In the flame retardant family, there is a hot additive in recent years: MCA, and it was even in short supply at one time. So what is MCA flame retardant do you understand? Is the flame retardant principle clear? Let’s take a look with the editor!
What are the nitrogen flame retardants?
Currently, nitrogen-based flame retardants mainly include three major categories: melamine , dicyandiamide, guanidine salts (guanidine carbonate, guanidine phosphate, condensed guanidine phosphate and guanidine sulfamate) and their derivatives, especially phosphate derivatives.
1.Melamine
Melamine is often used to make foaming components in expanded fire-retardant coatings. Its foaming effect is good and becomes carbon dense. In addition to being used as a flame retardant alone, the commonly used flame retardant varieties are derivative salts produced by reacting with acids. They are widely used in thermoplastic and thermosetting plastics such as PE, PP, PVC plastic and other fields; melamine is used in combination with liquid phosphate esters and is widely used in flame retardant polyurethane foam materials.
2.Dicyandiamide
Dicyandiamide is mainly used to make guanidine salt flame retardants, which can replace melamine, or be combined with melamine. European patent reports that dicyandiamide is mixed in proportion to 5% of the addition amount, which can make polyamide reach the flame retardant effect of UL94 V to 0 level, and this flame retardant has little effect on the tear strength of the material. In addition, dicyandiamide can make wood fireproof glue.
3. Guanidine salt
Guanidine salt is not only used as a drug and dye intermediate, but also as a flame retardant for cellulose matrix materials, such as wood, paper, cardboard, etc. This type of flame retardant has a long-lasting flame retardant performance, and has much smaller hygroscopicity than inorganic flame retardants and has good decorative performance, so it is widely used in the manufacture of high-end decorative wood. In addition, it can also be used as a component of foaming agent in the expansion fire-retardant coating.
4. Melamine cyanurate (MCA)
MCA is synthesized from melamine and melamine at a certain temperature with water as a medium. It is an additive flame retardant. It is non-toxic, odorless, and has a high decomposition temperature (very stable at 300℃ and decomposed above 600℃). It not only has good flame retardant effect, but also has small smoke during processing, good compatibility with polymer materials, and no surface migration. It is mainly used for flame retardant of polymer materials such as nylon, PBTh, PP, epoxy resin , silicone , polyurethane , rubber and other polymer materials. Its flame retardant effect is good, and it can have good synergistic effects with phosphorus, bromine and antimony flame retardants, or it can be used in combination with other additives to achieve good flame retardant effects. From an economic perspective, the flame retardant effect of making nylon materials is the most obvious. Literature reports: Adding MCA with a mass fraction of 10% can achieve the UL94 V-0 flame retardant standard in nylon 6, nylon 66 or their blends.
flame retardant mechanism
It is generally believed that after the nitrogen-based flame retardant is decomposed by heat, it is easy to emit non-combustible gases such as ammonia , nitrogen , deep nitrogen oxides, and water vapor. The generation of these gases and the decomposition of flame retardant will take away most of the heat, greatly reducing the surface temperature of the polymer.
and these non-combustible gases, such as nitrogen, not only dilute the concentration of oxygen and polymers in the air to be heat decomposed to produce combustible gases, but can also react with oxygen in the air to produce nitrogen, water and depth of oxide , which can achieve good flame retardant effect while consuming oxygen on the surface of the material.
flame retardant advantages
1. Low toxicity
biological experiments show that the toxicity index of halogen flame retardant required for materials with the same flame retardant properties is 5 times that of nitrogen flame retardant, and the amount of smoke generated by polymer materials treated with nitrogen flame retardant is low, second only to metal inorganic flame retardant fillers. Especially the smoke density in the early stage of the fire is small, giving people the opportunity to escape and facilitate fire extinguishing work in the early stage of the fire.
2. High flame retardant efficiency
Tests on the ignition time and exothermic rate of halide , metal oxide, phosphate flame retardants, inorganic hydrates, hydroxyl compounds, boronides, silicate , carbonate compounds, and nitrogen-containing compounds show that the efficiency of nitrogen-based flame retardants is the highest.
3. Little corrosiveness
The gases produced by nitrogen-containing compounds during combustion are very corrosive and will not have a great corrosion effect on electrical products. Experiments show that nitrogen-based flame-retardant electrical conductors or electrical devices can continue to be used after ignition.
4. No conflict with light stabilizer in the material
nitrogen flame retardant does not have groups that easily generate free radical like halides, so it does not consume the light stabilizer in some materials.
5. The thermal decomposition temperature is higher
There is no need to worry about the decomposition of the flame retardant during processing, which leads to flame retardant failure. The material can still maintain good mechanical properties and flame retardancy by extruding through a multi-effect extruder.
6. Environmentally friendly
Waste will not cause environmental pollution.
