acoustic products

Abstract

Embodiments of the present invention relate to an acoustic article comprising: meltblown microfibers; two or more polyester fibers forming a mesh matrix together with the meltblown microfibers, wherein a first polyester fiber in the mesh matrix is ​​of a different grade than a second polyester fiber, thereby generating less affinity between the fibers, and one of the two polyester fibers is a recycled polyester fiber; and a first sparse fabric layer and a second sparse fabric layer placed on opposite surfaces of the mesh matrix.

Description

Technical Field

[0001] This invention relates to an acoustic article for sound insulation. The acoustic article is provided for noise reduction and is suitable for automotive and aerospace applications. Background Technology

[0002] Noise, vibration, and harshness (NVH) is one of the most in-demand areas in the automotive industry. In today's world, automotive companies' NVH departments primarily focus on performance, weight, and cost. Related R&D is actively seeking new methods to test and evaluate noise levels and predict noise paths for effective noise control. Implementing improvements using conventional techniques often increases vehicle weight, thereby reducing fuel economy. While lightweight solutions exist, they have their own drawbacks, such as cost and manufacturing complexity. Furthermore, developing these solutions is technically challenging because measures taken to reduce weight often compromise the performance of the product across various aspects. Therefore, the need for sound insulation materials along noise paths is crucial for noise control, and extensive evaluations have been conducted on material optimization to effectively arrange materials that meet performance, weight, and cost requirements.

[0003] Sound-absorbing materials or absorbers play a crucial role in automotive NVH (Noise, Vibration, and Harshness) and are effectively used inside vehicles to improve cabin noise. These materials form an important part of the overall acoustic package of any typical vehicle. Existing sound-absorbing materials on the market can be categorized as absorbers that treat noise by absorbing it. Porous sound-absorbing materials have become more advanced over the years. They are safer, lighter, and more technologically advanced than other materials. Typical materials used as absorbers are felt, recycled wool fabrics, polyurethane foam, and blown microfiber (BMF)-based nonwovens. These materials generally treat noise by absorbing noise in the desired frequency spectrum.

[0004] Blow-molded microfiber (BMF)-based nonwovens are technologically more advanced and are known for their excellent sound absorption properties, especially at high frequencies. The combination of fine and coarse denier fibers produced using a melt-blown process makes them a stable, lightweight product suitable for automotive NVH applications.

[0005] Furthermore, the emergence of electric vehicles (EVs) or hybrid electric vehicles (HEVs) has created new types of noise sources, primarily from electric motors, road noise, wind noise, and auxiliary system noise. The automotive industry is increasingly focused on climate and circular science, thus placing greater emphasis on sound insulation materials with important properties related to sustainability and green chemistry. This necessitates the use of advanced materials with multifunctional properties to meet the challenging demands of current and emerging automotive NVH requirements.

[0006] Sound insulation or acoustic products are compressed during transport or molding. During transport, acoustic products may need to be compressed and rolled up for easy transport. During molding, sound insulation or acoustic products are combined with other layers, which may have a multi-layered structure, and are therefore compressed. The multi-layered structure used can vary based on application and multi-functional performance requirements. When acoustic products are compressed, their thickness decreases, and when the compressive force is released, the product may not return to the same shape and form as before compression, as is the case with blown microfiber (BMF) matrix absorbers. More specifically, the bulk or thickness in the z-direction of the product may not be restored. The sound absorption capacity of acoustic products increases with increasing mass and its natural thickness or bulk. For motor vehicles, acoustic products should fill the spaces and any voids in the vehicle's components after installation to effectively isolate noise. Sometimes, acoustic products need to be compressed for installation in target locations within vehicle components and then need to be restored from compression to fill voids and spaces within the vehicle components.

[0007] Therefore, there is a need for an improved acoustic product that exhibits good sound absorption properties and flexibility to conform to the structure of automotive components. Furthermore, this acoustic product should ideally be compressible and able to recover quickly from compression, and provide high sound insulation performance through improved sound absorption properties. Moreover, to meet the emerging needs of the automotive industry surrounding climate science and circular science, sustainability approaches need to be incorporated and integrated into the design of improved sound insulation materials. Summary of the Invention

[0008] Therefore, the present invention provides an acoustic article comprising: meltblown microfibers; two or more polyester fibers forming a mesh matrix together with the meltblown microfibers, wherein the grade of a first polyester fiber in the mesh matrix is ​​different from that of a second polyester fiber, thereby generating less affinity between the fibers, and one of the two polyester fibers is a recycled polyester fiber; and a first sparse fabric layer and a second sparse fabric layer placed on opposite surfaces of the mesh matrix.

[0009] In another exemplary embodiment, the acoustic article having meltblown microfibers comprises polypropylene, and the weight ratio of the first polyester fiber to the second polyester fiber in the mesh matrix containing the meltblown microfibers is 1:2, wherein the weight percentage of the meltblown fiber in the mesh matrix does not exceed 53%. Attached Figure Description

[0010] The accompanying drawings, which are incorporated herein and constitute a part of this disclosure, illustrate exemplary embodiments of the present disclosure, with the same reference numerals referring to the same parts in different drawings. The components in the drawings are not necessarily drawn to scale, but rather the emphasis is on clearly illustrating the principles of the present disclosure; therefore, the drawings should be considered illustrative. Furthermore, the embodiments shown in the drawings should not be construed as limiting the present disclosure, but rather as possible variations of the present disclosure illustrated herein for the purpose of highlighting its advantages.

[0011] Figure 1 A cross-sectional view of an acoustic article according to an embodiment of the present invention is shown.

[0012] Figure 2 An acoustic article having a barrier layer or barrier article according to an embodiment of the present invention is shown.

