What Materials Are Used In Flame Retardant Wires And Cables?

Technology Press

What Materials Are Used In Flame Retardant Wires And Cables?

Flame retardant wire, refers to the wire with fire retardant conditions, generally in the case of the test, after the wire is burned, if the power supply is cut off, the fire will be controlled within a certain range, will not spread, with flame retardant and inhibit toxic smoke performance. Flame retardant wire as an important part of electrical safety, the choice of its material is crucial, the current market commonly used flame retardant wire materials including PVC, XLPE, silicone rubber and mineral insulation materials.

cable

Flame retardant wire and cable material selection

The higher the oxygen index of the material used in the flame retardant cable, the better the flame retardant performance, but with the increase of the oxygen index, it is necessary to lose some other properties. If the physical properties and process properties of the material are reduced, the operation is difficult, and the cost of the material is increased, so it is necessary to reasonably and appropriately select the oxygen index, the oxygen index of the general insulation material reaches 30, the product can pass the test requirements of class C in the standard, if the sheathing and filling materials are flame retardant materials, the product can meet the requirements of Class B and Class A. Flame retardant wire and cable materials are mainly divided into halogenated flame retardant materials and halogen-free flame retardant materials;

1. Halogenated flame retardant materials

Due to the decomposition and release of hydrogen halide when the combustion is heated, hydrogen halide can capture the active free radical HO root, so that the combustion of the material is delayed or extinguished to achieve the purpose of flame retardant. Commonly used are polyvinyl chloride, neoprene rubber, chlorosulfonated polyethylene, ethylene-propylene rubber and other materials.

(1) Flame retardant polyvinyl chloride (PVC) : Due to the cheap price of PVC, good insulation and flame retardant, it is widely used in ordinary flame retardant wire and cable. In order to improve the flame retardancy of PVC, halogen flame retardants (decabromodiphenyl ethers), chlorinated paraffins and synergic flame retardants are often added to the formula to improve the flame retardancy of PVC.

Ethylene propylene rubber (EPDM) : non-polar hydrocarbons, with excellent electrical properties, high insulation resistance, low dielectric loss, but ethylene propylene rubber is flammable materials, we must reduce the degree of crosslinking ethylene propylene rubber, reduce the molecular chain disconnection caused by low molecular weight substances, in order to improve the flame retardant properties of the material;

(2) Low smoke and low halogen flame retardant materials
Mainly for polyvinyl chloride and chlorosulfonated polyethylene two materials. Add CaCO3 and A(IOH)3 to the formula of PVC. Zinc borate and MoO3 can reduce the HCL release and smoke amount of flame retardant polyvinyl chloride, thereby improving the flame retardancy of the material, reducing halogen, acid fog, smoke emissions, but may make the oxygen index slightly decreased.

2. Halogen-free flame retardant materials

Polyolefins are halogen-free materials, consisting of hydrocarbons that break down carbon dioxide and water when burned without producing significant smoke and harmful gases. Polyolefin mainly includes polyethylene (PE) and ethylene – vinyl acetate polymers (E-VA). These materials themselves do not have flame retardant, need to add inorganic flame retardants and phosphorus series flame retardants, in order to process into practical halogen-free flame retardant materials; However, due to the lack of polar groups on the molecular chain of non-polar substances with hydrophobicity, the affinity with inorganic flame retardants is poor, difficult to firmly bond. In order to improve the surface activity of polyolefin, surfactants can be added to the formula. Or in polyolefin mixed with polymers containing polar groups, so as to increase the amount of flame retardant filler, improve the mechanical properties and processing properties of the material, while obtaining better flame retardant. It can be seen that flame retardant wire and cable is still very advantageous, and the use is very environmentally friendly.


Post time: Dec-03-2024