Multilayer special-shaped section sound absorption material and preparation method thereof

Abstract

The invention relates to a multilayer special-shaped section sound absorption material and a preparation method thereof. The multilayer special-shaped section sound absorption material comprises a special-shaped layer, a bottom layer and a plurality of supporting assemblies evenly distributed between the special-shaped layer and the bottom layer. The supporting assemblies, the special-shaped layer and the bottom layer define a cavity. The special-shaped layer is of a multi-layer laminated structure, and the multiple layers are independently selected from any one of a linear layer, a circular layer and a pentagram-shaped layer and are different from one another; wherein the cross section of fibers used by the straight-line-shaped layer is straight-line-shaped; the cross section of the fiber used by the circular layer is circular; and the section of the fiber used by the pentagram-shaped layer is pentagram-shaped. When sound waves penetrate through the special-shaped layer, the sound waves can be reflected back and forth and spread among the linear layer, the circular layer and the pentagram-shaped layer of the special-shaped layer, and therefore sound energy can be further consumed, and the multilayer special-shaped section sound absorption material has good sound absorption performance.

Description

Technical Field

[0001] The invention relates to the technical field of nonwoven sound absorption technology, in particular to a multi-layer special-shaped cross-section sound absorption material and a preparation method thereof. Background Art

[0002] With the rapid development of industrialization and urbanization, noise pollution has become increasingly prominent, and people's requirements for the sound absorption performance of sound-absorbing materials have gradually increased. Most of the sound-absorbing materials in the prior art use fibrous materials, but due to the limitations of the structure and morphology of the fiber materials, their sound absorption performance is subject to certain restrictions, and the sound absorption performance in the low frequency band is poor. The traditional method of improving the sound absorption performance in the low frequency band includes increasing the thickness of the material, which makes the sound-absorbing material thick and heavy, and cannot meet people's daily needs.

[0003] Compared with traditional fibrous sound-absorbing materials, non-woven sound-absorbing materials have the characteristics of high porosity, fine fiber diameter, light and thin materials, wide raw material sources, low cost, simple production process, etc., and have broad application prospects. Patent CN110753613A proposes a method for preparing a non-woven sound-absorbing material, which is composed of stacking a porous sound-absorbing body and two or more non-woven fabrics, wherein the non-woven fabric has a plurality of long fiber filaments that are stretched and arranged in a single direction. The stacking method of the sound-absorbing material will increase the thickness of the sound-absorbing material and make the sound-absorbing material thick. Patent CN107366089A proposes a non-woven fabric made of multiple extremely fine fibers formed by thermoplastic resin as a sound-absorbing material, which reduces the weight and thickness of the sound-absorbing material, but the finer the diameter of the fiber constituting the non-woven fabric, the lower the mechanical strength of the fiber, and the mechanical strength of the non-woven fabric will also decrease accordingly. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problems of poor sound absorption effect and reduced mechanical strength of the sound absorbing material in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a multi-layer special-shaped cross-section sound-absorbing material and a preparation method thereof, which has good sound absorption performance at 500Hz-2500Hz. The porosity of the three special-shaped cross-section non-woven fabrics is different, and a variety of non-woven materials are combined into a composite material, so that their impedance characteristics are different. When sound waves pass through non-woven fabrics with different cross-sectional shapes, the sound waves will be reflected and propagated back and forth between the two, thereby further consuming sound energy. When the pore values ​​of the two materials are greatly different, the sound wave reflection and propagation path between the two interfaces are further increased. In addition, the cavity and the woven fabric also participate in the absorption of sound waves. The cavity extends the propagation path of the sound wave and increases the energy consumed when the sound wave propagates in the cavity; at the same time, the woven fabric and the cavity form a resonance cavity, and the resonance cavity improves the sound absorption effect of the multi-layer non-woven material, further improving the sound absorption performance of the sound absorbing material. The fiber structure of the nonwoven fabric presents a disordered arrangement state, which gives the nonwoven fabric higher flexibility and plasticity, making it adaptable to various complex curved shapes. At the same time, there is no obvious directionality between the fibers, making the nonwoven fabric have better deformability and stretchability. Therefore, the nonwoven fabric has good strength and wear resistance, and can meet the requirements of different application fields for material strength and durability. In addition, the present invention uses a foam bonding method to make the nonwoven fabrics bonded as a whole, which can achieve the purpose of enhancing mechanical strength.

