Textile fabrics after flame retardant finishing, not to say that fabric encountered fire source does not produce combustion, but its flammability is reduced, that is not easy to burn in a fire, the flames do not spread or low rate of spread, when the fabric away from the fire source quickly self-extinguishing, no longer continue to burn or smolder. The complexity and diversity of the fire blankets mechanism has been recognized, with the different types of flame retardants, flame retardant mechanism is different, and is applicable on all aspects of fire-retardant theory has not yet been established, but summed up There are four theories: covering theory, gas theory, hot on the catalytic dehydration theory.
, Generated in the vapor of the combustion reaction speed and the combustion process in a gas phase fire fighting equipment mechanism radical HO · and H · closely related to the concentration of the role of the flame retardant in the gaseous phase are mainly the high energy such as a radical into a stable free radicals and inhibit the combustion process carried out to achieve the flame retardant purposes.
Halo (bromo) derivative of the flame-retardant effect is considered to be by gas mechanism. When the the first brominated flame retardants MBr heat release bromine radicals:
MBr → M + Br · (4)
Or the release of hydrogen bromide HBr:
MBr → M + HBr (5)
Bromine radical release of combustible gas in the combustion Br · fabric RH reaction does not burn the gas hydrogen bromide:
Br · + RH → R · + HBr (6)
The hydrogen bromide can effectively suppress the disproportionation reaction (1) and the main exothermic reaction (3), so the hydrogen bromide is true flame inhibitors:
H · + HBr → H2 + Br · (7)
HO · + HBr → H2O + H · (8)
Reaction (7) is twice as fast than the reaction (8), and in the ratio of flame front H2/HO ·, showed that the reaction (7) is the main reaction to suppress combustion. In this case, the reaction (7) and the reaction (1) compete with each other, the result is an active H · is consumed, the activity of H · is consumed to determine the inhibitory effect. Reactions (8) and reaction (3) is also competing reactive HO · is also being consumed, and thereby inhibit the generation of heat in the combustion so that the combustion is further prevented.
Halogen (bromine) derivative compounds, antimony trioxide, can enhance the flame retardant effect. Antimony trioxide itself has no flame-retardant effect, however, it is common derivative with a bromine-containing compound when heated, can produce the following reaction:
Sb2O3 +6 HBr → SbBr3 +3 H2O (9)
SbBr3 +3 H · → Sb +3 HBr (10)
SbBr3 + H2O → SbOBr +2 HBr (11)
SbOBr + H · → SbO + HBr (12)
SbO + H · → SbOH (13)
Thus, the active H · be consumed in large quantities, also generates a large amount of the flame suppressor HBR, and thus play a more effective flame-retardant effect