Application and development trend of micron-scale microfibers in automotive trim systems.

In terms of design, automotive interior parts must have a large penetration rate and wall thickness to achieve high sound absorption or sound insulation performance, and leave sufficient reinforcement overlap and intervention when cooperating with surrounding environmental components, which is beneficial to NVH performance; To make the sound insulation pad cover as many areas as possible, such as the upper side of the structural column, the periphery of the ventilation duct, both sides of the middle safety channel, etc.; reduce the total area of unnecessary holes; the thickness of the sound insulation pad should be as thick as possible and evenly distributed.

In terms of material selection, automotive interior raw materials are mainly divided into porous materials and compactness materials. Porous materials include fibers and polyurethane foams, among which fiber-based materials are more widely used and adjustable indoor spaces are higher. The properties of porous materials are determined by the main parameters of the material's biot (relative density, porosity, flow resistivity, bumpy factor, characteristic length, Young's modulus, elastic modulus, vibration damping loss factor). The fiber felt with low density and high porosity has good high frequency sound absorption performance; the fiber felt with high fluid density has good high frequency sound insulation performance; when the fiber felt is used as a sound insulation pad, the lower elastic modulus is beneficial to improve the low frequency sound insulation performance.

Density materials include EVA sheet and PE plastic film, which play a key role in isolating and reflecting the sound wave frequency of the surface. The greater the quality, the better the performance. The two types of materials can be flexibly constructed with different electrical capacities, and the performance of the structure is determined by the order, thickness, and main parameters of the layers. For example, in the sound-absorbing fiber felt surface composite high-fluid-density fiber fabric, the low-frequency sound absorption performance can be efficiently improved; in the EVA + porous material composite structure, the thickness of the porous structure layer can be increased, which can improve the overall sound insulation performance.

The VOC concentration value in the car is the main index value that expresses the air quality index in the car. VOC is a general term for Volatile Organic Compounds, which refers to various organic substances with a melting point of 50 ° C~ 260 ° C under atmospheric pressure [4]. The key amount of VOC released in the car is related to the interior parts, including the roof, blanket sound insulation pad, front enclosure sound insulation pad, travel case decoration parts, car dashboard, seats and cushions and other components. The VOC performance of car interior products is critically harmed by materials, processing technology, post-processing technology, warehousing logistics and other fields.

Vehicle acoustic material package materials are mainly divided into PET fibers, PU polyurethane foam, plastics, leather products and plastics. Among them, the raw materials of PET fibers can generally be divided into four types: original ecological slicing, bottle flakes, recycled granules and foam. Bottle flakes, recycled granules and foams are recycled materials, which are unstable in origin and have weak VOC performance. For jeans cotton products, recycled jeans cotton fibers in cotton felt have a relatively pungent dye smell, resulting in a total odor choking problem.