25 / 04 2016

Dexine makes safer swing seats with reduced PAH content

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Rubber often contains carbon black; a substance giving rubber its traditional black colouring, and also imparting beneficial physical properties to the vulcanised end product. Carbon black is produced by pyrolysis of hydrocarbons at high temperatures. This process results in the formation of trace levels of organic impurities, such as PAHs (Low Polycyclic Aromatic Hydrocarbons), which can be toxic and harmful to humans. To protect children and ensure compliance with new European legislation Dexine has now developed rubber with reduced PAH levels for playground equipment.

Normally PAH levels contained in rubber would not be a problem for most uses as the PAHs are tightly absorbed in the carbon black surface. However, research has shown that PAHs are carcinogenic and so action has been taken. For example, in Germany the Geprufte Sicherheit (GS) voluntary safety mark encourages the reduction of PAH content in certain consumer-based rubber products.

Stronger regulatory action has now been taken across Europe with new legislation introduced in December 2015 to limit the levels of PAHs in articles supplied to the general public. Sports equipment, such as bicycles, golf clubs and racquets, as well as household utensils, walking frames, tools for domestic use and clothing, footwear and watch-straps, to name just a few, must contain no more than 1.0mg/kg each. Even stricter rules apply to children’s toys and child care items, which must not contain more than 0.5mg/kg each.

Dexine manufactures playground equipment, including swing seats, which are regulated under this new European legislation. To ensure compliance Dexine’s technical experts created a new formula in which the carbon black content has been significantly reduced. Non PAH fillers have been used to give the rubber more bulk and only the smallest amounts of carbon black remain for colouring. In addition, Dexine now uses paraffinic oil in the compound to replace the more commonly used aromatic oils, which contain higher PAH levels.

The result is a rubber swing seat that has been manufactured to the highest standards but which now contains minimal amounts of carbon black and PAH levels well under that stipulated under the new European legislation.