[0006] The first object of the present invention is to provide a multi-layered sound-absorbing material with a special-shaped cross section, the sound-absorbing material comprising a special-shaped layer, a bottom layer, and a plurality of supporting components evenly distributed between the special-shaped layer and the bottom layer, wherein the supporting components, the special-shaped layer and the bottom layer enclose a cavity;

[0007] The special-shaped layer is a multi-layer stacked structure, and the multiple layers are independently selected from any one of a straight-line layer, a circular layer, and a five-pointed star layer and are different from each other; wherein,

[0008] The fiber cross section used in the straight-line layer is straight-line shaped;

[0009] The fibers used in the circular layer have a circular cross section;

[0010] The fiber cross section used in the five-pointed star layer is in the shape of a five-pointed star.

[0011] Furthermore, the special-shaped layer is preferably three-layered. When the special-shaped layer is three-layered, the thickness of the sound-absorbing material is relatively thin and the sound absorption efficiency is better.

[0012] Furthermore, the fiber cross-sectional size used in the I-shaped layer is 8-12D.

[0013] Furthermore, the cross-sectional size of the fibers used in the circular layer is 8-12D.

[0014] Furthermore, the fiber cross-sectional size used in the five-pointed star layer is 8-12D.

[0015] Furthermore, the straight-line layer, the circular layer and the five-pointed star layer are all reinforced in a non-woven manner.

[0016] Furthermore, the bonding method between the straight layer, the circular layer and the five-pointed star layer is a chemical bonding process foam impregnation method, specifically: the reinforced non-woven fiber layer is mixed with the foam of the adhesive to form a non-woven material with a certain strength and structure. The adhesive is selected as polyvinyl acetate (PVAc), and is physically stirred to produce a stable foam. Subsequently, the initially formed non-woven fiber layer is mixed with the adhesive foam, and the adhesive in the foam is evenly distributed between the fibers. Finally, the impregnated fiber layer is heated at 75°C for curing.

[0017] Furthermore, the thickness of the special-shaped layer is 3-4 mm.

[0018] Furthermore, the bottom layer is a plain woven fabric, the warp density of the plain woven fabric is 100-200 strands / inch, and the weft density is 100-200 strands / inch.

[0019] Furthermore, the support assembly is a cylindrical structure with a radius of 1.5-3 mm and a height of 8-10 mm. The distribution density of the support assembly is 2-4 pieces / cm 2 The upper surface and the lower surface of the support component are connected to the special-shaped layer and the bottom layer, and the height of the support component is the distance between the special-shaped layer and the bottom layer.

[0020] Furthermore, the support component is made of PE material.

[0021] A second object of the present invention is to provide a method for preparing a multilayer sound-absorbing material with a special-shaped cross section, comprising the following steps:

[0022] S1, spinning with spinneret microholes having an interface structure of a straight line, a circle, and a pentagonal star, respectively, to obtain straight-line fiber filaments, round fiber filaments, and pentagonal star-shaped fiber filaments, and reinforcing the straight-line fiber filaments, round fiber filaments, and pentagonal star-shaped fiber filaments into a straight-line layer, a circle layer, and a pentagonal star layer, respectively;

[0023] S2. Use an adhesive to bond the straight-line layer, the circular layer, the five-pointed star layer, the supporting assembly and the bottom layer to obtain the multi-layer special-shaped cross-section sound-absorbing material.

[0024] Furthermore, the spinning method is selected from any one of wet spinning, melt spinning and electrospinning.

[0025] Furthermore, the fiber is made of nylon.

[0026] Furthermore, before spinning, the nylon polymer needs to be dissolved in a formic acid solution to form a uniform spinning solution.

[0027] Furthermore, the reinforcement in step S1 is specifically: the straight fiber yarn, the round fiber yarn, and the five-pointed star fiber yarn are respectively reinforced into corresponding non-woven fabrics by needle punching, and the needle punching density of the needle punching reinforcement is 50-150 needles / cm 2 The needling depth is 5-15mm and the step amount is 5-15mm.

