Preparation method of high-temperature-resistant glass fiber automobile sound insulation and sound absorption cotton

Abstract

This invention belongs to the field of automotive sound insulation materials technology, and specifically relates to a method for preparing high-temperature resistant glass fiber automotive sound insulation cotton. The method includes: Step 1, modifying the glass fiber with high-temperature resistant flexibility; Step 2, mixing it with low-melting-point fibers to form a web, and optionally introducing an ultra-fine glass wool layer; Step 3, pre-pressing and then laminating it with functional layers such as high-temperature resistant aluminum foil and porous damping layers; Step 4, using a stepped thermosetting process with a peak temperature ≤150℃ for shaping; and Step 5, post-processing and molding: after cooling, three-dimensional molding is performed to obtain the finished product. This invention solves the problems of poor flexibility and high-temperature resistance of traditional glass fiber cotton and traditional sound insulation cotton by synergistically combining surface modification, low-melting-point fiber bonding, multi-layer composite, and low-temperature curing technologies. The resulting product has excellent high-temperature resistance, good flexibility and formability, wide-band sound absorption and insulation performance, and environmentally friendly characteristics, making it particularly suitable for NVH control in high-temperature areas such as the automotive engine compartment and exhaust pipe perimeter.

Description

Technical Field

[0001] This invention relates to the field of automotive sound insulation materials technology, specifically a method for preparing high-temperature resistant glass fiber automotive sound insulation cotton. Background Technology

[0002] With the rapid development of the automotive industry towards lightweighting, comfort, and electrification, in-vehicle noise control has become one of the important technical indicators for measuring driving and riding quality. Automotive noise mainly comes from engine vibration, intake and exhaust systems, tire-road friction, body wind noise, and transmission system operation. These noises are transmitted to the cabin through air transmission or structural vibration, seriously affecting driving and riding comfort. As the core means of automotive noise control, sound insulation and sound absorption materials are widely used in engine compartments, wheel arches, floors, doors, roofs, and behind the dashboard to absorb mid-to-high frequency noise and isolate low-frequency vibration transmission. Among many sound insulation materials, fiberglass sound insulation and sound absorption cotton has become one of the mainstream sound insulation materials widely used in the automotive industry due to its excellent sound absorption performance, lightweight characteristics, chemical stability, and cost advantages.

[0003] Traditional automotive sound insulation materials often use PET cotton, PU foam, and EVA composite materials. These materials have good sound insulation and absorption performance at room temperature, but their heat resistance is insufficient when near high-temperature areas such as the engine and exhaust pipe. When exposed to temperatures above 100°C for a long time or even above 150°C for a short period, they are prone to softening, deformation, shrinkage, aging, and decomposition, leading to a sharp decline in sound insulation performance and potentially producing harmful gases or odors, affecting driving safety and passenger comfort. Fiberglass itself has advantages such as being non-flammable, heat-resistant, and having good dimensional stability, making it a potential substrate for sound insulation materials in high-temperature areas. However, traditional sound-absorbing cotton has the following problems: 1) The fibers are rigid, resulting in poor material flexibility after molding, making it difficult to conform to the complex shapes of automotive parts; 2) The friction between fibers is high, generating a lot of dust during production, which is unfriendly to worker health and the environment; 3) Pure fiberglass cotton has a narrow sound absorption spectrum, and its mid-to-low frequency sound absorption performance needs improvement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing high-temperature resistant fiberglass automotive sound insulation cotton. This method solves the problems of existing sound insulation cotton fibers having high rigidity, poor material flexibility after molding, difficulty in conforming to the complex shapes of automotive parts, high inter-fiber friction, high dust during production, which is unfriendly to worker health and the environment, and the narrow sound absorption spectrum of pure fiberglass cotton with insufficient mid-to-low frequency sound absorption performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution, comprising the following steps: Step 1, Preparation of high-temperature resistant modified glass fiber: A layer of composite surface treatment agent is uniformly applied to alkali-free glass fiber filaments with a flat diameter of 3-15 μm by atomization spraying. The composite surface treatment agent consists of the following components in parts by weight: 30-50 parts of high-temperature resistant film-forming agent (such as modified organosilicon resin, polyimide precursor solution), 10-20 parts of flexible segment modifier (such as hydroxyl-terminated silicone oil, polyurethane prepolymer), 20-30 parts of environmentally friendly adhesive (such as bio-based waterborne acrylic resin), 3-5 parts of coupling agent (such as silane coupling agent KH-550, KH-560), and 20-30 parts of deionized water. After spraying, the fiber is pre-dried at 100-120℃ for 3-5 minutes to obtain modified glass fiber with a flexible high-temperature resistant polymer film coated on the surface.

