When a fire occurs, halogen-containing flame retardant materials will generate a large amount of smoke and toxic corrosive hydrogen halide gas during the flame retardant process, causing secondary hazards. In February 2003, the European Union issued the RoHs (The Restriction of Hazardous Substances in Electrical and Electronic Equipment (Directive 2002/95 / EC) and WEEE (Waste Electri-cai and Electronic Equipment, Directive 2002/96 / EC) directives. The former is a directive on restricting and banning the use of certain toxic and harmful substances and elements in electrical and electronic equipment, and the latter is a directive on recycling waste electrical and electronic equipment. These two directives were transformed into the laws (regulations) of the 15 member states of the European Union in August 2004. The WEEE directive came into effect in August 2005 and the RoHs directive came into effect in July 2006. Western Europe is about to implement new flame retardant classification methods and testing standards in the building materials and other industries. China has also approved national standards for the combustion performance rating of building materials and products. This standard has the same characteristics as the above-mentioned new Western European standard, which is in evaluating material resistance In terms of flammability, the heat release rate, the rate of fire development, smoke generation, and the corrosion and toxicity of combustion products are emphasized. In order to pass such new standards, traditional halogen flame retardant materials will appear to be powerless. Carbon flame retardant plastics (especially intumescent flame retardant plastics) and thermosetting flame retardant plastics are also in compliance with the requirements of the RoHS directive for the restriction and prohibition of hazardous substances.

The new flame retardant system has a small amount of smoke during combustion and does not produce toxic and corrosive gases. Halogen-free flame retardant additives are mainly phosphorus-based compounds and metal hydroxides. These two types of compounds, which are non-volatile and do not generate corrosive gases during combustion, are known as pollution-free flame retardants. In addition, there are several new types of halogen-free flame retardants such as silicon-based flame retardants and nitrogen-based flame retardants. These new halogen-free flame retardants have become new products in line with the development trend of international standards.