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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 reaction. Compounds with one or more of the following flame retardant effects can be used as flame retardants.
1.Heat-absorbing effect
Compound thermal decomposition or release of crystalline water or dehydration, because of its heat absorption and the material temperature rise is inhibited, resulting in a flame retardant effect, known as the heat-absorbing effect. The effect is called heat-absorption effect. Such as borax, aluminum hydroxide, calcium carbonate, etc. Therefore, play 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 surface of the polymer, so that the thermal decomposition of the polymer material due to the production of the Flammable gases generated by thermal decomposition of polymer materials are difficult to escape, and the materials play the role of heat 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, H20, etc. can be used as dilution gases. 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. This kind of material can react with OH repeatedly and generate H2O, cut off the free radical reaction chain, inhibit the oxidation reaction. Chain of reaction, 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, the fire will also be outside the heat source to leave, due to heat Less and can not maintain 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 generation of flammable gases. For example, the use of acid or alkali to make cellulose dehydration reaction and decomposition into carbon and water, rather than flammable gases, so it can not catch fire. 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 efficiency of flame retardant, and can reduce the total amount of flame retardant.
1.Heat-absorbing effect
Compound thermal decomposition or release of crystalline water or dehydration, because of its heat absorption and the material temperature rise is inhibited, resulting in a flame retardant effect, known as the heat-absorbing effect. The effect is called heat-absorption effect. Such as borax, aluminum hydroxide, calcium carbonate, etc. Therefore, play 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 surface of the polymer, so that the thermal decomposition of the polymer material due to the production of the Flammable gases generated by thermal decomposition of polymer materials are difficult to escape, and the materials play the role of heat 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, H20, etc. can be used as dilution gases. 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. This kind of material can react with OH repeatedly and generate H2O, cut off the free radical reaction chain, inhibit the oxidation reaction. Chain of reaction, 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, the fire will also be outside the heat source to leave, due to heat Less and can not maintain 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 generation of flammable gases. For example, the use of acid or alkali to make cellulose dehydration reaction and decomposition into carbon and water, rather than flammable gases, so it can not catch fire. 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 efficiency of flame retardant, and can reduce the total amount of flame retardant.
