Phosphorus flame retardant

Phosphorus flame retardant system includes inorganic phosphorus flame retardant and organic phosphorus flame retardant. Phosphate and phosphonate are the most widely used organophosphorus flame retardants at present

Flame retardant mechanism

Phosphorus flame retardant is weak flame inhibitor; The flame retardant mechanism lies in the decomposition of phosphorous compounds into phosphorous oxy acid by heat, which can promote the dehydration carbonization of the polymer to produce a graphit-like coke layer, which can block the contact between the internal polymer and oxygen. The thermal conductivity of the coke layer is poor, so that the polymer is isolated from the heat source, slowing down the thermal decomposition, so as to play the role of flame retardant. The dehydration and carbonization process relies on the oxygen-containing groups of the polymer itself. For polypropylene, the molecular structure has no oxygen-containing group, and the flame retardant effect is not good when the phosphorus flame retardant is used alone. If combined with aluminum hydroxide and magnesium hydroxide can produce synergistic effect, so as to get a good flame retardant effect.


Nitrogen flame retardants

Nitrogen flame retardants mainly include three categories: triazine compounds melamine, dicyandiamide, guanidine salts and their derivatives, especially phosphate derivatives.

Flame retardant mechanism

when the temperature rises to a certain extent, the nitrogen flame retardant will be heated and begin to decompose. The decomposition products include non-combustible gases such as NO, NO2, NH3 and CO2, among which NH3 is the main component of the released gases. NH3 has functions of cooling, endothermic and diluting oxygen. The generation of these incombustible gases plays the purpose of heat absorption and oxygen isolation, and the endothermic reaction of the flame retardant in the decomposition process consumes most of the heat and significantly reduces the temperature of the burning surface of the flame retardant material, which all play the role of preventing the further combustion of the material and spreading the flame. Non-combustible gas substances not only dilute the concentration of oxygen and flammable gas at the combustion interface, but also consume oxygen in the air, oxidize with it, generate nitrogen, water and deep oxides, and achieve the purpose of flame retardant.

Aluminium-magnesium flame retardant

Aluminium-magnesium flame retardant used in organic silicon is mainly aluminum hydroxide and magnesium hydroxide. This kind of material has the advantages of good thermal stability, non-toxic, non-volatile, non-corrosive gas and small smoke emission.

Flame retardant mechanism

the decomposition process of aluminum hydroxide is an endothermic reaction (the heat absorption is about 2kJ/g), which can take away a lot of heat generated by combustion and reduce the temperature of combustion interface; In addition, one of the decomposition products is water vapor, which can cool and dilute the concentration of oxygen and flammable gases. Another decomposition product, alumina, is a dense inorganic oxide powder, which can be covered on the surface of polypropylene flame retardant material to form a protective carbon layer with heat insulation and oxygen isolation, and also has the effect of smoke suppression. The flame retardant mechanism of magnesium hydroxide is similar to that of aluminum hydroxide, but the decomposition temperature of magnesium hydroxide is 340~ 490℃, which is much higher than that of aluminum hydroxide. The thermal stability is relatively good, and the smoke suppression performance is better than that of aluminum hydroxide, while the heat absorption of the reaction is less than that of aluminum hydroxide. In addition, Mg(OH)2 can promote the carbonization of plastic surface. Al(OH)3 has no effect. However, Mg(OH)2 is more suitable than Al(OH)3 as flame retardant for the polymer with higher processing temperature. Usually two kinds of flame retardants synergies than used alone can achieve better flame retardant effect, the mechanism of synergistic flame retardant, aluminum hydroxide play a role of flame temperature is lower, but the heat absorption capacity is bigger, can effectively inhibit the rise of temperature, the temperature is high, plays a role of flame retardant magnesium hydroxide dehydrated endothermic reaction, both compound, foster strengths and circumvent weaknesses, It can enlarge the temperature range and prolong the time of flame retardant effect, so as to play the role of co-effect flame retardant.

Silicon-based flame retardant

Silicon-based flame retardant is a new type of halogen-free flame retardant, which is a charcoal-forming smoke suppression agent. It can not only endue the polymer with excellent flame retardant and smoke suppression properties, but also improve the processing properties and mechanical strength of the polymer.

Flame retardant mechanism

Organic silicone flame retardants in the combustion will occur earlier melt dripping phenomenon, which the organic silicone flame retardants drop material through the gap of the polymer substrate is transferred to the surface of the substrate, generate dense and stable (SiO2) containing silicon carbon layer, the layer containing silicon carbon layer is to prevent the combustion decomposition of combustible material to escape, but also have the effect of heat insulation oxygen insulation, Prevent the thermal decomposition of polymer materials, to achieve the purpose of flame retardant, low smoke, low toxicity; The flame retardant effect of inorganic silicon flame retardant belongs to the condensed flame retardant mechanism. It is generally believed that the flame retardant is achieved through the blocking and shielding effect of amorphous silicon or the protective layer of silicide formed during combustion.

Expansive flame retardant

Expansive flame retardant (IFR) is considered to be one of the development directions of halogen-free flame retardant materials because of its high flame retardant efficiency, low smoke, non-toxic, no corrosive gas release and other characteristics.

Flame retardant mechanism

IFR is generally a new type of composite flame retardant with phosphorus, nitrogen and carbon as the main components. It is usually composed of three parts -- charcoal-forming agent (carbon source), dehydrating agent (acid source) and expanding agent (gas source). In conventional IFR composite flame retardant, is usually as a source of acid ammonium polyphosphate (APP), as a carbon source is pentaerythritol (PER), as a source of melamine (MA), is the play to the role of the flame retardant mechanism is: when the temperature rises, the IFR carbon source under the action of acid source, the esterification reaction, the product of ester compounds; Followed by dehydration crosslinking reaction, the ester compounds of carbon formation, at the same time, the effects of the gas source decomposition in the carbonized material, make them form a closed, porous carbon layer, fluffy foam structure, the essence of which is carbon crystallite carbon layer, for the amorphous carbon structure, not burning, and it can be a partition between flame retardant polypropylene material and the heat source of heat conduction, The thermal degradation temperature of polyflame retardant propylene was increased. In addition, the closed foamed carbon layer can prevent the diffusion of gas, that is, prevent the diffusion of flammable gas generated by thermal decomposition, and at the same time block the flow of external oxygen to the surface of the uncracking flame retardant polypropylene material. Because the combustion can not get enough oxygen and heat energy, the burning flame retardant polypropylene material will self-extinguish.