The use of halogen-free flame retardants varies according to their types and application fields. Here are some common halogen-free flame retardants and how to use them:
1. Aluminum hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂)
Aluminum hydroxide and magnesium hydroxide are common inorganic metal compound flame retardants, which inhibit combustion by endothermic decomposition and dehydration.
Usage: Usually as an additive flame retardant directly added to the polymer matrix, through mechanical mixing evenly dispersed. The amount added depends on the desired flame retardant grade and the properties of the polymer matrix.
2.Expandable graphite
Expandable graphite is a new kind of halogen-free flame retardant, which is prepared by natural graphite after concentrated sulfuric acid treatment, washing, filtration and drying, and then expanded at 900-1000℃. It expands at high temperatures to form a carbon layer, which isolates oxygen and thus achieves flame retardant effect.
Usage: Also used as an additive flame retardant, it can be evenly dispersed into the polymer matrix by mechanical mixing. The amount of addition needs to be adjusted according to the specific formula and flame retardant requirements.
3. Nitrogen flame retardants
Nitrogen flame retardants will release non-combustible gas when heated, take away heat, reduce the combustion temperature, so as to achieve flame retardant purposes.
Usage: Can be used as a reactive flame retardant into the polymer chain, can also be used as an additive flame retardant. The specific use method depends on the type of nitrogen flame retardant and the properties of polymer matrix.
4. Phosphorus based flame retardants
Phosphorous flame retardants will produce phosphoric acid, metaphosphate and other substances during combustion, promote the dehydration and carbonization of polymers, form a carbon layer to isolate oxygen, so as to achieve flame retardant effect.
Usage: It can also be used as a reactive or additive flame retardant. As an additive flame retardant, it needs to be evenly dispersed into the polymer matrix by mechanical mixing; When used as a reactive flame retardant, it needs to be introduced into the polymer chain.
5. Usage methods for specific application scenarios
In the field of wire and cable, elastomer TPE halogen-free flame retardants are widely used to achieve the effect of self-extinguishing from fire. The use method is usually to evenly disperse the flame retardant into the TPE matrix, and make wire and cable products by extrusion or injection molding.
In the field of textiles, halogen-free flame retardants can be processed by dip baking, dip drying, spray and other methods. These methods involve immersing the fabric in a flame retardant solution and then securing the flame retardant to the fabric through steps such as pre-baking, baking, or drying.
Matters needing attention
When using halogen-free flame retardants, it is necessary to pay attention to their compatibility and dispersion with the polymer matrix. If necessary, the dispersion of flame retardant in polymer matrix can be improved by means of granulation technology and coating technology.
The amount of flame retardant added needs to be adjusted according to the specific formula and flame retardant requirements, too much or too little may affect the flame retardant effect and the performance of the polymer matrix.
When using halogen-free flame retardants, they should also consider their impact on the environment and human health, and choose products that meet environmental standards.
In short, the use of halogen-free flame retardants varies according to their types and application fields. In practical applications, it is necessary to choose the appropriate type and use method of flame retardants according to the specific situation to achieve the best flame retardant effect.