[0013] Figure 3 An acoustic article having barrier layers or barrier articles on both sides according to an embodiment of the present invention is shown.

[0014] Figure 4 An exemplary example of an acoustic article according to another embodiment is shown.

[0015] Figure 5 An acoustic product according to yet another embodiment is shown.

[0016] Figure 6 A method for manufacturing the acoustic article of the present invention according to an embodiment is shown.

[0017] Figure 7 and Figure 8 The sound absorption coefficients of the acoustic products tested for samples A and B are shown at frequencies from 200 Hz to 5000 Hz.

[0018] Figure 9 and Figure 10 The sound absorption coefficients (SAC) of acoustic products A and B are shown respectively at frequencies from 200 Hz to 5000 Hz.

[0019] Figure 11 Scanning electron microscope (SEM) images of samples A and B of acoustic artifacts are shown.

[0020] Figure 12 Optical microscope images of samples A and B of acoustic artifacts are shown.

[0021] Figure 13 The results of the bulk retention test of the acoustic article under static load conditions are shown compared with a standard meltblown base absorber with only one grade of polyester fiber.

[0022] Figure 14The sound absorption coefficients of acoustic product sample B with an additional nonwoven porous layer, tested using an impedance tube according to ASTM E1050, are shown in the range of frequencies from 200 Hz to 5000 Hz in the case of noise-oriented acoustic products. Detailed Implementation

[0023] For the purposes of the following detailed description, it should be understood that various alternative variations and sequences of steps are assumed in the invention, unless expressly stated otherwise. Therefore, it should be understood that the invention is not limited to the particularly exemplified system or embodiment, which may, of course, be modified. Unless otherwise defined, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] As used herein, the singular forms “a,” “an,” and “the” include references to the plural unless the context clearly indicates otherwise. The term “and / or” means one or all of the listed elements, or any combination of two or more of the listed elements.

[0025] The terms "preferred" and "ideally" refer to embodiments of the invention that, under certain circumstances, may provide certain beneficial effects. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of the invention.

[0026] When the term “about” is used to describe the end of a value or range, this disclosure should be understood to include the specific value or end mentioned.

[0027] As used herein, the terms “comprising,” “including,” “containing,” “characterized by,” “having,” or any other variations thereof are intended to cover non-exclusive inclusion.

[0028] The term "meltblown" refers to the process of extruding molten material through multiple spinnerets to form filaments, while simultaneously contacting the filaments with air or other refining fluids to refine them into fibers, and subsequently collecting the refined fiber layers.

[0029] The term "meltblown fiber" refers to fibers produced by the meltblown process.

[0030] “Microfiber” refers to meltblown fibers with a diameter of 10 μm or less (as measured using microscopy); “ultrafine microfiber” refers to microfibers with a diameter of 2 μm or less; and “submicron microfiber” refers to microfibers with a diameter of 1 μm or less.

[0031] "Medium fiber" refers to meltblown fibers with a diameter (as measured using microscopy) greater than 10 μm.

[0032] The term "incident sound wave" refers to a random or conventional sound wave within the audible frequency range emitted from a sound source toward an acoustic object.

[0033] As used below, noise sources can be, but are not limited to, internal combustion engines, electric vehicles and automotive / traction / air drive systems, or combinations thereof (in the case of hybrid drive systems).

[0034] This invention relates to acoustic articles for noise control applications. These acoustic articles control noise through the principle of noise absorption. Effective noise control is achieved by providing better sound absorption within the desired frequency range. This is accomplished using a nonwoven mesh matrix comprising blends of microfibers / fine denier fibers and coarse fiber / coarse denier fibers.

[0035] like Figure 1 As shown, the acoustic article 100 comprises meltblown microfibers 102 and two or more polyester fibers 104 and 106, which are combined to form a mesh matrix 108, which is a nonwoven mesh matrix. In one embodiment, the meltblown fiber 102 may be composed of polypropylene. Some examples of fiber-forming materials suitable for meltblown fibers include thermoplastic polymers (such as polycarbonate, polyester, polyamide (e.g., nylon), polyurethane), block copolymers (such as styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers), and polyolefins (such as polypropylene, polybutene, and poly(4-methyl-1-pentene)), polyphenylene ether, acrylic polymers, polyvinyl chloride, or combinations thereof. Meltblown fibers are those fibers prepared by meltblowing, for example as described in U.S. Patent No. 4,215,682 to Kubik et al., where the fiber-forming material is extruded into a gas stream through a spinneret. Typically, meltblown fibers are very long compared to short fibers. Unlike polyester fibers or short fibers, which typically have a specific or determinable length, meltblown fibers generally have an indefinite length. Although discontinuous meltblown fibers are sometimes reported, these fibers are typically long and well-entangled, making it generally impossible to remove a single complete meltblown fiber from a large quantity of such fibers or to trace a single meltblown fiber from beginning to end. Furthermore, the diameter of the hardened meltblown fiber may differ significantly from (e.g., much smaller than) the size of the source spinneret orifice used to prepare the molten fiber precursor. In one embodiment, the meltblown fiber 102 may constitute more than 50% by weight in the web matrix 108. In another exemplary embodiment, the meltblown fiber may constitute 53% by weight in the web matrix 108. In yet another exemplary embodiment, the meltblown fiber may constitute no more than 53% by weight in the web matrix 108.

