Why develop flame retardant ABS resin?
China has become a global home appliance manufacturing center, the consumer electronics industry has also developed rapidly, and the demand for the variety and quantity of synthetic resin is also increasing. ABS resin with high strength (toughness and rigidity) and good processability has become a large amount of engineering thermoplastic synthetic resin, with an average annual growth rate of about 3%. In the context of the weak market of ABS general materials, the demand for flame retardant ABS resin is still strong, which is gradually attracting people's attention.
ABS resin has low limiting oxygen index (only 18.3 ~ 20). It is a flammable polymer material. Its horizontal combustion speed is very fast, about 25 ~ 51mm / min. Due to the high styrene content of ABS resin, which is more than 55%, a large amount of black smoke is generated during combustion, which can continue to burn after leaving the fire. During the combustion process, the plastic softens, scorches and burns out, loses its performance, and releases a large amount of harmful gases. All this will limit the application of ABS resin.
Therefore, to broaden the application scope of ABS resin, we must pay attention to the safety and environmental protection in the process of production and application. It is necessary to endow ABS materials with fire and flame resistance and formulate corresponding product standards and application specifications. In recent years, the total value of products involving halogen-containing flame retardant materials exported to the EU (the organization has the ability to formulate high regional industry standards and reshape global rules in this process, that is, the Brussels effect) has reached hundreds of billions of yuan every year, and this trend is gradually reflected in the composition of domestic ABS consumption. Almost all ABS manufacturers at home and abroad regard flame retardant ABS as an important member of their product series.
Domestic ABS products are mainly of general grade, and other products such as flame retardant grade, plate grade, heat-resistant grade and ABS alloy are also produced. Flame retardant grade accounts for about 22% of the annual demand of ABS. In 2003, the domestic demand for flame retardant ABS reached 570000 T / A, including imported products, modified products of general materials and products produced with recycled materials.
Flame retardant ABS is mainly used for electrical and electronic equipment casings that require both electrical insulation and flame retardancy, such as computer display casings, TV casings, plug-ins, fuse boxes, vacuum cleaner casings, office automation equipment casings, outer barrels of washing machines, electrical switch parts, etc. Flame retardant ABS devices can reduce or prevent combustion accidents.
Through a lot of research work and production practice, the main synthesis methods of flame retardant ABS resin are as follows:
1. In the production process of ABS resin, reactive flame retardant is added as the fourth monomer for copolymerization. This method has complex process and high cost;
2. Use the mixing process and add flame-retardant polymers with flame retardancy and certain compatibility with ABS resin, such as polyvinyl chloride (PVC), chlorinated polyethylene (CPE), etc;
3. Use the mixing process and add inorganic or organic flame retardants. In practical application, in order to produce flame-retardant ABS resin with satisfactory flame-retardant properties, mechanical properties, electrical properties and smoke elimination, methods (2) and (3) are used, or the two are combined for comprehensive research and development.
It is a simple and efficient way to add flame retardant to ABS resin. Flame retardants used more include halogen flame retardants, halogen-free flame retardants, inorganic flame retardants and other types of flame retardants.
The development of halogen-free flame retardant technology of ABS resin is in the ascendant. The rapid development of smoke suppression technology of halogen-containing flame retardant ABS has laid a theoretical foundation for its realization of low smoke and low toxicity. The halogen-free flame retardant technology of ABS resin can not replace the halogen-free flame retardant technology of ABS resin. Halogen flame retardant ABS resin will still be the mainstream material of household appliances today and for a long time in the future.