ChangShu LiangYi adhesive Tape Industry Co.,Ltd.

 

Discussion on the mechanism of flame retardants

 

The paper introduced that combustion of polymer materials was retarded by an endothermic andcooling process,agasphase diluted,forming heat insulation layer and termination of free radical chain reaction whenflame retardant was added into polymer materials.The mechanism of flame retardants was review too,includinginorganic flame retardant,organic flame retardant and intumescent flame retardant.

 

2.1 Endothermic cooling

Some flame retardants in the heating process, its compounds containing flame retardant elements will undergo endothermic dehydration, phase change, decomposition and other endothermic reactions, reduce the temperature of the polymer surface and the combustion zone, thereby slowing down the polymer heat Decomposition speed to achieve flame retardant effect.

 

2.2 Gas phase dilution

In the combustion process, the material generates a large amount of flammable gas, such as carbon monoxide. The presence of flame retardants will produce a lot of incombustible gases, effectively diluting flammable gases and air, so as to achieve the flame retardant effect on the material.

 

2.3 Forming a Thermal Insulation

Some flame-retardant materials (such as phosphoric acid, boric acid) melt when heated, forming a glassy film on the surface of the material, impeding the supply of oxygen, and at the same time can play a role in insulation and reduce the release of flammable gas, resulting in flame retardant effect.

 

2.4 Termination of free radical chain reaction

In the process of polymer combustion, a large amount of generated radicals accelerate the gas-phase combustion reaction. If you can manage to capture and eliminate these free radicals, you can control the combustion and play a flame-retardant effect. The velocity of the gas-phase combustion reaction is closely related to the concentration of radicals HO and H. generated during the combustion process. The role of gas phase flame retardants is mainly to convert these high-energy free radicals into stable free radicals, inhibit the combustion process, and achieve the purpose of flame-retardant. Free radicals are in contact with the surface of dust particles and may lose their activity. The following reactions may occur on the surface of dust particles: H·+O2·-HO 2, which generates a large amount of activity on the surface of dust particles much lower than that of H·, HO·, etc. Base HO2, so as to achieve the purpose of suppressing combustion.

 

In general, flame retardants achieve flame retardance by absorbing, cooling, diluting, forming a heat-insulating layer, and terminating free-radical chain reactions, among which the first three are physical effects, and the latter is chemical. effect. The physical effects include endothermic, dilute flammable substances, and the effect of isolating air; chemical effects include carbonization, elimination of free radicals, and phosphoniumation.

 

 

Common flame-retardant insulating tapes include:PET film  Mara tape, non-woven margin adhesive tape, rubber margin tape, polyimide kapton tape, high temperature tape and so on.