[0036] In the mesh matrix 108, the grade of the first polyester fiber 104 may differ from the grade of the second polyester fiber 106. This difference in grade helps to create less affinity or less fusion between the two types of polyester fibers. This configuration of the mesh matrix 108, in which different grades of polyester fibers are selected, helps to produce higher bulk retention properties in the mesh matrix 108. In other words, the mesh matrix 108 may contain two or more different grades of polyester staple fibers, wherein one grade is recycled polyester staple fiber. In blown microfiber (BMF) methods, it is known in the art to use one grade of virgin polyester staple fiber and blend it with meltblown (MB) virgin polypropylene fibers. In another embodiment, more than two types of polyester fibers may be present in the mesh matrix, and they may be of different grades to maintain affinity between the polyester fibers. Furthermore, if more than two types of polyester fibers are present in the mesh matrix, more than one type of polyester fiber with the same grade, or multiple types and grades of polyester fibers, and various combinations thereof, may be present. In conventional or typical cases, nonwovens produced using the blown microfiber (BMF) method have blends or compositions of meltblown fine denier fibers and coarse denier fibers or coarse fibers made from polyester staple fibers. Therefore, the resulting web matrix has only one grade of coarse denier polyester staple fibers or coarse polyester staple fibers. In one embodiment, one or more polyester fibers in the web matrix 108 may be recycled polyester fibers. For example, the second polyester fiber 106 may be a recycled polyester fiber. Recycled polyester fibers may include, but are not limited to, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactide (PLA), or thermoplastic polymers, polyhydroxybutyrate (PHB), and polypropylene terephthalate (PTT), polycyclohexanedimethyl terephthalate, and blends and copolymers thereof. The polyester may be aliphatic polyester, aromatic polyester, or combinations thereof. In an exemplary embodiment, if any polyester fiber in the web matrix 108 is a recycled polyester fiber, it constitutes approximately 14% of the weight composition of the web matrix 108. In another exemplary embodiment, the weight ratio of the first polyester fiber to the second polyester fiber in the mesh matrix 108 comprising meltblown microfibers is 1:2, wherein the first polyester fiber (e.g., the first polyester fiber 104) is a recycled polyester fiber.

[0037] In one embodiment, one of the first and second polyester fibers may be a staple fiber. For example, the first polyester fiber 104 may be a staple fiber. In another embodiment, one of the polyester fibers may be multi-lobed polyester staple fibers (MLPS). A multi-lobed fiber is a fiber or filament having more than one critical point along its outer surface. The critical point is defined as the point where the absolute value of the slope of a straight line drawn perpendicular to the fiber's surface changes when the fiber is cut along a surface perpendicular to the fiber axis. Multi-lobed fibers do not have a circular cross-section. Multi-lobed fibers may include fibers with cross-sections of triangles, squares, trefoils, tetralobes, pentafoils, hexalobes, and more. Multi-lobed fibers may be continuous or discontinuous and may have a variety of fibers with a variety of cross-sectional shapes and a variety of denier / filaments. Staple fibers are typically added to the nonwoven fiber web in a cured form rather than meltblown into the web matrix 108. Regardless of their manufacturing method or composition, staple fibers are typically mechanically cut to a specific predetermined or identifiable length. Staple fibers are typically synthetic polymer materials. The choice of their composition allows them to be melt-bonded to each other and / or melt-bonded to meltblown fibers during typical molding processes (such as for forming molded respirator bodies). Alternatively, they may be made of materials with properties such as melting point that they do not bond to each other and / or to meltblown fibers during typical molding processes. The term "capable of thermal bonding" is generally used to define short fibers having one or more components capable of being melt-bonded to each other and / or melt-bonded to meltblown fibers to a certain extent, in relation to the short fibers used herein. In one case, some low melt-bonding grade polyester fibers used may act as an adhesive to bond the short fibers together and may impart a three-dimensional shape or stiffness to the fiber matrix. The term "not capable of thermal bonding" is generally used to define short fibers that do not have any components capable of being melt-bonded to each other and / or melt-bonded to the meltblown fibers used. Short fibers may be monocomponent or multicomponent fibers. Short fibers may be multicomponent fibers in which at least one component will soften during heating to allow the short fibers to be bonded to each other or to meltblown fibers. The different components can be different types of polymers (e.g., polyester and polypropylene), or they can be polymers of the same type but with different melting points. The multicomponent fiber can be a bicomponent fiber with a co-expanding side-by-side configuration, a co-expanding concentric skin / core configuration, or a co-expanding elliptical skin / core configuration.

[0038] Polyester fibers can have a variety of regular or irregular cross-sectional shapes, such as, but not limited to, circular, elliptical, rectangular, square, hexagonal, polygonal, octagonal, triangular, or any combination thereof. Polyester fibers can be crimped, substantially straight, twisted, helical, or a combination thereof. Crimped fibers can have a continuous wavy, coiled, or serrated shape along their length. Crimping is a process that folds the fiber like an accordion. Introducing crimping is to impart cohesion to the fiber bundle. This process helps the fibers remain bundled in subsequent manufacturing stages. Polyester fibers can contain crimped fibers with approximately 2 to 6 crimps per centimeter. In one embodiment, the crimped fibers in the polyester fiber can be 2.18 to 3.5 crimps per centimeter. The configuration of the polyester fiber can vary based on different parameters. In one embodiment, one polyester fiber in the polyester fiber can be in the denier range of 3D to 12D. According to another embodiment, the denier range of one or more polyester fibers can be in the range of 4D to 7D. However, in different embodiments, the length of the polyester fibers in the mesh matrix 108 varies. The short fiber length of the polyester fiber can be from about 32 mm to 102 mm. In one embodiment, the length of the polyester fiber in the mesh matrix 108 can be from about 51 mm to 76 mm. The strength of the polyester fiber can also vary, and it determines the fiber's ability to resist tension or breakage when subjected to tension or stress. The toughness of the polyester fiber can be from about 2 g / denier (GPD) to 7 g / denier (GPD). In one embodiment, the toughness of the polyester fiber in the mesh matrix 108 can be from about 2.8 g / denier (GPD) to 4.5 g / denier (GPD). The weight ratio of the first polyester fiber to the second polyester fiber in the mesh matrix 108 can be 1:2.

