Views:10 Author:Vera Publish Time: 2018-09-04 Origin:Site
Nylon 66 (PA66) has excellent comprehensive performance and is widely used in automobile, electronics, chemical industry, architecture and so on. The oxygen index (LOI) is 24% and still has a certain flammability, especially the glass fiber reinforced PA66 (GF/PA66) is prone to appear "candle core effect" during combustion, which limits the application field of PA66. Therefore, the flame retardant modification of PA66 has become an important research direction in this field.
At present, the flame retardant modification of PA66 is mainly realized by two ways:
Use additive flame retardants
Add flame retardant into PA66, letting the flame retardant dispersed in the matrix of PA66 resin by mechanical blending to improve the flame retardancy of PA66. This is the main method of flame retardant modification of PA66 at present. The flame retardant is only physically dispersed in the matrix of PA66 resin without chemical reaction. The additive flame retardants for PA66 mainly include halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, inorganic flame retardants and so on. The advantage of this method is that it is easy to use and can be used widely, but it has great influence on the performance of the material. At present, multiple flame retardants are often used to form flame retardant systems, which can improve the flame retardation efficiency and reduce the amount of flame retardants.
Use reactive flame retardants
The flame retardant was used as a reactive monomer to bind to the macromolecular chain of PA66 to make it a flame retardant in the structure unit of PA66. The method is characterized by good stability, durable flame retardant effect, little influence on the properties of materials, no volatile flame retardants, migration and so on, so it is an ideal method. The disadvantage is that the processing technology is complex and the cost is high, so its application is limited. Suitable for PA66 reactive flame retardants include phosphorus-containing polyols and halogenated anhydride, such as bis (hydroxyethyl) methyl phosphine, bis (4-carboxyphenyl) phenyl phosphorus oxide, bis (4-hydroxyphenyl) phenyl phosphorus oxide, etc. With the progress of science and technology and the development of industry, the demand of flame retardant nylon will increase day by day, and people pay more and more attention to the research and development of the flame retardant modification technology of nylon. The development trend of flame-retardant PA66 in the future is as follows:
Environment-friendly, low toxicity
With the improvement of people's awareness of health and environmental protection, halogen-containing flame retardants will be eliminated gradually. Halogen-free flame retardants and environment-friendly flame retardants will be the key development direction of flame retardant PA66 in the future, and their dosage will increase continuously.
For PA66 materials with high flame retardancy requirements, a single flame retardant is usually unable to meet the requirements, and a composite flame retardant with multiple flame retardants has an excellent synergistic effect, which can not only reduce the amount of flame retardant, but also improve the flame retardancy of the material. Therefore, it is one of the key directions of future research and development to develop composite flame retardant PA66 with excellent performance through composite technology.
The addition of flame retardant in PA66 can improve the flame retardancy of PA66, but it will lead to the decrease of mechanical and electrical properties of materials. Therefore, the development of a new multi-functional flame retardant system can improve the flame-retardance of PA66 at the same time. Reducing the negative effects on mechanical and electrical properties of materials will become a new research direction of flame retardant PA66.
With the continuous innovation of coating, microencapsulation, master granulation and so on, high efficiency will become the development trend of flame retardant PA66. The development of high efficiency flame retardant can not only reduce the influence of flame retardant on the original properties of PA66. It can also reduce the amount of flame retardant and reduce the cost of materials.
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