In recent years, epoxy resin (EP) has been widely used in various packaging materials, coatings, civil engineering, construction, adhesives, electronics and aviation. The oxygen index of ordinary EP is only about 19.8%, which is a flammable substance. Therefore, how to improve the flame retardant performance of EP has attracted extensive attention of domestic and foreign researchers.
The most commonly used methods to improve the flame retardant properties of EP are divided into two types: additive flame retardant technology and reactive flame retardant technology. At present, most of the domestic and foreign use of additive flame retardant technology. The so-called additive flame retardant technology is to disperse the flame retardant in the EP in physical form to obtain the flame retardant EP. But this will affect the mechanical properties of EP, etc. The flame retardants used can be divided into halogen-containing, phosphorus-containing, boron-containing, antimony-containing and other metal flame retardants according to the elements they contain. The flame retardant elements (such as halogen, P, Si, N, etc.) in the reactive flame retardant system (also known as reactive flame retardant) are eventually combined into the macromolecular chain of EP, which has the characteristics of migration resistance, thermal stability and size. Therefore, the development and application of active flame retardants is the direction of flame retardant development. Whether it is additive flame retardant technology or reactive flame retardant technology, halogen occupies a primary position.
With the progress of science and technology, people are fully aware of the harm caused by halogen flame retardant. When the materials treated with it are heated and burned, they will produce toxic, corrosive gases and a large amount of smoke, which will pollute the environment and cause secondary pollution. restricted its development. Therefore, looking for an alternative to halogen flame retardants - halogen-free flame retardants will become an important direction for future research and development.
1. Research status of additive flame retardant EP
Additive flame retardant technology has the characteristics of simple process and wide source of raw materials, and is currently the most commonly used EP flame retardant method. The currently used additive flame retardants can be divided into inorganic flame retardants (including fillers) and organic flame retardants.
(1) Flame retardant EP prepared by adding inorganic flame retardant
Generally, the most commonly used inorganic flame retardants for the preparation of halogen-free flame retardant EP are metal oxides (such as aluminum hydroxide, magnesium hydroxide), borides (such as zinc borate), inorganic phosphorus series (mainly including red phosphorus, phosphate and ammonium polyphosphate) etc.
(2) Metal oxides
Aluminum hydroxide [Al(OH)], also known as aluminum oxide trihydrate (ATH), has stable performance, low price and non-toxicity, and has flame retardant and smoke suppression effects. ATH has flame retardancy matching with EP-based composite materials in terms of thermal decomposition, and can lose crystal water in a zero-order reaction. The activated alumina formed after water loss can improve the flame-retardant ability of EP-based composite materials. At the same time, ATH can also increase the ability of the material to remove extra-carbon elements during the cracking process, and increase the amount of weightless residues under the condensed ring reaction conditions, and play the flame retardant effect of the condensed phase.
Edited by: Suzhou Eastop Chemical Co., Ltd.
