Bio-based and Conventional Flame Retardants for Polymers

The industrial production of commodity polymers expanded rapidly in the 1960s, resulting in an increased risk of fire. To mitigate this, the industry first sought to reduce the flammability of polymer materials by adding flame-retardant compounds. Subsequently, the aim was also to reduce the amount of smoke produced and its toxicity, which is responsible for the majority of fire-related fatalities. Halogenated flame retardants proved their effectiveness. However, for environmental reasons (in particular, the dissemination of flame retardants in the ecosystem) and despite their remarkable performance, most halogenated flame retardants were blacklisted at European level in the early 2000s because of their intrinsic toxicity and the massive release of corrosive gases during combustion. This led to the research and development of new halogen-free solutions.

As the issues of sustainable development and climate change become ever more important, so too does the need to develop flame-retardant materials and systems that are broadly in line with a policy of sustainability.

Four major families currently dominate the flame retardant market, which in 2011 accounted for 1.9 million tonnes at a value of $4.8 billion. In terms of volume, their market shares break down roughly as follows:

• 40% for mineral compounds ;

• 30% for halogenated compounds (mainly brominated) ;

• 15% for organic and inorganic phosphorus compounds ;

• 15% for antimony oxide and other compounds (mainly nitrogenous).

The aim of this article is therefore to present the different types of flame retardants used or available for use in the polymer processing industry, and to look ahead to new sustainable solutions. Halogenated flame retardants have been excluded from the scope of this article, for the reasons set out above, and are the subject of an article published in Techniques de l'Ingénieur: [AM3237] . Phosphorus-based flame retardants are also the subject of another publication in Techniques de l'Ingénieur: [AF6047] ....