Flame-retardant materials include organic flame-retardant materials and inorganic flame-retardant materials. The current flame-retardant materials are flame-retardant materials that can be achieved after the addition of flame retardants. In general, flame retardants are diverse in composition, organic flame retardants, and organic flame retardants. Inorganic flame retardants, organic flame retardants have good flame retardant effect, and relatively few additives. However, organic flame retardants have the disadvantages of high smoke generation and toxic gas release during combustion. Inorganic materials are non-toxic, non-smoke, non-volatile, and The advantages of cheap, but there are a lot of additives.
1, domestic and foreign development status
The flame retardant is a polymer synthetic material propellant. The flame retardant can be used to treat the polymer material flame-retardant so as to avoid burning of the material and to prevent the spread of fire. The synthetic material has the characteristics of smoke elimination, self-extinguishing property and flame retardancy. .
2, the advantages and disadvantages of commonly used flame retardants
In recent years, with the increase in the output of plastic products and the improvement of safety standards, flame retardant materials have become more widely used. In general, flame retardant materials can be divided into organic flame retardant materials and inorganic flame retardant materials. Among them, organic flame retardant materials are mainly Is a halogen additive, inorganic materials not only have a certain flame-retardant effect, but also produce hydrogen chloride and prevent smoke. In addition, inorganic flame-retardant materials are non-toxic, non-corrosive and inexpensive. Inorganic flame-retardant materials in the US, Japan and other countries consume over 60 %, However, China's consumption of inorganic flame retardant materials is less than 10%.
2.1 Halogen-based flame retardant
Halogen-based flame retardants are not only the most productive, but also the most widely used. The material added with this flame retardant can release hydrogen halide during the combustion process, and free radicals, thus preventing the transfer of the combustion chain, thus producing low-activity radicals and slowing down Combustion. Halogen flame retardants are generally used in thermoplastic materials and thermosetting materials. They not only have good compatibility with polymer materials, but also are easy to use. Therefore, they are popular in the market and widely used in automobiles, packaging, and textile industries.
2.2 Phosphorus Flame Retardants
Inorganic phosphorus flame retardants mainly include phosphate, red phosphorus, etc. Red phosphorus is widely used. Red phosphorus is a good flame retardant, but in practical applications, red phosphorus flame retardant materials are easily oxidized and release harmful Poisonous gases, the combustion of dust easily lead to explosion, there is a certain risk in the resin mixing and molding processing, therefore, the phosphorus flame retardant material is subject to certain restrictions. The improved red phosphorus flame retardant is added Metal hydroxides, to a certain extent, solved the problem of polymer material toxicity.
2.3 Nitrogen flame retardant
Commonly used varieties are melamine, melamine cyanurate (MCA), etc., often need to add synergist, nitrogen/phosphorus is the most commonly used synergistic flame retardant system, mainly used in PA, PU, PO, PET, PS, PVC and other resins .
Melamine cyanurate is a nitrogen-containing, halogen-free, environmentally friendly flame retardant that is particularly suitable for PA6 and PA66 without fillers. It has both powder and granular forms. When used as a flame-retardant polyamide foam When burning, the formed carbon foam layer protects the polymer, insulating it from heat and oxygen.
2.4 Metal Oxide Flame Retardants
Metal oxide flame retardants mainly add inorganic elements with essential flame retardancy as elemental or compound forms to the flame-retardant substrate, and are fully mixed with the polymer in a physically dispersed state, and pass through the gas phase or the condensed phase. Chemical or physical changes play a role in flame retardancy.
Aluminum hydroxide is the most widely sold flame retardant for inorganic hydroxides. It is mainly used for man-made rubbers, thermosetting resins and thermoplastics whose processing temperature is below 200°C. Aluminum hydroxide flame-retardant plastics have less smoke in flames. A prominent advantage.
Magnesium hydroxide is an inorganic flame retardant with better thermal stability. It is stable at over 300°C. It is widely used in many synthetic rubbers, resins, including engineering plastics and other resins under high temperature processing. In polymer systems To flame retardant, the role of smoke elimination. Combined use with ATH, complementary to each other, its flame retardant effect is better than using alone.
3, the future development trend of flame retardants
In the past 10 years, the growth rate of flame retardants in China has been maintained at 15% to 20%, and the current annual consumption is about 570,000 tons. In 2019, the consumption of flame retardants in China will increase to about 840,000 tons. The total consumption of agents is higher than the world average, but in terms of proportion, the application of fire-retardant materials in China is still far below the world average, and the gap between developed countries and Europe and the United States is even greater.
