phosphorus systemflame retardantDue to its own characteristics and performance has long been used as a flame retardant to use, it not only overcomes the halogen flame retardant combustion smoke volume, the release of toxic corrosive gas shortcomings, but also improve the inorganic flame retardant high addition amount and seriously affect the physical and mechanical properties of the material shortcomings, its excellent flame retardant effect, low smoke, low toxicity, no corrosive gas generation, has been widely used.

Phosphorus flame retardant is mainly through the material and oxidant, heat source between the formation of isolation film to achieve flame retardant effect. According to the different flame retardant effect of phosphorus compounds in different reaction zones, the flame retardant mechanism can be divided into condensed phase flame retardant mechanism and gas phase flame retardant mechanism. During combustion, phosphorus-based flame retardants are decomposed into phosphorus oxyacids (phosphoric acid, metaphosphoric acid, polymetaphosphoric acid, etc.) by heat, which have strong dehydration property and can dehydrate and carbonize materials into films, thus reducing combustible products. At the same time, phosphorus oxyacids are mostly viscous semi-solid substances, which can form a layer of glassy melt covering the coke layer on the surface of the material to reduce the air permeability of the carbon layer, the carbon layer is protected from continued oxidation and the spread of combustion is inhibited. Phosphorus flame retardant is a kind of free radical scavenger, in the combustion of the formation of PO radical, can be combined with the flame of H radical, so that the phosphorus flame retardant in the gas phase also play a flame retardant effect. In addition, the moisture generated by the phosphorus-based flame retardant during the flame retardant process can not only reduce the temperature of the condensed phase, but also dilute the concentration of combustibles in the gas phase, thereby achieving a good flame retardant effect.

In practical applications, red phosphorus flame retardants have many disadvantages:

Red phosphorus is very easy to absorb moisture and oxidation, the surface of the formation of phosphorus oxide or acid, while the release of highly toxic phosphine;

Red phosphorus has poor compatibility with most plastic matrix polymers, which affects material properties and is difficult to process;

The ignition point of red phosphorus is 240~250 ℃, and it is very sensitive to heat, friction and impact, so it has potential safety hazard in use;

Red phosphorus itself with a deep purple, easy to be its flame retardant products coloring;

Red phosphorus can enter the human body through inhalation, ingestion and skin contact. Regular intake of red phosphorus dust can cause chronic phosphorus poisoning; long-term skin contact can cause dermatitis;

Red phosphorus has certain toxicity to aquatic organisms, and also causes problems such as eutrophication.