[0039] Loose fabric layers are disposed on opposite sides of the mesh matrix 108, so that it is sandwiched between the loose fabric layers. More specifically, as... Figure 1As illustrated, a first sparse fabric layer 110 and a second sparse fabric layer 112 may be present, with a mesh matrix 108 situated between them. In other words, the first sparse fabric layer 110 and the second sparse fabric layer 112, in sheet or layer form, are located on both sides of the mesh matrix 108. The first sparse fabric layer 110 and the second sparse fabric layer 112 may be made of polyethylene terephthalate and polypropylene, respectively. The function of the sparse fabric is to protect the fibers within the mesh matrix 108. The sparse fabric is chosen to provide stability to the article 100. The sparse fabric acts as a bonding layer during the 3D / 2D molding process for bonding with other layers of sound insulation material, thereby forming a multilayer acoustic article. It is desirable to maintain the desired sound insulation performance without using any additional adhesive layers between the acoustic article and other subsequent sound insulation layers. In one embodiment, one side of the acoustic article is polyester sparse fabric and the other side is polypropylene sparse fabric; this flexibility facilitates strong bonding with other sound insulation layers belonging to a similar polymer family (polyester or polypropylene). Furthermore, in this case, bonding is achieved using heat and pressure during the 3D / 2D molding process without the use of any additional adhesives. The weight of the sparse fabric is selected based on application requirements and can range from approximately 10 g / m² (GSM) to 100 g / m² (GSM). In one embodiment, the weight of the sparse fabric on either side of the mesh matrix is ​​approximately 10 g / m² (GSM) to 25 g / m² (GSM).

[0040] The acoustic article 100 can be combined with other layers or articles (such as opaque articles, barrier articles, or porous articles) to be used as a multilayer sound insulation article. Figure 2 An acoustic article 100 is illustrated having a barrier layer or barrier article 200 to form article 202. The barrier layer 200 is positioned adjacent to one side 204 of the acoustic article 100. The barrier layer 200 blocks the propagation of sound waves by reflecting them. The barrier layer 200 can be a homogeneous, flexible, heat-reflective, and sound-reflective barrier formed using a combination of polymer resin and inorganic filler. In one embodiment of the invention, the barrier layer 200 may comprise a polymer, such as, for example, ethylene propylene diene monomer (EPDM), ethylene vinyl acetate (EVA), or an olefin-based polymer filled with particles having a higher density than the polymer. Suitable filler particles may include any of the materials described above as suitable sound-insulating materials. Examples of preferred filler particles include calcium carbonate, barium sulfate, and other mineral-based particles with a density greater than about 1 g / cm³. The barrier layer 200 can be formed by heat-treating at least one of the polymer resin and inorganic filler placed on a porous layer. In one embodiment, the barrier layer 200 may be bonded to the acoustic article 100. As used herein, the term “adhesion” includes chemical and mechanical methods known in the art for acoustically coupling (i.e., bonding and fixing) a barrier article to an acoustic article.

[0041] In another embodiment, article 300 comprises, for example, Figure 3 The acoustic article 100 is shown located on both sides 302 and 304 of the barrier layer 200. In one embodiment, the acoustic article 100 on both sides of the barrier layer 200 may have different thicknesses. The article 300 can be used in applications that require absorption of sound incident from both sides of the article and reflection of these sound waves by the barrier layer 200. In another embodiment, the acoustic article 100 on both sides 302 and 304 may have the same thickness, depending on the application requirements.

[0042] Figure 4 This is an exemplary illustration of article 400 according to another embodiment. The acoustic article 400 has a porous layer 402 on one side 404 and a barrier layer (e.g., barrier layer 200) above the porous layer 402 to form article 400. Available porous layers include, but are not limited to, nonwoven fiber layers, perforated membranes, particle beds, and open-cell structures such as open-cell foams, glass fibers, meshes, woven fabrics, and combinations thereof. Porous layers are generally permeable, allowing air or some other fluid to freely communicate between opposite sides of the layer. Such layers can also be semi-permeable (permeable along some, but not all, of their thickness dimensions) or impermeable. Nonwoven layers can be made from a wide variety of materials, including organic and inorganic materials. If the porous layer is a nonwoven fiber matrix, it acts as a sound absorber and comprises multiple fibers characterized by the fibers forming a sheet or mat through entanglement or point bonding, exhibiting a structure of interwoven individual fiber filaments, but not in a recognizable manner as in knitted fabrics. The porous layer 402 may be made of at least one fiber-forming polymer, but is not limited to at least one fiber-forming polymer. This at least one fiber-forming polymer may be, but is not limited to, nylon 6, nylon 66, cotton, polyester, polypropylene, and polyolefin-based fibers (such as polypropylene and polyethylene, polyester, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyurethane, polybutene, polylactic acid, polyphenylene sulfide, polysulfone, liquid crystal polymers, polyethylene-co-vinyl acetate, polyacrylonitrile, cyclic polyolefins and their copolymers and blends) and recycled wool fabrics (e.g., fabric waste or scraps). The porous layer 402 may be made of a variety of fibers having different deniers in the range of about 2D to 20D. Fibers with different deniers help achieve a loft retention property of 400 in the finished product.

[0043] The porous layer 402 may be bonded to the acoustic article 100 according to exemplary embodiments. As used herein, the term "bonded" includes chemical and mechanical methods known in the art for acoustically coupling (i.e., bonding and fixing) a barrier material to the acoustic article 100. In one embodiment, a barrier layer (e.g., barrier layer 200) may be formed over the porous layer (e.g., porous layer 402). According to one embodiment, the barrier layer 200 may be a homogeneous, flexible, heat-reflective and sound-reflective barrier formed using a combination of polymeric resin and inorganic filler. In another embodiment, the barrier layer 200 may be formed by heat-treating at least one of the polymeric resin and inorganic filler placed on the porous layer 402, so that the porous layer 402 and the barrier layer 200 are single units or articles rather than separate layers bonded to each other.

