Research status and development trend of flame-retardant polyamide 66

In today's increasingly severe fire situation, in order to avoid the occurrence of fire as much as possible, one of the primary considerations when choosing to use polymer materials is flame retardant performance. Compared with the probability of fire in the same environment before and after flame retardant treatment of the same material, it was found that the flame retardant treatment of the product is less likely to burn, and the flame retardant product is less likely to generate toxic and harmful combustion products, thus obtaining the convincing practical evidence that the use of flame retardants will indeed reduce the occurrence of fire. PA UD Tape.

Therefore, the use of flame retardants and flame retardant materials plays an extremely important role in reducing the lives and economic losses caused by fires. Since the 20th century, experts have counted the use of various types of plastic additives, and found that the total use of flame retardants has jumped to the second place, which also shows that the flame retardant modification of polymer materials is the general trend.

1, flame retardant polyamide 66 introduction

Polyamide, commonly known as nylon, is a kind of engineering material with excellent comprehensive properties and increasingly prominent importance. Polyamide 66 as one of the main products of engineering materials, in the face of more harsh use environment, such as high temperature, high pressure, high friction, its flame retardant performance has gradually become an important factor to judge the quality of materials.

In particular, polyamide 66 is an important raw material for the production of synthetic fibers, and many of its derivatives are processed into clothing, and its flame retardant properties are crucial. Therefore, the development of high flame retardant polyamide 66 new products is particularly urgent.

Although polyamide 66 is a self-extinguishing polymer, such as polyamide 66 vertical combustion level reached UL94V-2, the limiting oxygen index reached 22%~24%, showing a certain flame retardant performance, but it is far from meeting the requirements of the increasingly harsh use environment, the flame retardant performance of polyamide 66 needs to be further improved. To meet the urgent needs of the rapid development of society.

2. Research status

Flame-retardant modification methods of polyamide 66 mainly include:

Direct addition of flame retardants and polyamide 66 resin matrix blend composite method;

After finishing flame-retardant modification method by modifying groups with flame-retardant effect on polyamide 66 polymer molecular chain;

In the polymerization process of polyamide 66, flame retardant monomer was introduced into the copolymerization and flame retardant modification method.

2.1 Blending flame-retardant modification method

At present, the most widely used in the market is the blending flame retardant modification method, which is simple to operate, wide applicability, and can achieve better flame retardant effect.

Halogenated compounds are the most commonly used blended flame retardants of polyamide 66, mainly including pentabromodiphenyl ethers, brominated styrene, polydibrominated styrene, brominated epoxy resin, etc. Although the flame retardant effect of halogenated flame retardants is significant, it will sacrifice other performance indicators of polyamide 66, and require a larger amount of flame retardants to meet the requirements of flame retardant performance, and a larger amount of flame retardants will also lead to a decrease in the strength of polyamide 66, limiting its application, and flame retardants are easy to move out, and the flame retardant performance decreases significantly with the extension of time.

Halogenated polyamide 66 will emit a lot of smoke and toxic and harmful hydrogen halide gas in the combustion process, which will not only cause damage to the ecological environment, but also endanger human health. In recent years, with the improvement of environmental protection requirements, the state has gradually restricted the use of halogenated flame retardants by increasing the tax on halogenated flame retardants polyamide 66.

The method also has the following disadvantages, such as: the dispersion of the flame retardant in the polyamide 66 matrix is not good, which will affect the comprehensive performance of the material; Flame retardant molecules are easy to migrate out during reprocessing. At present, the flame retardant modification of polyamide 66 is mostly based on the physical blending of flame retardants added to the polyamide 66 matrix, the flame retardant and polyamide 66 system does not produce chemical reaction, no chemical bond is formed between each other, just a simple mixture, the blending system is prone to the microscopic phase separation of flame retardants and polymer matrix.

2.2 Flame-retardant modification method after finishing

The introduction of flame retardant groups refers to the construction of highly efficient flame retardant molecules in the design and research process of polymers. By using this method, the molecular structure of phosphoxanthrene/phosphoxanthrene/triazine trione, phosphoxanthrene/borate, alkyl hypophosphate/triazine trione, phosphoxanthrene/triazine was introduced into the polymer, and new high-performance flame retardant materials with different flame retardant groups were developed.

The researchers applied the above double base molecules to flame retardant epoxy resin, polylactic acid, polyamide and polycarbonate polymer materials, and obtained a variety of polymer flame retardant materials with higher flame retardant grade, higher limiting oxygen index and lower heat release rate under the condition of low addition amount of double base molecules.

After finishing flame retardant modification method is through the surface grafting, coating flame retardant and other methods of polyamide 66 fiber and fabric flame retardant modification, such post-treatment process often needs to be carried out in organic solvents, there are a lot of solvent use and recovery and other environmental problems, increase the process flow, improve the cost of products.

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