Flame retardant mechanism of intumescent system

The main components of the intumescent flame retardant system can be divided into three parts: acid source, carbon source and gas source. The acid source is generally an inorganic acid or a compound that generates an inorganic acid when heated to 100^-250°C, such as phosphoric acid, sulfuric acid, boric acid, various ammonium phosphates, phosphate esters and borates, etc.; the carbon source (char-forming agent) is The basis for forming the carbonized foam layer is generally carbon-rich polyhydroxy compounds, such as starch, pentaerythritol and its dimers, trimers, and organic resins containing light groups; the gas source (foaming source) is mostly amine or Amide compounds, such as melamine, dicyandiamide, amine polyphosphate, etc.

The structure of swelling system to form char is complex and has many influence factors. The chemical structure and physical properties of the polymer body, the composition of the intumescent flame retardant, the conditions during combustion and cracking (such as temperature and oxygen content), the crosslinking reaction rate, and many other factors will affect the structure of the expanded carbon. The thermal protection effect of the expanded carbon layer not only depends on the coke output, the height of the carbon layer, the structure of the carbon layer, and the thermal stability of the protective carbon layer, but also the chemical structure of the carbon layer, especially the appearance of the ring structure increases the thermal stability In addition, there are the strength of chemical bonds and the number of cross-linked bonds.

It is generally believed that the flame retardant mechanism of the expansion system is the condensed phase flame retardant. First, the amine polyphosphate is decomposed by heat to generate phosphoric acid and pyrophosphoric acid with strong dehydration effect, so that the pentaerythritol is esterified, and then dehydrated and carbonized. The water vapor formed by the reaction and the decomposition of melamine The ammonia gas expands the carbon layer and finally forms a microporous carbon layer, which insulates air and heat conduction, protects the polymer body, and achieves the purpose of flame retardancy.

Intumescent flame retardants added to polymer materials must have the following properties: good thermal stability, able to withstand high temperatures above 200°C during polymer processing; due to thermal degradation, a large amount of volatile substances will be released and residues will be formed. Therefore, the process should not have an adverse effect on the expansion and foaming process; this type of flame retardant is evenly distributed in the polymer, and when the material is burned, it can form a layer of expanded carbon that completely covers the surface of the material; the flame retardant must be Flame-retardant polymers have good compatibility, can not have adverse effects with polymers and additives, and can not excessively deteriorate the physical and mechanical properties of the material. Intumescent flame retardants are superior to general flame retardants in that they are halogen-free and non-antimony oxide: low smoke, less toxicity, and no corrosive gas; the carbon layer generated by intumescent flame retardants can absorb molten polymers that are on fire to prevent Its dripping spreads the fire.

Shawn

Regional Sales Manager

Zhejiang Ruico Advanced Materials Co., Ltd. (Stock No.873233)

Add: No.188, Liangshan Road, Linghu Town, Nanxun District, Huzhou City, Zhejiang Province, China 313018

Phone: +86 (572) 2903236

Fax: +86 (572) 2905222

WhatsApp: +86 15968208672

Cellphone: +86 15968208672

Website:www.ruicoglobal.com

E-mail: [email protected]