Sound absorption and noise reduction spacer fabric composite material for automotive trim and preparation method of sound absorption and noise reduction spacer fabric composite material

Abstract

The invention belongs to the technical field of automotive trim materials, and particularly relates to a sound absorption and noise reduction spacer fabric composite material for automotive trim and a preparation method thereof.The preparation method comprises the following steps that S1, a porous fiber sound absorption layer and a three-dimensional spacer fabric layer are prepared; polyester staple fibers are taken to be subjected to opening treatment and carding and then subjected to needling reinforcement, and a porous fiber sound absorption layer is obtained; taking polyester filament yarns as surface layer yarns, performing warp knitting to form an upper surface layer and a lower surface layer, and taking polyester monofilaments as middle connecting yarns to obtain a three-dimensional spacer fabric layer; s2, preparing a damping layer: compounding polyurethane emulsion with foam particles to obtain damping layer slurry, and uniformly spraying the damping layer slurry on the lower surface layer of the three-dimensional spacer fabric layer to obtain the damping layer; s3, the porous fiber sound absorption layer is laid on the upper surface layer of the three-dimensional spacer fabric layer, a stable layered structure is formed through hot-pressing compounding, and the spacer fabric composite material is obtained through drying treatment.

Description

Technical Field

[0001] This invention belongs to the field of automotive interior materials technology, specifically relating to a sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors and its preparation method. Background Technology

[0002] With the rapid development of the automotive industry, vehicle comfort has gradually become an important indicator of consumer concern, and in-vehicle noise level is one of the key factors in evaluating vehicle ride comfort. During operation, vehicles generate various types of noise, such as mechanical noise from engine vibration, rolling noise from tire-road friction, and aerodynamic noise from high-speed driving. These noises are transmitted into the passenger compartment through the vehicle structure, affecting the driving and riding experience.

[0003] Currently, commonly used sound-absorbing and noise-reducing materials in automotive interiors mainly include polyurethane foam, fiberglass sound-absorbing felt, and traditional non-woven fabrics. While these materials possess certain sound-absorbing properties, they still have some shortcomings in practical applications. Three-dimensional spacer fabric is a woven material with a three-dimensional structure, typically consisting of two layers of fabric connected by yarns to form a hollow cavity in the middle. This structure not only possesses good elasticity, breathability, and structural stability, but also can form a sound wave reflection and dissipation structure through the internal air layer, thus showing considerable application potential in the field of sound-absorbing materials.

[0004] However, existing three-dimensional spacer fabrics typically consist of upper and lower surface layers connected by vertical or inclined yarns, resulting in a relatively loose overall structure dominated by macroscopic pores. While this structure facilitates sound wave penetration, the low fiber surface area and uniform pore size lead to short propagation paths and energy dissipation primarily relying on limited air viscous resistance. Therefore, it suffers from the following main problems: first, absorption of mid-to-high frequency sound waves depends on limited fiber contact interfaces, limiting sound absorption efficiency; second, for low-frequency sound waves, the lack of effective damping structures allows for easy transmission, resulting in insufficient absorption; and third, the relatively interconnected internal channels allow sound waves to propagate "straight through," hindering effective multiple reflections and dissipation processes.

[0005] Therefore, how to significantly improve the mid-to-high frequency sound absorption performance while maintaining the advantages of high porosity and lightweight of three-dimensional spacer fabrics, and how to extend and enhance the sound absorption performance of materials in the low frequency range (100-500 Hz) to make up for the deficiencies of existing technologies, is a technical problem that urgently needs to be solved in this field.

[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0007] This disclosure provides at least one sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors and a method for preparing the same.

[0008] In a first aspect, embodiments of this disclosure provide a method for preparing a spacer fabric composite material, comprising the following steps: S1, preparing a porous fiber sound-absorbing layer and a three-dimensional spacer fabric layer respectively; wherein, the preparation of the porous fiber sound-absorbing layer includes: taking polyester short fibers, performing an opening treatment, then combing them into a uniform fiber web structure, and subsequently performing needle punching reinforcement in a needle punching device, so that the polyester short fibers in the fiber web structure are intertwined to obtain a porous fiber sound-absorbing layer; the preparation of the three-dimensional spacer fabric layer includes: taking polyester filaments as the surface yarn, and using a warp knitting process to form a composite material with... S1. A three-dimensional spacer fabric layer is obtained by using polyester monofilament as the intermediate connecting yarn between the upper and lower surface layers with a plain weave or mesh structure upper and lower surface layers; S2. A damping layer is prepared by: compounding polyurethane emulsion with foam particles, adding silane coupling agent and surfactant for dispersion, obtaining a damping layer slurry, and uniformly spraying it on the lower surface of the three-dimensional spacer fabric layer to obtain a damping layer; S3. The porous fiber sound-absorbing layer is laid on the upper surface of the three-dimensional spacer fabric layer, and a stable layered structure is formed by hot pressing, followed by drying to obtain a spacer fabric composite material.

