Retard Agent IFR

Flame retardant mechanism

Intumescent flame retardant is the process of flame retardant through expansion with generally three parts:

1. Acid source: also known as dehydrating agent or carbonization agent, it is usually inorganic acids and its salts, such as phosphoric acid, boric acid, ammonium phosphate, ammonium polyphosphate, etc.  They can interact with the fiber to promote the formation of carbide;

2. Carbon source: also known as carbon agent, mainly for some of the higher carbon content of polyhydroxy compounds or carbohydrates, such as fiber itself, starch, pentaerythritol and its two polymer and trimer;

3. Air source: It is a nitrogenous compound also known as foam source, which can release the inert gas, such as urea, dicyandiamide, etc.

Through the finishing of flame retardants made up of the above three parts comes fabrics. when heated, the acid source will decompose dehydrating agent, charry agent to generate lipid compounds, and then crosslinked with  ester dehydration to form carbon, releasing large amounts of gas at the same time to form fluffy porous carbon foam layer. There is a certain temperature gradient on the surface of the fabric and the carbon layer, which makes the the surface of  fiber's temperature much lower than that of flame, reduces the possibility of further degradation of the fiber and further release of the combustible gas, and isolates the entry of the outside oxygen, thus the fiber has a fire-retardant effect for a long time.

Types of Intumescent Flame Retardant

Nitrogen-Phosphorus Intumescent Flame Retardant

Single group of nitrogen - phosphorus intumescent flame retardant: compounds like phosphacyanogen oligomer, multi phosphate ester containing much nitrogen roll carbon source, acid source and gas source into one. Less smoke when burning with  dense and uniform layer makes the effect of flame retardant  remarkable. Such as phosphate melamine salt, two neopentyl glycol amine benzene two diphophate the starch phosphate salt, melamine, melamine phosphate sorbitol salt.

Mixed nitrogen phosphorus flame retardant is composed of several compounds. Such as ammonium polyphosphate as acid source, melamine as gas source, pentaerythritol as a carbon source in certain proportion can form a kind of intumescent flame retardant.
Intumescent Graphite Flame Retardant

The structure of natural graphite is a planar macromolecular structure, which can be specially treated  to form a special interlayer compound. When heated to more than 300 ℃, it can expand several hundred times along the direction of C-C axis.

As a flame retardant with good electrical properties, intumescent graphite flame retardant has the function of shielding electromagnetic wave when it is added to fabric.

Graphite is rich in resources. With its simple manufacture, low price, non-toxic, low smoke and no pollution to the environment, it is regard as a promising intumescent flame retardant. But it generally requires to be used together with other substances such as phosphorus, ammonium polyphosphate, melamine phosphate, so that the effect can be fully played out.