Audio items

Abstract

An acoustic article and associated methods of manufacture and use are provided. The acoustic article includes a continuous layer having a first elastic stiffness and a plurality of distributed masses having a second elastic stiffness disposed on a major surface of the continuous layer. The second elastic stiffness may be less than the first elastic stiffness to provide an acoustic metamaterial that exhibits an anti-resonant peak at a frequency less than 800 Hz. The acoustic article may be manufactured using an efficient and scalable process for producing low frequency acoustic barrier materials.

Description

Technical Field

[0001] Acoustic articles, as well as related manufacturing and usage methods, are provided herein. The acoustic article can be, for example, an acoustic metamaterial barrier.

Background Art

[0002] Noise pollution is generally defined as being regularly exposed to high sound levels that can potentially have an adverse effect on humans or other living organisms. Sound levels below 70 dB may not cause damage to living organisms, but prolonged exposure to noise above 85 dB can be dangerous. Noise sources are diverse and extensive, including traffic noise, automobile noise, aircraft noise, construction sites, and even noise from gatherings.

[0003] Various technologies have been considered to reduce noise pollution. Some of these include acoustic absorbers and barriers, as well as related articles that absorb or reflect noise. However, the effectiveness of these noise shielding solutions tends to be limited by the mass of the shielding material. This is because noise transmission is generally governed by the mass law, which states that the sound insulation provided by a solid barrier increases by approximately 5 - 6 dB for every doubling of the mass. Therefore, to improve the sound attenuation characteristics of an acoustic article, it is generally necessary to increase its thickness or density, which adds weight and size to the barrier.

Summary of the Invention

[0004] Distributed mass acoustic metamaterials, also referred to as decorative films, include mass elements that can vibrate out of phase with a substrate such as a film to which they are applied. These anti - resonance structures can exhibit acoustic article characteristics that exceed the transmission loss predicted by the mass law, at least in the frequency region of the anti - resonance band.

[0005] The anti-resonance behavior described above exhibits an unusual dependence on the stiffness of the mass on the decorative film, and it was found to be dependent on its mass, shape, and position. When the stiffness of the mass is less than that of the substrate, the anti-resonance peak can be shifted to lower frequencies as the stiffness of the mass decreases. In contrast, when the mass has the same stiffness as the substrate, or is stiffer than the substrate, the resonance peak may not be affected by the stiffness of the mass. Based on these observations, it is possible to provide acoustic articles based on composite materials with enhanced anti-resonance properties. Such composite materials can also be fabricated using efficient and scalable processes to produce these low-frequency barrier materials at a reasonable cost.

[0006] In a first embodiment, an acoustic article is provided. The acoustic article comprises a continuous layer having a first elastic stiffness and a plurality of distributed masses having a second elastic stiffness disposed on the main surface of the continuous layer, wherein the second elastic stiffness is smaller than the first elastic stiffness, and the acoustic article is an acoustic metamaterial exhibiting an anti-resonance peak at frequencies below 800 Hz.

[0007] In a second embodiment, an acoustic article is provided comprising a continuous layer having a first modulus of elasticity and a plurality of distributed masses having a second modulus of elasticity disposed on the main surface of the continuous layer, wherein the second modulus of elasticity is smaller than the first modulus of elasticity, and the acoustic article is an acoustic metamaterial exhibiting an anti-resonance peak at frequencies below 800 Hz.

[0008] In a third embodiment, a method is provided for manufacturing an acoustic article, the method comprising: providing a molded surface having a plurality of defined recesses; applying a reactive monomer mixture to the molded surface to at least partially fill the plurality of defined recesses; placing a continuous layer on the reactive monomer mixture; removing at least some excess reactive monomer mixture between the continuous layer and the molded surface; curing the reactive monomer mixture while it is in contact with the continuous layer to bond a plurality of distributed masses to the continuous layer; and optionally removing the continuous layer and the plurality of distributed masses from the molded surface.

[0009] A fourth embodiment provides a method for manufacturing an acoustic article, the method comprising: embossing a flat film to provide a molded surface having a plurality of defined recesses; applying a reactive monomer mixture to the molded surface to at least partially fill the plurality of defined recesses; removing at least some excess reactive monomer mixture from the molded surface; and curing the reactive monomer mixture to obtain a plurality of distributed masses adhering to the molded surface.

[0010] A fifth aspect provides a method for manufacturing an acoustic article, the method comprising: forming a flat polymer film to provide a molded surface including a plurality of defined recesses; applying a first reactive monomer mixture to the molded surface to at least partially fill the plurality of defined recesses; removing at least some excess reactive monomer mixture from the molded surface; curing the first reactive monomer mixture to provide a plurality of distributed masses; applying a second reactive monomer mixture to the plurality of distributed masses; curing the second reactive monomer mixture to provide a continuous layer attached to the plurality of distributed masses; and optionally removing the continuous layer and the plurality of distributed masses from the molded surface.

