Acting principle: formation of a solid surface layer of phosphorus compounds:
 
 
Formation of a protective layer by the production of polyphosphoric acid and carbonization, e.g. by release of water.
 

 

Further examples :

 
Resorcinol diphosphoric
acid tetraphenyl ester (RDP)
Ammonium polyphosphate
(APP)
Phosphine acid derivatives
Triaryl phosphates
Trichloropropylphosphate
(TCPP)
Red phosphorus