[0006] Step 2, Forming of the mixed fiber mesh: The modified glass fiber obtained in step one is opened and mechanically mixed with 5-15 wt% of low melting point hot melt fiber (copolyester or copolyamide fiber with a melting point of 110-130℃). The mixed fibers are laid into a uniform fiber web with a predetermined areal density (300-1500 g / m²) and thickness by air-flow web formation or mechanical carding process. During the web formation process, one or more layers of ultrafine glass wool (fiber diameter <3μm) can be introduced simultaneously to enhance the absorption capacity of mid-to-high frequency noise.

[0007] Step 3, Pre-compression and composite structure construction: The fiber web obtained in step two is fed into a pre-compressor and lightly pressed and shaped at room temperature. Subsequently, a functional layer is laminated onto one or both sides of the web, wherein the functional layer is at least one of the following: a) High-temperature resistant reflective aluminum foil layer, which is hot-pressed with a high-temperature resistant hot melt adhesive film at 120-140℃ and 0.1-0.3MPa to reflect heat radiation; b) Porous damping film layer, wherein the film is a butyl rubber / ethylene-vinyl acetate copolymer blended foam material filled with hollow ceramic microspheres, which is composited by hot pressing; c) Lightweight, high-temperature resistant nonwoven fabric surface layer, which is laminated by needle punching or hot melting to prevent fiber shedding and improve the feel.

[0008] Step 4, Low-temperature stepped thermosetting: The composite preform after step three is fed into a circulating hot air drying tunnel for stepped temperature-curing. The specific process is as follows: First stage: the temperature is increased from room temperature to 105-115℃ at a rate of 5℃ / min, and held for 5-10 minutes to melt the low-melting-point fibers and achieve initial bonding; Second stage: the temperature is further increased to 135-145℃ at a rate of 3℃ / min, and held for 10-20 minutes to fully cross-link and cure the composite surface treatment agent and functional layer adhesive, while avoiding excessive heat that could cause the material to become brittle; Third stage: the temperature is lowered to below 80℃, and the material is discharged.

[0009] Step 5, Post-processing and molding: After the material has been cured, it is cooled and trimmed. Based on the three-dimensional shape of the automotive parts, it is then hot-pressed or cold-stamped into three-dimensional shape using matching molds to produce a high-temperature resistant fiberglass automotive sound insulation cotton product that closely fits the surface of the parts.

[0010] As a preferred embodiment of the present invention, the step of mixing 5-10 wt% basalt fiber or ceramic fiber into an alkali-free glass fiber filament can further improve the temperature resistance limit and mechanical properties.

[0011] As a preferred embodiment of the present invention, the amount of low-melting-point hot-melt fiber added in step two is 8-12 wt%.

[0012] As a preferred technical solution of the present invention, when the aluminum foil layer is composited in step three, the aluminum foil thickness is 20-50μm, and a layer of glass fiber mesh can be composited between the aluminum foil and the fiber mesh to enhance the interlayer bonding force.

