Halogen-free flame retardant, also known as halogen-free low smoke environmental protection flame retardant or green environmental protection inorganic flame retardant material, is a flame retardant that does not produce toxic gases (such as halogenated gases such as hydrogen chloride) when burning. They use metal oxide as the main component of the compound formula system, and add a variety of inorganic and organic matter. Halogen-free flame retardants have the characteristics of non-ignition, non-explosion, less smoke, less toxicity and excellent flame retardancy. Now, let’s go into the large family of halogen-free flame retardants and understand their main types and characteristics.
The main types of halogen-free flame retardants
Inorganic flame retardant
Features: good stability, low toxicity or non-toxic, non-volatile during storage, not easy to precipitate from the plastic, rich raw material sources, low price, both flame retardant, filling dual functions, friendly to the environment.
Main species: including Sb2O3, Al(OH)3, Mg(OH)2, inorganic phosphorus series, etc. Among them, antimony trioxide (Sb2O3) is the most widely used variety of inorganic flame retardants, often used with organic halides, play a synergistic role; Aluminum hydroxide (Al(OH)3) can absorb a lot of heat and release water vapor during combustion, and play a role in flame retardant and smoke reduction; The flame retardancy of magnesium hydroxide (Mg(OH)2) is slightly poor, but its binding force with resin can be improved after surface treatment with coupling agent. Inorganic phosphorus flame retardant mainly refers to red phosphorus, which has high efficiency, smoke suppression, low toxicity and other flame retardant effects.
Halogen-free expansion flame retardant
Features: With phosphorus and nitrogen as the main components, it has high flame retardant, no melting dripping, excellent resistance to long-term or repeated exposure to the flame, no halogen, no antimony oxide, low smoke, non-toxic, non-corrosive gas generation and other advantages.
Composition: Mainly composed of acid source (such as phosphoric acid, sulfuric acid, etc.), carbon source (such as starch, pentaerythritol, etc.) and air source (such as urea, melamine, etc.) three parts.
Organophosphorus flame retardants
Features: Most of them have the advantages of low smoke, non-toxic, low halogen, halogen free, etc., in line with the development direction of flame retardants.
Main types: including phosphate ester, phosphite ester, phosphonate ester, organophosphorus salt and phosphorus oxide. Among them, phosphate ester and phosphonate ester are the most widely used. In recent years, new organophosphorus flame retardants such as phosphorus-nitrogen flame retardants or phosphorus-silicon flame retardants have been widely concerned because of their advantages of high efficiency, low smoke, low toxicity, and green environmental protection.
Silicone flame retardant
Features: New high efficiency, low toxicity, anti-melting dripping, environmentally friendly halogen-free flame retardant, is also a charcoal type smoke suppressant.
Main types: including silicone flame retardants and polysilboroxane flame retardants. They can form an insulating layer when burned, preventing heat exchange and contact with combustible gases, while promoting carbon production.
Nitrogen based flame retardants
Features: As a new and efficient flame retardant, it has been widely studied and paid attention to at home and abroad in recent years.
Main types: including melamine, melamine cyanuric acid (MCA), etc. The effect of nitrogen flame retardants is not good when used alone, but the expansive flame retardants combined with phosphorus-containing flame retardants show good flame retardancy.
Bio-based flame retardants
Features: With the advantages of biodegradability and non-toxic, it has become a hot spot of flame retardant research in the future.
Preparation: Different phosphorus groups are usually introduced on the main chain of vegetable oil to prepare biobased flame retardants.
Application of halogen-free flame retardants
Halogen-free flame retardants are widely used in the flame retardant treatment of wires and cables in electronic and electrical appliances, computers and communication equipment. Fire prevention of motor, transformer and other components in household appliances; Plasticizer and heat stabilizer components of plastic and rubber products; Paint additives and other fields. They can not only improve the flame retardant performance of the material, but also reduce the harm to the environment and the human body.
In summary, there are many members of the halogen-free flame retardant family, each with its own unique properties and advantages. With the advancement of science and technology and the improvement of environmental protection requirements, halogen-free flame retardants will play an important role in more fields.
