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The advantages of brominated flame retardants are that their decomposition temperatures are mostly between 200 and 300 degrees centigrade, which match the decomposition temperatures of various polymers. Therefore, brominated flame retardants can play a flame retardant role at the same time of gas phase and condensation with the smallest addition and the best effect. Over the past decade, the European "Green" environmental protection organizations have misunderstood the bromine flame retardants. Because of their irrational prejudice, the government has been restricted to relax the strict flame retardant standards for TV sets in the name of the toxicity of bromine flame retardants and adopt IEC65 combustion standards with lower fire safety factor. Over the next few years, these televisions became one of the main causes of fires in European countries, reaching a warning line of 165 fires per million units per year and 16 deaths per year. In the United States, only one TV set per million sets causes fires and no one dies. The result of this comparison forced Europe to formulate a new and stricter standard SBI. To replace the previous more relaxed standards.



These "green" environmental organizations also believe that brominated flame retardants can produce toxic smoke when burning. For this reason, the Brominated Science and Environment Forum (BDEF), the Brominated Flame Retardant Producers Association (BFRIP) and the European Brominated Flame Retardant Producers Association (EBFRIP) have completed a number of studies showing that brominated flame retardants can significantly reduce the emission of toxic gases during the combustion of flame retardant polymers, which is beneficial to the environment. 。 According to NIST (previous NBS), the toxic component of the total smoke generated by the polymer containing bromine flame retardant is only one third of the total smoke generated by the polymer without flame retardant.



In addition, the most recently discussed is that PBDPO produces toxic and carcinogenic polybrominated benzo (PBDD) and polybrominated dibenzofuran (PBDF) when burned. For this reason, the world-renowned brominated flame retardants manufacturer tested PBDEs through intermediaries, which showed that these products could pass the strict German Regulations and the regulations of the US Environmental Protection Agency (TSCA40_766.25), that is, there was no risk of BPDD and PBDF. Therefore, PBDEs are still popular in the United States, Japan and some European countries, and are used in a variety of polymers. At the same time, the production process of decabromodiphenylethane is becoming more and more perfect, its flame retardant performance is excellent, and it is a flame retardant with broad application prospects. At present, domestic manufacturers have produced the same product quality as foreign standards.



The annual increase rate of Decabrominated diphenyl ether production is the fastest in China. The consumption of Decabrominated diphenyl ether is ** and it is estimated that nearly 70,000 tons will be produced in 2027, while the import volume will not change much. Therefore, the supply of Decabrominated diphenyl ether will exceed the demand this year. The quality of some domestic decabromodiphenyl ethers is better than that of imported ones. The disadvantages of domestic decabromodiphenyl ethers lie in the high content of free bromine, the high content of iron impurities and the poor long-term storage stability. Although some factories have made improvements, they still need to do a good job of post-processing products in order to be comparable to imports in quality.

The quality of octabromoether is basically the same as that of foreign countries, but attention should be paid to improving the shape of products. Overseas countries have changed from traditional powder to granular. In recent two years, major domestic manufacturers have also produced granular octabromoether, which has made gratifying progress.



The thermal stability of hexabromocyclododecane affects its application effect in the processing of flame retardant products. The heat-resistant hexabromocyclododecane imported from abroad can maintain a stable structure at the processing temperature of general polymers, and once burned, it will not produce too much smoke. This is the improvement of hexabromocyclododecane in China.



As for tetrabromobisphenol A, if imported bisphenol A is brominated to produce products, the quality is often higher than that of domestic bisphenol A raw materials. Brominated flame retardants are still the main force in flame retardant technology all over the world. At present, the prejudice against brominated flame retardants will be confirmed with the further development of science. It will still be widely used in the next 20 years. Our evaluation is that we hate it, but we can not do without it. Other types of flame retardants in the family include phosphorus, triazine, silicon, intumescent and inorganic fillers. These flame retardants exert their unique flame retardant effects in various fields of application.



Among them, the organic phosphorus series of phosphorus flame retardants are mostly oil like, which are not easy to add in the process of polymer processing. They are commonly used in polyurethane foam, soft PVC, transformer oil, cellulose resin, natural and synthetic rubber. The red phosphorus in inorganic phosphorus system has good flame retardant effect and wide application because it is a pure flame retardant element, but its bright color restricts its application. The application of red phosphorus should pay attention to micronization and surface encapsulation (encapsulation), so that it can disperse well in polymer, has good compatibility with polymer, is not easy to migrate, and can maintain the flame retardancy of polymer for a long time. In addition, the degree of polymerization of ammonium polyphosphate is the key to determine the quality of the above two products. The higher the degree of polymerization, the better the flame retardant and fireproof effect. There are products with degree of polymerization of more than 100 in China, while the degree of polymerization of APP (ammonium polyphosphate) is more than 500 in foreign countries.



Triazine flame retardants are mainly melamine and its derivatives, which have multiple reaction functions and excellent thermal stability, durability and weather resistance. They have good flame retardant effect and compatibility with polymers, so they are widely used. Commonly used are melamine, melamine urea cyanate (MCA), etc.



Silicon based flame retardants are very small in domestic production and production. Intumescent flame retardants are developed as phosphorus and nitrogen based flame retardants in recent years. When these flame retardants are heated, a dense carbon foam layer is formed on the surface, which plays a role in heat insulation, oxygen isolation, smoke suppression, and can prevent droplets, and has good flame retardancy. Since 1992, there have been reports of successful research in China. So far, many research institutes have been engaged in the development of this field, but there are still no reports of industrial scale production.



There may be two reasons why the scale production has not been achieved: one is that there are unreacted inorganic acids in the product, which reflect the moisture absorption phenomenon on the surface of flame retardant products; the other is that the N-P intumescent flame retardant is the synthesis of some macromolecular compounds, and the last step is solid-state reaction. Its mass transfer and heat transfer process is too complex to industrialize.



Finally, the inorganic flame retardants need to be noted that antimony trioxide has always been classified into this category, but strictly speaking, antimony trioxide itself is not a flame retardant, it is only a synergist with halogen flame retardants. Aluminum hydroxide and magnesium hydroxide are the main inorganic flame retardants, especially when halogen-free flame retardants are advocated in some fields, they will become the first choice. Because inorganic flame retardants need to be added in a large amount, in some special cases will exceed the amount of polymer itself, therefore, it is bound to have a great impact on the physical and mechanical properties of polymers, which requires the treatment of inorganic flame retardants, namely, particulatization, surface activation. The purpose of micronization is to make them disperse evenly in polymers and play a flame retardant role in the bulk. Experiments show that to meet the same flame retardant standard, the dosage of micronization can be reduced appropriately. In addition, surface activation is to make the inorganic flame retardant compatible with the polymer, which can reduce the mechanical strength of the polymer itself due to the addition of a large number of inorganic flame retardants.



Recently, some articles have talked about the flame retardant superiority of inorganic nanoparticles. Our work experience shows that the addition of these nanoparticles may be beneficial to improve mechanical strength, but it will not have a great impact on the flame retardant performance. Because the flame retardant mechanism of inorganic flame retardant is to reduce the system temperature by releasing water vapor through thermal decomposition, and at the same time water vapor dilutes the flammable gas to achieve flame retardant effect. It is determined by the amount of water vapor, so it is related to the amount of flame retardant, and has nothing to do with whether the flame retardant is nanoparticles or not. Generally speaking, the particle size distribution of inorganic flame retardant is between 2 and 5 microns. Enough.