Halogenated flame retardants

Bromine, chlorine, fluorine and iodine, are the elements in the chemical group known as halogens. The word halogen derives from Greek, meaning 'salt-former', referring to elements which produce a salt in union with a metal. For example, sodium chloride, or table salt, is the most common example of a halogen salt.

Halogenated flame retardants act directly on the flame, the core of the fire. They are said to act “in the vapor phase”, meaning that they actually interfere with the chemistry of the flame. Chlorine and bromine are both effective in this role. Fluorine, however, is too stable to be an active flame retardant and iodine based compounds are too unstable to be flame retardants.

Chlorinated flame retardants are mainly used in plastics because they offer good stability.  However, compared to brominated flame retardants, higher quantities of chlorinated flame retardants are needed for achieving comparable flame retardancy.

Brominated flame retardants are often the most effective flame retardant considering both performance and cost.