Applications of Aluminum Hydroxide Flame Retardants (Part I)

Aluminum hydroxide flame retardants have extremely broad applications. They are not only used for flame retardancy but also for smoke suppression and reducing the generation of corrosive gases in materials. It can be used alone or in combination with other flame retardants. For polymers processed at temperatures below the decomposition range of aluminum hydroxide flame retardant (190–230°C), it serves as an excellent flame-retardant material. It is applied in elastomers, thermosetting resins, and thermoplastics, and is extensively used in styrene-butadiene latex for producing flame-retardant carpets. It is employed in the production of flame-retardant insulated rubber cables, insulating foam plastics, conveyor belts, roofing membranes, and hoses. Applications extend to bathroom fixtures, decorative wall panels, various covers, automotive protective covers, seating, truck components, electronic components including insulators and circuit boards, construction tools, and more. Nano-aluminum hydroxide can also be utilized in engineering plastics and aerospace materials.

Currently, aluminum hydroxide flame retardants are commonly used as filler-type flame retardants for flame-retarding EVA, LDPE, and LLDPE cable compounds, as well as for flame-retarding PP and numerous thermosetting polymers. At an addition level of 40%, aluminum hydroxide flame retardants can significantly delay the thermal decomposition temperatures of PE, PP, PVC, and ABS, delivering excellent flame retardancy and smoke suppression. Polyolefins containing 50% aluminum hydroxide are primarily used in Japan for food packaging materials. Flame-retarded polyolefins with 60% aluminum hydroxide can serve as building materials and interior trim for automobiles and ships.

(I) Application in Rigid Polyvinyl Chloride (PVC) Plastic Products

With the development of the building materials industry, rigid polyvinyl chloride (PVC) plastic products have gained widespread application, becoming an indispensable material in the national economy and daily life. However, when burned, PVC produces large amounts of smoke and decomposes into toxic and corrosive gases that cause suffocation—a primary cause of fatalities in fires. Incorporating aluminum hydroxide flame retardants into PVC effectively overcomes these drawbacks.

Ultrafine hydrated alumina enhances the oxygen index of PVC plastics. Aluminum hydroxide flame retardants treated with coupling agents can significantly reduce smoke density while minimally affecting mechanical properties. Within a dosage range of 20–30 parts, it serves as an excellent flame retardant and smoke suppressant with broad application prospects.

(II) Application in Polypropylene

(1) Aluminum hydroxide flame retardant exhibits pronounced flame retardancy and smoke suppression in polypropylene. As its dosage increases, the oxygen index rises linearly while combustion rate and smoke generation decrease markedly.

(2) Smaller particle size of aluminum hydroxide flame retardant correlates with superior flame retardancy and reduced adverse effects on mechanical properties.

(3) Surface treatment of aluminum hydroxide flame retardants using effective activators is an indispensable step for their application in polypropylene. Activated aluminum hydroxide flame retardants exhibit significantly less impact on the flame retardancy and mechanical properties of PP compared to non-activated ones.

(4) Aluminum hydroxide flame retardants can be used in combination with phosphorus-based and halogen-based flame retardants to enhance flame retardancy.