[0009] In one optional embodiment, the polyester staple fiber in S1 has a length of 38-42 mm and a linear density of 1.5-2.0 dtex.

[0010] In one optional embodiment, the density of needle punctures in S1 is 150-200 times / cm. 2 The frequency is 600-800 times / min.

[0011] In one optional embodiment, the linear density of the polyester filament in S1 is 75D / 36F to 150D / 72F.

[0012] In one optional embodiment, the weaving speed of the three-dimensional spacer fabric layer in S1 is 600–800 r / min, the spacing height between the upper and lower surface layers is 5–8 mm, and the areal density is 300–400 g / m³. 2 .

[0013] In one optional embodiment, S2 comprises the following components by mass: 5-10 parts of polyurethane emulsion, 1-5 parts of polyurethane foam particles, 0.5-2 parts of silane coupling agent, 0.1-0.5 parts of surfactant, and 10-20 parts of deionized water; wherein the ratio of the polyurethane emulsion to the deionized water is 1:1 to 1:3.

[0014] In one optional embodiment, the rotational speed of dispersion in S2 is 1000-1500 r / min.

[0015] In one optional embodiment, the hot pressing temperature in S3 is 110-130°C, the pressure is 0.3-0.5 MPa, and the hot pressing time is 3-5 min.

[0016] Secondly, this disclosure also provides a spacer fabric composite material, prepared by the method described above, wherein the spacer fabric composite material has a sound absorption coefficient of not less than 0.25 in the 100-500Hz frequency band, a sound absorption coefficient of not less than 0.40 in the 500-2000Hz frequency band, and a sound absorption coefficient of not less than 0.60 in the 2000-4000Hz frequency band.

[0017] Thirdly, embodiments of this disclosure also provide an automotive interior that employs the spacer fabric composite material as described above.

