Meta-aramid felt is used in industrial heat-resistant clothing and welding protective blankets.

Meta-aramid felt is a fire-resistant, flame-retardant, thermal-insulating fabric manufactured by needle-punching meta-aramid fibers. Meta-aramid, chemically known as poly(m-phenylene isophthalamide), is a high-performance synthetic fiber. Its felt products inherit the fiber’s outstanding intrinsic properties and, through a nonwoven structure, acquire new forms and functionalities, making them suitable for industrial and safety-protection applications that demand high-temperature resistance, flame retardancy, and electrical insulation.

Characteristics of meta-aramid felt:

1. High-temperature resistance and flame retardancy

The outstanding characteristics of meta-aramid felt are its exceptional high-temperature resistance and flame-retardant performance, which stem from its stable molecular structure. This material has a limiting oxygen index greater than 28%, classifying it as a hardly combustible material; it does not produce molten droplets in a flame and will self-extinguish once removed from the source of ignition. It can withstand continuous service at temperatures up to 200–220°C and thermal shock between 250 and 300°C, with short-term exposure to temperatures exceeding 400°C. At elevated temperatures, the material primarily undergoes carbonization and decomposition, a relatively slow process that effectively inhibits heat transfer.

2. Thermal Stability and Dimensional Stability

Under high-temperature conditions, the material exhibits excellent dimensional stability. For instance, after exposure to hot air at 250°C for a specified duration, its thermal shrinkage typically remains below 2%, with some premium grades achieving values of less than 1%. This low-shrinkage characteristic ensures that, when used as gaskets or thermal insulation layers in high-temperature service, the material maintains relatively stable shape and dimensions, thereby preventing seal failure or the formation of gaps in protective applications due to shrinkage.

3. Chemical Stability and Media Resistance

Meta-aramid felt exhibits excellent resistance to a wide range of chemical media. It is resistant to corrosion by most weak acids, weak bases, and saline solutions, and also demonstrates good stability in hydrocarbon-based substances such as lubricating oils and hydraulic fluids. This makes it suitable for complex industrial environments where chemically corrosive gases or liquids are present. However, its resistance to strong acids and strong bases is limited, and prolonged exposure can lead to performance degradation.

4. Physical and Mechanical Properties

Meta-aramid fibers themselves exhibit high strength, and the resulting felts possess notable tensile strength and tear resistance while maintaining good flexibility and compressive resilience. This material property facilitates subsequent processing operations such as cutting, sewing, and stamping, enabling the felts to conform to various shapes for wrapping, padding, or lining applications. Moreover, the porous structure of the felt provides some sound absorption and vibration-damping performance.

Applications of meta-aramid felt:

1. Security Protection Field

This is one of the primary application areas for meta-aramid felts. They serve as a critical thermal-insulation layer in specialized protective apparel, including fire-fighting suits, industrial heat-resistant garments (used in metallurgy, electric welding, glass manufacturing, and other trades), and linings for military combat uniforms. In the multi-layer structure of such protective clothing, the felt layer is positioned between the outer flame-retardant fabric and the inner comfort layer, with the main function of preventing external high temperatures from penetrating to the body, thereby slowing heat accumulation and providing thermal protection for the wearer. In addition, these felts are also directly used to manufacture fire blankets, welding protection blankets, and temporary fire barriers for use during maintenance of high-temperature equipment.

2. High-Temperature Industrial Filtration field

In industrial dust-collection systems that handle high-temperature flue gases, meta-aramid needle-felt is one of the core filter media used to manufacture filter bags. It is suitable for dust removal and purification from sintering-machine exhaust in steel plants, kiln-head and kiln-end exhaust in cement kilns, tail gases from carbon-black production, and certain high-temperature process gases in the chemical industry. Its typical operating temperature range is 180 to 200°C, with short-term peak temperatures reaching up to 220°C. Within this temperature range, it effectively captures particulate matter and exhibits excellent resistance to the acidic and alkaline corrosive components commonly found in flue gases.

3. Electrical Insulation Field

Leveraging its heat resistance and insulating properties, meta-aramid materials—in forms such as paper, felts, and fabrics—are employed in the insulation components of electric motors, transformers, electrical switches, and other equipment. For instance, they are used as slot insulation and interphase insulation in motors, or as insulating spacers within transformers. With an H-class (180°C) thermal rating, these materials meet the stringent requirements of high-end electrical equipment for reliable long-term operation under sustained high-temperature conditions.

4. Industrial Insulation and Sealing field

In thermal equipment at petrochemical plants, power stations, and other industrial facilities, meta-aramid felts can be used as insulation layers for pipelines, valves, and reactors, or as the lining material for detachable insulation jackets, thereby reducing heat loss and preventing personnel from suffering burns. At the same time, their soft and compressible properties also make them well suited for manufacturing high-temperature flange gaskets and sealing packings, which are employed in sealing applications requiring heat resistance and a certain degree of chemical stability.

5. Transportation Sector

In rail transit vehicles—such as high-speed trains and subways—and in automobiles, meta-aramid felts or composites can be used as sound- and heat-insulating layers and interior linings to meet the flame-retardant and safety standards for vehicle materials. In the automotive sector, they are also employed as thermal shields in the engine compartment, heat-resistant sleeves for exhaust pipes, and as reinforcing materials in high-performance brake pads, thereby enhancing the heat resistance and stability of braking components.

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