Why Is Flame Retardant "Aluminum Hydroxide" So Great?

Why Is Flame Retardant "Aluminum Hydroxide" So Great?

I. What is a flame retardant

Flame retardant is a special additive used to improve the combustion performance of combustible and flammable materials, which can make the material flame retardant, self-extinguishing, and smoke elimination, and can effectively improve the safe use of materials. Flame retardants are generally categorized into organic flame retardants and inorganic flame retardants. Organic flame retardants have been widely used because of their outstanding flame retardant effect and wide range of application. However, its shortcomings are also prominent, corrosive, burning smoke, accompanied by poisonous gas.

Inorganic flame retardants have relatively good thermal stability, do not produce corrosive gases and toxic gases, and have less impact on the environment. Compared with organic flame retardants, inorganic flame retardants are more in line with the requirements of environmental protection and fire safety, inorganic flame retardants have been the focus of research in recent years, with great market potential. Inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, magnesium oxide, antimony trioxide, sodium tetraborate, etc. Among them, aluminum hydroxide is the most widely used inorganic flame retardant, which has the functions of flame retardant, smoke elimination and filler, especially the ultrafine aluminum hydroxide after surface modification, and it can also improve the mechanical properties of materials.

II. Advantages of aluminum hydroxide flame retardant

Although the bromine flame retardant in organic flame retardant has the advantages of high flame retardant efficiency, low additive amount, wide range of application, etc., in order to comply with the development trend of high flame retardant, low smoke and harmlessness in the flame retardant market, the development and utilization of inorganic flame retardant has gradually gained more and more support from the booster.

Ultrafine aluminum hydroxide is stable in physical and chemical properties at room temperature, does not produce secondary pollution when burning, has high whiteness and excellent chromaticity index. And nano-aluminum hydroxide can not only improve the limited oxygen index of flame retardant polymers, increase the flame retardant properties, and help to improve the surface finish of polymer products and mechanical and electrical properties, and enhance its resistance to leakage, arc resistance and abrasion resistance. In addition, the composite use of aluminum hydroxide and other flame retardants is very ideal, and it is a kind of inorganic flame retardant with broad prospects.

III. Flame retardant mechanism of aluminum hydroxide

The flame retardant mechanism of aluminum hydroxide is relatively complex, consisting of the following mechanisms in concert with each other:

1. Reaction and heat absorption

As we mentioned above, aluminum hydroxide reacts with heat to generate aluminum oxide and water, and this reaction is a heat-absorbing reaction, the reaction formula is:

In this process, not only absorbed heat to delay the combustion of polymers, while the reaction of water vapor released also diluted the combustible gases and oxygen, will also participate in the condensed phase of the reaction.

2. Dilution

In addition to 1) mentioned in the water vapor can dilute the combustible gases and oxygen, due to aluminum hydroxide also plays a filling role, resulting in a reduction of polymer per unit volume, and filling of aluminum hydroxide plays a dilution role.

3. Covering effect

The reaction generated by the aluminum oxide and other carbides together to form a flame retardant barrier, inhibiting the spread of flame.

4. Carbonization

The flame retardant produces strong dehydrating substances under combustion conditions, which makes the plastic carbonized and not easy to produce flammable volatiles, thus preventing the flame from spreading.

IV. Disadvantages of aluminum hydroxide as a flame retardant

Although aluminum hydroxide performs well in the flame retardant field, it is not perfect. First of all, when aluminum hydroxide is used as a flame retardant, it usually requires a large amount of addition to achieve the desired flame retardant effect, which makes it a challenge to control the cost. Secondly, the addition of large amounts of aluminum hydroxide may have a significant impact on the physical properties of raw materials, such as reducing the strength and toughness of the material, increasing the material's hygroscopicity, etc., thus limiting the scope of application of the material and the use of performance.

V. Requirements for aluminum hydroxide in different industries

Excellent performance, so that the aluminum hydroxide in a number of industry sectors have performance. But when it is used in different industries, there are different requirements for quality.

1. EVA foamed material

EVA foamed material refers to the foam insulation material made of EVA and low-density polyethylene as raw materials and other additives by molding foam or injection foam. Since it is good for the environment, it is used in a large number of 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, and the amount of addition reaches about 60%. Due to the large amount of addition, so it is demanding on its stability, PH requirements for stability, the product can not have a trace of impurities, which makes the production process of aluminum hydroxide requirements are very strict, the price is also higher than other nanoscale products.

