In recent years, with the increasing awareness of global environmental protection, halogen-free flame retardant materials have been paid more and more attention, especially high-performance halogen-free flame retardant nylon materials are being welcomed.
However, the unmodified nylon has poor flame retardancy and belongs to flammable materials, and droplets occur in the combustion process, which is easy to cause fire in the use process. Therefore, the flame retardant modification of nylon has become a common concern and key issue in academia and industry today. Later, scientists added flame retardants to nylon, which changed its flame retardancy, and the use of nylon became more extensive.
For halogen-free flame retardant nylon, the word “halogen-free” is used to mark the types of flame retardants used. Flame retardants are divided into halogen-containing flame retardants and halogen-free flame retardants. Halogen-containing flame retardants, such as bromine flame retardants, are mostly used in the early modification industry. However, since the dioxin problem appeared in 1986, brominated flame retardants began to face tremendous environmental pressures, and the controversy about brominated flame retardants has not stopped in the world.
Halogen-free flame retardants solve this problem. The halogen-free flame retardants widely used in nylon are red phosphorus and melamine salts. Red phosphorus has high flame retardant efficiency and can improve the arc resistance of products, but its storage and color limitations greatly limit its application in nylon, generally only in nylon 6. Another halogen-free flame retardant used in nylon is melamine salt, mainly melamine urate and phosphate. They have good flame retardant efficiency, but their thermal stability is poor, and their electrical properties are poor in humid environment because of their moisture absorption.
| PVA 0588 ( PVA BP05) |
Halogen-free flame retardant nylon is added in the flame retardant content is very low or does not contain halogen group elements of bromine and chlorine. Halogen-free flame retardant nylon products have excellent flame retardant performance, flame retardant level up to UL94V0, with low precipitation, anti-dripping, high electrical performance and heat resistance, high CTI value, good electrical performance, high impact strength, environmental friendliness and environmental protection. Suitable for electrical connectors. The flame retardancy of the composites was improved by adding bromine flame retardants or halogen-free flame retardants which met the European ROHS standard. This granular nylon can withstand a processing temperature of 260 C.
In the process of using halogen-free flame retardant nylon granular materials, we sometimes encounter some labels, such as UL94V-0, UL94V-2 and so on.
Flammability UL94 is the most widely used standard for flammability of plastic materials. UL94V0 level can meet five standards and requirements: first, no sample still burns for more than 10 seconds after the test flame is removed; second, for each set of five samples, the total time of burning with the flame after 10 ignitions does not exceed 50 seconds; third, no sample burns to the fixture; fourth, no sample burns to the fixture; fourth, no sample burns melted liquid droplets ignite the following 12 “places”. Cotton; Fifth, without any sample, it continued to glow red for more than 30 seconds after the second removal of the test flame. Such a standard can completely avoid the occurrence of fire.
| PVA |
With the wider application of nylon engineering plastics, more and more varieties of flame retardants and the development and research of flame retardant technology, flame retardant nylon will develop in the following four directions in the coming decades:
One is the technology of compounding flame retardants. Many flame retardant manufacturers in the world are engaged in the development of new synergistic system, that is, the compounding of various flame retardants, in order to reduce the amount of flame retardant and improve the flame retardant performance, which not only reduces the price of flame retardant materials, but also reduces the loss of physical properties.
The second is non-halogenation, low toxicity and low halogenation. Many countries have banned or restricted the use of halogen-containing flame retardants, replaced by phosphorus, nitrogen-based flame retardants and inorganic flame retardants.
Third, multi-function. In some industries, nylon is required not only to have flame retardant properties, but also to have such properties as thermal conductivity, conductivity, antistatic and so on. A large number of other additives are needed to meet the user’s requirements.
| POLYVINYL ALCOHOL |
Fourth, the balance of cost and performance. Developing efficient flame retardant system can reduce the influence of flame retardant on the physical properties of materials, and reduce pollution and cost.