What is the Common Nitrogen-based Flame Retardants?

In the flame-retardant family, there is a hot flame-retardant MCA in recent years, even once in short supply. So what is MCA flame retardant do you understand? The principle of flame retardant is clear? Let’s take a look together!

What are the nitrogen-based flame retardants?

At present, the nitrogen-based flame retardants mainly include three categories: melamine, dicyandiamide, guanidine salts (guanidine carbonate, guanidine phosphate, guanidine phosphate condensed and guanidine sulfamate) and their derivatives, especially phosphate derivatives.

  1. Melamine

Melamine is often used as a foaming component in the manufacture of intumescent fireproof coatings, with good foaming effect and dense carbon formation. In addition to being used as a flame retardant alone, the commonly used flame-retardant species is a derivative salt produced by reaction with acid and is widely used in PE, PP and PVC plastics and other thermoplastic and thermosetting plastics. Combined with liquid phosphate, melamine is widely used in flame retardant polyurethane foam.

  1. Dicyandiamide

Dicyandiamide is mainly used in the manufacture of guanidinium salt flame retardants, which can replace melamine or be combined with melamine. European patents report that dicyandiamide mixed in equal proportions and added at 5% can make polyamide achieve UL94 V-0 flame retardant effect, and this flame retardant has little effect on the tear strength of the material. In addition, dicyandiamide can be used to make fireproof glue for wood.

  1. Guanidine salts

Besides being used as intermediates for drugs and dyes, guanidine salts are often used as flame retardants for cellulose-based materials, such as wood, paper and cardboard. These flame retardants have long-lasting flame-retardant properties and are much less hygroscopic than inorganic flame retardants and have good decorative properties, so they are widely used in the manufacture of high-grade decorative wood. In addition, it can also be used as a component of the foaming agent in intumescent fireproof coatings.

  1. Melamine cyanurate (MCA)

MCA is an additive flame retardant made from melamine and cyanuric acid at a certain temperature and synthesized with water as the medium. It is non-toxic, odourless and tasteless, and has a high decomposition temperature (very stable at 300°C, decomposing above 600°C). It not only has good flame-retardant effect, but also has small smoke during processing, good compatibility with polymer materials and no surface migration phenomenon. It is mainly used for flame retardant of nylon, PBT, PP, epoxy resin, organosilicon, polyurethane, rubber and other polymer materials. Its flame-retardant effect is good, and it can have good synergistic effect with phosphorus, bromine and antimony flame retardants, and can also be used in combination with other additives to obtain good flame-retardant effect. From the economic point of view, it is the most effective flame retardant for nylon materials. The literature reports that the addition of 10% mass fraction of MCA to nylon 6, nylon 66 or their blends can achieve UL94 V-0 flame retardant standard.

Flame retardant mechanism

It is generally believed that nitrogen flame retardants are prone to emit non-flammable gases such as ammonia, nitrogen, deep nitrogen oxides and water vapor when decomposed by heat. The generation of these gases and the decomposition of flame retardants absorb most of the heat, greatly reducing the surface temperature of the polymer.

And these non-flammable gases, such as nitrogen, not only play a role in diluting the oxygen in the air and the concentration of flammable gases produced by the thermal decomposition of polymers, but also react with oxygen in the air to produce nitrogen, water and deep oxides, consuming oxygen on the surface of the material while achieving a good flame retardant effect.

Flame retardant advantages

  1. Low toxicity

Biological experiments show that the toxicity index of halogen flame retardants required to achieve the same flame-retardant performance is five times that of nitrogen flame retardants, and the smoke emission of polymer materials treated with nitrogen flame retardants is low, second only to metal-based inorganic flame-retardant fillers. In particular, the smoke density at the beginning of the fire is small, giving people the opportunity to escape and facilitating the work of fighting the fire at the beginning.

  1. High flame-retardant efficiency

Through the halides, metal oxides, phosphate flame retardants, inorganic hydrates, hydroxyl compounds, borides, silicates, carbonate compounds, nitrogen compounds containing the ignition time and exothermic rate of the test shows that the efficiency of nitrogen flame retardants is the highest.

  1. Less corrosive
  2. The gases produced by nitrogen-containing compounds during combustion are very corrosive and do not have a significant corrosive effect on electrical products. Experiments have shown that nitrogen-based flame retardant treated electrical conductors or electrical components can continue to be used after a fire.

  1. No conflict with light stabilizers in materials

Nitrogen-based flame retardants do not have groups that can easily generate free radicals like halides, and therefore do not consume the light stabilizers in some materials.

  1. High thermal decomposition temperature

There is no need to worry about the flame-retardant decomposing during processing of the material, which could lead to flame retardant failure. The material retains good mechanical properties and flame retardancy even after extrusion by a multi-effect extruder.

  1. Friendly to the environment

The waste does not cause environmental pollution.

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