[0044] Figure 5 An acoustic article 500 according to yet another embodiment is illustrated. Article 500 includes a porous layer (such as porous layer 402) located above acoustic article 100. Porous layer 402 has been bonded Figure 4 The description is provided. The porous layer 402 can be bonded to the acoustic article 100 using methods known in the art.

[0045] Now, referring again to the obtained acoustic product 100, this product is lightweight, ranging from approximately 180 GSM to 1000 GSM, and possesses excellent sound insulation performance with very high sound absorption characteristics across the entire spectrum from 200 Hz to 5000 Hz. This lightweight acoustic product has a simplified construction, its function being to minimize the overall sound pressure level and enhance the overall sound quality of the application. This acoustic product also exhibits excellent thermal insulation and thermal management properties.

[0046] Furthermore, this acoustic product is suitable for sound insulation applications in areas prone to high temperatures, typically in automotive firewalls. It is also suitable for applications requiring sound insulation material to be placed near noise sources, often in automotive firewalls. The product can be compressed into complex shapes and designs suitable for various applications, such as automotive dashboards, and meets the flame retardancy standard "Federal Motor Vehicle Safety Standard (FMVSS 302)". Additionally, this acoustic product can be compressed to achieve the desired complex shapes required for specific applications using compression molding. Shapes that conform to the contours or shapes of surfaces separating the vehicle cabin from the engine compartment are desirable. Other moldable applications include electric motor encapsulation and engine mounting.

[0047] In tests conducted using an impedance tube according to ASTM E1050 on sample A, which weighs approximately 280 GSM and is 30 mm thick, the acoustic product (e.g., acoustic product 100) exhibits excellent overall absorption coefficients (200 Hz to 5000 Hz) (200 Hz: 7% absorption; 500 Hz: 16% absorption; 1000 Hz: 40% absorption; 2000 Hz: 80% absorption; 4000 Hz: 84% absorption; 5000 Hz: 76% absorption). Furthermore, in tests conducted using an impedance tube according to ASTM E1050 on sample B, which weighs approximately 380 GSM and is 38 mm thick, the acoustic product exhibits excellent overall (200 Hz to 5000 Hz) absorption coefficients. (200Hz: 8% absorption; 500Hz: 28% absorption; 1000Hz: 81% absorption; 2000Hz: 97% absorption; 4000Hz: 94% absorption; 5000Hz: 99% absorption).

[0048] In tests conducted in a reverberation chamber according to ASTM C423 on sample A, weighing approximately 280 GSM and 30 mm thick, the acoustic product exhibited excellent overall (200 Hz to 5000 Hz) absorption coefficients (200 Hz: 25% absorption; 500 Hz: 45% absorption; 1000 Hz: 67% absorption; 2000 Hz: 77% absorption; 4000 Hz: 72% absorption; 5000 Hz: 72% absorption). Furthermore, in tests conducted in a reverberation chamber according to ASTM C423 on sample B, weighing approximately 380 GSM and 38 mm thick, the acoustic product exhibited excellent overall (200 Hz to 5000 Hz) absorption coefficients (200 Hz: 18% absorption; 500 Hz: 70% absorption; 1000 Hz: 100% absorption; 2000 Hz: 96% absorption; 4000 Hz: 83% absorption; 5000 Hz: 83% absorption).

[0049] Furthermore, meltblown microfibers and short polyester fibers are present in the mesh matrix of the acoustic product. The meltblown microfibers and short polyester fibers are uniformly distributed throughout the mesh matrix. The meltblown microfibers are fine denier fibers with a fiber diameter of approximately 1 μm to 6 μm, while the short polyester fibers, observed using scanning electron microscopy (SEM), have a fiber diameter of approximately 27 μm to 40 μm. Further optical microscopy revealed that black recycled polyester short fibers, along with the meltblown microfibers and another grade of short polyester fibers, are present in the mesh matrix.

[0050] Furthermore, in tests conducted according to ASTM C522 on sample A, which weighs approximately 280 GSM and is 30 mm thick, the acoustic component exhibited good airflow resistance (380 mKS rayl). In tests conducted according to ASTM C522 on sample B, which weighs approximately 380 GSM and is 38 mm thick, the acoustic component exhibited good airflow resistance (1200 mKS rayl).

[0051] Additionally, the acoustic article exhibited excellent bulk retention characteristics under static load conditions. When a 2 kg static load was applied to an acoustic article with a sample size of 30 cm × 30 cm and maintained under the load for 7 days, its thickness was compressed by approximately 40% compared to the original thickness (30 mm). The thickness rebound (increase in bulk) immediately after the load was removed after 7 days was approximately 86.6% of the original thickness of the acoustic article. After further observation for 3 days, the thickness increased to 90% of the original thickness. The bulk retention characteristics of the acoustic article contribute to maintaining its sound absorption properties after molding. The high bulk retention characteristics of the acoustic article are due to the incorporation of two different grades of polyester fibers into the mesh matrix.

