Brief Introduction of Inorganic Flame Retardants

Brief Introduction of Inorganic Flame Retardants

Inorganic flame retardant refers to a kind of inorganic compounds added in the synthetic formula, which have good flame retardancy, co-effect flame retardancy and smoke suppression characteristics. Usually divided into aluminum hydroxide, magnesium hydroxide, red phosphorus flame retardant, ammonium polyphosphate and so on.

(1) Aluminum hydroxide

Aluminum hydroxide flame retardant, referred to as ATH, the main characteristics of the flame retardant: aluminum hydroxide heat decomposition of crystalline water. The reaction is a strong heat-absorbing reaction, when a certain amount of heat inhalation, you can produce the effect of cooling the polymer, while the chemical reaction of the steam generated can also be diluted flammable substances, thereby controlling the spread of the explosion, the production of anti-melting droplets, to promote the charring of the non-volatile, does not produce exudate, etc., high quality and low price, a wide range of sources can be sustained in the polymer medium efficacy, and safety, performance, and high temperature, and the characteristics of a good performance. It does not form harmful chemicals at high temperatures and reduces the rate of smoke generation when the material is ignited.

The specific surface size of ATH has little to do with the flame retardancy of the filler material, which is consistent with the flame retardancy mechanism discussed above. However, the increase of the specific surface layer of ATH also plays an important role in the thermodynamic properties of the filler material, and its tensile ability increases with the increase of the specific surface area of ATH (particle size reduction).

The main factor limiting its use in plastic products and rubber industry at home and abroad at present may be closely related to its specific surface quality, and one of the important ways in which the super-particulation of ATH can enhance the mechanical properties of the filler material."

In the PVC system according to the ATH wt% and 0.1 ratio system, the filler material at the beginning of the oxygen index does not rise quickly, and when the filling dosage of more than forty percent, its oxygen index increases rapidly, which chapter tastes if the ATH alone flame retardant its dosage must reach more than forty wt%, and Shao Changsheng et al. that its aerodynamic properties ester with the increase in the concentration of ATH and a significant decrease in the which also explains that the ATH is mainly an inert filler in wood."

(2) Magnesium hydroxide

Aluminum hydroxide is a new class of filled inorganic flame retardant, through the thermal decomposition of the release of bound water, and adsorption to produce a large amount of latent heat of the phase transition, to reduce the surface temperature of the high synthetic material it is filled in the flame, there is a control of polymer dissolution of the open to the formation of flammable gases in the function of cooling.

Yinsu Company utilizes the refining liquid of light burning powder obtained after removing sulfate, and produces magnesium hydroxide with good flame retardant effect without adding surfactant by taking ammonia of its refining liquid as the main raw material. The effects of ammonia passage rate, reaction temperature and crystal species addition on the production characteristics of magnesium hydroxide were also considered.

The results of the research concluded that, due to the reaction temperature increase, the finished product particle size, but the surface morphology still need to be changed, from irregular shape gradually into an approximate cubic block; due to the speed of ammonia, the performance of the product is also improved, but in the ammonia rate is too large, the dispersion of the product and the particles are also reduced accordingly: due to the increase in the amount of crystalline species added, the size of the magnesium hydroxide continues to improve, but the effect of the change of the surface morphology is not obvious. The effect is not obvious.

Experimental results show that, in the crystal seed addition ratio of three percent (mass fraction), ammonia flow rate of 300m L/min, magnesium precipitation temperature of ninety degrees Celsius, the production of aluminum hydroxide inorganic flame retardant effect is good; product D250 = 1.23 m, specific curvature of 6.3m2 high / g, utilization rate of more than eighty-one point two percent.

In summary, inorganic flame retardants have the following characteristics: less dangerous, so most of the inorganic flame retardants are relatively safe; high thermal safety, non-volatile, non-decomposition, with a long-lasting flame retardant effect, will not form a corrosive substance; relatively inexpensive: and the smoke rate is small, so a lot of inorganic flame retardants are very good demisting agent."