Flame retardants are functional additives that give flammable polymers flame retardancy. They are mainly designed for the flame retardancy of polymer materials. Common flame retardants include inorganic flame retardants, halogen flame retardants, phosphorus flame retardants and nitrogen flame retardants. This article mainly introduces the classic flame retardants of these types of flame retardants.
1. Halogen flame retardants
As an important variety of organic flame retardants, halogen flame retardants are the earliest type of flame retardants used. Due to their low price, good stability, small addition amount, good compatibility with synthetic resin materials, and the ability to maintain the original physical and chemical properties of flame retardant products, they are currently the world's largest organic flame retardant in terms of production and usage.
2. Phosphorus flame retardants
Phosphorus flame retardants include inorganic phosphorus flame retardants and organic phosphorus flame retardants. Inorganic flame retardants mainly include: red phosphorus, ammonium polyphosphate (APP), ammonium phosphate salts, phosphates and polyphosphates, etc.; organic phosphorus flame retardants mainly include: phosphate esters, phosphaphenanthrene (DOPO), phosphazene compounds, organic phosphinic acids and organic phosphinic salts, etc. Reply "flame retardant" to find more related articles.
3. Nitrogen flame retardants
Common varieties include melamine, melamine cyanurate (MCA), etc., which often need to be added with synergists and are used in resins such as PA, PU, PO, PET, PS, PVC, etc. Nitrogen/phosphorus is the most commonly used synergistic flame retardant system. Reply "flame retardant" to find more related articles.
Melamine cyanurate (MCA) (melamine)
Melamine cyanurate is a nitrogen-containing halogen-free environmentally friendly flame retardant that can make flame retardant materials reach UL94 V-0. It is particularly suitable for PA6 and PA66 without fillers. It belongs to the nitrogen series flame retardant and has two forms: powder and granular. When the polyamide foam flame-retarded by this product burns, the carbon foam layer formed protects the polymer and insulates heat and oxygen.
4. Inorganic flame retardants
Inorganic flame retardants (inorganic flame retardant) are made by fine processing of high-temperature resistant solutions with ultrafine inorganic metal oxides. Inorganic flame retardants mainly add inorganic elements with intrinsic flame retardancy to the flame-retarded substrate in the form of single substances or compounds, fully mix with polymers in a physically dispersed state, and play a flame retardant role through chemical or physical changes in the gas phase or condensed phase.
1. Antimony trioxide
It is an additive flame retardant and is often used in combination with other flame retardants and smoke suppressants. The components can produce a synergistic effect. Antimony trioxide first melts at the beginning of combustion, forming a protective film on the surface of the material to isolate the air, and reduces the combustion temperature through internal endothermic reactions. Antimony trioxide is vaporized at high temperatures, diluting the oxygen concentration in the air, thereby playing a flame retardant role.
2. Aluminum Hydroxide (ATH)
Aluminum hydroxide is the most sold flame retardant among inorganic hydroxides. It is mainly used for artificial rubber, thermosetting resins and thermoplastics with processing temperatures below 200°C. Plastics flame-retarded by aluminum hydroxide have a prominent advantage of low smoke generation in flames.
3. Magnesium Hydroxide (MDH)
Magnesium hydroxide is an inorganic flame retardant with better thermal stability. It is still stable above 300°C and is widely used in many artificial rubbers, resins, including engineering plastics and other resins processed at high temperatures. It plays a role in flame retardancy and smoke elimination in polymer systems. When used in combination with ATH, they complement each other and have better flame retardant effects than when used alone.