[0013] Compared with the prior art, the present invention provides a method for preparing high-temperature resistant glass fiber automotive sound insulation cotton, which has the following beneficial effects: 1. The preparation method of this high-temperature resistant glass fiber automotive sound insulation cotton involves modifying alkali-free glass fiber filaments by spraying a composite surface treatment agent. The composite surface treatment agent includes a high-temperature resistant film-forming agent, a flexible segment modifier, an environmentally friendly adhesive, and a coupling agent. A flexible high-temperature resistant polymer film is coated on the fiber surface. This modification gives the originally rigid glass fiber good flexibility while maintaining its high-temperature resistance, allowing the final sound insulation cotton to closely fit the curved surfaces of complex automotive parts such as engine compartments and wheel covers. This solves the problems of poor flexibility and difficult bonding of traditional glass fiber cotton after molding. By mixing 5-10 wt% basalt fiber or ceramic fiber into the alkali-free glass fiber filaments, the mixed fibers of different diameters and stiffnesses generate differentiated vibrations under the action of sound waves, forming a wider frequency band of energy dissipation. This effectively compensates for the insufficient low-frequency sound absorption performance of pure glass fiber cotton. Combined with the ultrafine glass wool layer introduced in step two, the material's ability to absorb low-frequency noise is further improved.

[0014] 2. The preparation method of this high-temperature resistant glass fiber automotive sound insulation cotton involves mixing modified glass fiber with low-melting-point hot-melt fiber (melting point 110-130℃), and then laying it up through air-flow web formation or mechanical combing web formation process. In the subsequent heat curing process, the hot-melt fiber softens and melts, bonding the glass fiber network into shape. This bonding method replaces the traditional resin impregnation process, significantly reducing dust flying during the production process, improving the working environment, reducing the harm to workers' health, and avoiding the use of organic solvents, making it more environmentally friendly.

[0015] 3. The preparation method of this high-temperature resistant fiberglass automotive sound insulation cotton adopts a stepped heating and curing process. In the first stage, the temperature is raised to 105-115℃ and held to allow the hot-melt fibers to initially melt. In the second stage, the temperature is raised to 135-145℃ and held to complete the full curing. The peak curing temperature does not exceed 150℃. This mild low-temperature curing process effectively protects the flexible high-temperature resistant polymer film formed in step one from damage, ensuring that the flexibility and high-temperature resistance of the modified fiberglass are preserved. It avoids polymer film aging and fiber embrittlement caused by high-temperature curing. After the fiber web is pre-pressed and shaped, functional layers such as a high-temperature resistant reflective aluminum foil layer, a porous damping film layer, or a lightweight high-temperature resistant non-woven fabric surface layer are laminated. The aluminum foil layer can reflect the radiant heat of the engine compartment, reducing the heat load of the heat source on the sound insulation cotton. The porous damping film layer enhances the damping effect on low and medium frequency vibrations. The non-woven fabric surface layer provides surface protection and aesthetics. The composite fiberglass mesh reinforcement layer improves the composite strength of the aluminum foil layer and the fiber web, preventing delamination. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation process of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0018] Example 1 Step 1, Preparation of high-temperature resistant modified glass fiber: Take E-CR alkali-free glass fiber chopped strands with a length of 50-80mm, and pre-mix 8wt% ceramic fibers, such as alumina fibers, into the alkali-free glass fiber to further improve heat resistance. Prepare a composite surface treatment agent with the following components by mass: 40 parts of silicone-modified acrylic resin emulsion as the high-temperature film-forming agent, 15 parts of polyurethane aqueous dispersion as the flexible segment modifier, 25 parts of carboxylated styrene-butadiene latex as the environmentally friendly adhesive, 4 parts of KH-550 silane coupling agent as the coupling agent, and 25 parts of deionized water. Mix the above components thoroughly in a mixing tank, and spray them evenly onto the surface of the continuously conveyed glass fiber strands using a spray gun. The sprayed fiber strands are immediately placed in a pre-drying tunnel and treated at 110℃ for 4 minutes to coat the fiber surface with a uniform and continuous flexible high-temperature resistant polymer film, thus obtaining modified glass fiber. This modified layer reduces the rigidity and surface energy of the fiber, increases its flexibility, and improves its affinity with resins or adhesives in subsequent processing.

