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Classification of halogen-free flame retardants


Release time:

Aug 09,2021

[Summary]There are many kinds of organic flame retardants, and the development speed is very fast. They can be divided into halogen flame retardants and halogen-free flame retardants. Halogen flame retardants are a kind of flame retardants used very early, but due to the release of toxic gases, their use is greatly restricted. Halogen-free flame retardants do not contain halogen, have good flame retardant effect, and the gas produced by thermal decomposition has low smoke and low toxicity, which is widely welcomed. Halogen-free flame retardants can be divided into phosphorus-containing flame retardants, nitrogen-containing flame retardants and intumescent flame retardants.

There are many kinds of organic flame retardants, and the development speed is very fast, which can be divided into halogen flame retardants andhalogen-free flame retardant. Halogen flame retardants are a kind of flame retardants used very early, but due to the release of toxic gases, their use is greatly restricted. Halogen-free flame retardants do not contain halogen, have good flame retardant effect, and the gas produced by thermal decomposition has low smoke and low toxicity, which is widely welcomed. Halogen-free flame retardants can be divided into phosphorus-containing flame retardants, nitrogen-containing flame retardants and intumescent flame retardants.

Organophosphorus flame retardant is one of the important types of flame retardants. It has the dual effects of flame retardant and plasticization. It can make the flame retardant completely halogen-free, improve the flow performance in plastic molding, and inhibit the toxic and corrosive gas produced by burning halogen flame retardants. Less than halogen flame retardants. Flame retardant mechanism is: on the one hand, the flame retardant thermal decomposition of phosphoric acid, phosphoric acid, polymetaphosphoric acid, these acids containing phosphoric acid has a strong dehydration performance, can make the polymer surface dehydration and carbonization, but elemental carbon can not produce flame evaporation combustion and decomposition combustion, so it has a flame retardant effect; On the other hand, the flame retardant generates PO · radicals by heating, and can absorb a large amount of H · HO · radicals, thereby interrupting the combustion reaction. Organic phosphorus flame retardants are mainly phosphoric acid esters, phosphonic acid esters, phosphine oxides and heterocycloes.

Phosphate flame retardant is a kind of additive flame retardant, which is widely used because of its rich resources and low price. Phosphate is prepared by the reaction of the corresponding alcohol or phenol with phosphorus trichloride and then hydrolysis. Phosphate flame retardants that have been successfully developed and widely used in the market include tricresyl phosphate, triphenyl phosphate, and triisopropyl phosphate. Ester, tributyl phosphate, trioctyl phosphate, tolyl diphenyl phosphate, etc. There are many varieties of phosphate esters and they are widely used, but most of the phosphate esters are liquid, poor heat resistance, volatile, and the compatibility with polymers is not ideal. For this reason, a number of new phosphate flame retardants have been developed at home and abroad, such as tris (1-oxo-1-phosphate -2,6, 7-trioxabicyclo [2,2,2] octane -4-methylene ) phosphate (Trimer) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2,2,2] octane (PEPA). Trimer is characterized by structural symmetry, phosphorus content of 21.1%,PEPA phosphorus content of 17.2%, these two phosphate flame retardants are white powder, thermal stability is very good, and the polymer has a good compatibility.


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