Red phosphorus halogen-free flame retardants have the following advantages and disadvantages:
Advantages
High flame retardant efficiency: Red phosphorus only contains the flame retardant element phosphorus, with a phosphorus content of up to 100% (it decreases slightly after coating but is still much higher than other phosphorus compounds). It has a high flame retardant efficiency and can achieve a good flame retardant effect with a small addition amount. For instance, when it comes to the flame retardancy of PET (polyethylene terephthalate), no other phosphorus-based flame retardants can match it.
Good thermal stability: It has excellent thermal stability, does not volatilize, does not produce corrosive gases, and can still maintain good flame retardant performance at high temperatures.
Excellent electrical insulation: It has good electrical insulation performance and is suitable for materials with electrical insulation requirements, such as in the fields of electronics and electrical appliances.
Low cost: China is a major country in terms of phosphorus resources in the world, with abundant reserves of red phosphorus, which gives it a relatively low cost advantage.
Good environmental performance: It is a halogen-free flame retardant. When burning, it produces no smoke, low toxicity and no corrosive gas, meeting environmental protection requirements.
Disadvantage
Strong hygroscopicity: Red phosphorus readily absorbs moisture in the air, generating substances such as phosphoric acid, which corrodes the surface of the product, causing it to lose its luster and original properties. Moreover, the corrosion gradually spreads to the inner layers.
Poor compatibility: As an inorganic substance, red phosphorus has poor compatibility with organic resins, making it difficult to disperse. This can lead to a decline in the performance of synthetic materials and an increase in resin viscosity, causing inconvenience to the subsequent treatment and use of resins.
Polluting the environment: When exposed to air for a long time, red phosphorus undergoes a slow chemical reaction, generating phosphorus-containing acids and releasing highly toxic PH₃ gas, which causes pollution to the environment.
There are potential safety hazards
Combustion and explosion hazard: Red phosphorus itself is flammable. Dry red phosphorus dust poses a risk of combustion and explosion and is classified as a hazardous chemical in China.
Impact on component performance: The hygroscopicity and instability of red phosphorus can affect the physical properties of plastic products, especially having a greater impact on the leakage of weak current components and the insulation of high-voltage components, which limits its flame-retardant application in the field of electrical components.
Product coloring: The deep purple-red color of red phosphorus can easily cause coloring of flame-retardant products, making it difficult to control the color of the produced products or increasing the cost of color matching.
There is a risk of toxicity: Frequent intake of red phosphorus dust can cause chronic phosphorus poisoning. Long-term skin contact can cause dermatitis. Red phosphorus is somewhat toxic to aquatic organisms and can also cause problems such as eutrophication of water bodies.
