Application of magnesium hydroxide flame retardant in aluminum-plastic panels: dual protection of fire prevention and environmental protection
As a lightweight, high-strength composite building material, aluminum-plastic panels are widely used in building curtain walls, interior decoration, advertising signs and other fields. However, the flammable nature of the polyethylene (PE) core material in traditional aluminum-plastic panels makes it a safety hazard in high temperature or fire scenarios. In recent years, with the increasingly stringent requirements of the construction industry for fire safety and environmental protection performance, magnesium hydroxide flame retardant has gradually become an important technical direction for the upgrading of the aluminum-plastic panel industry due to its unique flame retardant mechanism and environmentally friendly characteristics. This article will deeply explore the application advantages, technical principles and market prospects of magnesium hydroxide flame retardant in aluminum-plastic panels.
1. Background of the upgraded fire protection demand for aluminum-plastic panels
1. Stricter building safety regulations
According to the "Classification of Combustion Performance of Building Materials and Products" (GB 8624-2012), the combustion performance of building decoration materials must reach the B1 level (flammable materials) or above standard. The PE material of the traditional aluminum-plastic panel core can only reach B2 grade (combustible material). It is easy to decompose and release a lot of smoke and toxic gases at high temperature, which aggravates the spread of fire and the difficulty of personnel escape. The lessons learned from many building fire accidents at home and abroad in recent years have further promoted the iterative demand for flame retardant technology.
2. Driven by environmental protection policies
The EU RoHS Directive, China's "National Hazardous Waste List" and other regulations clearly restrict the use of halogen-containing flame retardants (such as bromine compounds) because they will produce highly toxic substances such as dioxins when burned. The market urgently needs to develop green halogen-free flame retardant solutions. Magnesium hydroxide flame retardant has become an ideal choice with its zero halogen, low smoke and non-toxic characteristics.
2. Technical advantages of magnesium hydroxide flame retardant
1. Analysis of flame retardant mechanism
Magnesium hydroxide (Mg(OH)₂) releases crystal water when it is decomposed by heat (about 340℃), absorbs a lot of heat, and effectively reduces the surface temperature of the material. At the same time, the decomposed magnesium oxide (MgO) covers the surface of the material to form a dense protective layer, isolating oxygen and inhibiting the release of combustible gases. This synergistic effect makes its flame retardant efficiency 20% - 30% higher than that of traditional flame retardants (such as aluminum hydroxide).
2. Outstanding environmental performance
No halogen pollution: It does not contain elements such as chlorine and bromine. It only produces water vapor and non-toxic magnesium oxide when burning, which complies with international environmental protection standards such as RoHS and REACH.
Low smoke characteristics: The smoke density index (SDR) is less than 50, which is much lower than the SDR>200 of halogen flame retardants. It can significantly improve visibility in the event of a fire and buy time for personnel evacuation.
Recyclability: After the waste aluminum-plastic board is crushed, the magnesium hydroxide component can be recycled through acid-base neutralization treatment, reducing the burden of construction waste on the environment.
3. Compatibility with the production process of aluminum-plastic board
Processing temperature matching: During the production process of aluminum-plastic board, the extrusion temperature of PE core material is usually between 180-220℃, while the decomposition temperature of magnesium hydroxide (340℃) is higher than this range, ensuring that the flame retardant will not fail prematurely during processing.
Dispersion optimization: Through surface modification technology (such as stearic acid coating), magnesium hydroxide particles can be evenly dispersed in the PE substrate to avoid the reduction of mechanical properties caused by agglomeration. Experiments show that the tensile strength of the aluminum-plastic plate core material with 40%-60% magnesium hydroxide added can still be maintained above 15MPa, meeting the requirements of GB/T 17748-2016 standard.
III. Production practice of magnesium hydroxide flame-retardant aluminum-plastic plate
1. Formula design and process optimization
In the typical formula, the amount of magnesium hydroxide added is 50%-65% of the total weight of the core material, and 5%-10% of the synergistic flame retardant (such as red phosphorus, zinc borate) is used to improve the flame retardant efficiency. During production, a twin-screw extruder is required for high-speed mixing to ensure that the flame retardant and PE resin are fully integrated. Test data from a well-known aluminum-plastic panel company showed that the sample with 55% magnesium hydroxide added passed the UL94 V-0 flame retardant test, and the limiting oxygen index (LOI) reached 32%, which was nearly doubled compared with the PE core material without flame retardant (LOI 17%).
2. Performance testing and certification
Fire test: Through the cone calorimeter test, the peak heat release rate (HRR) of magnesium hydroxide flame-retardant aluminum-plastic panel was reduced by 60%, and the total smoke release (TSP) was reduced by 75%.
Environmental certification: It complies with the EU EN 13501-1 fire protection standard and has obtained the China Environmental Label (Ten Ring Certification), which is suitable for hospitals, schools and other places with strict environmental protection requirements.
IV. Market prospects and challenges
1. Industry growth potential
According to Global Market Insights, the global flame retardant market will have an annual compound growth rate of 5.2% from 2023 to 2030, of which halogen-free flame retardants will account for more than 45%. In the field of aluminum-plastic panels, magnesium hydroxide flame retardant has gradually replaced aluminum hydroxide and become the mainstream choice. Domestic leading companies such as Jixiang and Huaertai have launched related products to seize high-end market share.
2. Technical breakthrough direction
The current shortcoming of magnesium hydroxide flame retardant is that high addition may affect the toughness of the material. Future research and development focuses include:
Nano-level modification: using nano magnesium hydroxide (particle size<100nm) to improve dispersibility and reduce the addition amount to less than 40%;
Composite flame retardant system: compounded with expanded graphite, silicone and other materials to construct multiple barrier effects.
V. Conclusion
The application of magnesium hydroxide flame retardant not only provides an efficient fire protection solution for the aluminum-plastic panel industry, but also responds to the development trend of global green buildings through its environmentally friendly characteristics. With the preparation technology