[0019] Step 2, Forming of the mixed fiber mesh: The modified glass fiber obtained in step one is opened, and low-melting-point polyester hot-melt fiber with a melting point of 120℃ is prepared. The amount of the added fiber is 10wt% of the total mass of the modified glass fiber. The modified glass fiber and the low-melting-point hot-melt fiber are thoroughly mixed in a mixing chamber. Then, the mixed fiber is sent into an air-flow web forming machine. By adjusting the airflow speed and the web laying speed, the fiber is evenly laid to form a fiber web with uniform basis weight. During the web laying process, a layer of ultrafine glass wool with a basis weight of 30g / ㎡ can be introduced simultaneously in the middle layer of the fiber web to enhance the absorption capacity of mid-to-high frequency sound waves.

[0020] Step 3, Pre-compression and composite structure construction: The fluffy fiber web obtained in step two is conveyed between a pair of heated pre-compression rollers and lightly pre-compressed at a pressure of 0.05 MPa and a temperature of 80°C to achieve initial thickness and shaping, forming a fiber web felt blank. A functional layer is laminated onto one side of the fiber web felt surface. In this embodiment, a layer of high-temperature resistant reflective aluminum foil is used as the heat insulation functional layer. The specific method is as follows: a high-temperature resistant aluminum foil with a thickness of 0.05 mm is prepared. The aluminum foil is pre-coated on one side with a layer of high-temperature resistant hot melt adhesive film based on polyester. The adhesive coating of the aluminum foil is then applied... The aluminum foil layer is bonded to one large surface of the fiber mesh felt and then fed into a hot press laminating machine. It is hot-pressed for 5 seconds at a temperature of 130℃ and a pressure of 0.2MPa to firmly bond the aluminum foil layer to the fiber mesh felt. To further enhance the bonding strength between the aluminum foil layer and the fiber mesh and prevent the aluminum foil from peeling off from the fiber layer during subsequent bending and forming, a layer of fiberglass mesh with a pore size of 2mm×2mm can be laid on the surface of the fiber mesh felt before bonding. Then, the aluminum foil and the fiberglass mesh / fiber mesh felt are hot-pressed together, and the fiberglass mesh is embedded in the hot melt adhesive to form a reinforcing structure.

[0021] Step 4, Low-temperature stepped thermosetting: The composite blank of the single-sided composite aluminum foil obtained in step three is sent into a circulating hot air drying tunnel for stepped heating and heat curing treatment. The specific process parameters are as follows: In the first stage, the temperature is increased from room temperature to 110°C at a rate of 5°C / min and held at 110°C for 8 minutes. During this stage, the low-melting-point hot-melt fibers begin to soften and melt, playing a preliminary bonding role and promoting further cross-linking of the composite surface treatment agent. In the second stage, the temperature is increased to 140°C at a rate of 3°C / min and held at 140°C for 15 minutes. This stage is the main curing and shaping stage. The low-melting-point fibers completely melt and flow, forming bonding points at the fiber intersections. The composite surface treatment agent is completely cured to form a stable coating, giving the fiber mesh a stable three-dimensional structure, thickness, and resilience. In the third stage, heating is stopped, and the temperature is naturally cooled to below 80°C in the drying tunnel.

[0022] Step 5, Post-processing and molding: The cured composite sound insulation cotton blank is removed from the drying tunnel and cooled to room temperature. As needed, it is then hot-pressed into a three-dimensional shape at 120°C using a vacuum forming machine or a 3D molding machine to create an irregularly shaped structure that matches the contour of the inner side of the target automotive part, such as the engine hood. After cooling and setting, it is precisely cut according to the part drawings using a CNC cutting machine or a punching die to obtain the final finished sound insulation cotton. Before leaving the factory, the finished product must undergo random sampling tests. The main test items include thickness, unit area mass, high temperature dimensional stability, and sound absorption coefficient measured according to relevant standards to ensure that its sound insulation performance meets the design requirements.

[0023] Example 2 The preparation process of this embodiment is basically the same as that of Example 1, except for the material selection, ratio and composite structure, which is intended to further illustrate the flexibility and feasibility of the present invention.

