In recent years, major fires caused by the ignition of polymer materials have been on the rise, and the flame retardancy of polymer materials has attracted more and more attention. However, most of the current flame retardant polymers are mainly achieved by adding halogen-containing flame retardants, which generate a large amount of smoke and toxic, harmful and corrosive gases during combustion, resulting in "secondary disasters". Therefore, studying the low-smoke and halogen-free flame retardant of polymer materials is of great significance for reducing the occurrence of fire and reducing the loss of life and property caused by fire. The use of clean and efficient inorganic flame retardants is an important way to improve the flame retardant properties of materials. Sb 2 O 3 is an additive flame retardant mainly used for flame retardant of plastic products (polyvinyl chloride, polyolefin, polyester) and textile fabrics. It can also be used for flame retardant of canvas, paper, paint, paint, etc. petrochemical agents, catalysts and other synthetic fibers, can also be used as a rubber, flame retardants, masking agents enamel industry, electronic industry materials like technical material. As the flame retardant auxiliary Sb 2 O 3 , the particle size and morphology have a great influence on the properties of the synthetic materials and the flame retardant effect. Particle size is an important indicator of Sb 2 O 3 products. The flame retardant treatment of synthetic chemical fiber and textile products often requires the particle size of Sb 2 O 3 to be in the nanometer range, and the particle size is fine, and the amount of Sb 2 O 3 which achieves the same flame retardant effect is also The less, and does not block the orifice, which is the key to flame retardant textiles. However, the inorganic flame retardant particles currently used are generally above the micron level, the flame retardant filling amount is large, the flame retarding efficiency is not high, and the problems caused by the processing technology and product performance are relatively serious. The nano-flame retardant is a block, a film, a multilayer film and a fiber obtained by agglomerating ultrafine flame-retardant particles having a particle size of 1 to 100 nm. By using a conventional inorganic flame-retardant material to be ultra-fine, the nano-particle itself is utilized. It has a quantum size effect, a small size effect, and a surface effect to enhance the interfacial action, improve the compatibility of the inorganic substance and the polymer matrix, and achieve the purpose of reducing the amount and improving the flame retardancy. The application of nanotechnology in traditional flame retardant materials has opened up a new field for flame retardant technology. Nano inorganic flame retardant composite materials provide a new way for the development of flame retardant polymer materials, and its emergence will lead to inorganic flame retardant industry. A historic change. 1. Synthesis method of nano inorganic flame retardant Has been the development of nano inorganic flame retardants are: antimony trioxide flame retardant Nano nano flame retardant aluminum hydroxide, magnesium hydroxide flame retardant nano nano layered double hydroxide flame retardant, nano pentoxide the antimony flame retardants and nano-calcium carbonate, nano titanium dioxide, nano zinc oxide. However, the nanometer calcium carbonate, nano titanium dioxide, nano zinc oxide and the like have low flame retardancy, and are generally only used as a filler. The nanometer antimony oxide flame retardant is used less, mainly for ultra-fine antimony trioxide and nano aluminum hydroxide. Nano-magnesium hydroxide and nano-layered compounds are mainly used. (a) nanometer antimony trioxide The particles of nano-Sb 2 O 3 are mostly obliquely long rectangular bodies, and can be used in combination with other flame retardants and smoke suppressing agents to produce a synergistic effect. Its synthesis methods are as follows: (1) Precipitation method SbCl 3 powder crystals are precipitated in concentrated hydrochloric acid to form nanoparticles; (2) Low-pressure evaporation, Sb 2 O 3 powder is placed in a sealed heating vessel for compaction, vacuuming, vacuuming The temperature is maintained at 30 Pa, and the temperature is raised to 610-630 ° C, Sb 2 O 3 ultrafine powder can be obtained, and the nanometer antimony trioxide is synthesized by the method, and the particle size is 43.3 nm; (3) the fire production process fine The crucible is melted into a mash at high temperature, the mash is contacted with oxygen in the air, and the ruthenium is oxidized to Sb 2 O 3 to volatilize, and the crystallization and cooling conditions are controlled to obtain Sb 2 O 3 white powder of different particle sizes. synthesis of nanoparticles of controlled granulometry; (4) method using an arc between the electrode and the metal antimony carbon electrodes produced by the arc discharge energy, Sb 2 O 3 can generate steam at a high temperature, then the vapor is condensed into fine particles, and then capturing to give a gum 0.01um or less fine powder, but this method is difficult to co nanoscale products; use antimony (5) plasma method in