Among halogen-free flame retardants, red phosphorus is a relatively good flame retardant with the advantages of small addition amount, high flame retardancy, low smoke halogen-free cable, low toxicity, and wide application. When red phosphorus is used together with inorganic flame retardants such as aluminum chloride and expandable graphite, composite halogen-free flame retardants such as phosphorus/magnesium, phosphorus/aluminum, and phosphorus/high-purity graphite can be produced, which can greatly reduce the amount of flame retardants and improve the production characteristics and physical properties of plastic products. However, red phosphorus is generally easy to oxidize and absorb moisture in the air, which can easily cause aluminum powder explosion, difficult to transport, and poor solubility with fiber materials, so its application range is limited. In order to make up for this deficiency, microencapsulation technology can be used to produce microencapsulated red phosphorus. Microencapsulated red phosphorus not only solves the original defects of red phosphorus, but also has the advantages of high efficiency, low smoke halogen-free cable, and no harmful gases. Its dispersibility, physical properties, heat resistance and flame retardancy have been improved and enhanced.
The results of the Limiting Flame Identification (LOI) and UL-94 test show that the flame retardant performance of the material is related to the amount of flame retardants used. With the increase of the amount of flame retardants used, the flame retardant effect first increases and then decreases. Adding too much flame retardant has a great impact on the physical properties of the material.
There are more than 70 kinds of brominated flame retardants. After rigorous evaluation, most of them are harmless to the human body and the environment. However, some brominated flame retardants with certain structures will produce dioxins under certain conditions (such as ethanol combustion). Dioxins include 210 chemical substances, they are very stable and have a high melting point. They are difficult to dissolve in water and can be dissolved in most organic solvents. They are colorless, odorless, fat-soluble substances that are easily accumulated in plants and pose a serious threat to the human body.
Different application sites have different requirements for flame retardancy. Generally speaking, people always expect the material to have a higher fire rating. But in fact, the test standards of various flame retardants have their limitations, and the results are corresponding. For example, UL94V-0 is better than V-2. But some home appliances require that the material has anti-arc ignition resistance, and V-2 is better than V-0. Because 94v-2 plastic cannot produce conductivity and slag under the effect of electricity, which greatly reduces the probability of fire, while 94v-0 plastic is just the opposite.
Polypropylene flame retardant is a powder suitable for granulation of modified materials. It needs to be mixed with other synergists for formula design. PP flame retardant masterbatch refers to a concentrated masterbatch mixed with flame retardant. Use medium and composite flame retardant, single screw granulation. It can also be a product or granule that can be directly produced.