[0011] In a sixth embodiment, an acoustic article is provided which is manufactured according to any of the methods described above. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view of an acoustic article according to one exemplary embodiment. [Figure 2] Figure 1 is a side elevation view of the acoustic article. [Figure 3] This is a photograph of a prototype acoustic article according to one exemplary embodiment. [Figure 4] Figure 3 is a transmission loss plot showing the performance of the acoustic prototype. [Figure 5] A perspective view of an acoustic article according to yet another exemplary embodiment. [Figure 6]This is a cross-sectional view illustrating an exemplary method for manufacturing an acoustic article. [Figure 7] This is a schematic diagram illustrating different methods for manufacturing acoustic articles. [Figure 8] This is a schematic diagram illustrating different methods for manufacturing acoustic articles.

[0013] Where reference letters in the specification and drawings are used repeatedly, they are intended to represent the same or similar features or elements of the present disclosure. Those skilled in the art should understand that many other modifications and embodiments can be devised and that they fall within the scope and spirit of the principles of the present disclosure. The drawings may not be drawn to scale.

[0014] definition "Ambient conditions" means 21°C and a pressure of 101.3kPa. "Curing" means changing the physical and / or chemical state of a composition, such as changing from a fluid to a less fluid state, from a sticky state to a non-sticky state, from a soluble state to an insoluble state, reducing the amount of polymerizable material by consuming it during a chemical reaction, or changing a material from a specific molecular weight to a higher molecular weight. "Cureability" means that it is possible to harden. "Elastic modulus" refers to the ratio of stress-shape increment to strain-shape increment in tension, as measured according to ASTM D882-18(2018). "Complete curing" means that the composition has cured to a state in which it is suitable for use in its intended purpose, such as being substantially cured. "Partial curing" means that the material has hardened to a state less than complete curing. A "polymer" refers to a molecule that has at least one repeating unit. "Substantially" means a significant amount, such as 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or 99.999%, or 100%. "Thickness" refers to the distance between opposing surfaces of a single-layer or multi-layer article.

Best Mode for Carrying Out the Invention

[0015] As used herein, the terms "preferred" and "preferably" refer to the embodiments described herein that can provide certain advantages under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances.

[0016] Furthermore, the listing of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0017] As used in this specification and the appended claims, unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural referents. Thus, for example, references to a component preceded by "a" or "the" may include one or more of the component and its equivalents known to those skilled in the art. Further, the term "and / or" means one or all of the listed elements, or any combination of two or more of the listed elements.

[0018] Note that the term "comprising" and variations thereof do not have a limiting meaning when these terms appear in the appended description. Furthermore, "a," "an," "the," "at least one," and "one or more" are used interchangeably herein. In this specification, relative terms such as left, right, front, rear, top, bottom, side, above, below, horizontal, vertical, etc. may be used, and in that case, they are from the perspective seen in a particular drawing. However, these terms are used only for the sake of simplicity of description and in no way limit the scope of the invention.

[0019] Throughout this specification, any reference to “one embodiment,” “a particular embodiment,” “one or more embodiments,” or “a certain embodiment” means that the specific features, structures, materials, or properties described in relation to that embodiment are included in at least one embodiment of the present invention. Therefore, the appearance of phrases such as “in one or more embodiments,” “in a particular embodiment,” “in one embodiment,” or “in an embodiment” in various places throughout this specification does not necessarily refer to the same embodiment of the present invention. Trademarks, where applicable, are written in all capital letters.

[0020] Partial diagrams of an acoustic article according to one exemplary embodiment are shown in Figures 1 and 2, from a plan view and a side view, respectively, and the acoustic article is hereafter represented by the number 100. In a preferred embodiment, the acoustic article 100 functions as an acoustic barrier. The applications of these acoustic barriers are not limited and may include, for example, vehicle door panels and mechanical enclosures, as well as aircraft fuselages. These articles can be used as interlayers or outer layers in combination with optionally foam or glass fiber absorbers in thermal insulation and soundproofing. When used as part of interior panel acoustic treatment, these materials may be used in combination with nonwoven acoustic absorbers. These articles may also be used in acoustic curtains which may be deployed in aerospace and industrial applications.

[0021] Figure 1 represents a unit cell of an acoustic article 100 extending along the xy-plane. It should be understood that this unit cell can be replicated to any extent along the xy-plane. Such replication can provide an acoustic article having any suitable area, shape, or size along this plane.

[0022] In this simplified example, the acoustic article 100 includes a continuous layer 102 having a main surface 104 facing upward in Figure 2. An exemplary mass 106 is placed on the main surface 104. As shown in Figure 2, the mass 106 has a linear shape and protrudes outward from the main surface 104 along the z-direction. Viewed from above, the mass 106 extends over a square area, with each side of the square having a length dimension "c". In this unit cell, the continuous layer 102 also extends over a square area, with each side of the square having a length dimension "a". Therefore, the mass 106 is c 2 It covers the area of ​​the main surface 104, and the proportion of the total area of ​​the main surface 104 is c 2 / a 2 This represents the unit cell shown in Figure 1; other unit cells such as rectangles, triangles, or hexagons are also possible.

