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Flame retardants are mainly used for flame retardant synthesis and natural polymer materials, including plastics, rubber, fiber, wood, paper, paint, etc. . According to a rough estimate, 65% to 70% of the world's flame retardants are used in flame retardant plastics, 20% in rubber, 5% in textiles, 3% in coatings and 2% in paper and wood. Electronic / electrical, transportation, building materials, furniture, textile flame retardant for several major users . In recent years, with the increasingly stringent fire safety standards and the rapid growth of plastic production, the global consumption of flame retardants and sales has shown an increasing trend , the total consumption has reached 1.2 million t / a or more, of which 85% Additive flame retardant, 15% reactive flame retardant . Among the many varieties, the largest amount of aluminum hydroxide (ATH), followed by halogen flame retardant. In the next 5 years, the global demand for flame retardants can reach an average annual growth rate of 4% to 5% (slightly higher in the Asia-Pacific region), by 2007, the global flame retardant can reach the total amount of 145-155 million t. North America, Western Europe, Japan is the largest consumer areas of flame retardants, accounting for 30% of the consumer market, 33%, 18%, Asia (excluding Japan) accounted for 19%. Recent market research shows that the US flame retardant market in 2003 increased by 969 million US dollars, the annual growth rate of 5% in recent years, the Japanese polymer additives market continued to decline, while the flame retardant has increased slightly . A wide variety of flame retardants, is currently the most widely used chlorine, bromine, phosphorus and phosphorus halide, inorganic flame retardants. Consumption of flame retardants in different parts of the world is different, the largest amount of inorganic flame retardants in Europe, and the United States, Japan, Asia, the largest consumption of brominated flame retardants, the United States and Japan, respectively, 35% And 40%, while Asia is as high as 60%. Specific consumption structure, Europe: 33% inorganic, bromine 28%, organic phosphorus 25%, 4% chlorine, the other 10%; the United States: bromine 35%, 26% organic phosphorus, , Chlorine 8%, other 7%; Asia: bromine 60%, inorganic 25%, chlorine 8%, organic phosphorus 7%; Japan: bromine 40%, inorganic 30% 20%, chlorine 2%, the other 8% .
1 China's development status of flame retardants [5 ~ 7] China's flame retardant production in plastic additives, is second only to the plasticizer of the second largest industry, production increased year by year, the market continues to expand. Since 1960, since the development and production of flame retardants, so far, China's total production capacity of flame retardants of about 150,000 t / a, engaged in research and development of flame retardant units have more than 50 varieties of flame retardants 120 Variety, more than 150 production units. In recent years, China's rapid development of flame retardant industry, such as the most important addition of brominated flame retardants decabromodiphenyl ether (DBDPO) sales in 1999 to 7000t / a, 2000, 9000t / a, 2001 13500t / a. Growth rate increased year by year, other halogen system in another important member of the chlorinated wax series has also greatly increased. There are phosphorus (including inorganic phosphorus and organic phosphate esters) and inorganic [mainly Al2 (OH) 3, Mg (OH) 2 and to help fire retardant Sb2O3, etc.] market is also expanding. However, according to the proportion of flame-retardant plastic products accounted for the total amount of plastic point of view, compared with the United States is still a big gap. The proportion of the United States is 40%, while China is less than 1%, even taking into account the US economy is 10 times the total for China, we also have a lot of room for expansion. China's flame retardant halogen-based flame retardants, accounting for more than 80% of the flame retardants, including chlorine (mainly chlorinated paraffin) accounted for 69%, and exports; but bromine is insufficient, still need each year Imports; as non-polluting, low toxicity of inorganic flame retardant only 17%, of which half of antimony trioxide, and aluminum hydroxide, magnesium hydroxide less than 10%. The main flame retardant varieties are 42, 52 chlorinated paraffin, there are a small amount of 70 chlorinated paraffin, polybrominated diphenyl ether, hexabromo ether, octabromo ether, poly 2,6 dibromo benzene ether, tetrabromide Bisphenol A and its oligomers, alkyl (aryl) phosphates, chlorine (bromine) phosphate, aluminum hydroxide (Mg), antimony trioxide, red phosphorus. China's proportion of flame retardants and the world's developed countries and regions, the gap between the consumption structure is very large, the current foreign flame retardants have tended to inorganic-based, and China is still a larger pollution, higher halogen flame retardant Based.