[0052] In one embodiment, the acoustic article (e.g., acoustic article 100) is placed in the vehicle's passenger compartment or engine compartment. The article is placed in such a manner that its surface is in contact with the body-in-white (BIW) surface or sheet metal. In another case, the acoustic article may contact the vehicle's trim. Similarly, the acoustic article may be placed in the engine / motor compartment such that its surface is in contact with the sheet metal of the vehicle's BWI. In other cases, the acoustic article may also be used as a wraparound sound insulation material or for encapsulating the vehicle's electric motor. Similarly, the acoustic article may be combined with impermeable or barrier materials or porous materials to serve as a multi-layered sound insulation material throughout the vehicle's engine compartment (firewall, hood, etc.) or passenger compartment (such as the dashboard front, floor, headliner, etc.). Some of these combinations have been combined with... Figure 2 , Figure 3 , Figure 4 and Figure 5 This has been explained. Such multi-layered combinations incorporating acoustic materials can also be placed at the bottom of the cockpit and passenger compartment, with the porous layers contacting the metal panels or bottom of the front and rear floors of the vehicle, and the impermeable or barrier layers facing the vehicle's interior. Acoustic materials can be used in many applications, including automotive, aerospace, marine, locomotive, building sound insulation (including concrete slab sound insulation), appliances, and other potential product applications requiring sound insulation properties. Furthermore, acoustic materials can be used to form multi-layered sound insulation materials using combinations of impermeable or barrier layers or nonwoven porous layers.

[0053] Furthermore, in tests conducted using impedance tubes according to ASTM E1050 on sample B, which was oriented towards a noise source and combined with an additional nonwoven porous layer, the acoustic material exhibited excellent overall (200Hz to 5000Hz) absorption coefficients. (200Hz: 29% absorption; 500Hz: 67% absorption; 1000Hz: 100% absorption; 2000Hz: 88% absorption; 4000Hz: 91% absorption; 5000Hz: 87% absorption). The acoustic material used here is sample B, weighing 380 GSM and 38 mm thick, combined with an additional nonwoven porous layer weighing 800 GSM and 30 mm thick.

[0054] Manufacturing Method

[0055] The acoustic article of the present invention (e.g., acoustic article 100) can also be used as... Figure 6 The process is illustrated below. The method begins by feeding polyester fibers through a feeding unit 600. The polyester fibers exiting the feeding unit 600 undergo carding in a carding unit 602. During carding, the fibers are transformed into uniform fiber bundles and made parallel to each other by removing fiber knots. This treatment is also to remove the largest impurities from the fibers, cleaning them and achieving proper blending of the polyester fibers. After carding, the fibers can be fed into a cross-laying unit 604, where the fibers are laid vertically and horizontally multiple times to form a cross-laid fiber web. These cross-laid fibers are blown onto a conveyor belt 608 by a fiber blowing unit 606. These fibers can be a mixture of two or more polyester fibers (610 and 612), such as... Figure 6 As shown. A loosely woven fabric layer 614 is laid on the conveyor belt 608, and polyester fibers fall onto it. The loosely woven fabric layer 614 is unwound from the loosely woven fabric roll 616. As... Figure 6 As shown, there is a meltblown unit 618, which has a hopper of an extruder 620 that receives polymer material molten due to heat and friction within the extruder 620 and the mechanical action of moving parts. The molten polymer material is compressed and homogenized. The high-pressure molten polymer material can flow into a metering pump (now in...) Figure 6(As shown in the diagram) to uniformly deliver material into the die assembly 622. The die assembly 622 includes a die 624 that allows molten polymer material to flow through its channels. The die 624 may have a tapered structure. The molten polymer material reaches the nose of the die 624. The nose is wide, hollow, and tapered, with holes that allow the molten polymer to be extruded through these holes to form filament bundles, which are then refined by hot air to form fine denier microfibers. The formed meltblown fibers are laid on top of polyester fibers on the conveyor belt 608. Now, a mixture of meltblown fibers and polyester fibers is on the bottom loose fabric layer 614. Near the end of the conveyor belt 608, another loose fabric layer 626 may be laid on top of this layer of meltblown fibers and polyester fibers. The loose fabric layer 626 is unwound from the loose fabric roll 628. The formed acoustic article 100 is removed from the conveyor belt 608 and may be rolled into a roll 630.

[0056] To determine the NVH performance improvement, thermal properties, and bulk retention characteristics of acoustic products, the following tests were conducted:

[0057] Sound Absorption Coefficient (SAC) - Noise measurements using impedance tube (normal incidence) per ASTM E1050 standard

[0058] Figure 7 and Figure 8 The sound absorption coefficients of the acoustic products tested for samples A and B are shown at frequencies from 200 Hz to 5000 Hz. The acoustic products used here are sample A, which weighs 280 GSM and has a thickness of 30 mm, and sample B, which weighs 380 GSM and has a thickness of 38 mm.

[0059] Key Observations :

[0060] a) In tests conducted on sample A, the acoustic product exhibited excellent overall (200Hz to 5000Hz) absorption coefficients. (200Hz: 7% absorption; 500Hz: 16% absorption; 1000Hz: 40% absorption; 2000Hz: 80% absorption; 4000Hz: 84% absorption; 5000Hz: 76% absorption)

[0061] b) In tests conducted on sample B, the acoustic product exhibited excellent overall (200Hz to 5000Hz) absorption coefficients. (200Hz: 8% absorption; 500Hz: 28% absorption; 1000Hz: 81% absorption; 2000Hz: 97% absorption; 4000Hz: 94% absorption; 5000Hz: 99% absorption)

[0062] The SAC results are shown in Table 1.

[0063]

[0064] Sound Absorption Coefficient (SAC) - Noise measurements using reverberation chamber (random incidence) per ASTM C423 standard

[0065] Figure 9 and Figure 10 The sound absorption coefficients (SAC) of acoustic product samples A and B are shown respectively at frequencies from 200 Hz to 5000 Hz.

[0066] The sample A used here weighs approximately 280 GSM and has a thickness of 30 mm, while the sample B used here weighs approximately 380 GSM and has a thickness of 38 mm.

