Principles of Flame Retardancy Technology and a Brief History of Its Development
Flame Retardance: A Technology for Enhancing Material Fire Resistance by Inhibiting the Combustion Process. Flame retardance refers to the application of physical or chemical means to delay or prevent the combustion of materials. Its core objective is to alter the thermodynamic or kinetic conditions of the combustion reaction, thereby making materials difficult to ignite when exposed to an external fire source, or enabling them to self-extinguish rapidly once the fire source is removed. This process effectively inhibits the spread of fire, thereby gaining critical time for personnel evacuation and firefighting rescue operations.
Flame retardant technologies are widely utilized across various sectors—including construction, electronics and electrical appliances, transportation, furniture, and textiles—serving as a vital means of safeguarding both public safety and property.
The fundamental principle of flame retardance lies in disrupting the equilibrium of the "fire triangle"—the three essential elements required for combustion: combustible material, oxidant (combustion-supporting agent), and heat (temperature).
Common flame retardant mechanisms include gas-phase inhibition (scavenging free radicals), condensed-phase inhibition (forming a carbonaceous char layer), and thermal quenching (absorbing heat to lower the temperature). Based on their method of application, flame retardant materials can be classified as either additive-type or reactive-type; based on their chemical structure, they can be categorized into various types, such as halogen-based, phosphorus-based, nitrogen-based, and inorganic-based systems. Driven by growing environmental awareness, the development of halogen-free, low-smoke, and low-toxicity flame retardant materials has emerged as the dominant trend within the industry.
A Brief History of Development: The history of flame retardant technology dates back to antiquity. As early as 450 BC, the Greeks utilized solutions of potassium aluminum sulfate (alum) to treat wood in order to enhance its fire resistance.
In 83 BC, the ancient Romans employed "alum solutions" to treat wooden fortifications as a defense against fire-based attacks.
Ancient China also witnessed similar applications, such as the "Tu Dawu" (coating large structures) fire-prevention technique practiced during the Spring and Autumn period, as well as the use of clay mixed with glutinous rice paste to create protective fire-resistant coatings.
Modern flame retardant technology traces its origins to the 19th century. In 1821, the French scientist Gay-Lussac discovered that a mixture of ammonium phosphate, ammonium chloride, and borax exhibited excellent flame-retardant properties when applied to textiles; this discovery is widely regarded as the inception of modern flame retardant technology.
In the 1930s, coinciding with the widespread adoption of synthetic polymer materials, researchers discovered the synergistic flame retardant system involving antimony oxide and chlorinated paraffin—a milestone in the evolution of modern flame retardant technology.
Contemporary flame retardant technology is generally considered to have emerged in the 1950s. Hooker Chemical Company developed reactive flame-retardant monomers, which subsequently paved the way for the emergence of a wide variety of halogen- and phosphorus-containing flame retardants.
Entering the 21st century, driven by increasingly stringent environmental regulations, halogenated flame retardants faced restrictions due to the toxic gases they generate during combustion. Consequently, halogen-free flame retardant technologies—such as phosphorus-nitrogen intumescent flame retardants, nano-flame retardants, and bio-based flame retardants—developed rapidly and have since become the industry mainstream.
