News

Research on Flame Retardancy of Automotive Materials and Application Trends of Flame Retardant Fibers in Vehicles

With the rapid development of the automotive industry, cars—used for commuting or transporting goods—have become indispensable tools in people’s lives. While automobiles provide convenience, they also pose safety risks, such as traffic accidents and spontaneous combustion. Due to the confined space and flammable interior materials, once a fire breaks out in a vehicle, it is often difficult to control, endangering the lives and property of passengers. Therefore, fire safety in vehicles should be a major concern for users.

Causes of vehicle fires can generally be categorized into:
(1) Vehicle-related factors, including electrical faults, fuel leaks, and mechanical friction caused by improper modifications, installations, or maintenance.
(2) External factors, such as collisions, rollovers, arson, or unattended ignition sources.

New energy vehicles, equipped with high-energy-density power batteries, are particularly prone to fires due to short circuits caused by collisions, punctures, thermal runaway from high temperatures, or excessive current during fast charging.

01 Research on Flame Retardancy of Automotive Materials

The study of flame retardant materials began in the late 19th century in the United States. With advancements in technology in recent years, there have been new demands for research on the flame retardancy of automotive interior materials, mainly in the following areas:

First, theoretical research on flame retardancy. In recent years, researchers in China have placed great emphasis on studying combustion mechanisms of various fibers and plastics, as well as the application of flame retardants.

Second, development of flame retardant materials. Currently, there are many types of flame retardant materials under development. Internationally, materials such as PPS, carbon fiber, and glass fiber have been successfully applied across various industries.

Third, research on flame retardant fabrics. Flame retardant fabrics are easy to produce and highly efficient. While flame retardant cotton fabrics are already well-developed, research on other flame retardant textiles remains limited in China.

Fourth, regulations and testing methods for flame retardant materials.

Automotive interior materials can be broadly classified into three categories:

Fiber-based materials (e.g., seats, carpets, seat belts)—the most widely used and in direct contact with passengers.
Plastic-based materials.
Rubber-based materials.

Fiber-based materials, being highly flammable and in close proximity to passengers, pose significant risks in case of fire. Additionally, some vehicle components, such as batteries and engines, are located near textile materials, increasing the likelihood of fire spread. Therefore, studying the flame retardancy of automotive interior materials is crucial to delay combustion and provide more escape time for passengers.

02 Classification of Flame Retardant Fibers

In industrial textile applications, automotive textiles occupy a significant share. An average passenger car contains approximately 20–40 kg of interior materials, most of which are textiles, including seat covers, cushions, seat belts, and headrests. These materials are closely related to the safety of drivers and passengers, necessitating flame retardant properties to slow flame spread and increase escape time.

Flame retardant fibers are defined as fibers that either do not ignite or burn incompletely upon contact with a fire source, producing minimal flames and self-extinguishing quickly once the fire source is removed. The Limiting Oxygen Index (LOI) is commonly used to measure flammability, with an LOI above 21% indicating low flammability.

Flame retardant fibers are divided into two categories:

Inherently Flame Retardant Fibers
These fibers possess built-in flame retardant groups in their polymer chains, enhancing thermal stability, increasing decomposition temperatures, suppressing flammable gas generation, and promoting char formation. Examples include:

Aramid fibers (e.g., para-aramid, meta-aramid)
Polyimide fibers (e.g., Kermel, P84)
Polyphenylene sulfide (PPS) fibers
Polybenzimidazole (PBI) fibers
Melamine fibers (e.g., Basofil)

Meta-aramid, polysulfonamide, polyimide, and PPS fibers have already been mass-produced in China.

Modified Flame Retardant Fibers
These fibers acquire flame retardancy through additives or surface treatments, including:

Flame retardant polyester
Flame retardant nylon
Flame retardant viscose
Flame retardant polypropylene

Modification methods include copolymerization, blending, composite spinning, grafting, and post-finishing.

03 Applications of High-Performance Flame Retardant Fibers in Automotive Protection

Automotive flame retardant materials must meet specific requirements due to space constraints. Unlike other applications, these materials should either resist ignition or exhibit controlled burn rates (e.g., ≤70 mm/min for passenger vehicles).

Additionally, considerations include:

Low smoke density and minimal toxic gas emissions to ensure passenger safety.
Anti-static properties to prevent fires caused by fuel vapor or dust accumulation.

Statistics show that each car uses 20–42 m² of textile materials, indicating vast growth potential in automotive textiles. These textiles are categorized into functional and decorative types, with increasing emphasis on functionality—particularly flame retardancy—due to safety concerns.

High-performance flame retardant textiles are used in: