Factors affecting the performance of flame-retardant needle-punched nonwovens for automotive interiors

With the improvement of people’s consumption level, the per capita ownership of cars has also increased rapidly. China’s automobile production will increase at an average annual rate of 30% to 55%. The rapid development of the automobile industry has led to the rapid development of a large number of related industries. In recent years, nonwoven materials have become more and more widely used in automobiles, and are mainly used for decoration of automobile ceilings, floors, trunks and other parts, as well as filter materials.

While the automobile manufacturing industry is developing toward economy and comfort, it is also developing in the direction of safety. That is, in addition to requiring high safety performance of the automobile itself, it also requires non-woven fabric materials for automobiles to have good performance. Safety, and the Flame retardancy of these materials is one of the important indicators of safety performance indicators. At present, there are relatively many domestic studies on flame-retardant nonwoven materials, but there are very few studies on flame-retardant needle-punched nonwovens for automobiles.

This study uses flame-retardant polyester fiber and ES fiber as raw materials to develop a flame-retardant needle-punched nonwoven product. The stiffness, air permeability, breaking strength, tearing strength, combustion performance and limit index were tested. Tested and analyzed the reasons affecting these performances. The production process flow of needle-punched nonwovens studied is: quantitatively weighing flame-retardant polyester and ES fibers → opening → blending → quantitative cotton → carding → web forming → pre-needle punching → barb 1 → forward punching 1 → Barb 2→Front thorn 2→Hot-calendering→Semi-finished product→Unwinding→Finished product. The calendering temperature is 220°C, and the roller rotation speed is 440r/min.

The influencing factors of the stiffness of needle-punched nonwoven fabrics mainly come from the quantitative and needle-punching processes. The greater the sample area density and needle-punching density, the stronger the interaction force and mutual entanglement between fibers, the less likely they are to bend, and the frictional cohesion force increases. The stiffness is higher; in terms of air permeability, the cloth with a small weight and thin thickness has a relatively weak blocking effect on air and a large air permeability. The increase in needle punching depth and density within a certain range will reduce the air permeability of nonwoven fabrics. This is because within this range, the fluffy fiber web is mainly made compact and dense through needle punching, reducing the air permeability in the fabric. pores and air channels; it can be seen from the longitudinal and transverse strength of the sample that the longitudinal strength of the needle-punched fabric is less than the transverse strength. This phenomenon is due to the difference in the longitudinal and transverse arrangement orientation of the fibers. The web-forming and cross-laying processes make the fibers more along the Needle punched fabric is oriented transversely.

As for the elongation at break, experiments show that the transverse elongation of needle-punched cloth is less than the longitudinal elongation. This is because the fibers are more oriented along the transverse direction of the cloth. When subjected to longitudinal tensile force, the transversely arranged fibers first start under the action of external force. Orientation along the longitudinal direction, and then the fiber is stretched and broken; the flame retardant performance is affected by the basis weight, laying process and calendering process. Samples with high surface density are relatively thick, have slow heat conduction, and require a large amount of heat for ignition. In addition, the effective pore size is small, the total void volume is small, and it is difficult to obtain sufficient oxygen. The oxygen concentration required for combustion is high, and the flame retardant effect is good. The transverse damage length of the sample in the test was greater than the longitudinal damage length, which shows that the flame retardant needle punched fabric has weaker transverse flame retardant properties than the longitudinal one. The reason for this phenomenon is related to the production process of the cloth. After the calendering process, the cloth becomes more compact and dense, the gaps between fibers are reduced, and the flame retardant effect is better.

To sum up, increasing the area density of needle-punched nonwoven fabrics can increase their stiffness, improve their mechanical properties, improve their flame retardant performance, and decrease their air permeability; calendering treatment makes the needle punched nonwovens The stiffness of the thorn nonwoven fabric increases, the air permeability decreases, the mechanical properties improve, and the flame retardancy is improved. Moreover, the transverse flame retardant performance of needle-punched nonwoven fabrics is better than the longitudinal flame retardant performance, and the flame retardant properties both meet the corresponding flame retardant requirements.

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