[0018] The beneficial effects of this invention are that the sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors and its preparation method employ a three-dimensional spacer fabric as a skeleton structure, which is combined with a porous fiber sound-absorbing layer to form a multi-layered structural system with high porosity. This invention does not simply use a three-dimensional spacer fabric, but rather performs multi-level synergistic improvements to its structural system: First, by constructing a porous fiber sound-absorbing layer, this invention composites a porous fiber sound-absorbing layer on the surface of the three-dimensional spacer fabric. Through a high specific surface area fiber network formed by needle punching, the original macroporous structure is transformed into a multi-scale pore system of "micropores + macropores." This results in a uniformly distributed three-dimensional fiber network structure within the material. This structure increases airflow resistance and sound wave propagation path, causing sound energy to continuously rub and dissipate between fibers, thereby effectively improving the material's absorption capacity for mid-to-high frequency noise and further improving the acoustic environment inside the vehicle. Second, a damping layer is introduced on the other side of the three-dimensional spacer fabric, and a viscoelastic damping structure is constructed using a polyurethane matrix and foam particles. It should be noted that three-dimensional spacer fabrics have high porosity and a through-channel structure, making it difficult for conventional damping materials to achieve stable adhesion on their surface. This often leads to over-permeation or localized accumulation, affecting structural stability and sound absorption performance. This invention reduces system viscosity by adjusting the ratio of polyurethane emulsion to water and introduces a silane coupling agent to enhance the interfacial bonding between the damping layer and the fiber surface, enabling the damping material to form a uniform and stable adhesion structure on the spacer fabric surface. Simultaneously, by introducing foam particles to construct a multi-scale damping structure, the polyurethane matrix undergoes viscoelastic deformation under the action of sound waves, while interfacial friction forms between the foam particles and the matrix, effectively converting sound energy into heat energy. This structure introduces an additional energy dissipation mechanism while ensuring that the air channels inside the three-dimensional spacer fabric are not completely blocked, thus significantly improving the material's low-frequency sound absorption performance. When low-frequency sound waves act, this structure can generate significant deformation and interfacial friction, converting sound energy into heat energy, effectively solving the problem of insufficient low-frequency sound absorption capacity of traditional three-dimensional spacer fabrics. This achieves synergistic absorption of mid-high and low-frequency noise, expanding the material's effective sound absorption frequency range. Furthermore, by adjusting the spacing height and connecting yarn structure of the three-dimensional spacer fabric, a non-straight-through curved propagation channel is formed inside, preventing direct sound wave penetration and further enhancing the reflection and dissipation of sound waves within the material. In summary, the composite material prepared by this invention possesses excellent softness, breathability, and structural stability. The three-dimensional spacer fabric ensures the material has a certain thickness and resilience, while the porous fiber layer improves comfort and breathability, enabling it to meet sound absorption and noise reduction requirements in automotive interior applications without compromising ride comfort.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0023] In this document, as used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0024] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0025] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] This disclosure provides a method for preparing a spacer fabric composite material, comprising the following steps: S1, preparing a porous fiber sound-absorbing layer and a three-dimensional spacer fabric layer respectively; wherein, the preparation of the porous fiber sound-absorbing layer includes: taking polyester short fibers, performing an opening treatment, then combing them into a uniform fiber web structure, and subsequently performing needle punching reinforcement in a needle punching device to make the polyester short fibers in the fiber web structure entangled with each other to obtain a porous fiber sound-absorbing layer; the preparation of the three-dimensional spacer fabric layer includes: taking polyester filaments as the surface yarn, and using a warp knitting process to form a plain weave or The upper and lower surfaces of the mesh structure are made of polyester monofilament as the intermediate connecting yarn to obtain a three-dimensional spacer fabric layer; S2, a damping layer is prepared by: compounding polyurethane emulsion with foam particles, adding silane coupling agent and surfactant for dispersion, obtaining a damping layer slurry, and uniformly spraying it on the lower surface of the three-dimensional spacer fabric layer to obtain a damping layer; S3, the porous fiber sound-absorbing layer is laid on the upper surface of the three-dimensional spacer fabric layer, and a stable layered structure is formed by hot pressing, followed by drying to obtain a spacer fabric composite material.

[0027] Specifically, the upper and lower skin structures and the lining yarn connection method in the three-dimensional spacer fabric layer are designed in a coordinated manner. If only one parameter is changed without matching adjustment, the material pore structure will be unbalanced, thereby affecting the sound absorption performance.

[0028] In some embodiments, specifically, the length of the polyester staple fiber in S1 is 38-42 mm, and the linear density is 1.5-2.0 dtex.

[0029] In some embodiments, specifically, the density of needle punctures in S1 is 150-200 times / cm. 2 The frequency is 600-800 times / min.

[0030] In some embodiments, specifically, the linear density of the polyester filament in S1 is 75D / 36F to 150D / 72F.

[0031] In some embodiments, specifically, the weaving speed of the three-dimensional spacer fabric layer in S1 is 600–800 r / min, the spacing height between the upper and lower surface layers is 5–8 mm, and the areal density is 300–400 g / m³. 2 .

[0032] In some embodiments, specifically, S2 includes the following components by mass: 5-10 parts of polyurethane emulsion, 1-5 parts of polyurethane foam particles, 0.5-2 parts of silane coupling agent, 0.1-0.5 parts of surfactant, and 10-20 parts of deionized water; wherein the ratio of the polyurethane emulsion to the deionized water is 1:1 to 1:3.

[0033] In some embodiments, specifically, the rotational speed of dispersion in S2 is 1000-1500 r / min.

[0034] In some embodiments, specifically, the hot pressing temperature in S3 is 110-130°C, the pressure is 0.3-0.5 MPa, and the hot pressing time is 3-5 min.

[0035] This disclosure also provides a spacer fabric composite material, prepared by the method described above. The spacer fabric composite material has a sound absorption coefficient of not less than 0.25 in the 100-500Hz frequency band, not less than 0.40 in the 500-2000Hz frequency band, and not less than 0.60 in the 2000-4000Hz frequency band.

[0036] This disclosure also provides an automotive interior that uses the spacer fabric composite material as described above.

