer may be perforated based upon a given application. [0071] A foil layer may be embossed. Embossing of the foil layers may be done uniformly or nonuniformly. Embossing may be done in any desired shape and/or pattern. The embossing may form localized regions of greater stiffness, greater flexibility, or both. The embossing may be designed to mate with one or more surfaces within a vehicle or a compartment. The embossing may improve acoustic performance of the article.

[0072] The foil layer may be any desired thickness to promote sufficient reflection and/or insulation of the article. The foil layer may have a thickness of about 50 microns or more, about 150 microns or more, or about 250 microns or more. The foil layer may have a thickness of about 500 microns or less, about 400 microns or less, or about 300 microns or less.

[0073] The foil layer may include a plurality of layers to make up the overall foil layer. For example, a first and a second foil layer may abut each other to provide an overall metallic portion of the composite structure, such as an air duct. An outermost foil layer (e.g., the first foil layer or the second foil layer) may act as a facing layer to directly face an external heat source and/or an internal heat source (e.g., from the air forced through the air duct). A secondary foil layer adjacent to the facing layer may provide insulation or reflective characteristics. For example, a facing foil layer may be an aluminum foil while an adjacent secondary foil layer may be stainless-steel, or vice versa.

[0074] The foil layer may be disposed directly over one or more of the layers of the composite structure, such as a nonwoven layer, a core material or layer of the core material, or a combination thereof. The foil layer may be in direct planar contact with one or more layers of the composite layer such that the abutment between the foil layer and the one or more layers of the composite layer is substantially free of any gap. Conversely, the foil layer may form one or more pockets between the foil layer and another layer of the composite material. While the foil layer described above may include embossing and/or micro-perforation, it should also be noted that the foil layer may be free of any embossment or perforations such that the foil layer is substantially planar. The foil layer may be impermeable. Impermeability may, for example, ensure sufficient transportation of the air within the air duct, reduce air loss or leakage, or both.

[0075] The composite structure may include one or more film layers. A film layer may be applied to the composite structure, may form an interior layer of the composite structure, may form an exterior layer of the composite structure(e.g., acting as a facing layer of the composite structure), or a combination thereof. The film layer may be a polymeric film The film layer may be a polyester (e.g., PET) film, a polyurethane film, a polyethylene film, or a combination thereof. By way of example, the film may be a low-density polyethylene (LDPE) film, a high-density polyethylene (HDPE) film, or both. While referred to as a layer, the film layer may be formed from one or more layers. The film may be permeable in at least one or more areas. The film may be impermeable. The film layer may be a multi-layer film, such as a film formed from thermoplastic polyurethane and thermoplastic polyester elastomer-based layers. For example, the film layer may include 1 or more layers, 2 or more layers, or 3 or more layers. The film layer may include 15 or fewer layers, 12 or fewer layers, or 10 or fewer layers. A multi-layered film may result in low permeability or in an impermeable layer. The film layer may exhibit high thermal barrier properties and may remain stable at extreme temperatures.

[0076] The film layer, the foil layer, or both may be impermeable as mentioned above. In such a case, the air flow resistance would be infinite, or near infinite, as air flow resistance is proportional to the inverse of the air permeability. As air permeability may be 0, or about 0, for a non-permeable material, the air flow resistance would then be infinite. Air permeability of the film layer or the foil layer may be about 0 l/m ² /s or more, about 50 l/m ² /s or more, or about 100 l/m ² /s or more at 200 Pa. Air permeability of the film layer or the foil layer may be about 400 l/m ² /s or less, about 300 l/m ² /s or less, or about 250 l/m ² /s or less at 200 Pa.

[0077] Turning now to the figures, FIG. 1 illustrates a close-up view of a ground recycled material 20. It is envisioned that such a ground material 20 may be formed using one or more scrapped material cutouts from previously manufactured composite structures. Such scrapped materials may be consolidated and ground to create the desired consistency of the ground material 20, such as a powdered-like form. Once the ground material 20 is formed from the recycled materials, the ground material 20 may be used for manufacturing a composite structure as taught herein. The ground material 20 may be used as-is or may be blended with one or more additives, such as one or more binders, prior to manufacturing of the composite structure.

