Intumescent flame retardants are environmentally friendly and highly efficient flame-retardant materials. Their flame-retardant effect mainly relies on the formation of a porous foam carbon layer on the material surface, achieving flame-retardant results through functions such as heat insulation, oxygen isolation, smoke suppression, and drip prevention. Its constituent elements mainly include the following three parts:
First, acid source (dehydrating agent)
The acid source is a key component in intumescent flame retardants. Its main function is to decompose and produce acidic substances when heated. These acidic substances can undergo esterification reactions with the carbon source, promoting the dehydration and carbonization of the carbon source. Common acid sources include inorganic acid salts and inorganic acid esters, such as ammonium phosphate salts, phosphate esters, borates and silicates, etc. Among them, ammonium polyphosphate is widely used due to its excellent performance. The selection of acid sources needs to take into account factors such as their decomposition temperature, acid strength, and compatibility with other components.
Second, carbon source (carbonizing agent)
The carbon source is the basis for forming the foam carbonized layer. It is some polyhydroxy compounds or carbohydrates with high carbon content. During the heating process, the carbon source can react with the acidic substances produced by the acid source, dehydrating and carbonizing to form a carbon layer. Commonly used carbon sources include pentaerythritol, sorbitol, starch, phenolic resin, etc. The selection of carbon sources needs to take into account factors such as their carbon content, hydroxyl content, and decomposition temperature to ensure that they can react with the acid source at an appropriate temperature and form a stable carbon layer.
Third, air source (foaming agent)
The gas source is another important component of intumescent flame retardants. Its main function is to decompose and produce a large amount of non-flammable gas when heated. These gases can fill the carbon layer, causing it to expand and foam, forming a porous foam structure. Commonly used gas sources include nitrogen-based compounds such as melamine, dicyandiamide and urea. The selection of the gas source needs to take into account factors such as its decomposition temperature, gas generation volume, and compatibility with other components to ensure that it can decompose at an appropriate temperature to produce sufficient gas, allowing the carbon layer to fully expand and foam.
