How does brucite powder improve the fireproof grade of aluminum-plastic panels to Class A?

In modern buildings, aluminum-plastic composite panels are widely used in curtain walls, interior decoration, advertising signs and other fields due to their light weight, beautiful appearance and convenient construction. However, traditional aluminum-plastic panels are flammable and release toxic gases due to the core materials of polyethylene (PE) and other organic materials, which can easily become the "fuse" for the spread of fire in a fire. Therefore, how to make aluminum-plastic panels reach Class A non-combustible standards through scientific formula design and material optimization has become the focus of technical research in the industry.

As a natural inorganic flame retardant, brucite powder is gradually becoming a key material for improving the fireproof grade of aluminum-plastic panels due to its excellent thermal decomposition performance and environmental protection characteristics. This article will systematically analyze how brucite powder can help aluminum-plastic panels achieve Class A fireproof upgrades from the aspects of its mechanism of action, application methods and performance.

1. The flame retardant principle of brucite powder and its adaptability to aluminum-plastic panels

Brucite (Brucite), with a chemical composition of Mg(OH)₂, is a natural mineral material with a layered structure. It begins to dehydrate and decompose at around 320°C during heating, generating magnesium oxide and releasing a large amount of water vapor:

Mg(OH)₂ → MgO + H₂O↑

This reaction process has three core functions:

Heat absorption and cooling: Each gram of brucite powder can absorb about 1.3 kJ of heat, effectively delaying the rise in the surface temperature of the material;

Diluting oxygen: The released water vapor can reduce the oxygen concentration in the combustion area and inhibit the spread of flames;

Forming a ceramic barrier: The generated magnesium oxide has a high melting point (2800°C) and good high temperature stability, forming a dense protective layer on the surface of the material to isolate heat sources and oxygen.

These characteristics make it particularly suitable for aluminum-plastic composite panels with polyolefin resins as the core material, which can significantly improve its flame retardant properties and effectively reduce the generation of smoke and toxic gases.

2. Application strategy of brucite powder in aluminum-plastic panels

To achieve the Class A fireproof target of aluminum-plastic panels, it is necessary to combine the material system, processing technology and product structure for systematic design. The following are the key implementation paths:

1. Optimization design of flame retardant formula

The addition ratio of brucite powder is the core parameter affecting the flame retardant performance. Experiments show that when its filling amount is controlled between 35% and 45%, its limiting oxygen index (LOI) can be significantly increased to more than 32% under the premise of ensuring the mechanical properties of the board, meeting the Class A non-combustible requirements.

In addition, the following synergistic additives can be introduced to further enhance the flame retardant effect:

Zinc borate: promotes the formation of carbon layer and improves the residual carbon strength;

Aluminum hydroxide: broadens the endothermic peak range and prolongs the fire resistance time;

Silicone masterbatch: improves the dispersibility of powder and enhances the interface bonding force.

2. Surface modification technology

Because brucite powder is a polar inorganic material, there is a problem of poor interface compatibility between it and the non-polar polymer matrix, which easily leads to a decrease in the mechanical properties of the material. For this reason, silane coupling agent is often used to coat its surface to improve its dispersion uniformity and bonding strength in the resin, so as to give full play to its flame retardant performance without affecting its bending and tensile properties.

3. Key points of process control

In actual production, the following process links should be focused on:

Mixing uniformity: Use high-speed mixing equipment to ensure that the powder and resin are fully integrated;

Extrusion temperature control: Avoid local overheating to cause premature decomposition of brucite;

Cooling and shaping rate: Reasonably control the cooling speed to prevent internal stress concentration from causing cracking or deformation.

3. Actual performance verification: Class A fireproof compliance analysis

In order to verify the actual flame retardant effect of brucite powder in aluminum-plastic panels, several testing agencies conducted systematic tests based on GB 8624 "Classification of Combustion Performance of Building Materials and Products" standard. The results showed:

Flaming Growth Rate Index (FIGRA): less than 120 W/s, in line with the limit of Class A non-combustible materials;

Total heat release (THR): less than 7.5 MJ/m²;

Smoke density (SDR): peak value less than 75, much better than Class B materials;

Toxic product content: The release of toxic gases such as CO and HCN is extremely low, meeting the safety requirements of public places.

At the same time, in the back-fire temperature rise curve test under simulated fire conditions, the back-fire surface temperature of the brucite powder flame-retardant aluminum-plastic panel did not exceed the critical value within 90 minutes, showing excellent thermal insulation performance and structural integrity.

IV. Market application value and development prospects

With the continuous tightening of the national fire protection regulations, especially the "Code for Fire Protection Design of Buildings" (GB 50016) puts forward the A-level non-combustible requirement for the exterior wall insulation and decorative materials of civil buildings, the flame-retardant aluminum-plastic panels with high-performance fire resistance have ushered in a broad market space.

Its main application scenarios include:

Commercial complexes, office buildings, airports, subway stations and other crowded places;

Special public facilities such as hospitals, schools, and nursing homes;

High-rise residential buildings, urban renewal projects and other engineering fields with strict requirements for fire safety.

In addition, with the advancement of green building materials policies, brucite powder, as a natural mineral resource, has both environmental protection and renewable advantages. In the future, it is expected to expand a wider range of application scenarios in new material systems such as bio-based resins and nano-composite materials.

With its unique physical and chemical properties, brucite powder has shown irreplaceable technical advantages in improving the fire protection level of aluminum-plastic panels to Class A. It not only solves the environmental and health risks brought by traditional halogen flame retardants, but also builds a multi-level fire protection system through efficient heat absorption, smoke suppression and carbonization mechanisms.

For modern buildings that pursue the unity of safety, environmental protection and functionality, brucite powder flame-retardant aluminum-plastic panels are undoubtedly one of the most competitive solutions at present. In the future, with the continuous advancement of materials science and the continuous improvement of manufacturing processes, this type of high-performance fireproof material will play a more important role in the building decoration industry.