[0024] In step one, the components of the composite surface treatment agent are adjusted as follows: 35 parts of polytetrafluoroethylene emulsion are selected as the high-temperature resistant film-forming agent; 20 parts of carboxylated styrene-butadiene latex are selected as the flexible segment modifier; 20 parts of vinyl acetate-ethylene copolymer emulsion are selected as the environmentally friendly adhesive; 5 parts of KH-560 silane coupling agent are selected as the coupling agent; 30 parts of deionized water are selected; and among the mixed fibers, alkali-free glass fiber accounts for 92 wt% and basalt fiber accounts for 8 wt%.

[0025] In step two, no ultrafine glass wool layer is introduced. The low-melting-point hot-melt fiber is selected from copolyamide fibers with a melting point of 125℃. The amount added is 8wt% of the total mass of modified glass fiber. The fiber web is formed by mechanical carding to make the fiber web have a certain directionality in order to optimize the mechanical properties in a specific direction.

[0026] In step three, a double-sided composite functional layer structure is adopted. First, on one side of the fiber mesh felt, a porous damping film with a thickness of 1mm is hot-pressed onto it at 135℃ and 0.15MPa using a high-temperature resistant hot melt adhesive film. The material is butyl rubber / asphalt composite material with added sheet filler, which is used to improve the damping loss factor of the sound insulation cotton and enhance the suppression of mid-to-low frequency structural vibrations. Then, on the other side of the fiber mesh felt, a layer of lightweight polypropylene (PP) spunbond nonwoven fabric is bonded to the surface of the fiber mesh by spraying hot melt adhesive. This serves to protect the surface, prevent fiber shedding, and improve the appearance.

[0027] The step-by-step thermosetting process parameters for step four are adjusted as follows: First stage: heat up to 108℃ and hold for 6 minutes; Second stage: heat up to 142℃ and hold for 12 minutes; the subsequent cooling steps are the same.

[0028] The subsequent processing in step five is the same as in Example 1.

[0029] Example 3 This embodiment provides a method for preparing sound insulation pads suitable for automotive flooring, with a focus on a multi-layer composite structure.

[0030] Steps one and two are the same as in Example 1, but in the web-forming process of step two, no ultrafine glass wool layer is introduced.

[0031] In step three, a "sandwich" composite structure is adopted. First, the pre-pressed and shaped fiber mesh is double-sided composited: one side is composited with a high-temperature resistant reflective aluminum foil layer using the method in Example 1, and the other side is composited with a lightweight PET high-temperature resistant non-woven fabric surface layer. Then, based on this double-layer composite structure, two single aluminum foil composite materials with the same structure but opposite non-woven fabric surfaces are bonded together with environmentally friendly hot melt adhesive through their exposed fiber mesh surfaces, thereby forming a four-layer symmetrical composite structure blank of "aluminum foil-fiber mesh-fiber mesh-aluminum foil". This structure has excellent heat insulation, sound insulation and damping performance.

[0032] The thermosetting process parameters for step four are the same as in Example 1, but the heat preservation time is appropriately extended by 5 minutes to ensure strong internal bonding.

[0033] In step five, the main method is planar cutting. The planar ...

[0034] As can be seen from the above embodiments, the preparation method provided by the present invention, through flexible high-temperature resistant surface modification of glass fiber, combined with the bonding effect of low-melting-point fiber and multi-layer functional composite structure design, achieves the curing and shaping of sound insulation cotton under low temperature conditions not exceeding 150°C. The sound insulation and noise reduction cotton prepared by this method not only retains the inherent high-temperature resistance and non-flammability of glass fiber material, but also significantly improves the flexibility of the material, reduces production dust, and broadens the sound absorption spectrum of the material by combining it with functional layers such as damping layer and reflective layer. It is especially suitable for high-temperature parts of automobiles with high requirements for temperature resistance, molding fit and comprehensive noise reduction performance.