2 development trend of flame retardants  Since 1908 G.A.Engelard and other natural rubber and chlorine reaction of flame retardant chlorinated rubber, and created a chemical method of flame retardant polymer has been a precedent, especially in recent years 40 years of rapid development of polymer industry needs, the rapid development of flame retardant technology to develop a number of efficient, new flame retardant. With the development of flame retardant technology, many new technologies have emerged.
2.1 microencapsulation technology [9,10] The microcapsule technology used in flame retardants, is developed in recent years, a new technology. The essence of microencapsulation is to disperse the flame retardants into tiny particles, encapsulate them with organic or inorganic substances to form microcapsule flame retardants, or use inorganic materials with large surface as the carrier, Agent adsorbed in the voids of these inorganic carriers to form a honeycomb microcapsule flame retardant. Microcapsule technology has many advantages, such as preventing the migration of flame retardants, improving flame-retardant efficiency, improving thermal stability, changing dosage forms, etc. It is also beneficial to compound and synergize the components and manufacture multifunctional flame-retardant materials. China is currently being explored, such as the Hunan Institute of Plastics has developed microencapsulated red phosphorus masterbatch, successfully used in PE, PP, PS, ABS resin, the flame retardant effect is good; Anhui Chemical Industry Research Institute developed microencapsulated phosphoric acid Microencapsulation of chlorinated paraffin wax 70, etc., also achieved very good results; Ju Jianfeng prepared superfine red phosphorus microcapsules flame retardant effect on the cotton fabric A-class standards.
2.2 ultra-fine technology [11 ~ 14] inorganic flame retardants with high stability, less volatile, low smoke toxicity and low cost advantages, more and more people are of all ages. But because of its poor compatibility with synthetic materials, large amount of added, making the mechanical properties of materials and heat resistance are reduced. Therefore, the modification of inorganic flame retardants to enhance its compatibility with synthetic materials, reduce the amount of inorganic flame retardants become one of the trends. At present, the aluminum hydroxide (ATH) ultrafine, nanotechnology is the main research and development direction. A large amount of ATH is added to reduce the mechanical properties of the material, and then by ATH to further refine the filling. But will play a rigid particle plastic enhancement effect. Especially nanoscale materials. As the role of flame retardancy is dominated by the chemical reaction, and the same amount of flame retardants, the smaller the particle size, the greater the specific surface area, the better the flame retardant effect. Ultrafine is also considered from the aspect of affinity, because aluminum hydroxide and polymer polarity is different, which led to its flame retardant composite materials processing technology and physical and mechanical properties of the decline, ultra-fine nano Of the ATH, due to enhance the interaction of the interface can be more evenly dispersed in the matrix resin, which can more effectively improve the mechanical properties of the blend. For example, when an equal amount (100 parts) of ATH is added to the EEA resin, the smaller the average particle size of the ATH, the higher the tensile strength of the blend. The use of ultra-fine flame-retardant polymer polymer will be the flexibility of organic polymers, low density, easy processing and the advantages of inorganic fillers and high hardness and hardness, heat resistance is better, not easily combined with a high degree of deformation, showing a strong Of the vitality.
2.3 Surface Modification Technology [15,16] inorganic flame retardants have strong polarity and hydrophilic, with the non-polar polymer material compatibility is poor, the interface is difficult to form a good combination and bonding. In order to improve its adhesion with the polymer and the interface affinity, the use of coupling agent for its surface treatment is one of the most effective way. Commonly used coupling agents are silanes and titanates. Such as the silane treatment of ATH, flame retardant effect, can be very effective to improve the bending strength of polyester and epoxy resin tensile strength. Ethylene-treated ATH can be used to improve the flame retardancy, heat resistance and moisture resistance of the crosslinked ethylene vinyl acetate copolymer. The titanate-based coupling agent and the silane coupling agent may be used in combination to produce a synergistic effect. In addition, alkyl ketene isocyanic acid and phosphorus-containing titanate, etc., can be used as A1 (OH) 3 surface treatment coupling agent. After surface modification, the surface activity of ATH was improved, the affinity between the resin and the resin was improved, the physical and mechanical properties of the product were improved, the processing fluidity of the resin was increased, the moisture absorption rate of the ATH surface was decreased, Flame retardant products of various electrical properties, but also the flame-retardant effect from V 1 to V 0 level. Liu Lijun, etc. will be modified aluminum hydroxide used in polypropylene, the specific surface area increases, lower oil absorption, good dispersion, filled with polypropylene significantly improved after the melting phenomenon, a better flame retardant effect, and The mechanical properties of the material have been improved.
