Flame retardant mechanism of flame retardant BOPP biaxial tensile film production line
DATE：2021/7/29 8:34:35 / READ： / SOURCE：This station
Flame retardant mechanism of flame retardant BOPP biaxial tensile film production line
When burning, organophosphorus flame retardants will decompose to form a non combustible liquid film of phosphoric acid. When further burning, phosphoric acid can be dehydrated to form metaphosphoric acid, and metaphosphoric acid can further form polymetaphosphoric acid. As polymetaphosphoric acid is a strong dehydrating agent, the polymer is dehydrated and carbonized, and a carbon film is formed on the surface of the polymer, which can block air and heat, so as to play a flame retardant role. Phosphoric acid is polymerized by heating to produce polymetaphosphoric acid, which has a strong catalytic effect on the dehydration of polymers (such as cellulose) to carbon. The results show that the gaseous product formed by the thermal decomposition of organic phosphorus contains Po ·, which reacts with H ·, oh · to inhibit the combustion chain reaction. Therefore, organophosphorus flame retardants have condensed phase and vapor phase flame retardancy, but more is carbonization. BOPP biaxially oriented film production line www.handern.comNitrogen flame retardants are mainly nitrogen-containing compounds. In recent years, non-toxic flame retardants are being sought at home and abroad to replace highly toxic halogen flame retardants. Melamine and its salts, such as cyanurate, have been commercialized. This kind of flame retardant absorbs heat under heating conditions and decomposes into non combustible gas to dilute combustibles, reduce surface temperature of combustibles and oxygen isolation, so as to reduce combustion speed. Intumescent flame retardant mainly acts as flame retardant in condensed phase by forming porous foamed carbon layer. The carbon layer is formed through the following steps: 1 at lower temperature (specific temperature depends on the nature of acid source and other components), the polyols which can be esterified by acid source and inorganic acids which can be used as dehydrating agents are released. The esterification reaction takes place at a temperature slightly higher than the released acid, and the amine in the system can be used as the esterification catalyst; The system melts before or during esterification; The carbonaceous gas source and the inorganic ester are further expanded by the reaction of the carbonaceous gas source and the water, and the carbonaceous ester is further formed by the reaction of the carbonaceous gas source and the residual alcohol; 5 when the reaction is close to completion, the system is gelatinized and solidified, and finally the porous carbon foams are formed. BOPP biaxially oriented film production line www.handern.com
Intumescent flame retardants may also have gas phase flame retardancy, because the phosphorus nitrogen carbon system may produce no and NH when heated, and they can also combine free radicals to terminate the combustion chain reaction. In addition, free radicals may collide on the particles that form the foam and interact with each other to synthesize stable molecules, resulting in chain reaction interrupted. BOPP biaxially oriented film production line www.handern.com
At present, the flame retardant mechanism of intumescent flame retardant is not very clear. According to the gas release of ammonium polyphosphate polyethylene and formaldehyde system (a new intumescent flame retardant) when heated, it is proposed that ammonium polyphosphate in the system may react according to the following reaction formula: some halogen flame retardants, mainly polybrominated diphenyl ether and its flame retardant polymers, during high-temperature cracking and combustion, It produces toxic polybrominated dibenzofurans (pbdf) and polybrominated dibenzodioxanes (PBDD). Based on human requirements for environmental protection, we should develop and use "green" products to ensure the realization of the strategy of sustainable development of the national economy. Therefore, the halogen-free of flame retardant materials is very popular all over the world. Some multinational flame retardant polymer material suppliers also began to provide halogen-free flame retardant engineering plastics to the market. In Europe, halogen flame retardants and their flame retardant polymers failed to obtain green environmental protection marks due to dioxin problems. Therefore, at present, some European countries restrict the use of halogen flame retardants, trying to promote the halogen-free process of flame retardant materials. However, some people believe that brominated flame retardants and their flame-retardant polymers produce pbdf and PBDD in very few specific environments, and the amount is very limited, and not all brominated flame retardants will produce these two poisons. At the same time, some valuable advantages of brominated flame retardants will not be easily abandoned by users, so halogen flame retardants and their flame-retardant polymers are still used. In the long run, flame retardant polymer materials should be developed in the direction of low toxicity, low smoke and no halogenation. Therefore, at least some halogen flame retardant materials will be treated carefully by users, but the halogen-free process of flame retardant materials will not be fast. BOPP biaxially oriented film production line www.handern.com
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