Why is magnesium hydroxide an essential flame retardant in the high-end cable industry?
In the field of high-end cable manufacturing, flame retardant performance is one of the core indicators that determine product safety and market competitiveness. With the continuous improvement of global requirements for power transmission safety and environmental protection, traditional halogen-based flame retardants are gradually being replaced by more efficient and environmentally friendly halogen-free flame retardant materials. Among them, magnesium hydroxide (Mg(OH)₂) has become an indispensable flame retardant in the high-end cable industry due to its unique chemical properties, environmental advantages and high cost performance. This article will deeply analyze the flame retardant mechanism, application advantages and market prospects of magnesium hydroxide, and reveal the reasons why it has become the "gold standard" of the industry.
1. Flame retardant mechanism of magnesium hydroxide: scientificity and high efficiency coexist
The flame retardant effect of magnesium hydroxide is mainly achieved through the following three mechanisms:
1. Endothermic decomposition: When the cable encounters high temperature (above 340°C), magnesium hydroxide absorbs a lot of heat and decomposes into magnesium oxide (MgO) and water (H₂O). This reaction can quickly reduce the surface temperature of the material and delay combustion.
2. Dilute combustible gas: The water vapor produced by decomposition can dilute the surrounding oxygen and combustible gas concentrations and inhibit the spread of flames.
3. Form a protective layer: The generated magnesium oxide covers the surface of the cable to form a dense insulation layer, blocking the further transfer of heat and oxygen.
Experimental data show that the limiting oxygen index (LOI) of cable materials with 40%-60% magnesium hydroxide added can reach more than 35% (the LOI of ordinary materials is only 18%-22%), and the flame retardant grade reaches the UL94 V-0 standard, meeting the needs of harsh scenarios such as nuclear power and high-speed rail.
2. Five core advantages of magnesium hydroxide compared to other flame retardants
1. Environmentally friendly and non-toxic
Unlike brominated flame retardants (containing halogens) that release dioxins and other carcinogens when burned, the decomposition products of magnesium hydroxide are only water and magnesium oxide, which fully complies with the EU RoHS, REACH regulations and China GB/T 19666-2019 standards, and is the preferred material for "green cables".
2. Strong high temperature resistance
The decomposition temperature of magnesium hydroxide is as high as 340℃, which is much higher than that of aluminum hydroxide (180-200℃). It can adapt to the high temperature environment (usually 200-250℃) in the cable extrusion molding process, avoiding premature decomposition and failure during processing.
3. Significant smoke suppression effect
In the combustion test, magnesium hydroxide can reduce the smoke density by 60%-80%, reducing the "secondary damage" in the fire (according to statistics, 80% of deaths in fires are caused by thick smoke). This feature makes it more advantageous in confined scenes such as tunnels and subways.
4. Flexible filling amount and stable mechanical properties
Nano-level magnesium hydroxide modification technology has achieved material toughness retention at high filling amount (60%), tensile strength ≥12MPa, elongation at break ＞150%, avoiding the embrittlement problem caused by excessive addition of traditional flame retardants.
5. Outstanding cost advantage
The global reserves of magnesium hydroxide are rich (China's magnesite reserves account for 30% of the world's total), and the market price is about 5,000-8,000 yuan/ton, which is only 1/3 of the phosphorus-based flame retardant, and the processing energy consumption is low, and the comprehensive cost performance is far superior to similar products.
III. Application examples of magnesium hydroxide in the field of high-end cables
1. High-voltage wiring harnesses for new energy vehicles
In 800V high-voltage cables of brands such as Tesla and BYD, magnesium hydroxide flame retardants account for 55%, and have passed the ISO 6722-2018 high temperature resistance test, and can work continuously for 5,000 hours at 150°C without performance degradation.
2. Offshore wind power corrosion-resistant cables
The North Sea wind farm in the UK uses XLPE insulated cables containing magnesium hydroxide, with a flame retardant grade of IEC 60332-3A, and the salt spray corrosion resistance life is increased to more than 25 years.
3. Special cables for aerospace
NASA's spacecraft cables use nano magnesium hydroxide composite materials, which have passed the ASTM E662 smoke toxicity test, with a smoke density of Ds <15 and a 90% reduction in toxic gas emissions.
IV. Industry trends: Magnesium hydroxide technology upgrades drive market growth
Grand View Research predicts that the global magnesium hydroxide flame retardant market will expand at a compound annual growth rate of 6.8% from 2023 to 2030, with the Asia-Pacific region (especially China) accounting for more than 45%. Technological breakthroughs include:
- Surface modification technology: Silane coupling agent coating improves dispersibility and increases flame retardant efficiency by 20%;
- Nanoscale preparation: Magnesium hydroxide with a particle size of ≤100nm can reduce the amount of addition by 30%;
- Compound synergistic system: Used in combination with zinc borate and carbon nanotubes, the flame retardant performance reaches UL94 5VA level.
Magnesium hydroxide is a strategic choice for sustainable development of the cable industry. Driven by the "dual carbon" goal, magnesium hydroxide has become the gold standard for high-end cable flame retardants with its halogen-free, low smoke and high efficiency. As technologies such as surface modification and nanomaterials mature, their application scenarios will be further expanded to emerging fields such as 5G communication cables and flexible electronic devices. For cable manufacturers, mastering magnesium hydroxide compounding technology is not only a necessary means to meet regulatory requirements, but also a core competitiveness to seize high-end market share.