2.4 complex coordination technology [17 ~ 19] in practice, a single flame retardant there is always the shortcomings of this or that, and the use of a single flame retardant is difficult to meet increasingly high demand. Combinations of flame retardants are phosphorous, halogen, nitrogen and inorganic flame retardants, or within certain types of composite, to seek the best economic and social benefits. Combining the advantages of two or more kinds of flame retardants, the flame retardant compound technology can complement the performance of flame retardants, reduce the amount of flame retardants, improve the flame retardant properties, processing properties and physical and mechanical properties. We usually add some bromine flame retardants in the phosphorus, so not only can improve the flame retardant effect, but also reduce the amount of flame retardants, reduce the impact on the environment. Such as polyolefin flame retardant, in order to achieve the same flame retardant effect, the need to add 5% P or 40% Cl or 20% Br, and P, Br complex, just add 0.5% P and 7% Of Br. South China University of Technology, Li Yonghua and other research on the silicone resin SFR100 and TBAB on the ABS have a synergistic effect, can effectively improve the flame-retardant properties of ABS and impact strength, and to improve its electrical properties. In short, the flame retardant compound, is to give full consideration to the thermodynamic properties of polymers after the selection of the most suitable flame retardant varieties, maximize the synergies of flame retardants, taking into account the various additives such as Plasticizers, heat stabilizers, dispersants, coupling agents, toughener interaction, to reduce the amount of flame retardant to improve the purpose.
2.5 smoke technology [7,10,20] In the fire, polymer combustion asphyxiation of smoke is very serious air pollution, but also to extinguish the fire caused great difficulties. So contemporary flame retardant and smoke suppression is paralleled, and for some plastics, such as PVC, smoke suppression is more important than flame retardant. Halogen-containing polymers, halogen flame retardants and antimony compounds are the main source of smoke. Therefore, in addition to the non-halogenated flame retardant is the main way to reduce the amount of smoke, the PVC and other halogen-containing polymers to add smoke suppression solution is another measure to smoke. Ferrocene is a commonly used organic smoke suppressant, the most suitable as a PVC smoke agent; molybdenum has so far been considered the best anti-smoking agent, such as ShemlnWilliams developed Kegad911A is a small amount of zinc and molybdenum complexes, Add 4% in PVC, polymer smoke can be reduced by 1/3. As molybdenum is more expensive, the use of zinc borate, ferrocene, aluminum hydroxide, silicon compounds with a small amount of molybdenum compound, is to solve the problem of smoke more realistic way, such as Climax Moly FR 201 is developed molybdic acid Ammonium and aluminum hydroxide complex, PVC added in the 5 to 10 copies, can reduce the amount of smoke 43%. Wang Dexi of the Institute of Chemistry, Chinese Academy of Sciences, added 2% silicone powder to the PC / ABS alloy to reduce the smoke density below 500.
2.6 Crosslinking technology [21,22] Cross-linked polymer flame retardant properties much better than the linear polymer, therefore, in the processing of thermoplastic add a small amount of crosslinking agent, the plastic into a part of the network structure, Not only can improve the dispersion of flame retardants, but also conducive to the combustion of carbon generated when the role of plastic to improve flame-retardant properties, and can increase the physical and mechanical properties of products, weathering, heat resistance. If a soft PVC to join a small amount of quaternary ammonium salt, so that it is heated to form cross-linked flame retardant materials; can also use radiation, adding metal oxides and crosslinking agents and other methods to cross-linked polymers. Jia Shaojin, University of Science and Technology of China, made the cross-linking of HDPE / EPDM flame retardant system by γ radiation, which not only reduced the flammable melt dripping during combustion, but also changed the surface structure and interface structure of the blended polymer, The mechanical strength. Taiwan's researchers have developed a phosphorus-containing flame retardant crosslinking agent made of varnish epoxy resin, the weight loss of 5% decomposition temperature Td = 383 ℃, UL 94 flame retardant index V0.
