Research on the characteristics of the structure of non-woven composite materials in automobile sound insulation and heat insulation

With the development of the automobile industry, people have higher and higher requirements for the comfort of automobiles. Non-woven fabrics have developed rapidly with their unique advantages and have become the protagonist of automobile textiles. They have low cost, high strength, shock absorption, and heat insulation. , Sound absorption, good hand feeling, good appearance, light weight, and excellent extensibility. It is suitable for compression molding and meets the modeling requirements that match the model. Non-woven fabrics have become an ideal vehicle material, replacing traditional textiles and plastic products. 1. Production of composite liner materials for automobiles. Liner materials for automobiles are generally used in the roof, door, body trunk and box body, and require shock absorption, sealing, and material extension properties to meet the needs of molding. . The non-woven composite material on the top of the car is generally: the main body and covering materials are non-woven fabrics processed by needle punching and shaping. The raw materials can be fibers or waste spinning materials, and the specification is 240-260g/m2. The other two materials are 65g/m2 polyester hot-rolled non-woven fabric and 25g/m2 polypropylene filament non-woven fabric. Polyester non-woven fabric is used as a reinforcement material for reinforcement and shaping, and polypropylene non-woven fabric is used as a hot-melt material for bonding. The three materials are combined and then molded. Automotive sound insulation felt: processed by acupuncture process, product specifications are 500-800g/m2, the main raw material is waste fiber, including leftovers from textile production, and part of hot melt powder or hot melt fiber is heated and molded. It can also be made by dipping, adding chemical adhesive, drying and molding. It adopts 2 layers of thin needle punched or hot-rolled non-woven fabric and polyurethane foam plastic composite to form a sandwich structure, which is molded after molding. 2. The structural changes before and after the material is compounded. Whether it is composed of waste spinning materials, non-woven fabrics or polyurethane foam plastics with fiber raw materials as the main body, although it has the general performance of automotive gaskets, its inherent performance The appearance can be changed by compounding. Non-composite non-woven materials, although they also have the general performance of automotive materials, but their internal performance and appearance are not as good as composite non-woven materials. 3. Research on thermal insulation properties Non-woven fabrics used in automobiles must be thermal insulation materials and have good thermal insulation properties. In summer, heat outside the car must be prevented from passing in, and heat inside the car must not be dissipated in winter. In-vehicle thermal insulation pad materials are generally composed of fiber materials, foam materials and so on. The heat transfer methods of materials include forced and natural convection. Heat is transferred from one surface of the material to another. The heat insulation effect is mainly reflected by the air-filled pores in the fabric, the fibers themselves and the gaps between the fibers. Because the air in the gap is basically static, the thermal conductivity is very low. Heat transfer takes place in three forms: conduction, convection, and radiation. In the process of heat transfer, it is affected by various factors such as the thickness of the insulation material, the weight of the square meter, the air permeability, the bulkiness and the movement of the outside air. Different heat insulation materials under different conditions, the heat transferred by various transfer methods is different. For example, various fibers in the waste spinning materials are mixed, the proportion of short pile is high, the yarn tendons and the cloth tendons are large, and the specific surface area of u200bu200bthe material is small. Therefore, it is difficult to analyze the influence of various factors of the material. Only the influence of thickness on heat transfer and thermal resistance is analyzed here . 4. Sound absorption and sound insulation performance When the car is running, the noise from the traffic noise from the outside and the noise from the car itself, such as the noise generated by the engine, the transmission system, the friction between the wheels and the ground, and other sources of noise are directly introduced into the car , Affecting the comfort of the ride. At the same time, the car's audio system must have a good sound-absorbing environment. Therefore, car interior materials must have the function of sound absorption and sound insulation. Non-woven fabric is a kind of porous sound-absorbing material. The randomly distributed fibers form numerous tortuous and interconnected micropores and pass to the surface. When sound waves hit the non-woven fabric, the energy is reflected, scattered, refracted, and diffracted. Part of the energy enters the pores, causing the air in the pores and the small fibers of the waste spinning material to vibrate. Due to friction and viscous resistance and the thermal conductivity of the fibers, most of the sound energy is converted into heat and absorbed, thereby reducing the reflected sound. The noise in the car is significantly reduced. 5. Conclusion (1) The non-woven gasket material for automobiles has the functions of low cost, high strength, shock absorption, heat insulation, sound absorption, etc., and can meet the requirements of use through processes such as compounding and molding. (2) Two layers of denser non-woven fabrics are compounded on the surface of the waste spun fiber web to improve its performance. Not only the hand feel becomes softer, but also the strength, heat insulation and sound insulation effects are improved, and it is also convenient for molding. (3) According to the experimental analysis, the heat insulation performance of the waste woven non-woven fabric for automobiles is better. The thickness of the non-woven fabric affects the heat transfer rate and thermal resistance. As the thickness increases, the heat transfer rate q decreases, and the thermal resistance R rises. Its thermal conductivity is u003d0.0379 (W/m•degree). (4) Sound insulation and sound absorption performance: According to the relationship between the thickness of the test material and the sound absorption coefficient, increasing the thickness of the material can improve the low-frequency sound absorption effect. Increasing the thickness has little effect on the high-frequency sound absorption performance.