Why flame retardant modification is so complicatedThere are many reasons for the complexity of flame retardant modification.
First, the combustion process is complicated
There are three conditions for combustion: combustibles, combustion aids, and reach the ignition point. Combustible materials have multiple phases (gaseous, liquid, solid, liquid with different vapor pressures, solids are dense and loose), combustion agents have concentrations and diffusions, and ignition points are high or low, so the combustion process is complicated. This involves open flames and smoldering.
In addition, the spread of fire is also part of the combustion. Therefore, there are many combustion test modes, such as vertical combustion, horizontal combustion, glow wire test, etc.
Second, the consequences and hazards of combustion are complex
Burning produces burnout, high temperature damage, smoke preventing escape and smoke poisoning.
Third, the flame retardant mechanism is complicated
Firstly, it involves gas phase flame retardant and condensed phase flame retardant. The gas phase is related to the generation of flame retardant gas and the history of flame retardant reaction. The condensed phase is related to the carbon formation process and carbon formation quality. In terms of flame retardants, many flame retardants are involved, including inorganic flame retardants and organic flame retardants. Organic flame retardants include halogenated flame retardants and halogen-free flame retardants. In addition, the coordination and compounding of different flame retardants is also an important content. The complexity of flame retardants is also reflected in the high loading of flame retardants, which poses challenges to the mechanical properties and other properties of flame retardant materials, such as heat resistance and toughness.
Fourth, the processing application is complicated
When melt blending is used for flame retardant modification, there is often a problem of thermal stability of the flame retardant, and thermal stability and flame retardance are an inherent contradiction. In addition, thin products, such as spinning, non-woven materials, flat yarns, films, etc., often have higher requirements for the particle size and content of flame retardants. Such as expanded flame retardant PP flat yarn, because the coated particle size is large, the flat yarn is often broken when stretched. When PE cable material is flame retardant with aluminum hydroxide, if the aluminum hydroxide is not well dispersed, or the surface is subject to large shear, an excessively high amount of flame retardant filling will cause powder fall and mold fouling. When the sulfonate + PTFE flame-retardant light-diffusing PC is extruded, if the PTFE coating is poor and agglomeration of PTFE occurs, pitting will occur on the surface of the extrudate.
Fifth, the flame retardant regulations are complicated
Flame retardant modification not only involves fire safety regulations, but also flame retardant toxicity and environmental pollution regulations, such as IEEE and UL fire protection regulations and flame retardant certification, ROHS directive and REACH certification, as well as governments and countries around the world. Relevant enterprises have various regulations.