What are the flame retardants

With the development of China's synthetic material industry and the continuous expansion of its application fields, flame retardants have broad market prospects in various fields such as chemical building materials, electronic appliances, transportation, aerospace, daily furniture, interior decoration, clothing, food, housing and transportation. In addition, the fields of coal field, oil field and forest fire extinguishing also promote the rapid development of fire retardant and fire extinguishing agent production in China. In China, flame retardant has become the second largest polymer modification additive after plasticizer. The current production capacity is about 200000 t / A, the annual production capacity is between 150000 T / A and the annual consumption is about 200000 t / A. The shortage is mainly imported from the United States and Israel, and the main imported products are organobromine and halogen phosphorus flame retardants. There are more than 60 flame retardant manufacturers in China, which can produce more than 50 kinds of products, mainly brominated phosphorus series. Brominated flame retardants are the most important series, accounting for about 30% of the organic flame retardants in China.


Organic flame retardant is still the main type and consumption of flame retardant in China, and the production and consumption of inorganic flame retardant is still small. However, in recent years, the development momentum is good and the market potential is large. Although halogenated flame retardants, which are the most commonly used flame retardants, have incomparable high efficiency compared with other flame retardants, their harm to the environment and human beings can not be ignored. Environmental protection is the focus of the development and application of additives, so domestic and foreign companies have been adjusting the product structure of flame retardants and increasing the development of efficient and environmentally friendly flame retardants.


1. Application and production status of environmentally friendly flame retardant


With the increasing awareness of environmental protection, safety and health, many countries in the world began to focus on the research, development and application of environmental friendly flame retardants, and some achievements have been made. According to the effective elements, flame retardants can be divided into phosphorus, chlorine, bromine, antimony, aluminum and boron based flame retardants. In this paper, halogen-free flame retardants, flame retardants and other flame retardants are introduced.


1.1 halogen free flame retardant


Environmental friendly flame retardant with halogen-free, low smoke and low toxicity has always been the goal of people. In recent years, some global flame retardant suppliers and applicators have shown high enthusiasm for flame retardant and halogen-free, and have invested a lot of efforts in the development of halogen-free flame retardants and flame retardant materials. According to the analysis, the main types of halogen-free flame retardant are phosphorus flame retardant and inorganic hydrate. The former mainly includes red phosphorus flame retardant, inorganic phosphorus ammonium polyphosphate (APP), ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphate ester, etc., and non Halogenated Phosphate of organic phosphorus series. The latter mainly includes magnesium hydroxide, aluminum hydroxide and modified materials such as hydrotalcite. Ammonium polyphosphate and hydrotalcite are the representative products of this series of environmental protection and good market prospects. The following two products are analyzed.


1.1.1 ammonium polyphosphate


Ammonium polyphosphate (APP) is a long chain inorganic polymer containing phosphorus and nitrogen. Its general formula is (nh4p03) n. Because of its good chemical stability, low moisture absorption, good dispersion, small specific gravity and low toxicity, it is widely used in plastics, rubber and fiber as flame retardant treatment agent in recent years; it can also be used to prepare intumescent fire retardant coating for ships, trains, cables and high-rise buildings; it is also used for the production of dry powder fire-extinguishing agent, which is used for large-scale coal field, oil well and forest In addition, it can be used as fertilizer. The polymerization degree of ammonium polyphosphate is the key to determine the product quality as a flame retardant. The higher the polymerization degree is, the better the fire retardant effect is. The degree of polymerization of app (ammonium polyphosphate) is more than 500. The development of domestic ammonium polyphosphate began in 1978. After more than 20 years of development, the production of ammonium polyphosphate in China has a certain foundation and basically meets the needs of the domestic market. In 2005, the output of ammonium polyphosphate in China exceeded 20000 tons, and there was a small amount of export in addition to meeting domestic demand. The production capacity of ammonium polyphosphate in China is mainly concentrated in Southwest China, East China and Central South China, with the largest output in Southwest China, followed by East China and Central South China. Ammonium polyphosphate is rarely produced in North China, Northeast China and Northwest China. The scale of domestic ammonium polyphosphate production units is small. The largest production plants are Guizhou Zunyi Xinyuan phosphating Co., Ltd. and Shifang Changfeng Chemical Co., Ltd., with the plant scale of 3000t / A, and Rongtai plant has reached 3000t / A. The second is Shanghai Xinhua flame retardant general plant with a production capacity of 2000 t / A. The general scale of the plant is 400-1000t / A, and the minimum production scale is only 300t / A. With the continuous expansion of the consumption market of ammonium polyphosphate, its output will continue to increase.


1.1.2 hydrotalcite


In the application of inorganic flame retardants, anionic layered functional materials as flame retardants are developing rapidly. It is a kind of inorganic compound with special structure. M2 + is divalent ion, generally magnesium, m3 + is trivalent metal ion and an - is anion. This material is called LDHs for short. Due to its unique layered structure, composition and adjustable anions, hydrotalcite has been widely used as an inorganic functional material in catalysis, ion exchange, adsorption, medicine and other fields. As a halogen-free high smoke suppression flame retardant, hydrotalcite can be widely used in plastics, rubber, coatings and other fields. The development of Mg based anionic layered functional materials in China started in the late 1990s. Although the development history is short, it has developed rapidly. In 1999, Beijing University of Chemical Technology cooperated with Yixing additive chemical plant to build a 500t / a hydrotalcite production line in Yixing, Jiangsu Province, becoming the first water skiing machine in China