[0078] FIG. 2 illustrates a close-up view of a composite structure 10 in accordance with the present teachings. A core material 14 is disposed or sandwiched between opposing nonwoven layers 12.

[0079] FIG. 3 illustrates a cross-sectional view of a composite structure 10 in accordance with the present teachings. The composite structure 10 includes a core material 14. The core material 14 may include one or more layers. The core material may be formed from one or more recycled materials, such as those shown as a ground material in FIG. 1 , one or more binders, one or more synthetic fibers, one or more natural fibers, or a combination thereof The core material may be formed from different layers of different materials. For example, the core material may include a layer of ground fibers (e.g., ground offal or ground off-cuts), an optional layer of synthetic and/or natural fibers, a layer of binder, an optional layer of another binder, or a combination thereof in any order.

[0080] The core material 14 is shown as being disposed along a first nonwoven layer 12A such that the first nonwoven layer 12A acts as a substrate for the core material 14. For example, prior to bonding or otherwise securing the core material 14 to the first nonwoven layer 12A or a second nonwoven layer 12B, the core material 14 or one or more layers thereof may be in a powdered form scattered along the first nonwoven layer 12A. As manufacturing of the composite structure 10 progresses, the second nonwoven layer 12B may be disposed on an opposing side of the core material 14 to sandwich the core material 14 between the nonwoven layers 12A and 12B. The core material 14 may be mechanically or adhesively joined to the nonwoven layers. The composite structure 10 as shown includes a film layer 16 disposed along the exterior surface of one of the nonwoven layers 12B and a foil layer 18 disposed along the exterior surfaces of the opposing nonwoven layer 12A. However, other configurations are also contemplated. The film layer and/or foil layer may be located in an area other than an external surface. The film layer may be located adjacent a different layer of the composite structure, such as a different nonwoven layer. The foil may be located adjacent a different layer of the composite structure, such as a different nonwoven layer. The composite structure may be free of a film, free of a foil, or both. The composite structure may include more than one film layer, more than one foil layer, or both.

[0081] FIG. 4 illustrates an exemplary cross-section of a composite structure 10, including a core material 14 and an optional film layer 16, a foil layer 18, or both, located on one side of the core material 14.

[0082] As an example, the core material may be an engineered compact acoustic layer adapted to face a cavity (e.g., a cavity of an air duct). The core material may be a fiber-based material. The core material may be a polyethylene terephthalate fiber-based material. The core material may include one or more binders (e.g., regular and/or high temperature binder). The engineered compact acoustic layer may have a thickness of about 1 mm or more or about 2 mm or more. The engineered compact acoustic layer may have a thickness of about 5 mm or less or about 4 mm or less. For example, the engineered compact acoustic layer may be about 2 mm to about 4 mm thick. [0083] The outer layer may be a thin, non-porous acoustic barrier layer. The acoustic barrier may be a film, foil, or both. For example, the film or foil may include or be made of low-density polyethylene (LDPE), high-density polyethylene (HDPE), nylon, metal (e.g., aluminum), or a combination thereof.

[0084] FIG. 5 illustrates an exemplary cross-section of a composite structure 10, including a core material 14, nonwoven layers 12 on opposing sides of the core material 14, and an optional film layer 16, a foil layer 18, or both, located on one of the nonwoven layers 12.

[0085] As an example, the core material may be a fiber-based material. The core material may include recycled materials (e.g., fibrous composite materials ground into short fibers or a powder). Recycled materials may include bi-component fibers or binder. The core material may be or may include a polyethylene terephthalate (PET) fiber-based material. The core material may include grinded PET powder or chips. The core may include one or more binders (e.g., regular and/or high temperature binder). The core may include LD powder. The core material may have a thickness of about 1 mm or more or about 2 mm or more. The core material may have a thickness of about 5 mm or less or about 4 mm or less. For example, the core material may be about 2 mm to about 4 mm thick.

[0086] A nonwoven material may be located on each side of the core material. The nonwoven materials may be the same. The nonwoven materials may be different. The nonwoven materials may have a weight of about 40 GSM or greater, about 50 GSM or greater, or about 60 GSM or greater. The nonwoven materials may have a weight of about 175 GSM or less, about 160 GSM or less, or about 150 GSM or less. For example, each nonwoven material may have a weight of about 60 GSM to about 150 GSM. In an application such as an air duct, it is contemplated that the nonwoven material without a film or foil located thereon may be adapted to face a stream of air. The nonwoven material may include bi-component fibers. For example, the nonwoven material may include a blend of PET fibers and bi-component fibers. The bi-component fibers may be present in an amount of about 10 wt% or greater, about 35 wt% or less, or both.