[0028] Furthermore, the adhesive is selected from one or more of polyvinyl acetate, polyurethane, styrene-butadiene rubber, polyurethane, nitrocellulose, and polyvinyl acetate.

[0029] Beneficial effects of the present invention:

[0030] (1) The multi-layered special-shaped cross-section sound-absorbing material provided by the present invention has good sound absorption performance at a frequency of 500Hz-2500Hz. The porosity of the three types of special-shaped cross-section non-woven fabrics is different, and the multiple non-woven materials are combined into a composite material, so that their impedance characteristics are different. When sound waves pass through non-woven fabrics of different cross-sectional shapes, the sound waves will be reflected back and forth between the two and propagate, thereby further consuming sound energy. Therefore, the multi-layered special-shaped cross-section sound-absorbing material of the present invention has good sound absorption performance.

[0031] (2) The cavity and woven fabric also participate in the absorption of sound waves. After the cavity is added, the propagation path of the sound wave is extended, which increases the energy consumed by the sound wave when propagating in the cavity; at the same time, the cavity formed between the woven fabric and the profiled layer acts as a resonance cavity, which can significantly improve the sound absorption effect of the profiled layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0033] Figure 1 The process flow chart of the multi-layer special-shaped cross-section sound-absorbing material of the present invention is as follows: 9, high-voltage power supply; 10, polymer solution; 11, five-pointed star nylon fiber; 12, cooling bellows; 13, spinneret; 14, extruder; 15, hopper; 16, straight nylon fiber; 17, coagulation bath; 18, spinneret; 19, round nylon fiber; 20, straight layer; 21, round layer; 22, five-pointed star layer;

[0034] Figure 2 It is a schematic diagram of the structure of the multi-layer special-shaped cross-section sound-absorbing material in the present invention; wherein: 1. a straight-line layer; 2. a circular layer; 3. a five-pointed star layer; 4. a supporting component; 5. a nylon woven fabric;

[0035] Figure 3 It is a schematic diagram of the sound absorption performance test of the multi-layer sound absorption material in the present invention; wherein: 6, woven fabric; 7, supporting material cavity; 8, multi-layer composite sound absorption material. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0037] In the present invention, the multi-layer special-section sound-absorbing material is mainly composed of three nylon non-woven fabrics with different sections, and the non-woven fabrics with different sections are bonded into a whole by a chemical bonding process foam impregnation method.

[0038] The PE supporting material structure is a cylinder with a height of 10mm and a radius of 2mm. It is distributed in an array between the non-woven fabric and the woven fabric, so that a cavity structure with a thickness of 10mm is generated in the multi-layer composite sound-absorbing material. Due to the existence of the cavity, the sound absorption band of the sound wave is widened, and the peak value will move to the medium and low frequencies, thereby improving the sound absorption performance of the medium and low frequencies. At the same time, the woven fabric also forms a resonance cavity with the cavity, and the sound absorption effect of the multi-layer non-woven material in the resonance cavity is improved, thereby significantly improving the sound absorption performance.

[0039] Example 1

[0040] This embodiment provides a method for preparing a multi-layer special-shaped cross-section sound-absorbing material, which specifically includes the following steps:

[0041] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0042] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0043] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0044] (4) Structural assembly of multi-layer special-shaped cross-section sound-absorbing materials: According to the experimental design requirements, three types of nylon non-woven fabrics with different cross-sections were cut and then neatly stacked in the order of a straight layer, a circular layer, and a five-pointed star layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, a woven fabric with a plain weave structure was bonded to the bottom.

[0045] Example 2

[0046] This embodiment provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The method is different from the first embodiment in that the stacking order of the special-shaped layers from top to bottom is a straight-line layer, a five-pointed star layer, and a circular layer. The method specifically includes the following steps:

[0047] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0048] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0049] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0050] (4) Structural assembly of multi-layer special-shaped cross-section sound-absorbing materials: According to the experimental design requirements, three types of nylon non-woven fabrics with different cross-sections were cut and then neatly stacked in the order of a straight layer, a five-pointed star layer, and a circular layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, a woven fabric with a plain weave structure was bonded to the bottom.

