New aluminum hydroxide and magnesium hydroxide grades with enhanced flame retardancy.: Fid-Bau Portal

New aluminum hydroxide and magnesium hydroxide grades with enhanced flame retardancy.

Lee, David A. / Herbiet, Rene

Synergistic additives to enhance the efficiency of mineral flame retardants such as ATH (aluminium hydroxide) and MDH (magnesium hydroxide) in plastics are widely used. Apart from e.g. zinc borates and silicone containing additives, nano clays have become very popular synergists due to their efficiency, mainly in polar polymer systems. The commercial use of nanocomposites in FR (flame retardant) systems is thus gaining momentum. It is a challenge for researchers, however, to develop new minerals with improved flame retardant properties where the use of synergistic additives is no longer necessary. Nanotechnology is a key to achieve this goal. New commercially available products are introduced with improved flame retardant properties based on aluminium and magnesium hydroxides and nanotechnology. The newly developed and commercialised ATH Char 41&42 and MDH Char 51&52 grades afford enhanced flame retardancy in polar polyolefin copolymers when compared directly with standard ATH and MDH grades. The efficiency of the new products is demonstrated using modern laboratory methods like cone calorimetry. Compared to the traditional mineral flame retardants, the new grades afford improved char formation, less dripping, less smoke, an increased time to ignition and improved heat release rate. In non-polar systems, such as polypropylene, less dripping and better char formation was observed (not discussed in this paper). Enhanced flame retardancy can be achieved even at lower filler load levels than traditional ATH and MDH. This allows users to fine tune and improve their system, optimising such properties as flame retardancy, mechanical and rheological properties. Though there is no limit for the use of the Char grades in polyolefins and its copolymers for wire and cable applications, in case of very demanding electrical properties after aging, their suitability should be investigated carefully. Again depending on the application and the related aging standards, it may become necessary to adjust the stabilisation system. Finally, PVC (polyvinylchloride) tends to discolour when Char grades are incorporated and their use is thus not recommended for this system.