Cleaning and liquid contact with solids – Apparatus – Sequential work treating receptacles or stations with means...
Patent
1993-03-04
1994-11-29
Vargot, Mathieu
Cleaning and liquid contact with solids
Apparatus
Sequential work treating receptacles or stations with means...
134 38, 134 61, 241 3, 241DIG38, 264 37, 264233, 264DIG69, 425308, 425DIG46, B29B 1702, C08J 1106
Patent
active
053687965
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for regenerating used articles of polyolefin to reusable raw material, in particular for regenerating used packaging foils made of polyethylene such as shrinking foils, bags and the like.
2. The Prior Art
Polyethylene is a polyolefin that is processed in large quantities for the manufacture of foils for packaging purposes. Articles such as, for example shrinking hoods, pouches and the like are manufactured from the foils.
Polyethylene, as a thermoplastic material, is repeatedly fusible and deformable due to its molecular structure. It is suitable for repeated reuse. However, any reprocessing to high-quality recycling products, preferably to PE foils with defined properties, is opposed by the fact that the used articles, in particular foils, are provided during their manufacture in an application-oriented way with additives such as antistatic agents, lubricants and thermo- or UV-stabilizers that are subsequently present in the recycling products manufactured therefrom in unknown quantities and combinations. Sorting of the used articles by ingredients is not possible for technical and economical reasons.
Recycling products, in particular foils loaded with such ingredients lead to problems in the course of their further processing, for example in the course of glueing, fusing or imprinting. Joining seams initially having good properties come apart in many cases only when in the user's hands.
In addition, the used foils contain degradation products such as non-polar PE waxes. The latter develop during the life time in the course of processing processes as well as due to the action of heat, light and weather. Such substances cause to some extent a considerable diminution of the properties of use of the recycling product, i.e., the foil.
Finally, the used foils, in particular packaging foils are imprinted to a greater or lesser extent. During the extrusion of regenerated materials to PE foils, such printing inks lead to a strong undefinable discoloration, so that only darkly dyed refuse bags can be manufactured from such materials.
Therefore, in order to be able to produce again high-quality foils from used polyethylene foil materials, it is necessary to removed from the used foils the foil additives, the non-polar PE waxes as well as the printing inks adhering thereto.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process by which used articles, preferably foils, can be regenerated to reusable, high-quality raw material.
According to the invention, the above object is achieved by subjecting the used articles shredded and under intensive motion to an extraction in a solvent bath containing an organic solvent.
The shredding of the foil wastes can be carried out in commonly used shredders. The ingredients are extracted from the shreds during the washing of the latter in an organic solvent, i.e., the ingredients and degradation substances are separated and concentrated in the solvent without any dissolution of the plastic material. The shreds are intensively moved during their dwelling time in the solvent bath, for example thoroughly stirred mechanically and/or eddied by produced turbulences, for example length- and crosswise currents. In this way, the shreds rub on one another and the printing inks adhering thereto are removed by the high friction. The printing inks so rubbed off are received by the solvent bath. The combination of extraction in the solvent bath and simultaneous intensive motion, for example by mechanical stirring, thus leads to removal of the adhering printing inks as well as separation or extraction of the ingredients and degradation substances from the foil waste. Following a predetermined dwelling time in the solvent bath, during which motion is produced continuously, the shreds thus treated in an advantageous manner in more or less one work step can be melted, shaped to granulate or agglomerate, and reused in the manufacture of high-quality polyethylene products.
Since
REFERENCES:
patent: 4073661 (1978-02-01), Buzga et al.
patent: 4138534 (1979-02-01), Tedesco
patent: 4173493 (1979-11-01), Kallas
patent: 4968463 (1990-11-01), Lavasseur
patent: 5169588 (1992-12-01), Estepp
patent: 5225130 (1993-07-01), Deiringer
patent: 5225137 (1993-07-01), Sadr
patent: 5236655 (1993-08-01), de Soet
Lorenz Arnulf
Walser Hans P.
Nordenia Verpackungswerke GmbH
Vargot Mathieu
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