[0051] Example 3

[0052] This embodiment provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The method is different from the first embodiment in that the stacking order of the special-shaped layers from top to bottom is a circular layer, a five-pointed star layer, and a straight layer. The method specifically includes the following steps:

[0053] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0054] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0055] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0056] (4) Structural assembly of multi-layer special-shaped cross-section sound-absorbing materials: According to the experimental design requirements, three types of nylon non-woven fabrics with different cross-sections were cut and then neatly stacked in the order of circular layer, star-shaped layer, and straight layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, the woven fabric with a plain weave structure was bonded to the bottom.

[0057] Example 4

[0058] This embodiment provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The method is different from the first embodiment in that the stacking order of the special-shaped layers from top to bottom is a circular layer, a straight layer, and a five-pointed star layer. The method specifically includes the following steps:

[0059] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0060] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0061] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0062] (4) Structural assembly of multi-layer special-shaped cross-section sound-absorbing materials: According to the experimental design requirements, three types of nylon non-woven fabrics with different cross-sections were cut and then neatly stacked in the order of circular layer, straight layer, and five-pointed star layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, the woven fabric with a plain weave structure was bonded to the bottom.

[0063] Example 5

[0064] This embodiment provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The method is different from the first embodiment in that the stacking order of the special-shaped layers from top to bottom is a five-pointed star layer, a circular layer, and a straight layer. The method specifically includes the following steps:

[0065] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0066] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0067] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0068] (4) Structural assembly of multi-layer special-shaped cross-section sound-absorbing materials: According to the experimental design requirements, three types of cross-section nylon non-woven fabrics were cut and then neatly stacked in the order of a five-pointed star layer, a circular layer, and a straight layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, a woven fabric with a plain weave structure was bonded to the bottom.

[0069] Example 6

[0070] This embodiment provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The method is different from the first embodiment in that the stacking order of the special-shaped layers from top to bottom is a five-pointed star layer, a straight layer, and a circular layer. The method specifically includes the following steps:

[0071] (1) Preparation of the linear layer: a spinning micropore with a linear cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to form a uniform spinning solution, the spinning solution is extruded through the micropores on the linear spinneret to extrude filaments to obtain nylon fiber filaments with a linear cross-section, and then the nylon fiber filaments are placed in a coagulation bath (a mixed solution of water and N,N-dimethylacetamide (DMAc) is used as a coagulation bath), the nylon fiber is coagulated into a solid state, the nylon fiber filaments are stretched and shaped, and then wound to obtain a nylon fiber product, and the nylon fiber product is reinforced by needle punching to make a nonwoven fabric.

[0072] (2) Preparation of circular layer: Processing spinneret micropores with circular cross-sectional structural shapes on the spinneret, placing nylon fiber dry slices into a screw extruder, allowing the polymer slices to be heated and melted in the melting zone to form a viscous polymer, extruding the viscous nylon polymer through the spinneret micropores on the spinneret to obtain circular cross-sectional nylon fiber yarns, cooling the nylon fiber yarns by side blowing, stretching and shaping by positive pressure airflow to obtain nylon fiber yarn products, and reinforcing the nylon fiber yarn products by needle punching to make nonwoven fabrics. The side blowing cooling temperature is 15-22°C, the humidity is 60-70%, and the wind speed is 0.50-0.60m / s. By adjusting the heating element outside the screw sleeve of the screw extruder, the melting and extrusion temperature is 300-200°C.

[0073] (3) Preparation of the five-pointed star layer: a spinneret with a five-pointed star cross-sectional structure is processed on a spinneret, a nylon polymer is dissolved in a formic acid solvent to prepare a spinning solution, the spinning solution is injected into a capillary spinneret, a high-voltage positive electrode is connected to the spinning solution to form a high-voltage electric field between it and a grounded receiver, the spinning solution is ejected under the action of the electric field and the solvent is cooled and evaporated in flight to form nylon fiber yarns on the receiver, and the nylon fiber yarns are reinforced by needle punching to form a nonwoven fabric. The spinning solution concentration is 10-20%, and the electric field voltage is 20 kV.

