关键词: 非织造空气过滤材料, 对位芳纶, 微纳米纤维, 空气过滤性能, 耐高温性能

Abstract: Demand for high-performance air filter materials has surged recently, spurred by critical high-temperature applications like industrial flue gas treatment and high-temperature dust removal. The fiber-based air filter materials with both excellent particle removal capability and thermal stability have become a research focus. However, traditional fiber-based air filter materials often face trade-offs between filtration efficiency and pressure drop, and the thermal stability of fiber-based air filter materials is always weak. This restricts their application in harsh and high-temperature environment. To address this problem, this study targets the development of high-performance composite air filter materials, taking para-aramid (PPTA) as the core material due to its inherent high-temperature resistance and mechanical strength. To achieve the integration of excellent air filtration performance and high-temperature resistance, this study adopts a composite preparation strategy. First, PPTA spunlaced nonwovens were selected as the substrate, and PPTA pulp was used as the raw material. The PPTA pulp was dispersed in an aqueous NaOH solution and mechanically stirred for a specific period to induce fiber fibrillation, successfully preparing PPTA micro-nanofibers with a feather-like structure that enhances particle removal. Subsequently, wet-laid technology was applied to deposit the PPTA micro-nanofibers onto the surface of the PPTA spunlaced nonwovens, and the composite material was obtained after drying. To optimize the performance of the composite air filter materials, this study systematically tested the structure and key properties of the samples, focusing on optimizing the PPTA fiber fibrillation process. The results show that when the mechanical stirring time is 6 hours, the prepared composite air filter material P4 achieves optimal comprehensive performance, characterized by a low average pore size (3.1 μm), an air permeability of 32.42 mm/s, a high PM2.5 filtration efficiency of 92.9%, and a filtration resistance of only 106 Pa, thereby achieving a balance between high efficiency and low-pressure drop. Moreover, the composite air filter materials exhibit outstanding high-temperature stability: the filtration efficiency remains almost unchanged after heat treatment, fully meeting the application requirements in high-temperature environments. The PPTA micro-nanofiber/spunlaced composite air filter material developed in this study offers valuable insights for developing thermally stable air filters. The findings can serve as a practical guide for future material selection, process optimization, and performance customization of related products, and futher promote the advancement and innovation of filtration technologies for harsh environments.

Key words: nonwoven air filter materials, PPTA, micro-nanofiber, air filtration performance, thermal stability