[0035] Based on the above specific description and common knowledge in the field, those skilled in the art can realize the present invention without creative effort, and can make adaptive adjustments to the parameters and materials of each step according to actual performance requirements.

[0036] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-temperature resistant glass fiber automotive sound insulation cotton, characterized in that, Includes the following steps: Step 1, Preparation of high temperature resistant modified glass fiber: Alkali-free glass fiber filaments are sprayed with a composite surface treatment agent and pre-dried to obtain modified glass fiber with a flexible high temperature resistant polymer film coated on the surface. The composite surface treatment agent includes a high temperature resistant film-forming agent, a flexible segment modifier, an environmentally friendly adhesive, and a coupling agent. Step 2, Forming of the mixed fiber mesh: The modified glass fiber obtained in Step 1 is mixed with low melting point hot melt fiber and laid into a uniform fiber mesh by air-flow web forming or mechanical combing web forming process. Step 3, Pre-compression and composite structure construction: After the fiber web obtained in step 2 is pre-compressed and shaped, at least one functional layer is composited on one or both sides of it; Step 4, Low-temperature stepped thermosetting: The composite blank obtained in Step 3 is subjected to stepped heating thermosetting treatment, with the peak curing temperature not exceeding 150℃. Step 5, Post-processing and molding: After cooling, perform three-dimensional molding to obtain the finished product.

2. The preparation method of a high-temperature resistant glass fiber automotive sound insulation cotton according to claim 1, characterized in that: The composite surface treatment agent in step one is composed of the following components in parts by weight: 30-50 parts of high-temperature film-forming agent, 10-20 parts of flexible segment modifier, 20-30 parts of environmentally friendly adhesive, 3-5 parts of coupling agent, and 20-30 parts of deionized water.

3. The preparation method of a high-temperature resistant glass fiber automotive sound insulation cotton according to claim 1, characterized in that: The pre-drying conditions in step one are 100-120℃ for 3-5 minutes.

4. The preparation method of a high-temperature resistant glass fiber automotive sound insulation cotton according to claim 1, characterized in that: The step described involves mixing 5-10 wt% basalt fiber or ceramic fiber into an alkali-free glass fiber filament.

5. The preparation method of a high-temperature resistant glass fiber automotive sound insulation cotton according to claim 1, characterized in that: In step two, the melting point of the low-melting-point hot-melt fiber is 110-130℃, and its addition amount is 5-15wt% of the total mass of the modified glass fiber. During the web formation process, one or more layers of ultrafine glass wool are introduced simultaneously.

6. The method for preparing a high-temperature resistant glass fiber automotive sound insulation and noise reduction cotton according to claim 1, characterized in that: The functional layer in step three is at least one of the following: a high-temperature resistant reflective aluminum foil layer, a porous damping film layer, and a lightweight high-temperature resistant nonwoven fabric surface layer.

7. The method for preparing a high-temperature resistant glass fiber automotive sound insulation and noise reduction cotton according to claim 6, characterized in that: When the high-temperature resistant reflective aluminum foil layer is laminated, a high-temperature resistant hot melt adhesive film is used for hot pressing at 120-140℃ and 0.1-0.3MPa. A fiberglass mesh reinforcement layer is laminated between the aluminum foil layer and the fiber mesh.

8. The method for preparing a high-temperature resistant glass fiber automotive sound insulation and noise reduction cotton according to claim 1, characterized in that: The step-by-step heating and thermosetting process in step four is as follows: First stage: heat up to 105-115℃ and hold for 5-10 minutes; Second stage: continue to heat up to 135-145℃ and hold for 10-20 minutes; Third stage: cool down to below 80℃.

9. The method for preparing a high-temperature resistant glass fiber automotive sound insulation and noise reduction cotton according to claim 1, characterized in that: Step five also includes cutting after molding to adapt to the use of different automotive sound insulation components.

10. The method for preparing a high-temperature resistant glass fiber automotive sound insulation and noise reduction cotton according to claim 1, characterized in that: In step five, the finished sound insulation cotton needs to undergo sound insulation quality testing.

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