[0087] FIG. 6 is a flow-chart illustrating a manufacturing process for a composite structure in accordance with the present teachings. The manufacturing process may include a primary process and a secondary process. The composite structure may include a core material 14 formed by distributing different materials in layers. The core material may be at least partially formed from scrapped or recycled material from other manufacturing processes. To utilize such materials, the cutouts or scraps may be first ground into a desired consistency. While such consistency may vary based upon a given application, it is envisioned that the cutouts or scraps may be ground into a powdered-like consistency. The powdered-like consistency may thus include fibers of a desired relatively short length to engage with additional layers of the composite structure. However, any consistency (e.g., course, fine, etc.) may be desired for the composite structure.

[0088] After grinding of the recycled materials, the ground material may be sent to the feed zone where the ground material is placed in a feeder column or hopper to feed the ground material into the manufacturing line. The feeder column may allow for controlled feed of the grinded powder. The ground recycled material may be mixed with one or more additives or one or more additional fibers. The ground recycled material may be free of additives and/or additional fibers. One or more additives or one or more additional fiber types may be in a separate feeder column for controlled feed of such fibers during formation of the core material. The additional fibers may be natural fibers or synthetic fibers. Natural fibers may include banana fibers, jute fibers, bamboo fibers, rice husk fibers, wheat husk fibers, viscose fibers, coconut fibers (e.g., coir), or a combination thereof. These fibers may also be ground, chopped, cut, or otherwise processed prior to being put into the feeder column and/or prior to deposition of the fibers upon a substrate or another layer of fibers.

[0089] After insertion into the feeder column or hopper, the ground material may be dispersed along a nonwoven layer. The nonwoven layer may be formed by a suitable nonwoven manufacturing process, such as wet-laying, needlepunching, SMS, or other methods. The nonwoven layer may vary in thickness and/or shape based upon a given application. The nonwoven layer may have a weight of about 50 grams per square meter to about 400 grams per square meter. Though, the weight of the nonwoven layer may be selected based on a given application. The feeder column or hopper may facilitate dispersion of the ground material along a surface of the nonwoven material, may allow for partial penetration of the ground material within the nonwoven material, or both. As such, the ground material may vary in orientation and density along the nonwoven material to ensure proper engagement between the ground material or ground mix and the nonwoven material. [0090] Additional materials in other feeder columns or hoppers may be separately applied in layers to form the core material on the nonwoven layer. One or more feeder columns may allow for a controlled distribution of synthetic and/or natural fibers that are separate from the ground fibers of recycled offal or off-cuts. The core material may be free of synthetic and/or natural fibers. The synthetic and/or natural fibers, if used, may be scattered on the nonwoven layer before scattering the ground fibers from the recycled materials. The synthetic and/or natural fibers, if used, may be scattered after scattering the ground fibers from the recycled materials.

[0091] One or more binders may be scattered on the nonwoven material or one or more layers of fibers already deposited on the nonwoven material. Where multiple binders are used, the binders may be mixed prior to distributing. Where multiple binders are used, the binders may be separately applied from separate feeder columns, hoppers, or other containers. Binders may include low- density and/or high-density polyethylene fibers or powder (LDPE and/or HDPE)). Low density polyethylene powder may have a glass transition temperature of about 60°C to about 100°C (e.g., about 80°C). High density polyethylene powder may have a glass temperature of about 75°C to about 115°C (e.g., about 95°C). Binders may be scattered before or after distribution of any of the ground fibers, natural fibers, and/or synthetic fibers.

[0092] As the materials are scattered separately to form the core material, distinct layers of each may be visible either to the naked eye or under magnification (e.g., 5x, lOx, 20x, lOOx). It is contemplated that some fibers may mix with other fibers (e.g., filling in between areas where previous depositions did not result in a fiber being in that location) such that distinct layers are not visible.

[0093] After dispersion or scattering of the ground material, natural and/or synthetic fibers, and one or more binders onto the nonwoven layer in separate deposition steps, the partial composite structure may enter a heating zone or be preheated. Heating may be completed at a temperature of about 50°C or more, about 60°C or more, or about 80°C or more. The temperature for preheating may be about 250°C or less, about 220°C or less, about 200°C or less, about 150°C or less, about 120°C or less, about 100°C or less, or about 90°C or less.

[0094] After the partial composite structure leaves the heating zone (e.g., along a conveyor), a second nonwoven layer may be placed on top of the core material to sandwich the core material between the two nonwoven layers. The nonwoven layers may be the same or different (e.g., same or different weights, thicknesses, compositions, shapes, methods of manufacture, etc.). That is, the nonwoven layers may include the same or different fiber compositions to engage and/or bond to the core material therebetween.

[0095] After placing the top nonwoven layer on the core material, the composite structure may complete a loom process, whereby one or more processes are completed to mechanically bond the layers to each other. For example, needle punching may be completed to mechanically engage the nonwoven layers and the ground material or ground mix to each other. However, such processing is not limited to needle punching and may include a variety of other types of mechanical interlocking, such as utilizing one or more fasteners (e.g., clips, screws, pins, etc ), stitching the layers to one another, or both.

[0096] Upon mechanically interlocking the layers of the composite structure during the loom operation, the composite structure may then be heated to a desired temperature to begin adhesively bonding the nonwoven layers to the core material. Such heating may be done in an oven (e.g., a gas-fired oven) at a temperature high enough to enable activation of the one or more binders located within the core material such that the one or more binders may bond to the nonwoven layers and the other fibers within the core material. It should be noted that the temperature may be selected based on the one or more binders used, one or more other fibers used, or both. The temperature in the oven may be a temperature greater than the temperature of the first heating zone. The temperature in the oven may be a temperature less than the temperature of the first heating zone. The temperature in the oven may be a temperature generally equal to the first heating zone, the temperature in the oven may be about 60°C or more, about 70°C or more, about 85°C or more, about 100°C or more, 120°C or more, about 150°C or more, or about 200°C or more. The temperature in the oven may be about 300°C or less, about 250°C or less, or about 225°C or less, about 200°C or less, about 175°C or less, or about 150°C or less. For example, the temperature in the oven may be about 70°C or greater, about 150°C or less, or both.

[0097] After baking the composite structure in the oven (e.g., gas-fired oven), the composite structure may complete a hot calendering process and/or a cold calendering process. A hot calender set temperature may be about 150°C or greater, about 170°C or greater or about 180°C or greater. A hot calender set temperature may be about 275°C or less, about 260°C or less, or about 240°C or less. A cold calender set temperature may be about 5°C or greater, about 7°C or greater, or about 10°C or greater. A cold calender set temperature may be about 50°C or less, about 35°C or less, or about 25°C or less. The calendering process may include one or more heated rollers that aid in forming a final thickness of the overall composite structure. Such thickness may be modified or adjusted based upon a desired resultant product application. Similarly, the calendering process may include one or more cold rollers to finalize or otherwise help maintain the thickness of the composite structure established by the one or more heated rollers. This may be the last step of the primary process.

[0098] In a secondary process, once the final thickness of the composite structure has been determined and hot calendering and/or cold calendaring has been completed, a film may be applied to one or more of the exterior surfaces of the composite structure. The film may be any desired type of film, such as but not limited to, a low-density or high-density polyethylene (LDPE or HDPE). The process for forming and applying the film may include scattering a powder (e.g., low density polyethylene powder) on the surface of the composite structure. The composite structure may be sent through another heating zone (e.g., via conveyor) and a lamination film layup may be applied. The film may be applied to an outer surface of the nonwoven layers or may be disposed along any exposed portion of the core material. However, it should be noted that a film need not be disposed on the composite structure and that manufacturing of the composite structure may be free of any film application.

[0099] Upon application of a film, the composite structure may undergo an additional hot calendering process and/or cold calendaring process to further maintain a thickness of the composite structure, set each layer in proper position, and/or ensure the layers are sufficiently adhered together. After the hot calendering process, or instead of a hot calendaring process, the composite structure may complete a cold calendering process with one or more cold rollers to finalize a thickness of the composite structure.

