Blending and extrusion of brucite powder and PE substrate: forming process of flame retardant layer for aluminum-plastic panel
In the field of building decoration materials, aluminum-plastic panels are widely used due to their advantages of light weight, beauty, and ease of processing. However, with the continuous improvement of fire resistance requirements for building materials, how to enhance the flame retardancy of aluminum-plastic panels while ensuring their comprehensive performance has become one of the key issues of concern in the industry.
In recent years, the technology of preparing flame-retardant core materials for aluminum-plastic panels by blending and extruding brucite powder as an inorganic flame-retardant filler with polyethylene (PE) substrate has gradually gained attention. This method not only effectively improves the flame retardant performance of the material, but also demonstrates certain advantages in terms of environmental friendliness and cost control.
1、 Basic characteristics and flame retardant mechanism of brucite powder
Magnesite is a natural mineral mainly composed of magnesium hydroxide (Mg (OH) ₂). It releases crystalline water and absorbs a large amount of heat during the heating process, thereby inhibiting combustion. Compared to traditional aluminum hydroxide flame retardants, brucite powder has a higher thermal decomposition temperature and begins to dehydrate and decompose at around 280 ℃, making it suitable for flame retardant modification of various polymer materials.
In addition, brucite powder is an environmentally friendly material that does not contain halogen elements and does not produce toxic gases and smoke during combustion, which is in line with the development direction of modern green building materials. Therefore, applying it to the flame retardant core material of aluminum-plastic panels not only meets the flame retardant requirements, but also takes into account environmental protection and safety.
2、 Blending modification of PE substrate with brucite powder
Polyethylene (PE) is the most commonly used resin matrix in aluminum-plastic panel core materials, with good processability and weather resistance. However, pure PE material itself is a flammable material with a low ultimate oxygen index, which makes it difficult to meet the fire protection standards for high-rise building exterior wall materials. By adding brucite powder for filling modification, its combustion performance can be effectively improved.
In the actual production process, brucite powder needs to undergo surface treatment to improve its compatibility with PE resin. Silane coupling agents or titanium ester additives are usually used to pretreat the powder, making it more evenly dispersed in the polymer matrix, reducing interface defects, and improving the overall mechanical properties of the composite material.
The blending process generally uses a twin-screw extruder for melt mixing, ensuring that the material is fully plasticized and uniformly dispersed. Subsequently, the blended material is extruded into shape through a mold, and after cooling and shaping, a flame-retardant core material with a certain thickness and width can be obtained.
3、 Application process of flame-retardant core material in aluminum-plastic panels
Aluminum plastic panels consist of two layers of aluminum alloy panels and an intermediate core material, where the performance of the core material directly affects the fire rating and physical and mechanical properties of the overall panel. When using brucite powder/PE blend material for core material manufacturing, the following points should be noted:
Formula design: Reasonably determine the addition ratio of brucite powder based on the target flame retardant level and mechanical performance requirements. Generally speaking, a filling amount between 40% and 60% can achieve good flame retardant effect, but excessive filling amount may lead to a decrease in material toughness.
Extrusion process control: Extrusion temperature, pressure, and cooling rate all affect the density and surface quality of the core material. Process parameters should be optimized according to different equipment conditions to ensure uniform internal structure of the core material, without bubbles or delamination.
Composite compression process: The bonding strength between the core material and the aluminum panel is also an important factor determining the overall performance of the aluminum-plastic panel. During the composite process, suitable adhesives should be selected and the hot pressing temperature and time should be controlled to ensure a tight bond between the layers.
Post processing performance: Flame retardant core materials should have good processability, such as stamping, bending, cutting, etc., to facilitate subsequent construction and installation.
4、 Technological advantages and market prospects
The preparation of flame-retardant core materials by blending and extruding brucite powder with PE has the following technical advantages:
Green and environmentally friendly: free of harmful halogen substances, non-toxic and harmless combustion products, in compliance with RoHS directive requirements.
Cost controllable: Compared to other high-performance flame retardants, brucite powder has a wide range of sources and relatively low prices, which helps to reduce overall material costs.
Good processing performance: After appropriate modification, it can be smoothly processed on conventional extrusion equipment without the need for significant modifications to the production line.
Stable flame retardant effect: It can continuously absorb heat and dehydrate in high temperature environments, effectively delaying the spread of fire.
At present, some domestic enterprises have applied this technology to actual production and achieved good market feedback. Especially in projects such as public buildings, commercial complexes, and transportation hubs that require high fire performance, the proportion of using this type of flame-retardant aluminum-plastic panel is gradually increasing.
5、 Challenges and improvement directions faced
Although the application prospects of brucite powder in flame-retardant aluminum-plastic panels are broad, there are still some technical challenges in the promotion process:
Decreased mechanical properties: High filling content may lead to increased brittleness of the material, which needs to be alleviated by toughening modification or introducing elastomers.
Poor processing flowability: The amount of powder filling will greatly affect the melt flowability, and it is necessary to optimize the formulation system or adjust the process parameters.
Long term stability to be verified: Further research is needed to determine whether brucite powder will undergo hydrolysis reactions in humid environments, which will affect the material's service life.
In the future, the comprehensive performance of brucite powder/PE composite materials can be further improved by developing new functional additives, optimizing composite processes, and exploring synergistic effects with other flame retardant systems, promoting their application in more high-end fields.
With the continuous enhancement of people's awareness of building safety and environmental protection, aluminum-plastic panel products with efficient flame retardant performance and green environmental protection will become the mainstream in the market. The blending and extrusion technology of brucite powder and PE substrate provides a practical and feasible path to achieve this goal. By continuously optimizing material formulas and processing techniques, we believe that this technology will occupy a more important position in the future building decoration materials industry.