2. Silicone rubber product

Silicone special aluminum hydroxide flame retardant need to join a variety of silane surface treatment, sieve out coarse particles, remove impurities, so that the powder as far as possible and the combination of silicone rubber is good, does not have an impact on the mechanical properties, and at the same time to play a flame retardant and filler of the dual efficacy. In addition, aluminum hydroxide can be used alone can also be used in conjunction with nitrogen and phosphorus flame retardants, the specific ratio needs to be added according to the formula.

3. Ink and Paint

Ink and paint are important printing materials, the former is mainly used in the printing industry, the latter at the same time with the role of protection and decoration. There is no obvious boundary between the two, and the requirements for aluminum hydroxide flame retardant are basically the same, i.e., it needs to have low oil absorption, no impurities, high whiteness, no precipitation and other characteristics.

4. TPU

TPU Chinese name for thermoplastic polyurethane elastomer, which has excellent high tension, high tensile strength, toughness and aging resistance, is a mature environmentally friendly materials. Aluminum hydroxide added to TPU/TPE materials, first of all, its particle size should be below 2.0 microns, with a uniform particle size distribution, so that it can be better integrated with other materials and enhance the wear and tear resistance of the material.

Secondly, it is necessary to do surface activation treatment for aluminum hydroxide, so that aluminum hydroxide can produce a good link with other materials, and at the same time, it also enhances the processing fluidity of aluminum hydroxide, so that aluminum hydroxide can be more uniformly distributed into the material, resulting in a good flame retardant effect.

VI. Preparation methods of aluminum hydroxide

The preparation method of ultrafine aluminum hydroxide has physical method and chemical method. Physical method usually refers to the mechanical method; chemical method includes seeding method, sol-gel method, precipitation method, hydrothermal synthesis method, carbon method, supergravity method and so on.

1. Mechanical method

Mechanical method is to crush and grind the washed and dried non-industrial grade aluminum hydroxide into fine ATH powder by stirring mill and air flow mill. The ATH powder produced by this method is irregular in shape, coarse in particle size and widely distributed, generally in the range of 5-15 μm, with poor product performance. The aluminum hydroxide produced by this method is used in the production of wires and cables, and its processing performance, ductility and flame retardant properties are far inferior to those of the aluminum hydroxide produced by the chemical method. Although the mechanical method has simple preparation process and low experimental cost, the impurity content of the product is high and the particle size distribution is not uniform, so it can not be widely used.

2. Seed separation method

The core of the commonly used seeding method is to add ultrafine ATH seeds into the prepared sodium aluminate solution, so as to prepare purer and finer ATH powder. The quality of the seed is an important factor affecting the particle size of ATH powder.

3. Sol-gel method

This method is mainly through the hydrolysis of aluminum compounds in a certain water bath temperature, stirring rate and pH value of the conditions to generate aluminum hydroxide colloid, and then under certain conditions into a gel, and finally after drying and grinding to produce a smaller particle size of aluminum hydroxide powder.

4. Precipitation method

There are two types of precipitation method: direct and uniform precipitation. Direct precipitation refers to the addition of precipitating agent in the aluminate solution, under certain conditions to produce high-purity ultrafine aluminum hydroxide. During the precipitation process, the degree of mixing of the precipitant with the solution is the key factor affecting the nature of the final product. Unlike direct precipitation, the uniform precipitation method has a slow growth rate.

5. Hydrothermal synthesis method

Hydrothermal synthesis is a method of preparing ATH by heating a closed reaction vessel, so that the raw materials are reacted at high temperature and high pressure in the medium of organic solvents.

6. Carbon fractionation

Carbon fractionation method is to pass CO₂ into sodium aluminate solution, through the control of reaction conditions to prepare aluminum hydroxide.

Conclusion:

After gaining an in-depth understanding of the many advantages of aluminum hydroxide flame retardants, the complex and efficient flame retardant mechanism and the application requirements in different industries, let's take a look at the flame retardants produced by YINSU Flame Retardant Company. Our company focuses on the research, development and production of high-performance flame retardants. Aluminum hydroxide products have ultra-fine particle sizes, are easy to disperse, and can be better integrated with other materials to achieve better flame retardant effects. In addition, YINSU Flame Retardant has developed a series of highly effective flame retardant solutions to address some of the potential drawbacks of aluminum hydroxide, such as uneven particle size distribution or insufficient processing performance. These innovative products not only enhance the performance of aluminum hydroxide, but also open up a broader space for the application of flame retardant materials. If you are interested in high-performance, environmentally friendly flame retardants, YINSU Flame Retardant Company is undoubtedly your trustworthy choice!