the autoclave for a high frequency plasma reactor, can effectively inhibit the formation of oxides of lead metal and the like, It is also possible to make the vaporized antimony trioxide The daughter is excited and ionized to form a large number of active groups, reducing the content of high valence, thereby obtaining Sb 2 O 3 with high purity; and also forming nano Sb 2 O 3 —SiO 2 by coprecipitation method. Composite flame retardant. Second, the application of nano inorganic flame retardants The nano inorganic flame retardant composite material refers to uniformly dispersing one or more inorganic flame retardant components in the material in a matrix of another component at a nanometer size or a molecular level, and because of the existence of ultrafine size, various The properties of the type of nano-inorganic flame-retardant composites are significantly improved over their corresponding macro or micro-scale composites. Compared with the original parent polymer, the nano-inorganic flame-retardant composite has improved and improved properties in the following aspects: First, improving mechanical properties and thermal properties, bending modulus (rigidity) is increased by 1.5 to 2 times, and friction is improved. Wear resistance, greatly improve heat resistance, heat distortion temperature rises by several tens of degrees, and the thermal expansion coefficient decreases to half of the original; second, it imparts functionality to the composite material, makes the material barrier, flame retardant, and improves the transparency of the material. , pigment coloring, electrical conductivity and magnetic properties; in addition, it can also improve the dimensional stability of the material. In particular, polymer/flame retardant nanomaterials will become a new generation of flame retardant polymer materials. The nano-flame retardant polymer combines the advantages of good flexibility, low density and easy processing of the organic polymer with the high strength and hardness of the inorganic filler, good heat resistance and high deformation resistance, showing a strong vitality. The preparation methods mainly include: ultrafine particle direct dispersion method, including milk solution blending method, solution blending method, mechanical blending method, melt blending method, etc.; molecular compounding method; "template" synthesis method; intercalation composite method Including monomer embedded polymerization method, polymer solution embedding method and polymer direct fusion embedding method; in-situ recombination method, including in-situ polymerization method and in-situ formation of filler method. At present, synthetic nanocomposite flame retardant materials are mainly as follows. (1) Polymer / antimony trioxide nanocomposite Polyethylene resin, flame retardant and other raw materials are mixed according to the ratio (90 parts of flame retardant LDPE, 12 parts of decabromodiphenyl ether, 6 parts of nano-Sb 2 O 3 ), which can be processed at the corresponding processing temperature. The oxygen index of the nano-Sb 2 O 3 /PE flame retardant polymer was 24.1. ABS plastic in a 5% addition of Sb 2 O 3 nanometers, can be prepared by Sb 2 O 3 / oxygen index of flame retardant ABS polymer was 19.3 nanometers; nano addition of 10% Sb 2 O 3 Sb 2 can be prepared The O 3 /ABS nano flame retardant polymer has an oxygen index of 20.9. 90 parts of flame retardant ABS resin, 10 parts of decabromodiphenyl ether and 5 parts of nano Sb 2 O 3 are mixed and processed at the corresponding processing temperature to obtain oxygen of Sb 2 O 3 /ABS nano flame retardant polymer. The index is 25.5. Cunnionl et al. used nanoscale antimony trioxide for flame retardant treatment of acrylonitrile-butadiene-styrene copolymer (ABS). There is no change in the impact strength of the obtained material, and the small-sized nanoparticles have a small refractive index, and the light propagation is hardly affected. 100 parts of PVC, 50 parts of DOP, 8 parts of chlorinated paraffin, 1.2 parts of lead stearate, 1.5 parts of barium stearate, nano-Sb 2 O 3 3 parts of flame retardant and other raw materials are mixed according to the ratio, and nano Sb 2 can be obtained. O 3 /PVC flame retardant polymer with an oxygen index of 30. In addition, Sb 2 O 3 can have a good synergistic flame retarding effect with ZnO, TiO 2 and the like. (2) Polymer / aluminum hydroxide nanocomposites In general, aluminum hydroxide is suitable for resins with lower processing temperatures, such as PP, PVC, polyurethane flexible foam, epoxy resin, unsaturated polyester, acrylic resin, etc., because of its low effective temperature range. In 2001, the application effect of aluminum hydroxide composite flame retardant on PVC cable material was discussed. The influence of flame retardant content on the flame retardancy and mechanical properties of the material was discussed. It was pointed out that the flame retardant property can be obtained by adding aluminum hydroxide flame retardant. The flame retardant material is V-0 grade, and its mechanical properties are basically not reduced. But so far, the use of ultra-fine aluminum hydroxide flame retardant ethylene-propylene rubber, the system's OI value can reach 