[0037] Example 1: Preparation of a sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors, comprising the following steps: (1) Select polyester staple fiber (length 38-42mm, linear density 1.5-2.0dtex) for opening treatment. Put 10g of polyester staple fiber into a small opening machine and treat for 10 minutes. Then, comb the fiber into a uniform fiber web. Send the fiber web into a needle punching machine for needle punching reinforcement. The needle punching density is 150 times / cm. 2 The needle puncture frequency is 600 times / min, thus obtaining a porous fiber sound-absorbing layer with a thickness of about 1mm.

[0038] (2) The three-dimensional spacer fabric layer is warp-knitted, with polyester filament yarn of 75D / 36F linear density and polyester monofilament yarn as the connecting yarn. The weaving speed is controlled at 600r / min, the spacing height is 5mm, and the areal density is 300g / m². 2 After weaving, a spacer fabric substrate with a stable three-dimensional structure is obtained.

[0039] (3) Add the polyurethane emulsion to deionized water at a ratio of 1:1, add 2.0% by mass of silane coupling agent KH-550 and 0.3% by mass of surfactant, and disperse at 1000 r / min for 10 minutes to ensure thorough mixing of all components and obtain a uniform damping coating solution. Then add 5% by mass of polyurethane foam particles (particle size 200-500 μm) and continue stirring for 5 minutes to ensure uniform dispersion of the damping sound-absorbing slurry, providing low-frequency sound absorption and damping functions for the composite material.

[0040] (4) A porous fiber sound-absorbing layer was laid on the surface of a three-dimensional spacer fabric. Damping sound-absorbing slurry was uniformly sprayed onto the bottom of the spacer fabric. The composite process was carried out by a flatbed hot press. The hot pressing temperature was controlled at 110℃, the pressure at 0.3MPa, and the time at 3 minutes. After hot pressing, the composite material was allowed to cool naturally to room temperature to stabilize the structure. It was then dried at 60℃ for 8 hours to further remove residual moisture and solvent, finally obtaining a composite material of automotive interior sound-absorbing and noise-reducing spacer fabric with a complete composite structure.

[0041] (5) To verify the sound absorption performance of the composite material of the present invention in different frequency ranges, its sound absorption coefficient in different frequency bands was tested and analyzed. The impedance tube method was used to measure the sound absorption performance of the material in the range of 100 to 4000 Hz, and the frequency was divided into low frequency band (100 to 500 Hz), mid frequency band (500 to 2000 Hz) and high frequency band (2000 to 4000 Hz).

[0042] Example 2: Preparation of a sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors, comprising the following steps: (1) Select polyester staple fiber (length 38-42mm, linear density 1.5-2.0dtex) for opening treatment. Put 12g of polyester staple fiber into a small opening machine and treat for 12 minutes. Then, comb the fiber into a uniform fiber web. Send the fiber web into a needle punching machine for needle punching reinforcement. The needle punching density is 180 times / cm. 2 The needle puncture frequency is 700 times / min, thus obtaining a porous fiber sound-absorbing layer with a thickness of about 1.5mm.

[0043] (2) The three-dimensional spacer fabric layer is warp-knitted, with polyester filament yarn as the face yarn, a yarn linear density of 120D / 64F, and polyester monofilament yarn as the connecting yarn. The weaving speed is controlled at 700r / min, the spacer height is 6mm, and the areal density is 400g / m². 2 After weaving, a spacer fabric substrate with a stable three-dimensional structure is obtained.

[0044] (3) Add polyurethane emulsion to deionized water at a ratio of 1:2, add 6.0% by mass of silane coupling agent KH-550 and 0.5% by mass of surfactant, and disperse at 1200 r / min for 15 minutes to ensure thorough mixing of all components and obtain a uniform damping coating solution. Then add 10% by mass of polyurethane foam particles (particle size 200-500 μm) and continue stirring for 10 minutes to ensure uniform dispersion of the damping sound-absorbing slurry, providing low-frequency sound absorption and damping functions for the composite material.

[0045] (4) A porous fiber sound-absorbing layer was laid on the surface of a three-dimensional spacer fabric. Damping sound-absorbing slurry was uniformly sprayed onto the bottom of the spacer fabric. The composite process was carried out by a flatbed hot press. The hot pressing temperature was controlled at 120℃, the pressure at 0.4MPa, and the time at 5 minutes. After hot pressing, the composite material was allowed to cool naturally to room temperature to stabilize the structure. It was then dried at 70℃ for 9 hours to further remove residual moisture and solvent, finally obtaining a composite material of automotive interior sound-absorbing and noise-reducing spacer fabric with a complete composite structure.

