1. Inorganic hydroxide flame retardant
The flame retardant mechanism of inorganic hydroxide flame retardants mainly has the following aspects:
(1) Aluminum hydroxide and magnesium hydroxide will absorb a lot of heat during the thermal decomposition process, thereby reducing the temperature of the silicone rubber surface and preventing it from continuing to burn;
(2) The water vapor generated by the decomposition of aluminum hydroxide and magnesium hydroxide can dilute the oxygen concentration around the silicone rubber, thus inhibiting the combustion;
(3) The surface layer formed by aluminum oxide and magnesium oxide generated during the combustion process can prevent heat transfer and help catalyze the formation of carbon, protecting the unburned part.

Aluminum hydroxide, magnesium hydroxide and flame retardant synergist have flame retardant effect on the properties of flame retardant silicone rubber, and agglomeration phenomenon will occur in the case of high filling amount, resulting in a decline in the physical and mechanical properties of the product. However, if the surface of aluminum hydroxide can be modified, this problem can be effectively solved.

2. phosphorus based flame retardants
Phosphorous flame retardants can be divided into inorganic phosphorous flame retardants and organophosphorous flame retardants, which have many varieties, wide uses, high efficiency and low toxicity. Inorganic phosphorus flame retardants are mainly red phosphorus and phosphoric acid, and organic phosphorus flame retardants include phosphate ester and phosphite ester.

3. Silicon flame retardant
Although the development of silicon flame retardants is late, but because of its excellent flame retardant properties, good processing properties and excellent mechanical properties, especially its environmental friendliness, it has attracted much attention and has broad development prospects. When the material is burned, the silicon flame retardant mostly migrates to the surface of the material, forming an oxygen insulating insulating protective layer containing silicon oxygen bonds and silicon carbon bonds, which can not only isolate the contact between oxygen and the material, but also prevent the decomposition products generated by combustion from escaping, at the same time, these compounds replace the organic components of the fuel.

4. Intumescent flame retardant
Intumescent flame retardants can be divided into physical intumescent flame retardants and chemical intumescent flame retardants according to their different expansion principles. Chemical intumescent flame retardants are halogen-free flame retardants with nitrogen and phosphorus as the main components. In the combustion process, the physically expanded flame retardant expands to form a "worm" -like structure and the carbon element in the molecular chain forms a dense carbon layer, which covers the surface of the combustion area with the "worm" -like structure, effectively inhibiting the transmission of matter and energy in the combustion area, so as to achieve the purpose of flame retardant.

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