Aluminum hydroxide flame retardant, can decompose chemically bound water (about 34.6%) at high temperatures. This is an endothermic reaction, thereby delaying the thermal degradation of the polymer and slowing or inhibiting the combustion of the polymer. Inhibit the temperature rise of the polymer, promote carbonization and smoke suppression. In addition, the large amount of released water vapor can dilute the concentration of combustibles and reduce the contribution of combustible gases to combustion. Reduces heat release and smoke generation from the system. It also helps to interrupt combustion.
When aluminum hydroxide flame retardant is decomposed by heat, it releases water, absorbs a large amount of latent heat, reduces the actual flame temperature on the surface of the material, slows down the degradation of the polymer to low molecules, reduces the occurrence of combustibles, and uniformly releases water vapor. Dilute the oxygen concentration on the surface, making it impossible to burn the surface. The decomposition temperature of aluminum hydroxide is about 205°C, and the dehydration reaction at 320°C has been basically completed, releasing crystal water, absorbing latent heat, and cooling (that is, cooling technology in flame retardant technology, a large amount of water vapor generated can dilute combustible gas.
In short, under the action of the flame, the aluminum hydroxide filled in the polymer decomposes and absorbs part of the heat released during the combustion process, which is equivalent to taking away the heat of the polymer, thereby reducing the temperature of the polymer and slowing down the degradation rate. This chemical cooling effect of dispersing and absorbing heat is the main reason for the flame retardancy of aluminum hydroxide. The water vapor released by the decomposition of aluminum hydroxide can dilute the concentration of the gas reactants in the flame zone and has a certain cooling effect. The filling of aluminum hydroxide into the polymer helps to form a carbonized layer during the combustion process, which not only prevents heat and oxygen from entering, but also prevents small molecule combustible gases from escaping. Of course, the latter two flame retardant effect is much smaller than the former. Aluminum hydroxide can effectively slow down the burning speed of the polymer, reduce the smoke produced by combustion, and capture harmful gases. From the point of view of use, aluminum hydroxide, unlike certain organic additive flame retardants, does not produce corrosive combustion products, nor does it evaporate from the polymer.
Aluminum hydroxide flame retardants carbonize combustible materials. Flame retardant effect is achieved. This flame retardant effect mainly works in the solid phase. This kind of flame retardant material is mainly phosphorus flame retardant (including organic phosphorus and inorganic phosphorus).
2. The flame retardant forms a non-volatile film under combustion conditions, isolating the air and achieving the purpose of flame retardant. The flame retardant effect mainly plays a role in the liquid phase. Such flame retardant materials mainly include borate, halide, antimony oxide, phosphorus and other flame retardant materials, or these materials react with each other to produce substances.
3. The decomposition products of flame retardants cut off the chain reaction of hydroxyl radicals. To achieve the purpose of flame retardant. The flame retardant effect mainly plays a role in the gas phase. Flame retardant materials are mainly halides and antimony oxide.
4. Dispersion of combustion heat and dilution of combustible substances. These flame retardant materials are mainly zinc borate, aluminum hydroxide, magnesium hydroxide, etc., This is mainly due to the large amount of heat-absorbing and non-combustible material decomposition to produce dilute combustible gas.
From the above way is not difficult to find. The carbonization of combustibles prevents the production of a large number of combustible gases from the source, so as to achieve the purpose of flame retardant. Therefore, the rest of the flame retardant method can easily play a role. This is why after using phosphorus-based flame retardants. Antimony halides and other flame retardant materials can be greatly reduced. Therefore, in the choice of flame retardant system, we can not ignore the use of phosphorus flame retardant materials.