[0067] Key Observations :

[0068] a) In tests conducted on sample A, the acoustic product exhibited excellent overall (200Hz to 5000Hz) absorption coefficients. (200Hz: 25% absorption; 500Hz: 45% absorption; 1000Hz: 67% absorption; 2000Hz: 77% absorption; 4000Hz: 72% absorption; 5000Hz: 72% absorption)

[0069] b) In tests conducted on sample B, the acoustic product exhibited excellent overall (200Hz to 5000Hz) absorption coefficients. (200Hz: 18% absorption; 500Hz: 70% absorption; 1000Hz: 100% absorption; 2000Hz: 96% absorption; 4000Hz: 83% absorption; 5000Hz: 83% absorption)

[0070] The SAC results are shown in Table 2.

[0071]

[0072] Morphological analysis of acoustic articles was performed using SEM and optical microscopy to understand the fiber distribution throughout the mesh matrix and the presence of fine and coarse denier fibers.

[0073] The acoustic product underwent scanning electron microscopy (SEM) and optical microscopy analysis.

[0074] Figure 11 Scanning electron microscopy (SEM) images of sample A, weighing approximately 280 GSM and 30 mm thick, and sample B, weighing approximately 380 GSM and 38 mm thick, are shown. The SEM images clearly show the presence of meltblown microfibers and short polyester fibers. The meltblown microfibers and short polyester fibers are uniformly distributed throughout the network matrix. The meltblown microfibers are fine denier fibers with a fiber diameter of approximately 1 μm to 6 μm, while the short polyester fibers have a fiber diameter of approximately 27 μm to 40 μm.

[0075] Figure 12Optical microscopic images are shown of sample A, weighing approximately 280 GSM and 30 mm thick, and sample B, weighing approximately 380 GSM and 38 mm thick. The optical images show that black recycled polyester staple fibers exist together with meltblown microfibers and another grade of staple polyester fibers in a mesh matrix.

[0076] Flame Resistance Test per FMVSS 302 standard

[0077] Test Procedure :

[0078] The test was conducted inside a test chamber, with the sample placed horizontally. The exposed side of the sample was subjected to a gas flame from below. The charring distance and the time taken to burn that distance were measured during the test. The results (i.e., the burning rate) are expressed in mm / min.

[0079] According to the FMVSS 302 level flame retardancy standard, the acoustic products passed, and the results are shown in Table 3. The acoustic products used here are sample A, weighing approximately 280 GSM and with a thickness of 30 mm, and sample B, weighing approximately 380 GSM and with a thickness of 38 mm.

[0080]

[0081] Thermal Conductivity Test per ASTM C518 standard (average temperature: 22.5 degrees Celsius)

[0082] The thermal conductivity of the acoustic components was tested at 22.5°C. The acoustic component samples showed that sample A had a thermal conductivity of 0.032 W / mK, and sample B had a thermal conductivity of 0.031 W / mK. The acoustic components used here are sample A, weighing approximately 280 GSM and with a thickness of 30 mm, and sample B, weighing approximately 380 GSM and with a thickness of 38 mm.

[0083] Hot Odor Test per SAE J1351

[0084] Test Procedure :

[0085] The specimen is a sample of the material or composite material being evaluated. The surface area of ​​the specimen (including all surfaces) is 250 cm². 2 ±25cm 2 (0.28ft) 2 ±0.028ft 2 Cut the specimen to any size compatible with the tank dimensions, as long as the specimen surface area remains at 250 cm². 2 .

[0086] Before testing, the sample was placed at 23℃±2℃ (70℉±2℉) and 50%RH±5%RH for 24 hours.

[0087] Test samples in both dry and moist conditions. For dry testing, place the sample in the container and cover with the lid and ring. For wet testing, after placing the sample in the container, spray 2 cc of distilled water directly onto the sample, then cover with the lid and ring. An empty container is also provided for control purposes; cover with the lid and ring.

[0088] Place the can in an oven preheated to 65°C ± 3°C (149°F ± 5°F) for 1 hour (± 5 minutes). This temperature was selected to represent automotive applications.

[0089] After heating in an oven for one hour, the cans were removed. The first member of the expert panel brought their head close to the control can (approximately 15 cm away) and removed the lid. Then, the first member cupped their hand, fanned the air escaping from the can to their nose, and slowly inhaled. The first member immediately repeated the procedure on the first sample (dry method) and recorded the corresponding rating (odor rating listed below). The time for removing the lid from the can should not exceed 5 seconds. The test was conducted in an environment free of airflow and polluting odors. The test results are shown in Table 4. Sample A used here weighed approximately 280 GSM and had a thickness of 30 mm, while sample B used here weighed approximately 380 GSM and had a thickness of 38 mm.

[0090] Odor Rating - Rating Descriptions

[0091] 1. No obvious odor

[0092] 2. A slight but noticeable odor

[0093] 3. It has a distinct odor, but it's not so strong as to be unpleasant.

[0094] 4. Strong, unpleasant odor

[0095] 5. A very strong, unpleasant odor

[0096]

[0097] The acoustic product did not exhibit any unpleasant odor.

[0098] Airflow Resistance Test per ASTM C-522

[0099] The airflow resistance of the acoustic components was measured for sample A, which weighs approximately 280 GSM and has a thickness of 30 mm, and sample B, which weighs approximately 380 GSM and has a thickness of 38 mm.

[0100] The test results are shown in Table 5.

