Chemistry periodic table of the first Ⅶ A group elements including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), collectively known as halogens. One astatine (At) for the radioactive elements in the product is almost non-existent, the first four elements in the product, especially in the organic polymer material to form. Products currently used mainly in the halogen flame retardant compound: PBB, PBDE, TBBP-A, PCB, hexa-dodecane, Tribromophenol, short-chain chlorinated paraffins; used to make refrigerants, insulating materials Ozone depleting substances: CFCs, HCFCs, HFCs and so on.
In the plastics and other polymer products to add halogens (fluorine, chlorine, bromine, iodine) to improve the ignition, and its advantages are: light than ordinary high-polymer materials, burning about 300 ℃. Burning, will emit halogen gases (fluorine, chlorine, bromine, iodine), rapid absorption of oxygen, so that the fire is out. But its drawback is that the release of high concentrations of chlorine, lead to reduced visibility caused not identify the escape path, while chlorine is highly toxic, affecting the respiratory system, in addition, halogen-containing polymers released from the combustion of halogen gas in the When combined with water vapor, will produce corrosive gases (hydrogen halide), for some equipment and buildings caused by corrosion.
PBB, PBDE, TBBPA and other brominated flame retardants are currently using more flame retardant, mainly used in electrical and electronic industries, including: circuit boards, computers, fuel cells, televisions and printers. The halogen-containing flame retardant materials, produce dioxins when burned, and in the environment can exist for years or even life-long accumulated in the organism, can not be discharged.
Mainly by the ozone layer, CFCs will encounter the absorption of harmful ultraviolet rays. UV rays break down the CFCs, releasing chlorine atoms, the ozone molecules into free oxygen molecules separate and dichloro-oxide molecules, thus destroying the ozone molecules. A chlorine atom can destroy over 100,000 ozone molecules. Destruction of the ozone layer, will greatly enhance skin cancer, cataracts and other eye diseases, the probability, will bring catastrophic consequences. In addition it may also cause food hazards, aquatic production, and the formation of the "greenhouse effect" (the earth's atmosphere warming).
Therefore, many large international companies are actively promoting the complete abolition of halogen-containing materials, such as the prohibition on the use of halogen flame retardants and other products.
Currently the requirements for halogen-free, different products have different standard limit: If no one halogen halogen wire and cable indicators: the value of all halogen ≦ 50PPM (according to regulations PREN 14582); combustion generated hydrogen halide content <100PPM ( According to regulations EN 5067-2-1); combustion generated hydrogen halide dissolved in water the pH of ≧ 4.3 (weak acid) (according to regulations EN-50267-2-2); products after combustion in a closed container through through a beam of light transmittance rate ≧ 60% (according to regulations EN-50268-2). Halogen-Free PCB, bromine, chlorine content of less than 900ppm, (bromine + chlorine) is less than 1500ppm.