[0046] (5) To verify the sound absorption performance of the composite material of the present invention in different frequency ranges, its sound absorption coefficient in different frequency bands was tested and analyzed. The impedance tube method was used to measure the sound absorption performance of the material in the range of 100 to 4000 Hz, and the frequency was divided into low frequency band (100 to 500 Hz), mid frequency band (500 to 2000 Hz) and high frequency band (2000 to 4000 Hz).

[0047] Example 3: Preparation of a sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors, comprising the following steps: (1) Select polyester staple fiber (length 38-42mm, linear density 1.5-2.0dtex) for opening treatment. Put 20g of polyester staple fiber into a small opening machine and treat for 15 minutes. Then, comb the fiber into a uniform fiber web. Send the fiber web into a needle punching machine for needle punching reinforcement. The needle punching density is 200 times / cm. 2 The needle puncture frequency is 800 times / min, thus obtaining a porous fiber sound-absorbing layer with a thickness of about 2mm.

[0048] (2) The three-dimensional spacer fabric layer is warp-knitted, with polyester filament yarn of 150D / 96F linear density and polyester monofilament yarn as the connecting yarn. The weaving speed is controlled at 800 r / min, the spacing height is 8 mm, and the areal density is 500 g / m². 2 After weaving, a spacer fabric substrate with a stable three-dimensional structure is obtained.

[0049] (3) Add polyurethane emulsion to deionized water at a ratio of 1:3, add 10% by mass of silane coupling agent KH-550 and 1.0% by mass of surfactant, and disperse at 1200 r / min for 15 minutes to ensure thorough mixing of all components and obtain a uniform damping coating solution. Then add 10% by mass of polyurethane foam particles (particle size 200-500 μm) and continue stirring for 10 minutes to form a uniformly dispersed state of the damping sound-absorbing slurry, providing low-frequency sound absorption and damping functions for the composite material.

[0050] (4) A porous fiber sound-absorbing layer is laid on the surface of a three-dimensional spacer fabric. Damping sound-absorbing slurry is uniformly sprayed onto the bottom of the spacer fabric. The composite process is carried out by a flatbed hot press. The hot pressing temperature is controlled at 120℃, the pressure is 0.5MPa, and the time is 5 minutes. After hot pressing, the composite material is allowed to cool naturally to room temperature to stabilize the structure. It is then dried at 80℃ for 10 hours to further remove residual moisture and solvent, finally obtaining a composite material of automotive interior sound-absorbing and noise-reducing spacer fabric with a complete composite structure.

[0051] (5) To verify the sound absorption performance of the composite material of the present invention in different frequency ranges, its sound absorption coefficient in different frequency bands was tested and analyzed. The impedance tube method was used to measure the sound absorption performance of the material in the range of 100 to 4000 Hz, and the frequency was divided into low frequency band (100 to 500 Hz), mid frequency band (500 to 2000 Hz) and high frequency band (2000 to 4000 Hz).

[0052] Comparative Example 1 (1) Select polyester staple fiber (length 38-42mm, linear density 1.5-2.0dtex) for opening treatment. Put 20g of polyester staple fiber into a small opening machine and treat for 15 minutes. Then, comb the fiber into a uniform fiber web. Send the fiber web into a needle punching machine for needle punching reinforcement. The needle punching density is 200 times / cm. 2 The needle puncture frequency is 800 times / min, thus obtaining a porous fiber sound-absorbing layer with a thickness of about 2mm.

[0053] (2) The three-dimensional spacer fabric layer is warp-knitted, with polyester filament yarn of 150D / 96F linear density and polyester monofilament yarn as the connecting yarn. The weaving speed is controlled at 800r / min, the spacing height is 8mm, and the areal density is 50g / m². 2 After weaving, a spacer fabric substrate with a stable three-dimensional structure is obtained.

