Flame retardant rubber profiles are not “non-combustible” rubbers. No material is completely fireproof; if conditions are suitable, they will ignite. The characteristic of flame-retardant rubber is that, once it reaches its ignition point, it can delay the combustion process and will quickly extinguish once the temperature drops.
From the simple fire prevention requirements of the 1970s, to the focus on flame retardancy and smoke suppression in the 1980s, to the application of non-toxic flame-retardant systems in the 1990s, and the emphasis on environmental protection in the new millennium, the development history of flame-retardant rubber reflects the continuous improvement in human safety and environmental requirements.
How is flame retardancy achieved in flame retardant extruded rubber profiles?
- Composite synergistic flame-retardant system: By adding multiple flame retardants physically, these retardants work in the gas phase or condensed phase, sometimes with dual functions, forming a strong flame-retardant barrier.
- Char-forming agents and char-forming catalysts: These additives increase the rubber’s char yield at high temperatures, forming a protective layer that slows down the spread of fire.
- Blending modification: By blending with other polymers and using physical or chemical methods to improve the rubber’s crosslinking density, its flame-retardant properties are enhanced.
- Rubber/inorganic nanocomposites: By combining with inorganic nanoparticles, new composite materials are formed that not only improve flame-retardant performance but also maintain the rubber’s elasticity.
- Intrinsic flame-retardant rubber: Flame-retardant elements such as halogens, phosphorus, and nitrogen are introduced into the rubber macromolecules to create rubber with intrinsic flame-retardant properties.
With advancements in technology, flame-retardant rubber has made breakthroughs not only in flame-retardant performance but also in smoke suppression and environmental protection. Through the synergistic effects of multiple flame-retardant systems, the material’s performance is maintained while the toxicity of the flame-retardant systems is reduced, achieving a safer and more environmentally friendly balance.
How about China flame retardant extruded rubber profiles?
In recent years, China’s flame-retardant rubber market has grown rapidly, driven by the acceleration of urbanization, investments in infrastructure, and the emerging industries of new energy vehicles, rail transit, and aerospace. Market demand continues to increase. China is the world’s largest producer and consumer of synthetic rubber, accounting for about half of the global total production capacity. In 2023, China’s synthetic rubber production reached 9.097 million tons, a year-on-year increase of 8.2%.
It is particularly widely applied in the building, transportation, and electronics sectors. The scale of China’s flame-retardant rubber market continues to expand, driven by technological innovation and the expansion of application fields.
- Building sector: With the rapid development of China’s polymer materials industry, flame-retardant materials are widely used in chemical building materials and other fields, especially the application of halogen-free flame retardants, which meet international standards and have excellent flame-retardant and environmental performance. They are widely used in airports, high-speed rail, and high-rise buildings. These applications not only improve building safety but also promote the goal of green development.
- Transportation sector: The rapid development of the new energy vehicle industry has driven the growth of the flame retardant market. Flame-retardant power cables used in electric vehicle and charging station applications continue to be advanced.
- Electronics sector: Flame retardants have become the second largest polymer material modifier after plasticizers.
Flame-retardant rubber formulation design is key to improving its performance. Common flame retardants include halogenated compounds (e.g., chlorinated paraffin), aluminum hydroxide, sodium borate, molybdenum oxide, and tris(phenyl)phosphate. These flame retardants work by inhibiting the combustible gases produced during the rubber’s high-temperature decomposition or by isolating oxygen from reaching the polymer’s combustion surface, thereby enhancing the rubber’s flame-retardant properties. Additionally, increasing the crosslinking density of vulcanized rubber can also enhance its flame resistance.
China flame-retardant rubber profiles industry is improving formulations and adopting new flame retardants to develop rubber with higher flame-retardant efficiency and lower environmental impact.
Research progress in new flame retardants for flame-retardant rubber profiles in China:
- Application of nanomaterials: Carbon nanotubes (CNT), graphene, and halloysite nanotubes (HNT) are widely researched and applied. These materials significantly improve the flame-retardant performance of natural rubber (NR) by forming barriers, capturing free radicals, and promoting the formation of continuous polymer network structures.
- Synergistic flame-retardant systems: To enhance both flame retardancy and mechanical performance, researchers have adopted synergistic flame-retardant systems. For example, organic montmorillonite (OMMT), carbon materials, and halloysite nanotubes (HNT) are used to enhance the flame-retardant performance of NR. The application characteristics of the TCP/OMMT flame-retardant system in NR composites have been thoroughly studied.
- Research on halogen-free flame retardants: Phosphorylated cashew nut shell liquid prepolymer and brominated phosphoric cashew nut shell liquid derivatives are used to modify natural rubber to improve its stress relaxation and flame-retardant properties. Additionally, new nitrogen-containing flame retardants have been explored for synthesis and application in polypropylene.
- Application of phosphorus-based flame retardants: Phosphorus compounds such as phosphate esters and antimony trioxide are widely studied for their applications in rubber. Phosphate esters decompose when heated, generating phosphoric acid, which promotes the dehydration and carbonization of the polymer, forming an isolating effect. Antimony trioxide helps in flame retardancy by shielding surfaces, reducing temperature, and terminating chain reactions.
- Application of ammonium polyphosphate (APP): As an efficient inorganic halogen-free flame retardant, ammonium polyphosphate (APP) has been widely used in the flame-retardant treatment of rubber, plastics, fibers, wood, and paper. Its development is moving toward microfine, specialized, and series production to fully exploit its flame-retardant and extinguishing properties.
In the future, China’s flame-retardant rubber industry will place more emphasis on material innovation and environmental performance. On one hand, by improving formulations and adopting new flame retardants, it will develop rubber with higher flame-retardant efficiency and lower environmental impact, expanding its applications in electric vehicles and green buildings. On the other hand, by combining smart materials and 3D printing technology, it will offer intelligent flame-retardant rubber components that can adapt to complex designs and customized needs, driving the industry towards more intelligent and efficient development.