[00100] FIG. 7 is an exemplary process flow diagram for constructing a composite structure in accordance with the present teachings. Variations in order of distribution of fibers and/or binders are contemplated. Variations in machinery, additions, or omissions of certain steps or machines are also contemplated.

[00101] Fibers or powder formed from recycled materials such as offal or off-cuts that have undergone a grinding process are sent to a feed zone where they are put into a feeder column to be distributed. An optional separate feeder column contains and/or distributes synthetic and/or natural fibers. [00102] A nonwoven layer 12 (shown as a solid thick line) is supplied on a conveyor. Synthetic and/or natural fibers are scattered as a layer 22 (shown as a dashed line with short dashes) on the nonwoven layer as the conveyor advances. Grinded fibers are scattered as a layer 24 (shown as a dashed line with long dashes) atop the layer of scattered synthetic and/or natural fibers 22 as the conveyor advances. Binder is scattered as a layer 26 (shown as a line with alternating dots and dashes) atop the layer of scattered grinded fibers 24. While not shown, another binder may be distributed separately from the layer of binder 26.

[00103] The nonwoven layer and core material (e.g., made up of layers of natural and/or synthetic fibers, layers of grinded fibers, layers of binder) may be sent through a first heating zone. [00104] Following the first heating zone, a nonwoven layer 12 is positioned atop the opposing side of the core material.

[00105] The material is then sent through a needle loom to secure one or more layers together, to secure one or more nonwoven layers to the core material, to mechanically entangle fibers of the nonwoven layer(s) and/or core material, or a combination thereof. After exiting the needle loom, the material is sent through an oven, such as a gas fired oven. After leaving the oven, the material is sent through a hot calendering zone followed by a cold calendering zone.

[00106] If a film or foil is to be added, a powder is scattered on the material, such as LD powder, and the material goes through a second heating zone (e.g., lamination), and a lamination film is added to the top of the material. The material then goes to a second cold calendering zone.

[00107] Depending on requirements of the resulting composite structure, the material may be sent through a slitting and cutting operation to achieve a desired size.

[00108] While the core substrate is described as being in form of powder or being distributed as a powder, it is also possible that the core material may be formed by or may include layup embedded between two nonwoven layers.

[00109] FIG. 8 illustrates an exemplary air duct 30 in accordance with the present teachings. The air duct 30 may be formed from the composite material described herein (see FIGS. 2-5). While varying geometries may be possible, the air duct 30 as shown includes an outer surface 34 forming an overall shape of the air duct. The outer surface may include one or more bends, one or more angles, one or more contoured portions, one or more linear segments, or a combination thereof. [00110] The outer surface 34 opposes an inner surface 36 (see FIG. 9) of the air duct 30. The inner surface defines the shape of a cavity 32 of the air duct 30. The inner surface may have a similar shape to the outer surface 34 or may differ. The distance between a point on the outer surface 34 and an opposing point on the inner surface 36 may form an overall thickness of the air duct 30 at that point. The walls formed by the composite material may form a thickness of the air duct as measured between the inner surface and the outer surface. The air duct 30 includes one or more openings of the cavity 32 to allow for air flow through the air duct 30 between an HVAC system and an endpoint (e.g., a cabin of a vehicle).

[00111] The air duct may be thermoformed or molded. As shown in FIGS. 8 and 9, the air duct 30 includes one or more flanges 38. The flanges 38 extend or otherwise project from the outer surface 34 of the air duct 30. During thermoforming or assembly of the air duct, the flanges 38 may form a surface along which one or more pieces of the air duct to secure another piece of the air duct. For example, the air duct may include a first portion to a second portion (e.g., a top half and a bottom half) that are each individually formed via thermoforming, molding, compression, other processes, or a combination thereof. Once the halves are formed, the top half and the bottom half may be secured to one another along the flanges 18 using a secondary operation, adhesive, mechanical connection, or a combination thereof to form the overall shape of the air duct.

[00112] FIG. 9 illustrates cross-section 2-2 of the air duct 30 of FIG. 8. The air duct includes an outer surface 34 and an opposing inner surface 36, the inner surface 16 defining the shape of a cavity 32 of the air duct 30. As shown, the air duct 30 includes flanges 38 that project outwardly. The air duct 30 is formed of two sheets of composite structures 10 as described herein, joined together at the flanges 38.

