Modification of plastics in the home appliances, electronic appliances, automobiles and other fields often require the application of flame retardant, flame retardant can be modified by adding flame retardant. Brominated flame retardant and halogen-free flame retardant.
Flame retardant
Flame retardants, also known as flame retardants, flame retardants or flame retardants, impart flammable properties to flammable polymers as a functional aid, most of which are those of the ⅤA (phosphorus), ⅦA (bromine, chlorine) and AA (Antimony, aluminum) family of compounds.
Modified plastic flame retardant principle
First, the endothermic effect
Any burning in a relatively short period of time to release the heat is limited, if we can in a short time to absorb part of the heat emitted by the heat, then the flame temperature will be reduced to the combustion surface and the role of gasification has been Flammable molecules into free radicals will reduce the heat, the combustion reaction will be a certain degree of inhibition.
Under high temperature conditions, the flame retardant undergoes a strong endothermic reaction, absorbing some of the heat released by the combustion, reducing the temperature of the combustible surface, effectively suppressing the generation of flammable gases and preventing the spread of combustion.
Second, the role of coverage
Flame retardants added to the combustible material, the flame retardant at high temperatures can form a glassy or stable foam cover, isolated oxygen, with thermal insulation, oxygen, to prevent the outward combustion of combustible gases, so as to achieve flame retardant purpose.
Such as organic phosphorus-based flame retardants when heated to produce a more stable structure of cross-linked solid material or carbide layer formation of carbide on the one hand to prevent the polymer further pyrolysis, on the other hand can prevent the internal thermal decomposition Produce into the gas phase to participate in the combustion process.
Third, inhibit the chain reaction
According to the chain reaction theory of combustion, it is the free radical that is required to maintain the combustion, and the flame retardant acts on the gas-phase combustion zone to capture the free radicals in the combustion reaction so as to prevent the propagation of the flame and to reduce the flame density in the combustion zone. The combustion reaction rate drops until it stops.
Fourth, non-flammable gas suffocation effect
When the flame retardant decomposes non-combustible gas when it is heated, the concentration of the combustible gas decomposed from the combustible material is diluted below the lower limit of combustion, and also has a dilution effect on the oxygen concentration in the combustion zone to prevent the combustion from continuing to reach the flame retardant effect.
Plastic flame retardant grade
Flammability UL94 grade - is the most widely used plastic material flammability standards .It is used to evaluate the ability of the material to be extinguished after ignition.According to the burning rate, burning time, anti-drip ability and whether the dripping beads can have a variety of judgments method.
Plastic Flame Retardant: Increased by 5 to 5VA from HB, V-2, V-1, V-0 and 5VB HB: Lowest Flame Retardant Grade in UL94
With the development of flame retardants and flame retardant compounding technology. Flame retardant compounding technology refers to the phosphorus, halogen, nitrogen and inorganic flame retardants, or within a certain type of flame retardant Due to the flame retardant in practical applications, a single flame retardant often have some defects, it is difficult to meet the increasing requirements of people, so by flame retardant compounding technology, you can combine two or two The advantages of the above flame retardant, and learn from each other, to maximize the synergistic effect of flame retardants in order to reduce the amount of fire-retardant effect and enhance the role.