[0074] (4) Structural assembly of the entire multi-layer special-shaped cross-section sound-absorbing material: According to the experimental design requirements, three types of cross-section nylon non-woven fabrics were cut and then neatly stacked in the order of a five-pointed star layer, a straight layer, and a circular layer. The non-woven fabrics were bonded with polyvinyl acetate (PVAc). Then, several cylindrical PE supporting material structural parts with a height of 10 mm and a radius of 2 mm were evenly bonded under the stacked multi-layer composite non-woven material in an array-like distribution. Finally, a woven fabric with a plain weave structure was bonded to the bottom.

[0075] Comparative Example 1

[0076] This comparative example provides a method for preparing a multilayer sound-absorbing material. The difference from Example 1 is that step (4) is replaced by: Structural assembly of the entire multilayer sound-absorbing material with a special cross-section: according to the experimental design requirements, three circular cross-section nylon non-woven fabrics are cut, and then the three cut non-woven fabrics with the same cross-section are repeatedly stacked neatly, and the non-woven fabrics are bonded with polyvinyl acetate (PVAc), and finally a woven fabric with a plain weave structure is bonded to the bottom.

[0077] Comparative Example 2

[0078] The present comparative example provides a method for preparing a multilayer sound-absorbing material. The difference from Example 1 is that step (4) is replaced by: assembling the entire multilayer nonwoven sound-absorbing material structure: according to the experimental design requirements, three pieces of nylon nonwoven fabrics with a straight cross-section are cut, and then the three pieces of nonwoven fabrics with the same cross-section are repeatedly stacked neatly, and the nonwoven fabrics are bonded with polyvinyl acetate (PVAc), and finally, a woven fabric with a plain weave structure is bonded to the bottom.

[0079] Comparative Example 3

[0080] The present comparative example provides a method for preparing a multilayer sound-absorbing material. The difference from Example 1 is that step (4) is replaced by: assembling the entire multilayer nonwoven sound-absorbing material structure: according to the experimental design requirements, three nylon nonwoven fabrics with a five-pointed star-shaped cross-section are cut, and then the three cut nonwoven fabrics with the same cross-section are repeatedly stacked neatly, and the nonwoven fabrics are bonded by a chemical bonding process foam impregnation method, and finally a woven fabric with a plain weave structure is bonded to the bottom.

[0081] Comparative Example 4

[0082] The present comparative example provides a method for preparing a multi-layer sound-absorbing material with a special-shaped cross-section. The difference from Example 1 is that step (4) is replaced by: Structural assembly of the entire multi-layer sound-absorbing material with a special-shaped cross-section: according to the requirements of the experimental design, three types of nylon non-woven fabrics with cross-sections are cut, and then the cut non-woven fabrics are neatly stacked in the order of a straight-line layer, a circular layer, and a five-pointed star layer. The non-woven fabrics are bonded to each other by a chemical bonding process foam impregnation method without cavities, and finally a woven fabric with a plain weave structure is bonded to the bottom.

[0083] Comparative Example 5

[0084] This comparative example provides a method for preparing a multi-layer sound-absorbing material with a special cross-section. The difference from Example 2 is that step (4) is replaced by: Structural assembly of the entire multi-layer sound-absorbing material with a special cross-section: according to the requirements of the experimental design, three types of nylon non-woven fabrics with cross-sections are cut, and then the cut non-woven fabrics are neatly stacked in the order of a straight layer, a five-pointed star layer, and a circular layer. The non-woven fabrics are bonded to each other by a chemical bonding process foam impregnation method without cavities, and finally a woven fabric with a plain weave structure is bonded to the bottom.

[0085] Comparative Example 6

[0086] This comparative example provides a method for preparing a multi-layer special-shaped cross-section sound-absorbing material. The difference from Example 3 is that step (4) is replaced by: Structural assembly of the entire multi-layer special-shaped cross-section sound-absorbing material: according to the experimental design requirements, three types of cross-section nylon non-woven fabrics are cut, and then the cut non-woven fabrics are neatly stacked in the order of a circular layer, a five-pointed star layer, and a straight layer. The non-woven fabrics are bonded by a chemical bonding process foam impregnation method without cavities, and finally a woven fabric with a plain weave structure is bonded to the bottom.