[0023] Useful anti-resonance properties may be achieved, for example, when the mass 106 is spread over a range of 5 percent to 80 percent, 10 percent to 70 percent, or 15 percent to 60 percent of the total area of ​​the main surface 104, or, in some embodiments, when it is spread over a range of less than, equal to, or greater than 5 percent, 6, 7, 8, 9, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 percent.

[0024] Referring again to Figure 2, the mass 106 is shown to have a thickness "b", and the continuous layer 102 is shown to have a thickness "t". If there is variation in thickness, dimensions b and t can represent the average thickness of the mass 106 and the continuous layer 102 across the main surface 104, respectively. To give flexibility to the entire acoustic article 100 and to allow sufficient vibration of the mass 106 to achieve the desired anti-resonance characteristics in the system, it is generally desirable that the thickness t is small compared to the thickness b. The thickness t may be 2.5 percent to 100 percent, 5 percent to 90 percent, or 10 percent to 80 percent of the thickness b, or in some embodiments, it may be less than, equal to, or greater than 2.5 percent, 3, 3.5, 4, 5, 7, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 percent.

[0025] The thickness b of mass 106 may be in the range of 500 micrometers to 2000 micrometers, or in some embodiments, it may be in the range of 500 micrometers, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or less than, equal to, or greater than 2000. The thickness t of the continuous layer 102 may be in the range of 50 micrometers to 2000 micrometers, or in some embodiments, it may be in the range of 50 micrometers, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or less than, equal to, or greater than 2000.

[0026] According to the unit cells shown in Figures 1 and 2, the entire acoustic article 100 may consist of one or more unit cells containing corresponding masses 106 uniformly distributed along the main surface 104 of the continuous layer 102. Here, the distributed masses 106 are arranged in a two-dimensional replication pattern along the main surface 104, but this is not necessarily required. In an alternative embodiment, the masses 106 are not positioned in a predetermined location, but rather are distributed randomly or semi-randomly across the main surface 104.

[0027] In the acoustic article 100, the distributed masses 106 are distinct, that is, each mass 106 is physically separated from its adjacent masses 106. In alternative embodiments, and depending on the method used to manufacture the acoustic article 100, the distributed masses 106 may also be interconnected by a relatively thin web of material (i.e., a base layer). Optionally, this base layer is integral with the distributed masses 106 and has the same composition.

[0028] In preferred embodiments, the continuous layer 102 and the distributed mass 106 are composed of a first polymer and a second polymer, respectively. In some embodiments, the first and second polymers are selected to have significantly different mechanical properties. Either the distributed mass 106 or the continuous layer 102 can be independently made from a wide variety of materials, including metals, polymers, ceramics, and composite materials. With regard to useful polymers, either the distributed mass 106 or the continuous layer 102 can be independently made from poly(meth)acrylates, polyalkylenes, polyalkylene oxides, polyesters, polycarbonates, polyurethanes, polyamides, polyepoxides, polycyclic aromatics, polysulfones, polyimides, silicones, protein or cellulose polymers, or blends or copolymers thereof. In certain embodiments, the continuous layer, the distributed mass, or both components can be independently made from polyalkylenes, polyurethanes, or silicone rubber.

[0029] Notwithstanding the foregoing, the continuous layer 102 is not particularly limited in its composition or structure and may be made from a solid or porous polymer film, a metal foil, a porous foam, a woven or nonwoven fiber layer, or a combination thereof. If it is a polymer, the continuous layer 102 may be made from a thermoplastic or thermosetting polymer. Preferably, the continuous layer 102 has sufficient strength and elasticity so that the distributed mass 106 remains firmly fixed within the acoustic article 100 for the desired application.

[0030] The continuous layer 102 may have an elastic modulus of 500 MPa to 5000 MPa, 900 MPa to 3000 MPa, or 1000 MPa to 2500 MPa, or in some embodiments, it may have an elastic modulus of 500 MPa, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, or less than, equal to, or greater than 2500 MPa. The distributed mass 106 may have an elastic modulus of 0.1 MPa to 500 MPa, 0.5 MPa to 300 MPa, or 1 MPa to 200 MPa, or in some embodiments, it may have an elastic modulus of 0.1 MPa, 0.2, 0.3, 0.4, 0.5, 0.7, 1, 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 150, 170, 200, 220, 250, 270, or less than, equal to, or greater than 300 MPa.

[0031] Depending on the end application, the polymer has a glass transition temperature (or T) of 250°C, 200°C, 150°C, 100°C, 50°C, 0°C, -50°C, or below -100°C. g ) may have different glass transition temperatures. Different glass transition temperatures may be selected for the polymer in the continuous layer and the polymer of mass.

[0032] When the elastic stiffness of the continuous layer 102 exceeds that of the distributed mass, a significant improvement in the low-frequency acoustic barrier performance of the acoustic article 100 was observed, such as at frequencies below 800 Hz. This is due to a shift to lower frequencies of the anti-resonance peaks arising from the vibration modes of the distributed mass. Furthermore, it was found that this shift in the anti-resonance peaks caused by decreasing the elastic stiffness of the distributed mass (or conversely, increasing the elastic stiffness of the continuous layer) only occurs when the stiffness of the distributed mass is less than the stiffness of the continuous layer. The optimal range of material properties may be influenced by the dimensions of the acoustic article, considering the interaction between the thickness of the components and their stiffness.

[0033] Elastic stiffness is a function of both thickness and modulus of elasticity, and the above condition can be achieved by increasing the modulus of elasticity of the distributed mass 106 relative to the modulus of elasticity of the continuous layer 102, decreasing the thickness of the distributed mass 106 relative to the thickness of the continuous layer 102, or any combination of both. With respect to the actual relative thickness dimensions of the distributed mass 106 and the continuous layer 102, it may be advantageous for the modulus of elasticity of the continuous layer to be 1.1 to 50000, 5 to 10000, or 10 to 1000 times greater than the modulus of elasticity of the multiple distributed masses, or, in some embodiments, it may be advantageous for it to be 1.1, 1.2, 1.5, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 200, 500, 1000, 2000, 5000, 10000, 15000, 20000, 30000, 40000, or less than, equal to, or greater than 50000 times.

[0034] In various embodiments, the continuous layer 102 and the distributed mass 106 may have significantly different densities. Useful embodiments may use a distributed mass 106 having a first density and a continuous layer 102 having a second density, where the first density is 50 to 1000 percent, 80 to 500 percent, 100 to 300 percent of the second density, or, in some embodiments, less than, equal to, or greater than 50 percent, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 140, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, or 1000 percent.

[0035] Achieving a desired combination of the stiffness and density of the continuous layer 102 relative to the stiffness and density of the distributed mass 106 can be at least partially achieved by incorporating appropriate fillers into the first and / or second polymers constituting the continuous layer 102 and the distributed mass 106, respectively. By including specific fillers, for example, the elastic modulus of the first or second polymer can be effectively increased or decreased compared to the respective polymers in their unfilled state. Furthermore, by including fillers, the density of the first or second polymer can also be increased or decreased compared to the respective polymers in their unfilled state.

[0036] In a preferred embodiment, the first polymer contains a filler that increases the overall modulus of elasticity of the continuous layer. In the same or alternative embodiment, the first polymer contains a first filler that decreases the overall density of the continuous layer. Advantageously, by selectively blending the first and / or second polymers with suitable fillers, enhanced acoustic metamaterial properties can be provided in the acoustic article 100, even when the continuous layer 102 and distributed mass 106 are made from the same base polymer. In certain embodiments, the filler may consist of expandable microspheres, chemical blowing agents, glass, ceramic, or polymer bubbles. It is also possible to use physical blowing agents containing gases such as nitrogen, carbon dioxide, or air.

[0037] Figure 3 shows an actual prototype of an acoustic article 200 fabricated using additive manufacturing, where a relatively soft mass 206 is placed on a relatively hard continuous layer 202. The acoustic performance characteristics are incorporated into the transmission loss measurement data in Figure 4. These data show the difference in acoustic performance produced by two samples that differ only in the elastic stiffness of their respective masses: 0.5–1 MPa for the soft mass and 2–3 GPa for the hard mass. Both the soft and hard masses were square, with a thickness of 1 millimeter and a side length of 2 centimeters. In both cases, the underlying continuous layer was circular, with a diameter of 64 centimeters and a thickness of 400 micrometers, and was made from the same material as the soft mass.

[0038] Figure 5 provides a partial view of an acoustic article 300 according to another embodiment, which includes two different sets of distributed mass, demonstrating that the masses do not need to have the same shape or size. As shown, the article 300 has a continuous layer 302 having a first set of masses 306 having a hexagonal shape in the plan view and a second set of masses 307 having a cross shape in the plan view. As shown by this embodiment, the sets of masses 306, 307 do not need to be equal to each other, and the sets of masses 306, 307 can cover significantly different surface areas.

[0039] Figure 6 shows a method 350 for manufacturing the aforementioned acoustic article using a structured surface, such as one provided by a fabrication tool. Advantageously, this method and the methods described later can be carried out either as a batch process or a scalable continuous manufacturing process.

[0040] Method 350 uses a tool 352, which has a molding surface 353 containing a plurality of defined recesses 354. The recesses 354 are duplicated over a portion of the tool 352, and each recess 354 has a shape that is the inverse of the desired shape with respect to the distributed mass. The illustrated recesses 354 have a generally rectangular shape, but any suitable moldable shape can be used.

[0041] Tool 352 can be made from any suitable material, including metals such as steel, aluminum, and magnesium, and polymers such as silicone and polyurethane thermosetting resins. The manufacture of tool 352 is not particularly limited and can be achieved using any of the various methods known in the art, including casting, embossing, milling, and additive manufacturing.

