Basic knowledge of inflatable flame retardants

Inflatable flame retardants are developed in recent years, mainly composed of phosphorus and nitrogen, containing this kind of flame retardants when heated, the surface can form a layer of dense carbon foam layer, play insulation, oxygen, smoke suppression, but also to prevent the drop, with good flame retardants.Successful reports have been reported in China since 1992, and up to now there have been several units engaged in this area of development, but no reports of industrial-scale production have been reported.

There may be two reasons why the large-scale production has not been achieved: first, there are inorganic acids left in the products that have not yet been reacted, which are reflected in the surface of flame retardant products with absorption of moisture;Another is that NP expansion flame retardants are synthesized from macromolecular compounds, and the latter step is solid phase reaction. The process of mass transfer and heat transfer is so complicated that it has been difficult to be industrialized up to now.Later on, it should be noted that antimony trioxide has been classified into this category, but strictly speaking, antimony trioxide itself is not a flame retardant, it is only a co-agent with halogen flame retardants.Aluminum hydroxide and magnesium hydroxide are the main force of inorganic flame retardants, especially when halogen free flame retardants are advocated in some fields, they will become the choice.Because inorganic flame retardants need to add a large amount, in some special cases will exceed the amount of the polymer itself, therefore, it is bound to have a very large impact on the physical and mechanical properties of the high polymer, which requires inorganic flame retardants to be treated, that is, particulate, surface activation.

The purpose of the micrification is to distribute them evenly in the polymer and to act as flame retardant everywhere in the body phase.The experiments show that the amount of microparticles can be reduced to meet the same flame retardant standard.In addition, the surface activation is to make the compatibility between the inorganic flame retardant and the high polymer good, which can reduce the mechanical strength of the high polymer due to the addition of a large number of inorganic flame retardant.Some recent articles have talked about the advantages of flame retardancy of inorganic nanoparticles. Our working experience suggests that the addition of these nanoparticles may be beneficial to improve mechanical strength, but will not have much effect on flame retardancy.For flame retardant mechanism of inorganic flame retardant is through thermal decomposition to release water vapor to reduce the system temperature, water vapor and dilute the combustible gases at the same time to achieve flame retardant effect, it is the amount of water vapor to determine its flame retardant effect, therefore is related to the amount of flame retardant, has nothing to do with whether flame retardant nanoparticles, in general the size distribution of inorganic flame retardants in between 2 mu mu m m5 is sufficient.