Why are intumescent flame retardant systems becoming more and more popular

Intumescent flame retardant systems, like intumescent fire retardant coatings, also require three types of materials: dehydration carbonization catalyst (acid source), char forming agent (carbon source) and blowing agent (gas source). When they are mixed into organic polymers, a carbon foam layer is formed on the surface of the material after heating, which not only plays the role of heat insulation and oxygen insulation, but also blocks the escape of flammable volatiles from the surface and the molten droplets of polymers falling phenomenon. The carbon foam layer is a physical fire-blocking mechanism, resulting in a greatly reduced amount of escaping combustion product gas and its toxicity.

The difference between the intumescent flame retardant system and the intumescent fire retardant coating is that the former is added to the polymer body and processed together with the polymer. Therefore, strict requirements are put forward for this kind of flame retardant system. the

First of all, it is required that the intumescent flame retardant system has good thermal stability, can withstand the polymer processing temperature, and will not undergo thermal decomposition. The general processing temperature is 200~250℃. the

Secondly, the flame retardant must reach a certain concentration to form a certain thickness of carbon foam layer on the surface when heated. A large amount of addition will have a certain impact on the physical properties of the polymer material. In order to overcome this disadvantage as much as possible, various surface treatment techniques are used to disperse it as uniformly as possible in the polymer material to achieve the purpose of reducing the dosage. the

Thirdly, when the polymer material is thermally decomposed, a large amount of flammable gas and decomposition residues are formed, which cannot affect the foaming performance of the intumescent flame retardant system. the

In order to achieve the best expansion effect, the composition of the formulation must be well selected, requiring that the various forming processes match each other. the

When a matrix material, such as a thermoplastic, is heated, it softens, creating a reaction medium. Polyphosphoric acid is produced due to the thermal decomposition reaction of acid source materials (such as APP). It promotes the dehydration and carbonization of carbon source materials (such as pentaerythritol) to form a carbon-containing polymer structure. At the same time, the gas source material produces a large amount of gas products, which causes the carbonaceous polymer to expand. The progress of the crosslinking reaction increases the viscosity of the system, prevents the gas from escaping, and forms a carbon foam layer along with the curing reaction. The in terms of flame retardancy of polypropylene materials, the intumescent flame retardant system is much superior to other systems. The main reason is that the softening temperature and decomposition temperature of PP are well matched with the expansion process of the intumescent system.

The intumescent flame retardant system not only has good flame retardancy, but also can maintain good mechanical strength of the material, and can reduce the concentration of CO and the emission of smoke during combustion. the

   With the continuous expansion of the application range of PP, PE, EAV and other materials and the continuous improvement of flame retardant requirements, the intumescent flame retardant system will increasingly show its great advantages.