[0042] As shown, the rolling bank of the fluid composition 356 is applied and spread across the tool 352 by the overlayer 358. Rollers 360, 362 assist in spreading the overlayer 358 and composition 356 across the tool 352. In some embodiments, the pressure applied to the tool 352 by the rollers 360, 362 may be adjustable to ensure that the composition 356 substantially fills the recesses 354 within the tool 352. Preferably, the recesses 354 are completely filled with composition 356 for optimal fidelity in the shape and size of the distributed mass obtained therefrom.

[0043] Increasing the pressure applied by rollers 360 and 362 can also help push out excess composition 356 from the area above the molded surface, thereby adjusting the thickness of excess composition 357 that does not enter the recess 354. This excess composition 357 remains on top of the molded surface 353 and does not need to be detrimental to the performance of the acoustic article. Once solidified, the integrated base layer interconnects the distributed mass with one another. Although not critical, it is generally preferable that the thickness of this base layer be thinner than the depth of the recess 354.

[0044] Composition 356 is generally a polymer composition or its reactive precursor. For example, composition 356 may be a molten thermoplastic polymer extruded from an extruder or other mixing device (not shown). When a polymer molten material is used, the tool 352 is generally made of a metal that can withstand the temperature of the molten polymer. Heat transfer to the tool 352 may also help to accelerate the subsequent solidification of the molten composition 356. Alternatively, composition 356 may be a reactive mixture of one or more monomers and often one or more initiators and / or catalysts, which is solidified by a polymerization (or curing) process after being applied to the molding surface 353 of the tool 352. Curing processes are known in the art. Depending on the properties of the initiator in composition 356, curing can be initiated by chemical radiation such as exposure to ultraviolet or visible light, exposure to an electron beam, or by heating composition 356 to a suitable temperature.

[0045] The coating layer 358 represents a continuous layer that remains bonded to composition 356 after solidification. The composition of the coating layer 358 is not particularly limited, but it is preferable that damage or deterioration of the coating layer 358 resulting from the casting process described above is minimal or nonexistent. It is even more preferable that the coating layer adheres strongly to adjacent compositions 356 after solidification.

[0046] If the coating layer 358 is porous, mechanical retention can help enhance interlayer adhesion with the solidified composition 356. If the composition 356 is a molten thermoplastic, the coating layer 358 can be made from metal foil, a solid or porous polymer film, a porous foam, a woven or nonwoven fiber layer, or a combination thereof. In some cases, heat resistance and the ability to transmit radiation through the coating layer 358 may be required to maintain the integrity of the coating layer 358 within the layer assembly and to ensure that proper solidification or curing occurs. More broadly, the composition of the coating layer 358 is not limited to a specific material and may include any of the compositions already described with respect to continuous layers and distributed mass.

[0047] Figure 7 shows a method 450 that has many similarities to the previous method 350, except that the tool is replaced with a film 452 having a number of recesses 454, as shown in the figure. In this schematic diagram, the fluid composition 456 is applied to the film 452 so that the recesses 454 are filled. Optionally, although not shown, a wiping step can be performed to remove at least some excess composition 456 present on the film 452. This wiping step can create a generally flat exposed main surface, which is part of a thin base layer 457, integrated with the separate volumes of composition 456 contained within the recesses 454. The composition 456 is then solidified by cooling or curing as described above.

[0048] As previously stated, the presence of the thin base layer 457 was not judged to significantly degrade the anti-resonance properties of the entire acoustic article. Nevertheless, if desired, the base layer 457 can be removed through one or more further steps. This can be achieved, for example, by a removal manufacturing process using mechanical or chemical means such as polishing, skiving, or reactive etching. Such a process can provide an acoustic article in which the distributed mass obtained from solidifying composition 456 is completely separate, i.e., separated from each other.

[0049] In the next step, the continuous layer 458 is placed on the base layer 457, and then in the final step, the continuous layer 458 and the solidified composition 456 are collectively removed from the film 452 to provide a finished acoustic article. In a variation of this method, the solidified composition 456 may be removed from the film 452 before the continuous layer 458 is applied to the base layer 457. It is also possible to omit the removal of the film 452 so that the film 452 remains as part of the finished acoustic article. The film 452 and the continuous layer 458 may independently consist of any of the compositions previously described for the coating layer 358.

[0050] The continuous layer 458 can be bonded to composition 456 thermally or adhesively. If composition 456 has not fully cured or solidified, it may be possible to enhance the interlayer adhesion by laminating a coating layer while composition 456 is only partially cured, i.e., before complete curing or solidification occurs. The continuous layer 458 can be prepared by applying a reactive monomer mixture (which may be a second reactive monomer mixture in some embodiments) to composition 456, and then curing this reactive monomer mixture to obtain a continuous layer.

