With the development of production and science and technology, people constantly put forward a variety of new requirements for materials.At this time, including rubber, plastics, fibers, coatings, adhesives and other high polymer materials gradually meet the needs of people, and produced a huge impact on human production and life.However, polymer materials have a common disadvantage, that is, most of them are flammable or flammable, oxygen index is mostly between 16% and 19%.The air contains 21% oxygen, so these materials can be ignited and kept burning in the air as long as a fire source is available.Obviously, such polymer materials can not meet the using requirements in most occasions, so in order to convert it from flammable/combustible materials into flame retardant materials that are not easy to be lit or self-extinguishing soon after lighting, the addition of flame retardant is essential.    

Among the flame retardants of choice, Aluminum hydroxide (also known as aluminum hydroxide trihydrate [AI(OH)3] and ATH) is a kind of flame retardant material with a white powder appearance, crystalline and amorphous.Because it has three functions of flame retardant, smoke elimination and filling, and is chemically inert, non-toxic and will not produce secondary pollution, it is known as pollution-free flame retardant at home and abroad, and is a typical representative of inorganic flame retardant, accounting for more than 80% of the consumption of inorganic flame retardant.

At present, the aluminum hydroxide used as flame retardant is mainly α-Ai (OH)3, which belongs to monoclinic crystal system.Compared with other inorganic flame retardants, the advantages of aluminum hydroxide are mainly shown in the following four aspects:

① Heat absorption and cooling effect is outstanding

The crystal water content in aluminum hydroxide is as high as 34.46%. When the ambient temperature rises to more than 300℃, all the water is precipitated out.Since water has a high specific heat, it absorbs a great deal of heat from its surroundings when it is converted to steam.Magnesium hydroxide also contains crystal water, but the water content is only 30.6%, not as good as aluminum hydroxide.

② in the combustion does not produce smoke and harmful, toxic substances

③ large filling capacity

④ abundant resources and low price

⑤ wide application

The excellent performance of aluminum hydroxide has made its performance in many industries and fields.But when it is used in different industries, there are different requirements for quality.

1. EVA foaming materials

EVA foaming material refers to the foaming insulation material made of EVA and low density polyethylene as raw materials and other additives after molded foaming or injection foaming.Because it is good for the environment, it is widely used in indoor and public places, so it has high requirements for flame retardant performance.

The flame retardant system of EVA foaming material generally adopts a single aluminum hydroxide, with the addition amount reaching about 60%.Due to the large amount of addition, it requires strict stability, stable pH, and no impurity in the product, which makes the production process of aluminum hydroxide very strict, and the price is higher than other nanoscale products.

2, silicone rubber products

Silica gel special aluminum hydroxide flame retardant needs to add a variety of silane surface treatment, screen out the coarse particles, remove impurities, make the powder as far as possible and silicone rubber combined well,  not affect the mechanical properties, while playing the dual effect of flame retardant and filling.In addition, aluminum hydroxide can be used alone or in combination with nitrogen and phosphorus flame retardants, and the specific proportion should be added according to the formula.

3, ink coating

Inks and coatings are important printing materials. The former is mainly used in the printing industry, while the latter is used for protection and decoration.There is no obvious boundary between the two, and the requirements of aluminum hydroxide flame retardant are basically the same, that is, it needs to have low oil absorption rate, no impurities, high whiteness, no precipitation and other characteristics.

4, TPU

TPU is thermoplastic polyurethane elastomer, it has excellent high tension, strong and aging resistance characteristics, and it is a mature environmental protection material.Aluminum hydroxide added in TPU/TPE material, first of all, the particle size should be less than 2.0 microns, particle size distribution is uniform, can better integrate with other materials, improve the wear resistance and tear resistance of the material.Secondly, to do surface activation treatment of aluminum hydroxide, so that aluminum hydroxide can have a good link with other substances, at the same time, but also enhance the processing fluidity of aluminum hydroxide, aluminum hydroxide can be more evenly distributed to the material, produce a good flame retardant effect.