Flame-retardant ABS is made from YISHION ABS resin, with high thermal stability,
flame retardants and so on. The preparation methods of Flame Retardant ABS are
usually divided into two types. One is copolymerization of monomers containing
halogen elements in graft polymerization, and then the flame retardant ABS is
prepared. This method is difficult to achieve satisfactory flame retardancy because
of the limitation of the amount of fourth monomers during copolymerization. The
two is to blend the compounds or polymers containing halogen elements and other
flame retardant additives and ABS resin to make blends of flame retardant ABS,
which has been widely used in industrial production. The flame retardant is easily
decomposed, carbonized or yellowing at high temperature, so the forming temperature
should be as low as possible. It is usually set below 190 C (the resin melt temperature
is below 220 C). "Carbonization" is not bad, the flame retardancy principle can be
divided into four mechanisms: (1) isolation of oxygen and promoting polymer
carbonization to reduce flammable gas production and flame retardancy; (2) produce
non flammable gases to dilute oxygen concentration to slow combustion speed; (3)
heat absorption and release of water gas before the combustion occurs, The flame
retardant effect is achieved by lowering the temperature; (4) interfering with the
formation of free radicals by chemical means. According to the composition, the
addition type flame retardants mainly include Inorganic Flame Retardant, halogen
flame retardant (organic chloride and organic bromide), phosphorus flame retardant,
and phosphorous compound is a promising combustible in the global halogen free
combustible agent. Organic phosphate, such as BDP and RDP, is the main phosphorus
burning inhibitor in China. The refractory carbonization layer (char) is formed on the
plastic surface after the plastics are heated, and the carbonized layer obstruct the
flow of the combustible gas and the heat radiation produced by the combustion to
achieve the purpose of flame retardancy. Since oxygen molecules are beneficial to
the formation of carbonized layers, such flame retardants are especially suitable for
oxygenated resin materials such as PET. On the one hand, the formation of carbonized
layer can prevent further pyrolysis of polymer, and on the other hand, it can prevent
its internal thermal decomposition producing organisms into the gas phase and
participate in the combustion process.
HB: burns slowly on the horizontal set of samples, and the combustion speed
is less than 76 mm/min for the material less than 3mm; V2: stops burning within
30 seconds on the vertically placed sample and allows droplets to be dripped
down; V1: stops burning in 30 seconds on the vertically placed sample and
allows droplets to be dripped without burning; V0: is vertical. The placed sample
stopped burning for 10 seconds and allowed to drop the non burning particles;
5VB: stopped burning in 60 seconds on the vertically placed sample and allowed
holes to appear on the sample; 5VA: stopped burning in 60 seconds on the
vertically placed sample, not allowed to drop, and no holes were allowed to
appear on the sample. It can be seen that flame retardancy V0 > V1 > V2.
The so-called V1, V2 flame retardant is not appropriate, after all, is determined
by the UL94 standard, ABS is usually added four bromo bisphenol -A (TBBPA)
as flame retardant.