38 or more, and the mechanical properties have improved. The synergistic flame retardant of nano-Sb 2 O 3 —Al(OH) 3 composite flame retardant can be prepared by single component precipitation method, alkoxide hydrolysis method and coprecipitation method. Sb 2 O 3 and AI(OH) 3 can complement each other: Sb 2 O 3 has the advantages of less dosage and little effect on the physical and mechanical properties of the resin itself, but it produces black smoke when burned, and is more expensive; Al(OH) 3 has the advantages of not generating corrosive gas, low smoke generation and low price, and the disadvantage is that the addition amount is large, and the mechanical properties of the product are greatly affected. However, they all have a flame retardant effect in the gas phase and the solid phase, so the two have a true synergistic effect. Third, the flame retardant mechanism of nano inorganic flame retardant Sb 2 O 3 The flame retardant mechanism of nano flame retardants comes down to the following aspects: (1) partitioning heat conduction and heat radiation or wall effect Nano Sb 2 O 3 , in the initial stage of combustion, first melts, forming a dense protective film on the surface of the material to block the air, thereby playing a flame retardant effect. (2) Promoting the formation of non-combustible compounds The reaction of the flame retardant with the combustibles at high temperatures can lead to the formation of charcoal, which acts to block the air and isolate the thermal decomposition of the combustibles. The high dispersion of the nano-flame retardant can fully promote the formation of carbon, and the nanoparticles are fully dispersed in the carbonized layer to act as a skeleton, so that the formed carbonized layer has good rigidity and strength, and can resist the flow of smoke generated in a fire. airflow. The ultra-fine Sb 2 O 3 is efficiently dispersed in the polymer material to efficiently form dense SbC in the flame retarding process. Moreover, a flame retardant such as aluminum hydroxide, magnesium hydroxide, layered double hydroxide or silicate can react with the polymer at a high temperature to decompose a relatively large specific non-combustible gas (such as CO 2 ) to cause physical coverage. The function, which isolates the air, has achieved a fire-extinguishing effect. (III) Capture of gas phase free radicals Sb 2 O 3 uses a condensed phase flame retardant and a chain reaction free radical OH to achieve flame retardancy. Antimony trioxide generally needs to be synergistically flame retardant with halogen. When heated, HCl is first released, and SbOCl is formed, and then SbOCl is thermally decomposed to generate SbCl 3 while sucking a large amount of heat. SbCl 3 decomposes Cl free radical at flame temperature and combines with active H, OH, etc. in the flame. To suppress the flame. At the same time, SbCl 3 has a large vapor ratio and is attached to the surface of the material to shield the air and condense into droplets or solid particles over the flame. The energy is consumed on the solid surface, causing the burning speed to slow down or stop. At the same time, the generated HX can terminate the radical chain reaction generated by the burning of the plastic, and the nano-dispersed flame retardant helps to fully capture the free radicals. (4) Nanofiller action After filling a flame retardant such as nanometer antimony trioxide, aluminum hydroxide, magnesium hydroxide, layered double hydroxide or silicate, the concentration of the combustible polymer is uniformly decreased, and the concentration of the combustion product is reduced. Fourth, the characteristics of nano flame retardants Nano flame retardants can improve the mechanical properties of materials, reduce the amount of flame retardants used, and meet the process requirements. Nano-aluminum hydroxide flame retardant is the earliest development, the technology is relatively mature, but its decomposition temperature is relatively low, often can not meet the polymer processing temperature requirements, its application is limited. There have also been a lot of reports on the preparation of ultra-fine antimony trioxide flame retardant and nano antimony pentoxide flame retardant. These flame retardants are generally only used as flame retardant synergists, mainly used in plastic products (polymerization). The flame retardant of vinyl chloride, polyolefin, polyester and textiles can also be used as a flame retardant for canvas, paper, oil, etc., but it is generally required to be shared with halogen-containing flame retardants and cannot meet environmental protection requirements. Nano-magnesium hydroxide flame retardants play an important role in flame retardants due to their unique properties. Magnesium hydroxide is an environmentally friendly green flame retardant without harmful substances in the production, use and disposal process, and it can neutralize the acidic and corrosive gases generated during the combustion process. The high fluidity of nanometer magnesium hydroxide can greatly improve the processing performance of polymer flame retardant materials, and can fundamentally solve the serious damage caused by the high filling amount to the mechanical properties of