[0087] The sound absorption performance of the sound absorbing materials prepared in Examples 1 to 6 and Comparative Examples 1 to 6 was tested, and the results are shown in Table 1. The experimental instrument used for the sound absorption test is the AWA6128 standing wave tube sound absorption tester produced by Hangzhou Aihua Instrument Co., Ltd., which adopts the standing wave tube method according to the national standard GBJ88-1985.

[0088] The tensile strength test uses the YG065 electronic fabric strength machine of Laizhou Electronic Instrument Co., Ltd. According to the national standard GB / T3917.3, the prepared woven fabric samples are subjected to tensile strength tests. The test process is as follows: 1. The three non-woven fabric samples are evenly cut to prepare 5 5cm×30mm strips in the horizontal and vertical directions. 2. The parameters of the electronic fabric strength machine are set as follows: tensile speed 100mm / min, interval 200mm. 3. Place the cut strips in the clamp of the fabric strength machine and clamp them. Each horizontal / vertical strip is stretched at a constant speed 5 times, and the data is recorded, and the average value is finally calculated.

[0089] Table 1 Sound absorption performance test of the sound absorbing materials prepared in Examples 1-6 and Comparative Examples 1-3

[0090]

[0091] Table 2 Sound absorption performance test of the sound absorbing materials prepared in Examples 1-3 and Comparative Examples 4-6

[0092] Sound absorption coefficient Example 1 Example 2 Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 100Hz 10.8％ 7.6％ 10.9％ 9.2％ 10.2％ 9.2％ 200Hz 11.8％ 9.2％ 11.4％ 8.7％ 11.2％ 11.2％ 375Hz 13％ 10.2％ 11.6％ 9.8％ 14.5％ 12.5％ 400Hz 15.9％ 10.9％ 15.8％ 10.1％ 14.9％ 13.9％ 500Hz 18.3％ 15.6％ 18.3％ 10.5％ 16.3％ 15.3％ 630Hz 21.5％ 18.2％ 24.2％ 13.4％ 17.7％ 16.7％ 800Hz 30.6％ 29.4％ 32.6％ 19.8％ 19.4％ 20.4％ 1000Hz 41.4％ 39.4％ 45.5％ 26.1％ 24.5％ 25.5％ 1250Hz 55％ 54％ 56.6％ 46.1％ 38.2％ 33.2％ 1600Hz 70.1％ 67.5％ 70.8％ 53.5％ 50.2％ 47.2％ 1800Hz 76.8％ 75.1％ 78.9％ 66.9％ 65.4％ 56.6％ 2500Hz 94％ 88.6％ 84.4％ 77.1％ 74.7％ 70.8％

[0093] Table 3 Mechanical properties test results of three nonwoven fabrics

[0094] parameter Circular cross-section nonwoven fabric Linear cross-section nonwoven fabric Pentagram cross-section nonwoven fabric Porosity 92.60％ 89.20％ 94.80％ Breaking strength(N) 538.8 541.2 168.9 Elongation at break(mm) 116.7 119.2 109.9 Elongation(%) 58.3 59.6 55.9

[0095] In Table 1 and Table 2, the implementation standard for the sound absorption coefficient test is GBJ88-1985.

[0096] The porosity and mechanical strength of three nylon nonwoven fabrics with different cross-sections were tested, and the results are shown in Table 3.

[0097] Based on the data in Table 1 and Table 2, it can be concluded that, compared with other comparative examples, the multi-layer special-section nylon nonwoven sound-absorbing material prepared in Example 1 has a significantly better sound absorption coefficient at 100-2500 Hz, and the sound absorption coefficient at 2500 Hz is as high as 94%.

[0098] In addition, compared with Example 1, the overall sound absorption coefficients of Examples 2 to 6 are all reduced. This is because the arrangement order of the nylon nonwoven fabrics with different profiled cross-sections is different, which makes the energy consumption of the sound wave entering the multi-layer composite nonwoven material different. In Example 1, since the multi-layer composite nonwoven material is formed by compounding the porosity from small to large, their impedance characteristics are different. When the sound wave passes through the nonwoven material with a circular cross-section and enters the pentagonal cross-section material, the sound wave will be reflected back and forth between the two and propagate, thus further consuming sound energy. When the pore values ​​of the two materials are greatly different, the sound wave reflection and propagation path between the two interfaces is further increased.