[0101]

[0102] Loft Retention Test under Static Load Conditions

[0103] Figure 13 The results of the bulk retention test under static load conditions for acoustic articles are shown compared to a standard meltblown-based absorber with only one grade of polyester fiber. The acoustic articles used here are sample A, weighing approximately 280 GSM and 30 mm thick, and comparative sample B, weighing approximately 240 GSM and 23 mm thick. For a sample size of 30 cm × 30 cm, a static load of 2 kg was considered here. The initial thicknesses of acoustic article sample A and comparative sample B were measured. A static load of 2 kg was applied to the 30 cm × 30 cm samples and maintained under the load condition for 7 days. The thickness under the load was measured. After seven days, the load was removed, and the recovered thickness was measured. The samples were further maintained under normal conditions without any load for 3 days, and the recovered thickness was measured again.

[0104] Key observations:

[0105] a) Compared to comparison sample B, acoustic product sample A exhibits excellent loft retention characteristics after static loading conditions.

[0106] b) The bulkiness retention properties of acoustic products help maintain sound absorption properties after molding.

[0107] c) Compared to sample B (a standard meltblown absorber with only one grade of polyester fiber), the acoustic product sample A has a higher loft retention characteristic due to the addition of two different grades of polyester fiber.

[0108]

[0109] Tensile Strength Measurement

[0110] The tensile strength of an acoustic product was evaluated. The acoustic product included sample A, which weighed approximately 280 GSM and had a thickness of 30 mm, and sample B, which weighed approximately 380 GSM and had a thickness of 38 mm. The tensile strength was evaluated in both the longitudinal (MD) and transverse (CD) directions. The sample size was 250 mm × 50 mm, and the tensile speed was 200 mm / min.

[0111] The tensile strength results for samples A and B are shown in Table 7.

[0112]

[0113] Sound Absorption Coefficient (SAC) - Noise measurements using impedance tube (normal incidence) per ASTM E1050 standard

[0114] Figure 14This diagram shows the sound absorption coefficient of acoustic product sample B with an additional nonwoven porous layer, tested according to ASTM E1050 standards using an impedance tube in the case of a noise-facing acoustic product, at frequencies from 200 Hz to 5000 Hz. The acoustic product used here is sample B, weighing 380 GSM and 38 mm thick, combined with an additional nonwoven porous layer weighing 800 GSM and 30 mm thick.

[0115] Key Observations :

[0116] a) In tests conducted on sample B, which was combined with an additional nonwoven porous layer, the acoustic article exhibited excellent overall (200 Hz to 5000 Hz) absorption coefficients. (200 Hz: 29% absorption; 500 Hz: 67% absorption; 1000 Hz: 100% absorption; 2000 Hz: 88% absorption; 4000 Hz: 91% absorption; 5000 Hz: 87% absorption)

[0117] The SAC results are shown in Table 8.

[0118]

[0119] Although the invention has been described in considerable detail with reference to certain preferred embodiments and examples thereof, other embodiments and equivalents are possible. While numerous features and advantages of this disclosure, as well as functional and process details, have been set forth in the foregoing description, this disclosure is merely illustrative and changes in detail are possible within the principles of this disclosure and to the maximum extent indicated by the general broad meaning of the terms. Therefore, various modifications to the systems and processes currently disclosed are possible without departing from the intended scope and spirit of this disclosure. Thus, in one embodiment, such modifications to the currently described disclosure are included within the scope of this disclosure.

Claims

1. An acoustic article, the article comprising: Meltblown microfibers; Two or more polyester fibers, said two or more polyester fibers together with said meltblown microfibers forming a mesh matrix, wherein the grade of the first polyester fiber in said mesh matrix is ​​different from the grade of the second polyester fiber, thereby creating a lower affinity between these fibers, and wherein at least one of said two polyester fibers is a recycled polyester fiber; and A first sparse fabric layer and a second sparse fabric layer are placed on opposite surfaces of the mesh matrix.

2. The article of claim 1, wherein the meltblown microfiber is polypropylene.

3. The article according to claim 1, wherein the weight ratio of the first polyester fiber to the second polyester fiber in the mesh matrix is ​​1:

2.

4. The article according to claim 1, wherein at least one of the polyester fibers is multileaf polyester staple fiber (MLPS).

5. The article of claim 1, wherein the meltblown microfibers constitute no more than 53% by weight of the mesh matrix.

6. The article of claim 1, wherein the denier of the polyester fiber is in the range of about 3D to 12D.

7. The article of claim 1, wherein the denier of the polyester fiber is in the range of about 4D to 7D.

8. The article according to claim 1, wherein the short fiber length of the polyester fiber is about 51 mm to 76 mm.

9. The article of claim 1, wherein one or more of the polyester fibers have a toughness of about 2.8 GPD (g / denier) to 4.5 GPD (g / denier).

10. The article according to claim 1, wherein the number of crimps of one or more of the polyester fibers is from 2.18 to 3.5 crimps / cm.

11. The article of claim 1, wherein the basis weight of the acoustic article is about 180 GSM to 1000 GSM.

12. The article of claim 1, wherein the first loose fabric layer is one of polyethylene terephthalate and polypropylene.

13. The article of claim 1, wherein the second loose fabric layer is one of polyethylene terephthalate and polypropylene.

14. The article of claim 1, wherein the article has an airflow resistance of 300 Mks Rayl to 800 Mks Rayl in the case of GSM 280.

15. The article of claim 1, wherein the article has an airflow resistance of 350 Mks Rayl to 450 Mks Rayl in the case of GSM 280.

16. The article of claim 1, wherein the article has an airflow resistance of 500 Mks Rayl to 2000 Mks Rayl in the case of GSM 380.

17. The article of claim 1, wherein the article has an airflow resistance of 1200 Mks Rayl to 2000 Mks Rayl in the case of GSM 380.

18. The article of claim 1, wherein the article has a loft retention property, wherein when removed from a static load condition of 2 kg / 900 cm² observed for 7 days, the loft retention percentage is at least 85% compared to the original thickness.

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