polymer flame retardant materials. Therefore, nano-magnesium hydroxide is likely to be non-toxic and low smoke halogen-free phosphorus-free flame retardants new one in the future development of environment-friendly, and the field of polymer nano-retardant material is the most important breakthrough. The addition of layered inorganic compounds (such as clay , graphite , aluminum-magnesium hydroxide, etc.) developed in recent years to polymers can produce polymer/nanocomposites with special flame retardancy. Potential applications include aircraft interior materials, fuel tanks, electrical or electrical components, structural components within the shroud, brakes and tires. Compared to conventional flame retardants, similar or better flame retardant properties are achieved, the concentration of layered compounds required is relatively low, and the physical properties of some polymers are not reduced, but are greatly improved. Another advantage is that the layered compound remains intact at higher temperatures during combustion and acts as an insulating layer, reducing the release of volatile decomposition products of the polymer, thereby providing self-extinguishing properties. It is very obvious that magnesium-aluminum basic carbonate with special crystal form is a promising high-efficiency, non-toxic, low-smoke inorganic flame retardant, because it has non-toxic, low-smoke, no corrosive gas, no The advantages of secondary pollution have been widely used. Polymer/layered nanocomposites have much better mechanical properties, thermal properties, flame retardancy, anisotropy, etc. than conventional filler materials, and do not damage the environment. They are considered as substitutes for some traditional flame retardants. In addition, in addition to special flame retardant properties, nano-flame retardants can also impart versatility to materials such as toughening, strengthening material strength, enhancing material scrub resistance, antibacterial, bactericidal and self-cleaning functions, and organic waste gas and liquid. Photocatalytic degradation, etc. V. Research directions and recommendations The research and development of nano flame retardants is a new way to solve the scientific problems of low smoke, low toxicity and halogen free flame retardant of polymer materials. The purpose of conducting research in this field is to develop new flame retardant technologies for environmentally safe and clean fire prevention and control, and provide a scientific basis for practical applications. The future development direction should be considered from the following aspects: (1) Preparation methods, storage and transportation of nano-scale superfine flame retardant powder, mainly exploring flame retardant powders with less environmental pollution and less agglomeration, and methods for their manufacture, and expanding their application fields; (2) Studying and screening of flame retardants, flame retardant organic modifiers and inorganic additives to study nano-scale superfine composite flame retardant powders and their coordinated flame retardant effects to meet the requirements of flame retardant coordination system And reduce the amount of flame retardant; (3) Studying the compatibility and dispersibility of the flame retardant composite system, so that the polymer nanocomposite has more excellent flame retardant properties and is beneficial to industrialization; (4) Studying the flame retardant mechanism of polymer nanocomposites, and clarifying the microstructure and formation mechanism of nanocomposites; (5) Studying the pyrolysis process of nanocomposites, the structural changes before and after combustion, and the microstructure of the carbonized layer, in-depth discussion of its flame retardant mechanism, revealing the thermal stability, flame retardant properties and toxicity of combustion products, and guiding the synthesis of new materials A comprehensive performance optimized flame retardant polymer composite; (6) Exploring the corresponding relationship between flame retardant mechanism and structure of polymer/inorganic nanocomposites, laying a theoretical foundation and experimental basis for further research and application of materials; for polymer/inorganic flame retardant nanocomposites used as structural materials Materials, study the structural strength and residual stress changes under fire conditions, which is of great significance for evaluating the structural stability of the members under heat conditions; (7) Using computer simulation means to establish the appropriate theoretical model to explore the relationship between the structure and properties of various layered double hydroxides, and to synthesize layered double hydroxides and composite materials of predetermined structure and properties; (8) From the perspective of molecular design, study the relationship between properties and structure of nanocomposites, study the relationship between nanocomposite structure and combustion reaction mechanism, and prepare new high performance flame retardant polymer/inorganic nanocomposites, and Research on synthetic routes and reaction mechanisms. 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Nano inorganic flame retardant Sb