When properly recycled, old plastic parts in junkyards can find second life in new products. Sony’s new Bravia LCD TV makes use of parts made from flame-retardant polystyrene regenerated by a new in-house system in a Sony facility in Japan. By recycling polystyrene waste from previously sold Sony CRT TVs and polystyrene foam packaging materials, Sony can reduce CO2 emissions by 30–40% compared with the use of new materials, and also cut production costs.
Conventionally, polypropylene has been the preferred candidate for recycling in the consumer electronics industry. Polystyrene, despite being the key plastic material used in TV parts, had been overlooked in this area due to the difficulty of removing extraneous substances and ensuring sufficient flame and impact resistance. As for polystyrene foam packaging, it had only been reused as polystyrene foam products because of the material’s fragility and lightness.
Sony’s new proprietary additive, however, enhances the heat and impact resistance of polystyrene foam to a sufficient level for use in TV parts. With it, Sony’s Inazawa TEC (Inazawa City, Aichi Prefecture, Japan) was able to overcome previous technical obstacles and turns recycled polystyrene waste into parts for the Bravia LCD TV line, which is scheduled for introduction in Japan in spring 2008.
Researchers at HP made a similar breakthrough recently, as the company found a way to recycle its ink jet print cartridges and regular water bottles into new cartridges that are competitive in performance with those made of virgin materials. HP says since piloting the program, it has used enough recycled plastic to fill more than 200 tractor trailers and created more than 200 million ink jet cartridges globally. Last year, the company used more than 5 million lb of recycled polyethylene terephthalate (PET) in its ink jet cartridges, and it is committed to using twice as much in 2008.
One major hurdle during the research process was how to recycle PET of different grades into a new material with the same properties as the highly engineered, glass-filled PET specifically formulated for the HP ink jet cartridges. Additives play a key role. The research team uses them in combination with recycled bottle resin and PET to offset lower viscosity, as well as thermal and mechanical property changes. The additives comprise chain extenders, which control the molecular weight; impact modifiers, which provide the right amount of resistance for the product drop test; and nucleating agents, which restore the crystalline nature of PET. Because the recycled bottle resin contains no fibers, additional glass fiber also has to be added. The result is a recompounded, reengineered material that works with existing molds and manufacturing lines. For this, HP was presented with the environmental stewardship award from the Society of Plastics Engineers in March.