What is magnesium hydroxide flame retardant

Magnesium hydroxide is a new type of filled flame retardant. It releases bound water when it is decomposed by heat absorbs a large amount of latent heat to reduce the surface temperature of the synthetic material it fills in the flame. The generated combustible gas is used for cooling.

development path

Magnesium hydroxide is an inorganic flame retardant filler for polymer-based composite materials with good application prospects. Like aluminum hydroxide, magnesium hydroxide flame retardant relies on the chemical decomposition of heat releases water when heated to play a flame retardant effect, so it has non-toxic, low smoke magnesium oxide generated after decomposition is chemically stable, There are advantages such as secondary pollution. However, compared with halogen-containing organic flame retardants, to achieve a comparable flame retardant effect, the filling amount should generally reach more than 50%. Since magnesium hydroxide is an inorganic substance, the compatibility between the surface the polymer base material is poor, such a high filling amount, if it is subjected to surface modification treatment, after filling into the polymer material, it will lead to composite materials The mechanical properties are reduced. Therefore, it must be surface-modified to improve its compatibility with the polymer base material, so that the mechanical properties of the filler material does decline, even partially improve the mechanical properties of the material.

The experiment proves that unmodified magnesium hydroxide exists in the form of agglomerates in PP. Although the powder itself is very fine, there is a clear difference between the particle agglomerates the PP matrix due to the incompatibility of the particle surface with the PP matrix. The boundaries are even empty. The voids formed after the magnesium hydroxide particles escaped during brittle fracture indicate that the unmodified magnesium hydroxide only acts as a filler flame retardant in PP, does chemically bond with PP. The surface-modified magnesium hydroxide is evenly dispersed in the PP matrix, the particles are mostly dispersed in the material in the form of primary particles small agglomerated particles.

related policy:

In December 2000, my country formulated the industry standard for powdered magnesium hydroxide (HG/T3607-2000) began to implement it on December 1 of the same year. This is the only professional standard seen so far. The production scale of magnesium hydroxide with different specifications varieties abroad is very large, its application in different fields has a history of more than 20 years, but no official standards have been introduced. Therefore, my country's industry standards are very pioneering.

Flame retardant mechanism:

Magnesium hydroxide decomposes when it is heated (340-490 degrees) to absorb the heat of the surface of the combustion to flame retardant effect; at the same time, it releases a large amount of moisture to dilute the oxygen on the surface of the combustion, the activated magnesium oxide generated by the decomposition adheres to the surface of the combustible further prevents it The burning proceeded. Magnesium hydroxide only does produce any harmful substances during the entire flame retardant process, but its decomposition products can also absorb a large amount of harmful gases smoke generated by the combustion of polymers such as rubber plastics while flame retardant. Active magnesium oxide continuously absorbs Incompletely burnt melting residues eliminate smoke prevent droplets while stopping combustion quickly, are an emerging environmentally friendly inorganic flame retardant.

classification:

Flame retardants can be divided into organic flame retardants inorganic flame retardants according to chemical composition. Organic flame retardants are divided into two series of phosphorus series halogen series. Because organic flame retardants have the disadvantages of high toxicity smog, they are gradually being replaced by inorganic flame retardants.

The main varieties of inorganic flame retardants are aluminum hydroxide, magnesium hydroxide, red phosphorus, antimony oxide, tin oxide, molybdenum oxide, ammonium molybdate, zinc borate, etc. Among them, aluminum hydroxide magnesium hydroxide have large heat absorption due to decomposition , produce H2O can play a role in air isolation, after decomposition, the oxide is also a high temperature resistant substance, so the two flame retardants can only play a flame retardant role, but also can play a filling role, it has no corrosion Halogen harmful gases, non-volatile, long-lasting effect, non-toxic, smoke-free, non-dropping, etc.

Variety comparison:

At present, the amount of aluminum hydroxide in China is large, but as the processing temperature of high polymers increases, aluminum hydroxide easily decomposes reduces the flame retardant effect. Magnesium hydroxide has the following advantages over aluminum hydroxide:

1. The thermal decomposition temperature of magnesium hydroxide reaches 340℃, which is 100℃ higher than aluminum hydroxide, which is beneficial to increase the processing temperature of plastics, accelerate the extrusion speed, improve the plasticizing effect, shorten the molding time, the surface gloss of the product is high. There will be surface defects, at the same time, it guarantees super peel strength.

2. Uniform particle size distribution, good compatibility with the substrate, little effect on the mechanical properties of the product.

3. Magnesium oxide produced after the combustion dehydration of magnesium hydroxide is a high-strength, high-heat-resistant material, which can be used as a layer of protective wall to isolate fire sources toxic harmful gases. Magnesium hydroxide has a strong neutralizing ability with acids. Quickly neutralize the acid gases SO2, NOx, CO2, etc. generated in the plastic combustion process.

4. Magnesium hydroxide has high decomposition ability, high flame retardant efficiency, strong smoke suppression ability, low hardness, low friction to equipment, which helps to extend equipment life.

5. The price is low. Magnesium hydroxide is half the price of aluminum hydroxide. The large filling volume can greatly reduce the cost of the product.

Product details:

Model particle size (μm) mesh whiteness Mg (OH) 2 purity

ZR105 ≤2 5000 ≥92 ≥94

This model can be directly applied in the rubber industry.

Model particle size (μm) mesh whiteness Mg (OH) 2 purity

GX105 ≤2 5000 ≥92 ≥94

This model is mainly used in polyolefin materials such as PE, which is beneficial to improve the tensile strength.

Model particle size (μm) mesh whiteness Mg(OH)2 purity

TX105 ≤2 5000 ≥92 ≥94

This model can be used in low-grade products of rubber materials, which is conducive to improving dispersion

Model particle size (μm) mesh whiteness Mg(OH)2 purity

YX105 ≤2 5000 ≥92 ≥94

This model is used for rubber materials PVC materials, has good dispersion in products.