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The main reason for the flame retardant to play the role of flame retardant is that in the process of polymer combustion can prevent or inhibit its physical changes or oxidation reactions. Compounds that have one or more of the following flame retardant effects can be used as flame retardants.
1. Heat absorption effect
When a compound is decomposed by heat or releases crystalline water or dehydrates, the temperature rise of the material is suppressed due to its heat absorption, thus producing a flame retardant effect, which is called the heat-absorbing effect. Such as borax, aluminium hydroxide, calcium carbonate and so on, thus playing a flame retardant effect.
When a compound is decomposed by heat or releases crystalline water or dehydrates, the temperature rise of the material is suppressed due to its heat absorption, thus producing a flame retardant effect, which is called the heat-absorbing effect. Such as borax, aluminium hydroxide, calcium carbonate and so on, thus playing a flame retardant effect.
2. Covering effect (isolation effect)
Flame retardant at higher temperatures to generate a stable cover layer or decomposition of foam-like substances, covering the polymer surface, so that the polymer material due to thermal decomposition of combustible gases generated by the difficult to escape, and materials to play a role in thermal insulation and air insulation, so as to achieve the effect of flame retardant. Such as phosphorus ester compounds and fireproof foam coatings.
Flame retardant at higher temperatures to generate a stable cover layer or decomposition of foam-like substances, covering the polymer surface, so that the polymer material due to thermal decomposition of combustible gases generated by the difficult to escape, and materials to play a role in thermal insulation and air insulation, so as to achieve the effect of flame retardant. Such as phosphorus ester compounds and fireproof foam coatings.
3. Dilution effect
The mechanism is to produce a large number of non-combustible gases during thermal decomposition, so that the combustible gases produced by the polymer materials are diluted and do not reach the combustible concentration range. For example, CO2, NH3, HCI, H2O, etc. can be used as dilution gas. Ammonium phosphate, ammonium chloride, ammonium carbonate, etc. can produce this kind of non-combustible gas when heated.
The mechanism is to produce a large number of non-combustible gases during thermal decomposition, so that the combustible gases produced by the polymer materials are diluted and do not reach the combustible concentration range. For example, CO2, NH3, HCI, H2O, etc. can be used as dilution gas. Ammonium phosphate, ammonium chloride, ammonium carbonate, etc. can produce this kind of non-combustible gas when heated.
4. Inhibition effect
This is a class of inhibitors that can cut off the chain reaction of fire burning radicals. These substances can be repeatedly reacted with - OH and generate H2O, cut off the free radical reaction chain, inhibit the oxidation reaction occurs, so that it is not so intense to the extent of the fire, that is, it is in a strong heat environment, fire will also be out of the heat source to leave the heat, due to the small amount of heat and can not be maintained combustion, self-extinguishing from the fire. Commonly used bromine, chlorine and other organic halogen compounds have this inhibitory effect.
This is a class of inhibitors that can cut off the chain reaction of fire burning radicals. These substances can be repeatedly reacted with - OH and generate H2O, cut off the free radical reaction chain, inhibit the oxidation reaction occurs, so that it is not so intense to the extent of the fire, that is, it is in a strong heat environment, fire will also be out of the heat source to leave the heat, due to the small amount of heat and can not be maintained combustion, self-extinguishing from the fire. Commonly used bromine, chlorine and other organic halogen compounds have this inhibitory effect.
5. Transfer effect
Its role is to change the mode of thermal decomposition of polymer materials, thereby inhibiting the production of flammable gases. For example, the use of acid or alkali to make cellulose dehydration reaction and decomposition into carbon and water, rather than combustible gases, so it can not catch fire and burn. Flame retardants such as ammonium chloride and ammonium phosphate belong to this category.
Its role is to change the mode of thermal decomposition of polymer materials, thereby inhibiting the production of flammable gases. For example, the use of acid or alkali to make cellulose dehydration reaction and decomposition into carbon and water, rather than combustible gases, so it can not catch fire and burn. Flame retardants such as ammonium chloride and ammonium phosphate belong to this category.
6. Synergistic effect
Here is the main flame retardant and use. Some compounds used alone without flame retardant effect or effect is not great, take and can enhance the flame retardant effect. Such as antimony trioxide and halogen compounds and can greatly improve the flame retardant efficiency, and can reduce the total amount of flame retardants.
Here is the main flame retardant and use. Some compounds used alone without flame retardant effect or effect is not great, take and can enhance the flame retardant effect. Such as antimony trioxide and halogen compounds and can greatly improve the flame retardant efficiency, and can reduce the total amount of flame retardants.
