Flame retardants | a safety shield for the plastics industry

Introduction：

In modern life, plastics are everywhere, from lightweight and portable daily necessities to high-end and complex industrial products. However, most plastic materials are naturally flammable. Once they encounter a fire source, the fire will spread rapidly, which may not only turn property into ashes, but also seriously threaten people's lives. The birth of flame retardants is like a safety umbrella for the plastics industry, becoming the key to ensuring the safe application of plastic products.

Working principle of flame retardants
Flame retardants, as a chemical auxiliary agent that can inhibit or delay the combustion process of materials, have a variety of action mechanisms:
Endothermic effect: Some flame retardants will undergo endothermic reactions when heated, such as aluminum hydroxide decomposition at high temperatures to generate aluminum oxide and water. The evaporation of water takes away a lot of heat, effectively reducing the surface temperature of the material, making it difficult to continue burning.
Covering protection: Some flame retardants will form a dense protective film on the surface of the material during the combustion process. For example, intumescent flame retardants expand when heated to form a porous carbon foam layer, which separates oxygen from combustible substances, thereby preventing combustion from continuing.
Chain reaction inhibition: Combustion is essentially a chain reaction initiated by free radicals. Some flame retardants can capture free radicals produced by combustion and interrupt chain reactions. For example, hydrogen halides produced by the decomposition of halogen flame retardants can react with free radicals, reduce the number of free radicals, and inhibit combustion.
Dilution effect: Certain flame retardants release a large amount of non-flammable gases such as carbon dioxide and ammonia when decomposed by heat. These gases dilute the concentration of combustible gases, reduce the oxygen content, and make combustion unsustainable.

Reasons why flame retardants are crucial to the plastics industry
Enhance fire safety: Plastic products are widely used in places with dense personnel or expensive equipment such as buildings, furniture, and electronic appliances. After adding flame retardants, the risk of fire in plastic products is greatly reduced. Even if a fire occurs, it can effectively delay the spread of the fire and buy precious time for personnel evacuation and fire rescue. For example, the use of plastics containing flame retardants in building decoration materials can prevent fires from spreading rapidly in buildings and protect the lives of people.
Compliance with regulatory standards: With the improvement of fire safety awareness, countries have introduced strict regulations and put forward clear requirements for the flame retardant properties of plastic products. Plastic manufacturers must use flame retardants to make their products meet the corresponding flame retardant standards before they can enter the market for sale. For example, the EU's RoHS directive and the US's UL standard have strict regulations on the flame retardant properties of plastic parts of electronic and electrical products. Companies can avoid legal risks and enhance their brand image and market competitiveness by following regulations.
Expanding the scope of application: The use of flame retardants allows plastics to be involved in special fields with extremely high fire safety requirements. In the aerospace field, plastic parts inside aircraft must have excellent flame retardant properties to ensure flight safety; in automobile manufacturing, adding flame retardants to plastic interior parts inside the car can reduce the probability of fire in traffic accidents and protect the lives of passengers. The strict requirements for the flame retardant properties of plastics in these high-end fields have promoted the innovation of flame retardant technology and opened up a broader market for the plastics industry.
Improving product quality and stability: Flame retardants can also optimize the physical properties and stability of plastic products to a certain extent. Some flame retardants can enhance the thermal stability of plastics, making them less likely to deform or decompose in high temperature environments and extending their service life. Moreover, the addition of flame retardants usually does not have a serious negative impact on the basic properties of plastics, such as mechanical strength and processing performance. Instead, it helps to improve the overall quality of the product and meet consumers' dual needs for durability and safety of plastic products.

Common flame retardant types and their characteristics
1. Halogen flame retardants: This is a widely used type of flame retardant, mainly including bromine and chlorine. Its advantage is that it has high flame retardant efficiency, only a small amount of addition is needed to achieve significant effects, and it has little effect on the physical properties of plastics, and can be widely used in various types of plastics. However, halogen flame retardants may release toxic and harmful gases when burned, which poses potential hazards to the environment and human health. With the tightening of environmental protection requirements, its use is subject to certain restrictions, but it is still used in specific fields.
2. Phosphorus flame retardants: Phosphorus flame retardants include organic phosphorus and inorganic phosphorus compounds. Organic phosphorus flame retardants have good flame retardant effects, good thermal stability, and plasticizing effects, which can improve the processing performance of plastics. Inorganic phosphorus flame retardants, such as red phosphorus, have high flame retardant efficiency and low cost, but they are dark in color, which will affect the appearance of plastic products, and there are certain safety hazards during storage and use, so they usually need to be coated.
3. Inorganic hydroxide flame retardants: Aluminum hydroxide and magnesium hydroxide are typical representatives. They are non-toxic, smokeless, and do not produce corrosive gases. They are environmentally friendly flame retardants. When thermally decomposed, they absorb a large amount of heat and release water vapor, which plays a role in heat absorption and dilution. However, the addition amount of inorganic hydroxide flame retardants is large, which may affect the mechanical properties of plastics. Generally, it is necessary to modify the surface to enhance compatibility with plastics.
4. Intumescent flame retardant: This is a new type of environmentally friendly flame retardant, composed of an acid source, a carbon source and a gas source. When heated, the acid source decomposes to produce acid, which dehydrates and carbonizes the carbon source, and the gas source decomposes to produce gas, which causes the carbonized layer to expand to form a porous foam carbon layer, achieving flame retardant effects of heat insulation, oxygen isolation and smoke suppression. Intumescent flame retardants have high flame retardant efficiency, low smoke, low toxicity, and good compatibility with plastics. They are one of the important directions for the development of flame retardants in the future.

Conclusion:

Flame retardants play a pivotal role in the plastics industry. They are related to the fire safety of plastic products, ensuring compliance with regulatory requirements, expanding the application field of plastics, and improving product quality. With the advancement of science and technology and the enhancement of environmental awareness, flame retardant technology is moving towards high efficiency, environmental protection, and multifunctionality. The plastics industry should pay close attention to the development of flame retardants, select them reasonably, and continuously improve the safety and quality of plastic products to create a safer and more comfortable living environment for people.