Reinforced PAN Nonwoven Filter Media for High-Temperature Filtration
Solution Overview
Problem
Existing filter materials fail to meet the demands of high-temperature applications above 260°C, are prone to thermal degradation, and lack electrical conductivity, chemical resistance, and corrosion resistance, posing risks of sparking and mechanical failure.
Innovation Solution
A reinforced nonwoven fabric comprising pre-oxidized polyacrylonitrile (PAN) layers, optionally carbonized, with reinforcement layers of metal fibers, metal wires, pre-oxidized PAN fibers, or carbon fibers, providing thermal and electrical conductivity, high chemical resistance, and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional filter materials (PTFE, m-aramid, polyimide) are used, then the filter medium can be used up to approximately 260°C, but it cannot withstand temperatures higher than 260°C due to thermal degradation and mechanical failure
Solution Approach 1:
The filter medium uses a composite structure combining a nonwoven fabric layer made of pre-oxidized PAN fibers with a reinforcement layer made of heat-resistant materials (basalt fibers, carbon fibers, or metal wires). This composite structure allows the filter to withstand temperatures above 260°C while maintaining mechanical integrity, as the reinforcement layer provides structural support that prevents creep and failure at high temperatures.
Solution Approach 2:
The invention changes the material parameters by using pre-oxidized PAN fibers instead of conventional polymer fibers. Pre-oxidized PAN has superior thermal stability compared to PTFE, m-aramid, and polyimide, allowing the filter medium to operate at temperatures above 260°C without thermal degradation. The oxidation process transforms the polymer structure to resist thermal breakdown.
2Device complexity
If non-conductive filter media are used, then the filter structure is simple, but static charging leads to sparking and flying sparks that can damage the filter structure
Solution Approach 1:
The reinforcement layer is selectively designed with electrically conductive materials (carbon fibers, metal wires, or basalt fibers) to provide local electrical conductivity where needed. This localized approach prevents static charging and sparking without requiring the entire filter medium to be conductive, thus maintaining simplicity while eliminating the harmful sparking effect in critical areas.
Solution Approach 2:
The invention converts the potentially harmful static electricity buildup into a beneficial feature by using conductive reinforcement materials that dissipate static charges. The same reinforcement layer that provides mechanical strength also serves to prevent sparking, turning a structural component into a protective element against electrical hazards.
3Reliability
If textile filter media made of high-performance polymer fibers are used, then the filter medium has good chemical resistance, but it exhibits creep that leads to mechanical failure
Solution Approach 1:
The filter medium combines a nonwoven fabric layer with a reinforcement layer made of materials that do not exhibit creep (carbon fibers, metal wires, or basalt fibers). This composite structure maintains the chemical resistance of the pre-oxidized PAN fibers while the reinforcement layer provides dimensional stability and prevents mechanical failure from creep, especially at high temperatures.
4Temperature
If a reinforced nonwoven fabric with carbonized PAN is used, then the filter medium has high temperature resistance and electrical conductivity, but the manufacturing process is more complex
Solution Approach 1:
The PAN fibers are pre-oxidized before being incorporated into the nonwoven fabric structure. This preliminary oxidation treatment is performed during fiber production, so the thermal stabilization step is completed beforehand. When the filter medium is manufactured, the pre-oxidized fibers only require carbonization at high temperature, which is a simpler process than oxidizing and carbonizing from scratch, thus reducing overall manufacturing complexity while achieving the desired thermal and electrical properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The filter medium withstands temperatures above 260°C, prevents sparking, maintains structural integrity, and exhibits excellent chemical resistance, enabling efficient filtration of gases and liquids without the need for cooling and warming steps, and can be used in catalytic processes.
Implementation Method 1
The pre-oxidized PAN is subjected to a thermal treatment under the exclusion of oxygen and a protective gas atmosphere. This thermal treatment can produce partially carbonized PAN or carbonized PAN.
Implementation Method 2
The pre-oxidized PAN is subjected to a thermal treatment under the exclusion of oxygen and a protective gas atmosphere.
Implementation Method 3
there is a need for a reinforced nonwoven fabric with at least one thermally and/or electrically conductive layer
Implementation Method 4
there is a need for a reinforced nonwoven fabric with at least one thermally and/or electrically conductive layer
Data Source
Figure 1~4
AI summary
The invention relates to a filter medium comprising a reinforced non-woven fabric, to a method for the production thereof, and to the use thereof.