[0051] Figure 8 shows a method 550 that is similar to method 450 in that it uses a film 552 having a molded surface with a plurality of recesses 554 for receiving a composition 556. In this method, the film 552 is made by molding a flat film 551. The molding of the flat film 551 can be carried out by a thermal embossing process. Embossing, as known in the art, can be carried out by heating a film made from a thermoplastic material above its glass transition temperature, and then pressing the heated film against a structuring tool (which can also be heated). In a continuous process, the structuring tool can take the form of a heated steel embossing roll, and a molten web from an extrusion die can be used instead of a preheated film. In this embodiment, the surface on which the embossing process is performed has the same topological features as that of the distributed mass of the acoustic article. The film 552 can also be a metal foil that is stamped to provide the recesses 554.

[0052] In the method shown in Figure 8, unlike the method in Figure 7, the film 552 remains as part of the acoustic article even after the composition 556 has been applied to its molded surface and solidified to form distributed mass. Therefore, the film 552 functions as a continuous layer interconnecting the distributed mass, even though it has a non-flat shape that conforms to the outwardly protruding profile of the distributed mass rather than the flat top surface of the distributed mass.

[0053] As a further option, although not shown here, a second continuous layer may be laminated or otherwise deposited in a subsequent step on the exposed upper surface of film 552 and the exposed solidified composition 556. In this case, the second continuous layer functions as a planar continuous layer capable of encapsulating distributed mass between two films, such a configuration may be desirable. Such a configuration may be used, for example, when the solidified composition 556 requires protection from harmful environmental factors such as UV light, oxygen, and moisture in its intended application. [Examples]

[0054] The purposes and merits of this disclosure are further illustrated by the following non-limiting embodiments, but the specific materials and their quantities, as well as other conditions and details, referenced in these embodiments should not be construed as unduly limiting this disclosure. Unless otherwise stated, all parts, percentages, ratios, etc., in the embodiments and elsewhere in this specification are by weight.

[0055] [Table 1]

[0056] Test method: Airborne sound transmission loss The method of ASTM E90-09 (2016) was followed with some modifications. The 1.2m × 1.2m (3.94ft × 3.94ft) opening between the reverberation chamber and the detection chamber was reduced to 64.77cm × 66.04cm (25.5inch × 26inch) by a 5.08cm × 10.16cm (2inch × 4inch) frame and a 1.59cm (0.625inch) thick drywall. The sample was trimmed and sealed to prevent leakage. Transmission loss TL (dB) was measured.

[0057] Test of normal incidence measurement of acoustic properties of porous materials The methodology of ASTM E2611-19 was followed. Normal incidence transmission loss TL n [dB] was measured.

[0058] Example 1 Step 1: Tool Creation A 71.12 cm × 71.12 cm (28 inch × 28 inch) magnesium printing plate with a thickness of 0.635 cm (0.25 inch) was fabricated by St. Cloud Engraving (St. Cloud, MN). 13.5 mm × 13.5 mm (0.53 inch × 0.53 inch) unit cells were placed 9 mm (0.35 inch) apart and rotated 45 degrees. The etching depth was 0.99 mm (0.039 inch).

[0059] 10 grams of UV9300, 0.2 grams of UVC9380C, and 45 mL of heptane were mixed in a 118.29 mL (4 oz) amber glass bottle. 20 mL of the UV9300 / UV9380C / heptane solution was added to another amber glass bottle containing 100 mL of heptane. This solution was poured into a 250 mL (8.45 oz) Aldrich flask-type atomizer (available from Sigma-Aldrich, St. Louis, MO, United States). Using nitrogen as the propellant in the atomizer, the plate was coated with the solution. After drying, the coating was UV-cured using an RC-600 pulsed 500-watt UV curing system (available from Xenon Corporation, Wilmington, MA, United States). After UV curing, the plate was placed in an oven preheated to 80 degrees Celsius. After 20 minutes, the plate was removed from the oven and allowed to cool.

[0060] Step 2: Replication The resin was prepared by blending P6210, SR238, and TPO in a weight ratio of 75 / 25 / 0.5. The tool (prepared in Step 1) was placed in the center and positioned on a 60.96 cm × 121.92 cm (24 inches × 48 inches) electrically heated hot plate. The hot plate was heated to 65°C (150°F), which heated the tool to approximately 54.4°C (130°F). The tip of an IUPILON 75 micrometer, 72.39 cm × 83.82 cm (28.5 inches × 33 inches) high-haze polycarbonate film (olefin pre-mask side up), obtained from Mitsubishi Chemical (Tokyo, Japan), was taped approximately 1.27 cm (1 / 2 inch) from the end of the tool. A 1.5-meter diameter aluminum roller (identified as 360 in Figure 6) and a 1.5-meter diameter steel roller (identified as 362 in Figure 6) were placed on the film bonded to the tool. The film was then folded over the metal roller. Resin beads were poured onto the tool, enclosing the first row of cavities. The steel roller was rotated manually, and the aluminum roller was slowly advanced to fill the cavities and laminate the film onto the tool. Additional resin was added as needed. After lamination was complete, the steel roller was returned to its starting position and rotated again across the laminated tool to minimize the resin thickness.

[0061] This is a Firepower FP501 300X20 WC395 (20W / cm² at 395nm) antenna with a 30.48cm (12-inch) window, obtained from Phoseon Technology (Hillsboro, OR, United States). 2 The resin was cured using an LED system. The cured resin adhered to the film, and the composite film peeled off easily from the treated tool surface.

