Modifiers spur growth in PET recycling There has been significant growth in recycling PET in recent years throughout the world. Japanese company Kaneka has now developed impact and viscosity modifiers that can improve the properties and processing of recycled PET, which opens up the possibility of many new applications. Plastics Additives & Compounding reports. The volume of recycled PET bottles has grown dramatically over the past ten years. In Europe 600,000 metric tonnes of PET was recycled in 2003, while Japan is now collecting 50% of PET bottles for recycling - 400,000 metric tonnes of virgin PET was used in 2003 compared to 200,000 metric tonnes of recycled PET. However, existing applications have primarily been restricted to spinning of fibres. Applications have been restricted because the viscosity of recycled PET is poor, meaning that it is difficult to process. In addition, the impact strength
of recycled PET is another weak point of recycled PET. Kaneka Corporation has developed Kane Ace MP-20 and Kane Ace MP-40 to enhance the viscosity of recycled PET. The improvements in viscosity - the result of a crosslinking reaction - now mean that recycled PET can be used in a wider variety of processes, including injection moulding and extrusion. As well as fibres, the company says that potential applications now existing for recycled PET include sheet, bottles, injection moulded products and increasingly bottle to bottle recycling.
Kane Ace MP-40 has been developed for transparent applications. Figure 1 shows the effect of viscosity improvement using Kane Ace MP-40.
Impact modifiers In order to improve the mechanical properties of recycled PET, Kaneka has developed Kane Ace M-400 and Kane Ace M-600 as impact modifiers. They improve the impact resistance of PET by providing a core synthetic rubber impact modifier that is dispersed in the PET resin. Kaneka adds that Kane Ace M-400 is suitable for outdoor applications. Uniform dispersion in the PET is the key. Impact strength can be increased up to 100 kJ/m2 with a modifier dosage of up to 20 phr. Figure 2 shows the effect of the impact strength improvement at 23°C by Kane Ace M-400/M-600. Kaneka adds that benefits in synergy can be achieved by using MP-20 in combination with M-400 and M-600 to lead to a big increase in viscosity - see Figure 3.
New applications
Figure 1:The effect of viscosity improvement using Kane Ace MP-40.
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Kaneka has demonstrated the possibilities of new applications for recycled PET. Using 1% MP-40 pens have been manufactured by injection moulding with R-PET. An egg box of three layer sheet made by extrusion uses 0.5% MP40 with R-PET in the middle inner layer. Products made with the impact modifier M-400 have included rubbish bins made ISSN1464-391X/05 © 2005 Elsevier Ltd.All rights reserved.
Modifiers with 5% M-400 by injection moulding. Coloured plates have been extruded in RPET with 15% M-600. Bottles can be
produced that can be transparent or opaque, with the transparent bottle made from R-PET with 10% MP-40 by direct
blow moulding. Bottles requiring impact resistance are opaque and can be made from R-PET with 10% MP-20 and 20% M-400 by direct blow moulding. One of the latest products made from recycled PET include profiles, which have been produced with 5% MP-20 and 20% M-400 by extrusion. Kane Ace MP/M products are not yet suitable for food applications, however, Kaneka lists a number of outlets for recycled PET. The bottles can be used for detergents and toners, for example. Injection moulded applications include stationery, toys, containers, chairs, rubbish bins and pallets. Extruded sheet can be transparent or opaque.
Profiles
Figure 2:The effect of impact strength improvement at 23°C by Kane Ace M-400/M-600.
Figure 3: Synergy effects of MP-20 when combined with M-400, M-600.
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Other possible extruded parts include pipes, profiles, foamed profiles and plates. Waste disposal bags can also be produced by inflation moulding. Twin screw extrusion is necessary for manufacturing recycled PET compounds with Kane Ace MP/M products. Kaneka asserts that the possibilities for recycled PET using Kane Ace MP viscosity boosters and Kane Ace M impact modifiers are significant providing both potential reductions in material cost and environmental benefits. The samples have currently all been produced in Japan and the Kane Ace products are also currently manufactured there. However, Kaneka also manufactures impact modifiers and processing aids for PVC in Belgium. Although the two additives required for Kane Ace MP/M products are not allowed by European Union regulations for food contact applications, the company does want to develop this possibility, which would obviously widen the scope of suitable applications for recycled PET. Contact: Kaneka Belgium NV Tel: +32 14 25 78 00 Fax: +32 14 25 78 81 E-mail:
[email protected] Website: www.kaneka.be Plastics Additives & Compounding July/August 2005