[0054] (3) Construct a composite structure by laying a porous fiber sound-absorbing layer on the surface of a three-dimensional spacer fabric and performing composite processing using a flatbed hot press. The hot pressing temperature is controlled at 120℃, the pressure at 0.5MPa, and the time at 5 minutes. After hot pressing, the composite material is allowed to cool naturally to room temperature to stabilize the structure. It is then dried at 80℃ for 10 hours to further remove residual moisture and solvent, finally obtaining a composite material of automotive interior sound-absorbing spacer fabric without a damping layer.

[0055] (4) To verify the sound absorption performance of the comparative material in different frequency ranges, its sound absorption coefficient in different frequency bands was tested and analyzed. The impedance tube method was used to measure the sound absorption performance of the material in the range of 100 to 4000 Hz, and the frequency was divided into low frequency band (100 to 500 Hz), mid frequency band (500 to 2000 Hz) and high frequency band (2000 to 4000 Hz).

[0056] Sound absorption performance test: Referring to the People's Republic of China National Standard GB / T18696.1-2004 "Measurement of Sound Absorption Coefficient and Acoustic Impedance in Acoustic Impedance Tubes - Part 1: Standing Wave Ratio Method", the sound absorption performance of the composite sound-absorbing material prepared in this invention was tested using a standing wave tube sound absorption coefficient tester. The composite sound-absorbing material has dimensions of 20cm×10cm×20mm, and the sound center frequencies are 400Hz, 1000Hz, and 2000Hz, respectively. The results are expressed as sound absorption coefficients. Five parallel tests were performed, and the average value was taken, as shown in Table 1.

[0057] Table 1 Test Results

[0058] Specifically, in the low-frequency range, the damping layer plays a decisive role. The damping layer, made of polyurethane and foam particles, can provide vibration energy dissipation, thereby compensating for the low-frequency sound absorption shortcomings of the three-dimensional spacer fabric and fiber layer.

[0059] Specifically, in the mid-frequency range, the porous fiber sound-absorbing layer plays a major role. The three-dimensional fiber network formed by needle punching has a high specific surface area and a uniformly distributed microporous structure, which can significantly increase airflow resistance, causing sound waves to undergo multiple reflections and frictions between the fibers, thereby effectively dissipating sound energy through viscous loss. At the same time, the support structure provided by the three-dimensional spacer fabric can extend the sound wave propagation path, further improving the mid-frequency sound absorption performance.

[0060] Specifically, in the high-frequency range, the synergistic effect of the material's multi-scale porous structure is more pronounced. High-frequency sound waves, with their shorter wavelengths, more easily penetrate the micropores within the fiber layer, undergoing strong scattering and multiple reflections within the porous structure, thus being fully absorbed. Furthermore, the spatial structure of the three-dimensional spacer fabric helps increase the complexity of the sound wave incident path, working in conjunction with the porous fiber layer to improve high-frequency sound absorption efficiency.

[0061] It should be noted that the differences in sound absorption performance in the mid-to-high frequency range between Examples 1 and 3 mainly stem from the varying degrees of synergistic matching between the structural parameters of the porous fiber sound-absorbing layer and the structural parameters of the three-dimensional spacer fabric. As the fiber layer thickness, needle-punching density, and fiber content increase, the internal microporous structure of the material gradually becomes more complete, increasing airflow resistance and thus enhancing the viscous dissipation capability of sound waves in the mid-frequency range. Simultaneously, the spacing height, yarn linear density, and areal density of the three-dimensional spacer fabric gradually increase, lengthening the sound wave propagation path and enhancing internal reflection and scattering, thereby significantly improving high-frequency sound absorption performance.

[0062] In Example 3, the microscopic pore structure and the macroscopic support structure achieve a better match, forming a uniform multi-scale pore system. This allows sound waves to undergo multiple reflections, scattering, and frictional dissipation within the material, resulting in optimal sound absorption performance in the mid-to-high frequency range. In contrast, Example 1, due to its thinner fiber layer and insufficient structural matching, suffers from a shorter sound wave propagation path and lower dissipation efficiency, thus exhibiting relatively poor sound absorption performance.