[00113] Illustrative Examples

[00114] Example 1

[00115] Table 1 below shows the normal incidence sound absorption coefficient of exemplary composite structure configurations in accordance with the present teachings. Specifically, Samples 1-4 are tested at various frequencies as measured at a side of the composite structure facing the sound source. Sample 1 is a standalone material using about 70% line offal grind and about 30% LD powder. Sample 2 is a standalone material using about 70% PET staple fibers and about 30% bicomponent fibers. Sample 3 is a composite structure using Sample 1 as a substrate. Sample 4 is a composite structure using Sample 2 as a substrate. Samples 1 and 2 are formed of similar structures, whereby Sample 1 includes recycled materials while Sample 2 includes virgin materials. Similarly, Samples 3 and 4 are formed of similar structures, with Sample 3 having recycled materials and Sample 4 having virgin materials in accordance with the present teachings. It should be noted that the recycled material refers to the core layer materials recycled according to the process and descriptions mentioned herein. Table 1 below is also shown visually in FIG. 10 of the present application.

Table 1.

[00116] As shown above, Sample 1 performs substantially similar, or better, than the nonrecycled (i.e., conventional) composite structures of Sample 2. That is, no performance decrease is found when using recycled materials for the core layer in accordance with the present teachings. Similarly, Samples 3 and 4, with at least Sample 3 incorporating the recycled core materials in accordance with the present teachings, outperform the conventional Sample 2 structure. [00117] Table 2 below shows the normal incidence sound transmission loss of Samples 1-4 as identified above. Table 2 below is also shown visually in FIG. 11 of the present application.

Table 2.

[00118] As shown above, the average sound transmission loss between Sample 1 and Sample 2 is similar. Additionally, the average sound transmission loss between Sample 3 and Sample 4 is similar.

[00119] Table 3 below shows the normal incidence sound absorption coefficient for two samples at various distances. Each sample composition is tested by a source set at four different distances away from a facing layer of the samples: 0 mm away; 25 mm away; 50 mm away; and

100 mm away. Table 3 is also shown visually in FIG. 11 of the present application.

Table 3.

[00120] As shown above Samples 1 and 2 perform substantially similar to one another. That is, Sample 1 utilizing a recycled core layer does not inhibit performance when compared to the more conventional structure of Sample 2.

[00121] Example 2

[00122] Testing of four samples - Samples 5, 6, 7, and 8 - is performed to determine sound absorption coefficients (SAC) for the various samples according to ASTM 1050 and ISO 10534 Part II. Testing of the samples is also performed to determine the sound transmission loss (STL) according to ASTM E2611.

[00123] Sample 5 is a porous material having a core of polyethylene terephthalate and polypropylene fibers. The core has a weight of 950 GSM. Nonwoven facings are located on each side of the core, with one nonwoven facing having a weight of 200 GSM and the other nonwoven facing having a weight of 190 GSM. The total weight of the sample is 1340 GSM.

[00124] Sample 6 is the material of Sample 5 with a non-porous film on the external surface. The total weight of the sample is 1480 GSM.

[00125] Sample 7 is a porous material including a core of grinded polyethylene terephthalate powder (small chips) and a binder sandwiched between two nonwoven facings. The total weight of the sample is 1200 GSM. [00126] Sample 8 is a material including a core of grinded polyethylene terephthalate powder (small chips) and a binder sandwiched between two nonwoven facings. A non-porous film (e.g., LDPE) is on the external surface. The total weight of the sample is 1350 GSM.

[00127] Table 4 below shows the sound absorption coefficient (SAC) for Samples 5-8.

Table 4.

[00128] The results show that Sample 7 is on par with Sample 5. The SAC result of Sample 6 is slightly better than Sample 8, though it will be almost 5% when taken on a large sample basis.

[00129] Table 5 below shows the sound transmission loss (STL) for Samples 5-8.

Table 5.

[00130] The results show that the STL result of Samples 7 and 8 perform better than Samples

5 and 6, respectively. Samples 7 and 8 are also lighter in weight than Samples 5 and 6, respectively.

