Classification of flame retardants

Organic Flame Retardants

(1) Halogenated Flame Retardants

No matter what kind of combustion theory is used to design polymeric flame retardants, it is mainly based on three aspects: cooling; termination of the chemical reaction of combustion; cut off the heat source. The flame retardant mechanism of halogenated flame retardants is just the combination of these three, and a little use can give plastics a good flame retardant effect. However, flame retardants produce a lot of smoke and toxic and corrosive gases when burned, which can cause corrosion of circuit system switches and other metal objects, and cause more serious damage to the human respiratory system and other organs, and are usually eliminated. .

(2) Organic Flame Retardants

Organic Flame Retardants react with the polymer matrix or its decomposition products during combustion to form P-O-C bondsand, forming the carbonized protective layer, or a cross-linking reaction to form a polyaromatic network compound with good thermal stability, thus playing a flame retardant role.

(3) Nitrogen-based flame retardants

Nitrogen-based flame retardants are mainly triazine compounds, i.e. melamine and its salts, melamine cyanurate, polyamides, etc. Nitrogen-based flame retardants when heated, emit CO2, NO2, N2, NH3, H2O and other non-flammable gases, which can dilute the combustible gases, cover and surround the polymer, and block the contact between the polymer and the oxygen in the air. At the same time, nitrogen can capture high-energy free base, inhibit the continuous combustion of polymers, so as to achieve the purpose of flame retardancy.

(4) Intumescent Flame Retardant

Intumescent Flame Retardant is a new type of compound flame retardant that has been widely used in recent years.has attracted attention in the field of flame retardant in my country. It has a unique flame retardant mechanism and the characteristics of no teeth, low smoke and low toxicity, and is an important way to make flame retardants toothless. Due to the synergistic effect of the \"three sources\" of acid source, carbon source and gas source, the intumescent flame retardant system forms a dense porous carbon foam layer on the surface of the material during combustion to prevent the flame from spreading and propagation. Intumescent flame retardants are divided into phosphorus-nitrogen series intumescent flame retardants and halogen-free graphite intumescent flame retardants. Nitrogen-based intumescent flame retardants are flame retardants with mononitrogen as the main component. Due to the synergistic effect between phosphorus and nitrogen, the flame retardant mechanism is multiple and shows good flame retardant performance. Ammonium polyphosphate (APP) has ahigh phosphorus content, high nitrogen content, good thermal stability, low hygroscopicity, good dispersibility, low toxicity and smoke suppression.It is a good nitrogen-based intumescent flame retardant. Expanded graphite flame retardant uses the characteristics of graphite to form interlayer compounds, chemically treats natural flake graphite to form a special interlayer compound, and decomposes the interlayer compound after high temperature treatment. At the same time, graphite expands along the carbon axis at high speed to form expanded graphite (EG) [i4]. The flame retardant mechanism of EG belongs to the condensed phase flame retardant mechanism, which is flame retardant by slowing down or interrupting the production of combustibles from solids. EG begins to expand after being heated to a certain extent, and the expanded graphite flakes are not only the carbon source in the expansion system, mbut also a heat-insulating layer, which can slow down and terminate the decomposition of the polymer; at the same time, a large amount of heat is absorbed during the expansion process, which lowers the system temperature; In addition, during the expansion process, the release of acidic ions into the interlayer can promote dehydration and carbonization.

(5) silicone series, drill series and others

Organosilicon series have excellent effects of high efficiency, non-toxic, low toxicity and anti-dropping, which have little effect on material processing performance and physical properties, and have good smoke suppression It is a kind of polymer flame retardant which is very popular now.

Prev: Existing problems in the application of textile loading in my country