Polyimide nonwoven fabric composite aramid filament fabric used as a liner for high‑temperature conveyor belts.

Polyimide nonwoven fabric composite aramid filament cloth is made by combining polyimide felt with aramid filament cloth. The polyimide felt is produced through needle punching of short fibers, resulting in a three-dimensional, porous, and fluffy structure that inherently boasts excellent thermal insulation, sound absorption and cushioning, as well as high‑efficiency filtration performance. At the same time, its soft texture allows it to conform well to irregular surfaces. The aramid filament cloth is woven from high‑strength aramid filaments in both warp and weft directions, forming a dense, smooth, and highly durable woven fabric that offers exceptional tensile strength, tear resistance, abrasion resistance, and dimensional stability.

Polyimide nonwoven fabric originates from polyimide fibers, often hailed as “golden polymers.” The molecular structure of this material incorporates rigid aromatic heterocycles, endowing it with unparalleled high-temperature resistance. It can withstand long‑term operating temperatures exceeding 260°C, and in short bursts, it can endure extreme heat above 500°C without melting or burning—only undergoing slow carbonization. In addition, it boasts excellent chemical corrosion resistance, outstanding electrical insulation properties, and superior radiation resistance, including resistance to gamma rays. When produced in the form of short fibers via needle punching or hydroentangling, the nonwoven fabric develops a fluffy, porous three‑dimensional network structure. This structure is rich in layers of still air, giving it an extremely low thermal conductivity and making it a lightweight, high‑performance material for thermal insulation, soundproofing, and cushioning applications.

Aramid filament fabric specifically refers to woven fabrics made from para‑aramid filament yarns. The molecular chains of para‑aramid are highly oriented and crystalline, giving it core characteristics such as an exceptionally high specific strength—more than five times that of high‑quality steel—as well as a high specific modulus. It also boasts outstanding impact resistance, cut resistance, and tear resistance. The fabric woven from these filaments features a dense, smooth surface with excellent dimensional stability, fatigue resistance, and durability. It can withstand and distribute enormous tensile and shear stresses at both ambient and elevated temperatures, making it an outstanding structural load‑bearing layer.

The polyimide nonwoven fabric is laminated with aramid filament fabric, creating a composite material that goes beyond simple stitching—it forms a system characterized by complementary functions and synergistic effects. The polyimide nonwoven layer, positioned on the side facing the heat source or requiring thermal insulation, serves as both a “thermal barrier” and a “buffer layer.” Its porous structure effectively blocks heat from penetrating inward, shielding internal components and the aramid layer on the back side from direct exposure to high temperatures. At the same time, its soft texture helps absorb some vibration and mechanical impact.

The aramid filament fabric layer serves as the “structural skeleton” and “load‑bearing layer” of the composite material. It provides the primary mechanical strength required by the composite, resisting tensile, tear, and wear forces during service, thereby ensuring the integrity and dimensional stability of the overall structure under load. Even more critically, when the polyimide layer begins to carbonize under extreme high temperatures, the aramid layer—whose long‑term temperature resistance is approximately 200–220°C—can continue to maintain the structural integrity of the entire assembly in a protected state, providing the system with a valuable window of time for evacuation or emergency response.

This composite material not only boasts temperature resistance approaching the upper limit of polyimide, but also exhibits the high strength and toughness characteristic of aramid fibers. At the same time, it addresses the issues of rapid strength degradation in pure aramid fabrics at high temperatures, as well as the relatively low mechanical strength of pure polyimide nonwovens, which makes them unsuitable for direct load bearing.

Properties of polyimide nonwoven fabric composite aramid filament fabric:

1. Chemical Resistance and Weather Resistance

It exhibits excellent resistance to common acids, bases, salts, and organic solvents, while also being UV‑resistant and radiation‑resistant, making it suitable for complex and harsh chemical and outdoor environments.

2. High Flame Retardancy and Thermal Insulation

Both fabrics are inherently flame‑retardant materials; after compounding, they exhibit a very high limiting oxygen index (the LOI of aramid fiber is 29, while that of polyimide fiber can reach 44). When exposed to fire, they do not melt or drip, self‑extinguish upon removal from the flame, and can form a stable, insulating char layer. Even after direct flame ablation, the composite material still maintains excellent mechanical properties.

3. Excellent durability and lightweight design

Compared with traditional heavy-duty metal heat shields or asbestos products, it is lightweight, significantly reducing equipment load while offering excellent resistance to aging and most chemical media, boasting a long service life and requiring minimal maintenance.

4. A Mechanical Performance That Balances Rigidity and Flexibility

The material as a whole not only possesses sufficient tensile and tear strength, but also maintains a certain degree of flexibility and processability, allowing it to be cut, sewn, or molded into various complex shapes—such as protective covers, thermal insulation sleeves, sealing gaskets, and more—to accommodate different equipment and structures.

Applications of Polyimide Nonwoven Fabric Composite Aramid Filament Cloth:

1. High-Temperature Industrial Insulation and Sealing

The fabric is easy to secure and install, and it can withstand scratches from on-site conditions, forming a robust and durable “thermal insulation blanket” or “sealing gasket” used for thermal insulation wrapping of high‑temperature pipelines, valves, and kilns in the steel, power, and chemical industries; as well as fire‑resistant partitions in aerospace engine compartments.

2. High‑End Protective Clothing

It adopts a sandwich structure consisting of “aramid fabric (outer layer) / polyimide felt (intermediate insulation layer) / comfortable lining.” The aramid fabric provides basic flame retardancy and abrasion resistance; when exposed to extremely high heat sources, the polyimide felt forms a robust carbonized insulation barrier that effectively slows down heat transfer and protects the wearer. It is used as the insulation layer in fire-fighting suits, firefighting uniforms, and specialized industrial workwear.

3. Transportation and Aerospace

Composite structures integrate multiple requirements—such as thermal insulation, fire resistance, weight reduction, noise reduction, and structural reinforcement—into a single solution, meeting the modern transportation industry’s demands for multifunctional, lightweight materials. They are used in fire‑resistant and sound‑insulating interior panels for high‑speed trains and aircraft.

4. New Energy and High-End Manufacturing

It can be used as a thermal isolation layer for lithium battery packs, as a lining for high‑temperature conveyor belts, or as a heat‑insulating barrier in specialized welding and smelting equipment to prevent heat diffusion from causing safety incidents.

5. High‑Performance High‑Temperature Filtration

The dense aramid fabric or coated surface can perform surface filtration, capturing most of the coarse particles; the fluffy polyimide felt in the inner layer provides deep filtration, trapping fine particles. At the same time, the felt’s structure ensures low resistance and high dust capacity, while also delivering superior dust removal performance. It is spun into filter material for dust removal from high‑temperature flue gases generated by waste incineration, coal‑fired boilers, cement kiln exhausts, and similar applications.

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