[00131] Example 3

[00132] Samples are formed as sample air duct pieces to carry out Sound Pressure Level (SPL) measurements when the samples are assembled with a common HVAC assembly inside a hemi- anechoic chamber. Each sample is individually connected to the common HVAC assembly for testing. Once connected, the HVAC assembly is operated at the following supply voltages: about 12.6 V; about 9.3 V; about 7 V; and about 5 V. Air flow for each tested sample is measured using a digital anemometer at each supply voltage and an optical tachometer is used to measure blower speed within the HVAC assembly. The SPL of each sample is measured at various locations to simulate the driving conditions of a driver and passenger, including center of left-hand (LH) and center of right-hand (RH) side air vent outlets within a vehicle cabin, a passenger ear level (Co- DEL), and a driver ear level (DEL). A summary of the aforementioned testing is shown in Table

6 below. It should also be noted that the Root Mean Square (RMS) sound pressure levels were calculated on l/3 ^rd Octave spectrum from 20 Hz to 20,000 Hz.

[00133] The Baseline sample is configured as a conventional air duct baseline component. It is a plastic injection and blow molded part. [00134] Samples 9A and 9B are a porous material having a core of polyethylene terephthalate and polypropylene fibers. The core has a weight of 950 GSM. Nonwoven facings are located on each side of the core, with one nonwoven facing having a weight of 200 GSM and the other nonwoven facing having a weight of 190 GSM. The total weight of the sample is 1340 GSM.

[00135] Samples 10A and 10B are a material including a core of grinded polyethylene terephthalate powder (small chips) and a binder sandwiched between two nonwoven facings. A non-porous film (e.g., LDPE) is on the external surface. The total weight of the sample is 1350 GSM.

[00136] Samples 11 A and 1 IB are the material of Samples 9A and 9B with a non-porous film on the external surface. The total weight of the sample is 1480 GSM.

[00137] Testing is conducted multiple times. Results of the tests are shown in Tables 6 and 7 below.

Table 7.

[00138] In accordance with Tables 6 and 7, Tables 8 and 9 below show the overall noise value differences and air flow differences for the tests conducted on Samples 9A, 9B, 10A, 10B, 11A, and 1 IB. Each measured value for the samples is measured as a difference when compared to the measurements taken for the baseline sample (i.e., baseline sample measurement value minus a measurement value for Samples 9A, 9B, 10A, 10B, 11 A, and 11B).

Table 8. Table 9

[00139] As shown above, the samples formed of various composite structure compositions as described herein showed a significant improvement (i.e., decrease) in the sound pressure level (SPL) as measured in decibels (dB).

[00140] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. The above description is intended to be illustrative and not restrictive. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use.

[00141] Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the teachings. The scope of the teachings should, therefore, be determined not with reference to this description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The omission in the following claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter, nor should it be regarded that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter. [00142] Plural elements or steps can be provided by a single integrated element or step. Alternatively, a single element or step might be divided into separate plural elements or steps. [00143] The disclosure of "a" or "one" to describe an element or step is not intended to foreclose additional elements or steps.

[00144] While the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings.

[00145] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. [00146] The disclosures of all articles and references, including patent applications and publications, are incorporated by reference herein in their entirety for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference in their entirety into this written description.

[00147] Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. Plural structural components can be provided by a single integrated structure. Alternatively, a single integrated structure might be divided into separate plural components. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention.

[00148] Unless otherwise stated, a teaching with the term “about” or “approximately” in combination with a numerical amount encompasses a teaching of the recited amount, as well as approximations of that recited amount. By way of example, a teaching of “about 100” encompasses a teaching of 100 +/- 15.

[00149] The preferred embodiment of the present invention has been disclosed. A person of ordinary skill in the art would realize however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.

[00150] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference herein in their entirety for all purposes. Other combinations are also possible as will be gleaned from the following claims, which are also hereby incorporated by reference in their entirety into this written description.

Reference List

10 Composite Structure

12 Nonwoven Layer

12A First Nonwoven Layer

12B S econd N onwoven Lay er

14 Core Material

16 Film Layer

18 Foil Layer

20 Ground Material Layer of scattered natural and/or synthetic fibers Layer of scattered grinded fibers Layer of scattered binder Air duct Cavity Outer surface Inner surface Flange