[0062] Step 3: Evaluation A test of airborne sound transmission loss was conducted, and the results are shown in Table 2.

[0063] [Table 2]

[0064] Example 2 Step 1: 3D printing The resin was prepared as described in Preparation Example 3 of International Patent Application No. 2020 / 003133 (Mac Murray et al.), which has been assigned to the assignee of this invention. This resin was used in combination with a ProMaker LD10 3D printer obtained from Prodways Tech (Merrimack, NH United States) to create a 3D printed sample. Before printing, the PET film was fixed to the LD10 granite build platform with double-sided tape, and a layer height of 100 micrometers was used. The printer used 385 nm light to solidify the resin with the print pattern shown in Figure 5. Before printing, the print pattern of the sample was modeled using SOLIDWORKS CAD software (Waltham, MA United States).

[0065] After printing, the samples were rinsed in a propylene carbonate bath, followed by an isopropyl alcohol bath, for 1 minute each. The samples were air-dried and post-cured for 30 minutes under nitrogen purging in a CA3200 UV chamber (obtained from Clearstone Technologies Inc., Hopkins, MN, United States) using simultaneously active 365, 385, and 405 nm light-emitting diodes (LEDs). Finally, the samples were heated in a 100°C oven for 30 minutes to reduce yellowing.

[0066] Step 2: Evaluation We conducted a test of the acoustic properties of a porous material using a 100 mm impedance tube with normal incidence, and the results are shown in Table 3.

[0067] [Table 3-1]

[0068] [Table 3-2]

[0069] All documents, patent documents, or patent applications cited in the above patent application relating to the patent document are incorporated herein by reference in their entirety in a consistent manner. In the event of any inconsistency or contradiction between any part of the incorporated references and this application, the information in the foregoing statement shall prevail. The foregoing statement is intended to enable a person skilled in the art to practice the disclosure set forth in the claims and should not be construed as limiting the scope of the disclosure, which is defined by the claims and all their equivalents. The following are exemplary embodiments. [Item 1] A continuous layer having a first elastic rigidity, An acoustic article comprising a plurality of distributed masses having a second elastic stiffness, disposed on the main surface of the continuous layer, wherein the second elastic stiffness is smaller than the first elastic stiffness. The aforementioned acoustic article is an acoustic metamaterial that exhibits an anti-resonance peak at frequencies below 800 Hz. acoustic goods. [Item 2] A continuous layer having a first elastic modulus, An acoustic article comprising a plurality of distributed masses having a second elastic modulus, disposed on the main surface of the continuous layer, wherein the second elastic modulus is smaller than the first elastic modulus. The aforementioned acoustic article is an acoustic metamaterial that exhibits an anti-resonance peak at frequencies below 800 Hz. acoustic goods. [Item 3] The acoustic article according to item 1 or 2, further comprising a base layer extending continuously on the main surface, wherein the base layer is integral with the plurality of distributed masses. [Item 4] An acoustic article according to any one of items 1 to 3, wherein the plurality of distributed masses are arranged in a two-dimensional replication pattern. [Item 5] The acoustic article according to any one of items 1 to 4, wherein the plurality of distributed masses are spread over 5 percent to 80 percent of the total area of ​​the main surface. [Item 6] The acoustic article according to any one of items 1 to 5, wherein the continuous layer has an elastic modulus of 500 MPa to 5000 MPa. [Item 7] The acoustic article according to any one of items 1 to 6, wherein the plurality of distributed masses have an elastic modulus of 0.1 MPa to 500 MPa. [Item 8] An acoustic article according to any one of items 1 to 7, wherein the elastic modulus of the continuous layer is 1.1 to 50,000 times greater than the elastic modulus of the plurality of distributed masses. [Item 9] The acoustic article according to any one of items 1 to 8, wherein the continuous layer comprises a first polymer which is a thermosetting polymer. [Item 10] The acoustic article according to item 9, wherein the continuous layer and / or the distributed mass comprises polyalkylene, polyurethane, or silicone rubber. [Item 11] The acoustic article according to any one of items 1 to 10, wherein the continuous layer includes a first filler that increases the overall modulus of elasticity of the continuous layer. [Item 12] The acoustic article according to any one of items 1 to 11, wherein the continuous layer comprises a first filler that reduces the overall density of the continuous layer. [Item 13] The acoustic article according to any one of items 1 to 12, wherein the plurality of distributed masses contain a second filler that reduces the overall elastic modulus of the plurality of distributed masses. [Item 14] The acoustic article according to any one of items 1 to 13, wherein the second polymer contains a second filler that increases the overall density of the plurality of distributed masses. [Item 15] An acoustic article according to any one of items 1 to 14, wherein the continuous layer has a first thickness, the plurality of distributed masses have a second thickness, and the first thickness is 2.5 percent to 100 percent of the second thickness. [Item 16] A method for manufacturing an acoustic article as described in any one of items 1 to 15, To provide a molded surface having multiple defined recesses, Applying a reactive monomer mixture that at least partially fills the plurality of defined recesses to the molded surface, Placing the continuous layer on the reactive monomer mixture, To remove at least some excess reactive monomer mixture between the continuous layer and the molded surface, The reactive monomer mixture is cured while in contact with the continuous layer, thereby bonding the multiple distributed masses to the continuous layer. Selectively removing the continuous layer and multiple distributed masses from the molded surface, Methods that include... [Item 17] The method of item 16, further comprising embossing a flat film to provide the molded surface. [Item 18] A method for manufacturing acoustic articles, To provide a molded surface containing multiple defined recesses by embossing a flat film, Applying a reactive monomer mixture that at least partially fills the plurality of defined recesses to the molded surface, To remove at least some excess reactive monomer mixture from the molded surface, The reactive monomer mixture is cured to obtain a plurality of distributed masses attached to the molded surface, Methods that include... [Item 19] A method for manufacturing acoustic articles, To form a flat polymer film and provide a molded surface that includes a plurality of defined recesses, The first reactive monomer mixture is applied to the molded surface to at least partially fill the plurality of defined recesses, To remove at least some excess reactive monomer mixture from the molded surface, The first reactive monomer mixture is cured to provide a plurality of distributed masses, Applying the second reactive monomer mixture to the aforementioned multiple distributed masses, The second reactive monomer mixture is cured to provide a continuous layer attached to the plurality of distributed masses, Selectively removing the continuous layer and multiple distributed masses from the molded surface, Methods that include... [Item 20] Acoustic articles manufactured in accordance with the methods described in item 18 or 19.