[0063] In summary, this invention, concerning a sound-absorbing and noise-reducing spacer fabric composite material for automotive interiors and its preparation method, employs a three-dimensional spacer fabric as a skeleton structure, combined with a porous fiber sound-absorbing layer to form a multi-layered structural system with high porosity. The three-dimensional spacer fabric provides a stable spatial support structure while maintaining the material's lightweight nature, and forms continuous air channels within the fabric, causing sound waves to undergo multiple reflections and attenuations within the material, thus significantly improving the overall sound absorption performance. Secondly, by constructing a porous fiber sound-absorbing layer, this invention creates a uniformly distributed three-dimensional fiber network structure within the material. This structure increases airflow resistance and the sound wave propagation path, causing sound energy to continuously rub and dissipate between the fibers, effectively improving the material's absorption capacity for mid-to-high frequency noise and further improving the acoustic environment inside the vehicle. Thirdly, this invention introduces a damping layer into the composite structure, forming a multi-scale damping structure through a polyurethane matrix and foam particles, which generates significant energy dissipation under the action of sound waves. This structure compensates for the insufficient absorption capacity of traditional fiber sound-absorbing materials for low-frequency noise, thereby achieving synergistic absorption of mid-to-high frequency and low-frequency noise and expanding the effective sound absorption frequency range of the material. Furthermore, the composite material prepared by this invention possesses excellent softness, breathability, and structural stability. The three-dimensional spacer fabric ensures that the material has a certain thickness and resilience, while the porous fiber layer improves comfort and breathability, enabling it to meet the requirements for sound absorption and noise reduction in automotive interior applications without compromising passenger comfort.

[0064] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a spacer fabric composite material, characterized in that, Includes the following steps: S1, respectively prepare porous fiber sound-absorbing layer and three-dimensional spacer fabric layer; The preparation of the porous fiber sound-absorbing layer includes: taking polyester short fibers, opening them, combing them into a uniform fiber web structure, and then reinforcing them by needle punching in a needle punching device, so that the polyester short fibers in the fiber web structure are entangled with each other to form a three-dimensional cross-linked structure, thereby obtaining a porous fiber sound-absorbing layer. The preparation of the three-dimensional spacer fabric layer includes: taking polyester filament as the surface yarn, using warp knitting process to form an upper surface layer and a lower surface layer with plain weave or mesh structure, and using polyester monofilament as the intermediate connecting yarn between the upper surface layer and the lower surface layer to obtain a three-dimensional spacer fabric layer. S2, preparing the damping layer includes: compounding polyurethane emulsion with foam particles, adding silane coupling agent and surfactant for dispersion to obtain a damping layer slurry, and uniformly spraying it onto the lower surface of the three-dimensional spacer fabric layer to obtain the damping layer; S3, the porous fiber sound-absorbing layer is laid on the upper surface of the three-dimensional spacer fabric layer, and a stable layered structure is formed by hot pressing and bonding, followed by drying to obtain the spacer fabric composite material.

2. The preparation method according to claim 1, characterized in that, The polyester staple fiber in S1 has a length of 38–42 mm and a linear density of 1.5–2.0 dtex.

3. The preparation method according to claim 1, characterized in that, The acupuncture density in S1 is 150-200 times / cm. 2 The frequency is 600-800 times / min.

4. The preparation method according to claim 1, characterized in that, The linear density of the polyester filament in S1 is 75D / 36F to 150D / 72F.

5. The preparation method according to claim 1, characterized in that, The weaving speed of the three-dimensional spacer fabric layer in S1 is 600-800 r / min, the spacing height between the upper and lower surface layers is 5-8 mm, and the areal density is 300-400 g / m³. 2 .

6. The preparation method according to claim 1, characterized in that, S2 comprises the following components by mass parts: The mixture consists of 5-10 parts polyurethane emulsion, 1-5 parts polyurethane foam particles, 0.5-2 parts silane coupling agent, 0.1-0.5 parts surfactant, and 10-20 parts deionized water. The ratio of the polyurethane emulsion to the deionized water is 1:1 to 1:

3.

7. The preparation method according to claim 1, characterized in that, The dispersion speed in S2 is 1000-1500 r / min.

8. The preparation method according to claim 1, characterized in that, The hot pressing temperature in S3 is 110-130℃, the pressure is 0.3-0.5MPa, and the hot pressing time is 3-5min.

9. A spacer fabric composite material, characterized in that, The spacer fabric composite material prepared by the method described in any one of claims 1-8 has a sound absorption coefficient of not less than 0.25 in the 100-500Hz frequency band, not less than 0.40 in the 500-2000Hz frequency band, and not less than 0.60 in the 2000-4000Hz frequency band.

10. An automotive interior, characterized in that, The spacer fabric composite material as described in claim 9 is used.

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