No abstract

It is necessary to remove chlorine effi ciently from municipal waste plastics (MWP) that contain polyvinyl chloride (PVC) and other plastics containing chlorine. In this article we consider thermal degradation liquefaction technology. In Japan, the chlorine content of reclamation oil products must be kept below 100 ppm owing to the quality standard for pyrolysis oil. Liquefaction dechlorination technology for MWP is still an important issue to study. The twin-screw extruder that has been developed as dechlorination technology for blast furnaces and coke ovens has a shorter residence time for dechlorination than other dechlorination technologies. In this article, we used a single-screw extruder for the dechlorination process because it also has a short residence time. Experiments on the dechlorination process were carried out by using a single-screw extruder to assess its dechlorination performance. Practical use of the single-screw was demonstrated by the operation of a commercial oil reclamation plant operated by Sapporo Plastic Recycle Co., Ltd. (SPR). Moreover, an investigation of cascade recycling was carried out in 2008 in which material recycle wastes were mixed with MWP and processed by chemical recycling (liquefaction). It was demonstrated that cascade recycling is an effi cient recycling combination and contributes to local feedstock recycling. However, it was shown that MR wastes affect the quality of the reclamation oil when they make up more than 40% of the feed mix. If the quantity of MR wastes is kept below 40%, the reclamation oil is able to meet the quality standard. The SPR plant can be operated safely and in a stable manner.

Sapporo Plastics Recycling Co., Ltd., (SPR) started its commercial operation of waste plastics liquefaction in 2000. At fi rst only hydrocarbon oil was reclaimed, this being derived from the waste plastics liquefaction process under the Japanese Containers and Packaging Recycling Law. Presently, thermal degradation residue and hydrochloric acid are being produced as by-products in addition to the hydrocarbon oil. As a result, the SPR plastics liquefaction plant has achieved a high reclamation rate of 96%, and 93% of the recycled products have been reused in Hokkaido, where SPR is located. The technical problems caused by corrosion and clogging have been solved.

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This paper describes improvement of corrosion resistance of CoNi films by surface passivation. The CoNi films were obliquely evaporated on polyethylene terephthalate (PET) films, and passivated by a newly developed mild oxidation method. The passivated films were subjected to environmental exposure test at a relative humidity of 90% and a temperature of 60 °C. No changes of recording performance were observed even after a one-month exposure. The chemical structure of the passive layer formed on the CoNi films was studied by x-ray photoelectron spectroscopy and reflected electron diffraction. It was concluded that their strong corrosion resistance was attributed to the very thin, amorphous cobalt(III) oxyhydroxide formed on the surface, containing a small amount of Co2+ ions.