2.7 macromolecular technology [23 ~ 25] the development of the current flame retardant technology presents many new trends, macromolecule technology is a new research in flame retardant just one of the new technology in recent years, its research is very active, and made a Series of results. For example, the new development of brominated flame retardants is to improve the bromine content and increase the molecular weight, we all know, the main drawback of brominated flame retardants will be reduced by the anti-UV stability of the substrate, the combustion generated more Smoke, corrosive gases and toxic gases, so its use is subject to certain restrictions. Now some companies and research departments are through macromolecular technology to change this situation, such as the United States Ferro company PB 68, the main component of brominated polystyrene, molecular weight of 15,000, bromine up to 68%; bromine chemical company and Ameribrom companies were the development of poly-pentabromophenol-based acrylic acid, containing 70.5% of bromine, molecular weight of 30,000 to 80,000. These flame retardants are particularly suitable for all kinds of engineering plastics, in terms of migration, compatibility, thermal stability, flame retardant, etc., are much better than many small molecule flame retardants, may become the next replacement products. Beijing Productivity Center to promote the development of the NG9401, a phosphorus / nitrogen synergistic system of polymer flame retardants, compared with the original flame retardant, when it is not dripping combustion, heat resistance is better than the general low Molecular phosphorus flame retardant. The flame retardant can adjust the molecular weight and P / N ratio, and make the carbon source, the acid source and the gas source expand into carbon flame retardant system to obtain the optimal combination. Halogen-free flame retardant materials and technology is currently very active in the development, which halogen-free phosphate ester compounds developed rapidly. However, these phosphoric acid ester-based compounds need to be improved in their volatility, low heat resistance, flame-retardant properties, and mechanical properties of the resin materials. BAO Zhi-su developed a macromolecular phosphate, to overcome the shortcomings of the previous low-molecular-weight phosphate. This is a polyaryl-containing silicon bisphosphate, not only has excellent flame retardancy, but also has high thermal stability, low volatility, good compatibility with the resin, no effect on the processing performance, durability, light, Water and other advantages, but also both stabilizers and pigments and other additives to add the role of dispersant can be widely used in thermoplastic and thermosetting resin flame retardant. Polymerization of organic phosphorus flame retardants has also become the focus of the development, have emerged in a series of good compatibility, high stability of the new high molecular weight or polymer type of organic phosphorus flame retardants. For example, the United States GreatLake company CN 1197, Department of pentaerythritol phosphate flame retardant, can be used for epoxy and unsaturated polyester resin composite materials such as flame retardant; to CN 1197 intermediates derived from a series of new flame retardants , Such as the use of CN 1197 and acrylic acid reaction containing cage-like phosphate ester structure of flame-retardant acrylic, ammonium polyphosphate compound can be used for polypropylene flame retardant, the effect is very significant. (PSPPP), polyphenylphosphonic acid diphenyl ester (PAPPP) and polyphenylphosphonic acid bisphenol A ester (PBPPP) have been synthesized by Wang et al. PSPPP is prepared from bisphenol S and phenylphosphonic dichloride by melt polycondensation. The number average molecular weight is more than 104. The product has high thermal stability and has excellent flame retardancy for PET. PAPPP Phenylphosphonic dichloride and p-aminophenol as raw materials, the diazotization and interfacial polycondensation reaction obtained, the compound has a low decomposition temperature and high residue, has a good flame retardant PBPPP is phenylphosphono bis Chlorine and tetrabromobisphenol A as raw materials. The product has high molecular weight, good thermal stability and good flame retardancy to PET.
3 China's flame retardant industry with China's overall sustained and rapid economic development, with the accession to the WTO and the world economy, in particular, the continuous improvement of China's fire-retardant regulations, ushered in a great opportunity for development, but also face severe Of the challenges. We should improve the development of innovative capacity to promote the flame retardant industry will move towards environmental protection, low toxicity, efficient multi-functional direction.