Claims

1. A film forming a continuous layer having a first elastic rigidity, An acoustic article comprising a plurality of distributed masses having a second elastic stiffness, disposed on the main surface of the continuous layer, wherein the second elastic stiffness is smaller than the first elastic stiffness. The aforementioned acoustic article is an acoustic metamaterial that exhibits an anti-resonance peak at frequencies below 800 Hz. The film has a non-flat shape that conforms to the outwardly protruding profile of the distributed mass. acoustic goods.

2. A film forming a continuous layer having a first elastic modulus, An acoustic article comprising a plurality of distributed masses having a second elastic modulus, disposed on the main surface of the continuous layer, wherein the second elastic modulus is smaller than the first elastic modulus. The aforementioned acoustic article is an acoustic metamaterial that exhibits an anti-resonance peak at frequencies below 800 Hz. The film has a non-flat shape that conforms to the outwardly protruding profile of the distributed mass. acoustic goods.

3. The acoustic article according to claim 1 or 2, further comprising a base layer extending continuously on the main surface, wherein the base layer is integral with the plurality of distributed masses.

4. The acoustic article according to claim 1 or 2, wherein the plurality of distributed masses are arranged in a two-dimensional replication pattern.

5. The acoustic article according to claim 2, wherein the first elastic modulus of the continuous layer is 1.1 to 50,000 times the second elastic modulus of the plurality of distributed masses.

6. The acoustic article according to claim 1 or 2, wherein the continuous layer comprises a first polymer which is a thermosetting polymer, and the continuous layer and / or the distributed mass comprises polyalkylene, polyurethane, or silicone rubber.

7. The acoustic article according to claim 1 or 2, wherein the continuous layer has a first thickness, the plurality of distributed masses have a second thickness, and the first thickness is 2.5 percent to 100 percent of the second thickness.

8. A method for manufacturing an acoustic article according to claim 1 or 2, To provide a molded surface of the film having a plurality of defined recesses, Applying a composition containing a reactive monomer mixture that at least partially fills the plurality of defined recesses to the molded surface, Placing the continuous layer on the reactive monomer mixture, To remove at least some excess reactive monomer mixture between the continuous layer and the molded surface, The reactive monomer mixture is cured while in contact with the continuous layer, thereby bonding the multiple distributed masses to the continuous layer. Methods that include...

9. The method according to claim 8, further comprising forming a flat film to provide the molded surface.

10. A method for manufacturing acoustic articles, To form a flat film and provide a molded surface that includes a plurality of defined recesses, Applying a composition containing a reactive monomer mixture that at least partially fills the plurality of defined recesses to the molded surface, To remove at least some excess reactive monomer mixture from the molded surface, The reactive monomer mixture is cured to obtain a plurality of distributed masses attached to the molded surface, Includes, The film remains as part of the acoustic article. method.

11. A method for manufacturing acoustic articles, To form a flat polymer film and provide a molded surface that includes a plurality of defined recesses, The first composition containing a reactive monomer mixture is applied to the molded surface to at least partially fill the plurality of defined recesses, Removing at least some excess first composition from the molded surface, The first composition is cured to provide a plurality of distributed masses, Applying a second composition containing a reactive monomer mixture to the aforementioned plurality of distributed masses, The method includes curing the second composition to provide a continuous layer attached to the plurality of distributed masses, The film remains as part of the acoustic article. method.

Images