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Magnesium Hydroxide Flame Retardant

Hebei Messi Biology Co., Ltd. stated that magnesium hydroxide is a new type of filling flame retardant. It releases bound water when decomposed by heat and absorbs a large amount of latent heat to reduce the surface temperature of the synthetic material it fills in the flame. It has the effect of inhibiting the decomposition of polymers and cooling the generated combustible gases.

The preparation method of magnesium hydroxide flame retardant

Definition of magnesium hydroxide flame retardant

The decomposed magnesium oxide is also a good refractory material, which can also help improve the fire resistance of synthetic materials. At the same time, the water vapor it releases can also be used as a smoke suppressant. Magnesium hydroxide is recognized as an excellent flame retardant with triple functions of flame retardant, smoke suppression and filling in the rubber and plastic industry. It is widely used in polymer materials such as rubber, chemicals, building materials, plastics and electronics, unsaturated polyesters, paints, and coatings. In particular, it can replace aluminum hydroxide for flame retardant, smoke suppression and antistatic for mine air duct coating cloth, PVC whole core conveyor belt, flame retardant aluminum-plastic plate, flame retardant tarpaulin, PVC wire and cable material, mine cable sheath, and cable accessories, and has excellent flame retardant effect. Compared with similar inorganic flame retardants, magnesium hydroxide has better smoke suppression effect. Magnesium hydroxide does not emit harmful substances during production, use and disposal, and can also neutralize acidic and corrosive gases produced during combustion. When used alone, the dosage is generally 40% to 60%.

Development of magnesium hydroxide flame retardant

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 chemical decomposition to absorb heat and release water when heated to play a flame retardant role. Therefore, it has the advantages of non-toxicity, low smoke, and the chemical properties of magnesium oxide generated after decomposition are stable, and no secondary pollution. However, compared with halogen-containing organic flame retardants, to achieve a comparable flame retardant effect, the filling amount generally needs to reach more than 50%. Since magnesium hydroxide is an inorganic substance, the compatibility of the surface with the polymer base material is poor. Such a high filling amount, if it is not subjected to surface modification treatment, will lead to a decrease in the mechanical properties of the composite material after filling it into the polymer material. Therefore, it is necessary to perform surface modification treatment to improve its compatibility with the polymer matrix, so that the mechanical properties of the filling material do not decrease, and even improve some of the mechanical properties of the material.

Experiments have shown that unmodified magnesium hydroxide exists in the form of agglomerates in PP. Although the powder itself is extremely fine, there are obvious boundaries and even voids between the particle agglomerates and the PP matrix due to the incompatibility of the particle surface with the PP matrix. The voids formed after the escape of magnesium hydroxide particles during brittle fracture indicate that the unmodified magnesium hydroxide only plays a role of filling and flame retardant in PP, and does not chemically bond with PP. The surface-modified magnesium hydroxide is evenly dispersed in the PP matrix, and most of the particles are dispersed in the material in the form of primary particles or small agglomerated particles.

Policies related to magnesium hydroxide

In December 2000, my country formulated the relevant industrial powdered magnesium hydroxide industry standard (HG/T3607-2000) and implemented it on December 1 of the same year. The HG/T3607-2007 standard is currently used. This is the only professional standard seen so far. The production scale of magnesium hydroxide of different specifications and varieties abroad is very large, and its application in different fields has a history of nearly 20 years, but there has been no official standard issued. Therefore, the proposal of my country’s industry standard is very groundbreaking.

Flame retardant mechanism of magnesium hydroxide

When heated (340-490 degrees), magnesium hydroxide decomposes and absorbs the heat on the surface of the burning material to achieve flame retardant effect; at the same time, it releases a large amount of water to dilute the oxygen on the surface of the burning material, and the active magnesium oxide generated by the decomposition adheres to the surface of the combustible material to further prevent the combustion. During the entire flame retardant process, magnesium hydroxide not only does not produce any harmful substances, but its decomposition products can also absorb a large amount of harmful gases and smoke produced by the combustion of polymers such as rubber and plastics while flame retardant. Active magnesium oxide continuously absorbs incompletely burned molten residues, which quickly stops the combustion while eliminating smoke and preventing molten droplets. It is an emerging environmentally friendly inorganic flame retardant.

Classification of magnesium hydroxide flame retardants

Flame retardants can be divided into two categories according to their chemical composition: organic flame retardants and inorganic flame retardants. Organic flame retardants are divided into two series: phosphorus series and halogen series. Due to the disadvantages of organic flame retardants such as high toxicity and smoke in decomposition products, 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 and magnesium hydroxide absorb large amounts of heat during decomposition and produce H2O, which can isolate the air. The oxides after decomposition are high-temperature resistant substances. Therefore, the two flame retardants can not only play a flame retardant role, but also a filling role. It has the characteristics of not producing corrosive halogen and harmful gases, non-volatile, long-lasting effect, non-toxic, smokeless, and dripless.

Preparation before using magnesium hydroxide flame retardant

There may be some accidents in the application stage of magnesium hydroxide flame retardant, so it is very important to make full preparations before use, which can not only improve the flame retardant effect of the flame retardant, but also make the whole process safer. The matters needing attention are as follows:

1. Sample test before flame retardancy. It is necessary to take some samples for flame retardant testing. The purpose of this is mainly to test whether the flame retardant can meet the specified flame retardant standards and whether the flame retardant is suitable for the flame retardant material to avoid wasting the flame retardant.

2. The surface of the substrate should be properly cleaned before flame retardant, and it is best not to have oil, water marks, dust, etc. on the surface.

3. Before flame retardant, understand the use method, temperature and flame retardant time of the flame retardant clearly to avoid wasting the flame retardant and the material.

Hebei Messi Biology Co., Ltd. stated that in order to prevent the waste of flame retardants and the occurrence of safety problems, these need to be given enough attention before and after the use of magnesium hydroxide flame retardant.

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