Summary: The 13th International Polyester Recycling Symposium, held on the 1st of October 2008 in Bad Oeynhausen

The 13th International Polyester Recycling Forum from Dr. Thiele Polyester Technology (www.polyester-technology.com) was held this year on the premises of Gneuss Kunststofftechnik GmbH (www.gneuss.com) in Bad Oeynhausen, Germany. This annual forum is normally held in hotels in various locations around the world. This year, however, due to the fact that Gneuss is celebrating the 25th anniversary of the founding of the company, the proceedings were held on at Gneuss in elegant marquees. The number of delegates was also higher this year due to the growing interest in the developments of the Polyester recycling industry. In 14 presentations, over 140 delegates and guests from all areas of Europe and South America were informed about the latest developments on the raw material market, as well as in the manufacturing and processing of PET bottle flakes to final products.

The Market
As an introduction, Andrew Noone from PCI, portrayed a picture of the largest and most dynamic of markets - ´collected PET-bottles.´ In 2007, the worldwide collection of PET-bottles was 4,53 million tons and was recycled into 3,64 million tons of flakes. With 2,6 million tons used for fibers, 0,39 million tons for bottles (bottle to bottle recycling) and 0,37 million tons for A-PET (thermoforming) sheet production, 0,17 million tons for strapping tape and 0,12 for miscellaneous purposes. Until 2010 the accumulative outcome of the collected PET-bottles is estimated at just under 6 million tons, which is more than the anticipated >15% p.a. growth.

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The Creation of PET-Flakes
An important problem in the dynamic accumulative PET-recycling market is the continuously increasing number of claims regarding the quality of the bottle flake. Gradually the quality level of is now moving closer to expected standards. Dr. Ing. Martina Lehmann from MAKS GmbH discussed the problems regarding quality control and reliability within the method of analysis of the PET flakes and discussed ways of implementing better quality standards. A combination of analysis methods is presently being used, which facilitate the fastest and easiest reproducible measurement of the quality of the flakes. S+S GmbH presented "Actual Coherence: the procedure of effectively sorting to eventual preparation of PET bottles into flakes". Thanks to the concerted use of various detection methods such as Multi-channel high frequency detection, CCD-Camera with picture manipulation and NIR-Sensors one can detect metals, foreign polymer as well as foreign fabrics with computer controlled flow-rates; separation of these products from the plastic is achieved. There are several basic approaches to flake manufacturing. Werner Herbold of Herbold Meckesheim GmbH presented a robust procedure of flake production, which poses no other specific claims on the quality of the accumulated bottles. Next to the development of the grinding mill with its force feed system, emphasis is laid on an intelligent system of water flow and preparation. Krones AG opts for another approach which was presented by Bernard Esmarch. Through the combination of accurate raw material selection out of well known resources, a throughput of 500 to 1000 kg/h and a specialized hot wash production, the new Krones-Process PET-flakes meets with FDA requirements with regard to the foods compatibility, and is able to directly achieve the production of the PET-bottles. Questions regarding the process development were answered by Holger Bachman of Lurgi Zimmer GmbH of the PET-recycling industry who described the analytical methods and quality controls of laboratories and technical centers as well as the development and modifications of the polyester material.

Processing of PET-Flakes
Dr. Axel Hannemann presented the Multi-rotation system (MRS) the latest development from Gneuss Kuntstofftechnik GmbH. A specialized multiple screw extruder with large surface exchange and vacuum extraction of the water vapour in the melt phase, forms together with the automatic and process a constant melt filtration system RSFgenius and the newly developed online Viscometer represents an efficient package for processing PET bottle flakes. For the processing of PET without pre-drying on a twin screw extruder with venting, the company Coperion, formerly known as W&P, undoubtedly plays a leading role, due to their 16 years of experience since they launched this concept at the K`92. Ms. Sabine Schoenfeld presented details of the important process characteristics within the manufacturing procedure, where short dwell times with good surface exchange and moderate mechanical strain, crucial for the effective elimination of the moisture. The inherent machine concept was then discussed by Dr. Thomas Winkelmann from Kraus Maffei Berstorff in which he detailed the manufacture of the undried PET on the co-rotating twin screw extruder. Especially interesting was the high humidity level of > 4500 ppm with the correlation between moisture and IV-breakdown which needs to be monitored. The coherence between the IV-breakdown, vacuum and extruder speed was also illustrated. Advantages of this method as opposed to the conventional technology, is a reduction in costs and a higher effectiveness as well as allowing more flexibility. Mr. Andreas Blin from Bruckner Formtec GmbH enlightened the delegates with regard to the manufacture of thermoforming sheet from A-PET-bottle flakes. Another new innovation was that of the XL-roller, by which the melting film arranges itself applying electrostatic forces without the need for calander stack rollers. A practical example is the new MRS-technology from Gneuss which allows the manufacture of high-strength strapping bands out of PET-bottle flakes without pre- drying; this method was presented by Dr. Lorenzo Maldarelli of Sima s.r.l. Sima is currently the market leader for equipment for strapping tape and together with Gneuss devised a process which reduces the cost of material, investment, maintenance and energy and therefore can put the accepted methods into place.

Presently the biggest application for the PET-bottle flakes is the production of the staple fiber. Mr. Erwin Glawion from Fleissner GmbH gave an extremely impressive visual presentation of actual factors in the melt quality of the PET-recylates in the spinning process and sources of the most important spinning defects. As Mr. Glawion previously discussed; the method for measurement, including the pressure and process constants of melting filtration in the spinning of the polyester regeneration are highly significant phases of the key function.

Ms. Sabine von Bila-Natzmer and Mr. Soehnke Friedebold explained the use of the staple fiber technology employed by Oerlikon Neumag in band polyester recycling. An example based on an application of PET-bottles in Russia, was illustrated first hand by Mr. Friedebold with an impressive picture documentation of the problems in the formation of such technology in this geographical region. He covered the flake preparation as well as with the fiber process and customer specific solutions and compromises. On one hand is the entire fiber process, on the other the customer specific expenditure.

Further in the ascendancy is the procedure of collecting PET-bottles and the process of manufacturing to food industry compatible bottle grade chip or pellets. On behalf of Buhler AG, the market leader in the processing of solid state polymerization (SSP); Mr. Andreas Christel gave a brief explanation regarding the wide range of "bottle-to-bottle" technology (B-2-B). The combination of established crystallizers with the direct crystallization which follows the granulating of the still hot granulate reduces the investment and energy expenditures. Another benefit in the manufacturing with SSP is that the PET-bottle flakes are treated in a nitrogen environment. The large surface of the flakes guarantees high reaction speeds and the short dwell time leads to low operating and energy costs. All Buhler SSP-procedures achieve effective decontamination and fulfill FDA standards.

Gneuß Kunststofftechnik GmbH + Dr. Thiele Polyester Technology, Bad Oeynhausen + Bruchköbel, Germany

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