[0099] Compared with Examples 1 to 6, the sound absorption coefficients of Comparative Examples 1 to 3 are all reduced, mainly because the composite stacking of nylon fibers with different cross-sections can increase the number of pores through which sound waves pass and the contact surface between air and fibers during the propagation of sound waves, thereby consuming more energy when sound waves pass through the material, achieving a better sound absorption effect. The composite sound-absorbing material obtained by simply repeatedly stacking nylon nonwoven fabrics with the same cross-section makes the sound wave propagation distance and refraction times inside it not as good as the nonwoven fabric prepared by mixed stacking.

[0100] Compared with Examples 1 to 3, the sound absorption performance of Comparative Examples 4 to 6 also decreased, mainly because after the cavity was removed, the propagation path of the sound wave was shortened, reducing the energy consumed when the sound wave propagated in the cavity. At the same time, after the cavity was removed, the resonance cavity formed by the woven fabric and the cavity no longer existed in the sound absorbing material, so that the sound absorption performance decreased significantly.

[0101] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A multi-layered special-section sound-absorbing material, characterized in that: The multi-layer special-shaped cross-section sound-absorbing material comprises a special-shaped layer, a bottom layer, and a plurality of supporting components evenly distributed between the special-shaped layer and the bottom layer, wherein the supporting components, the special-shaped layer and the bottom layer are enclosed to form a cavity; The special-shaped layer is a multi-layer stacked structure, and the multiple layers are independently selected from any one of a straight-line layer, a circular layer, and a five-pointed star layer and are different from each other; wherein, The fiber cross section used in the straight-line layer is straight-line shaped; The fibers used in the circular layer have a circular cross section; The fiber cross section used in the five-pointed star layer is in the shape of a five-pointed star.

2. The multi-layer special-shaped cross-section sound-absorbing material according to claim 1, characterized in that: The straight-line layer, the circular layer and the five-pointed star layer are reinforced in a non-woven manner.

3. The multi-layer special-shaped cross-section sound-absorbing material according to claim 1, characterized in that: The thickness of the special-shaped layer is 9-12 mm.

4. The multi-layered special-section sound-absorbing material according to claim 1, characterized in that: The bottom layer is a plain woven fabric, the warp density of the plain woven fabric is 100-200 threads / inch, and the weft density is 100-200 threads / inch.

5. The multi-layered special-section sound-absorbing material according to claim 1, characterized in that: The height of the support assembly is 8-12 mm, and the distribution density of the support assembly is 2-4 pieces / cm 2 .

6. The multi-layered special-section sound-absorbing material according to claim 1, characterized in that: The support component is made of PE material.

7. A method for preparing a multilayer sound-absorbing material with a special-shaped cross section according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, spinning with spinneret microholes having an interface structure of a straight line, a circle, and a pentagonal star, respectively, to obtain straight-line fiber filaments, round fiber filaments, and pentagonal star-shaped fiber filaments, and reinforcing the straight-line fiber filaments, round fiber filaments, and pentagonal star-shaped fiber filaments into a straight-line layer, a circle layer, and a pentagonal star layer, respectively; S2. Use an adhesive to bond the straight-line layer, the circular layer, the five-pointed star layer, the supporting assembly and the bottom layer to obtain the multi-layer special-shaped cross-section sound-absorbing material.

8. The preparation method according to claim 7, characterized in that: The spinning method in step S1 is selected from any one of wet spinning, melt spinning and electrospinning.

9. The preparation method according to claim 7, characterized in that: The reinforcement in step S1 is specifically: the straight fiber yarn, the round fiber yarn, and the five-pointed star fiber yarn are respectively reinforced into corresponding nonwoven fabrics by needle punching, and the needle punching density of the needle punching reinforcement is 50-150 needles / cm 2 The needling depth is 5-15mm and the step amount is 5-15mm.

10. The preparation method according to claim 7, characterized in that: The adhesive is selected from one or more of polyvinyl acetate, polyurethane, styrene-butadiene rubber, polyurethane, nitrocellulose and polyvinyl acetate.

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