Sepg. residues from plastic packs - by washing with suitable solvent, e.g. cyclohexane, and treating fractions to recover solvent and polymers

摘要

Rsidues of material left in plstics packs are sepd. by the use of a suitable solvent in which the packaging polymer is insol., pref. a volatile satd. hydrocarbon and cyclohexane in particular. Existing designs of washing plant can be used for washing with cyclohexane given certain modifications, e.g. to ensure there is no chemical attack or explosion. Polymer residues themselves do not float in this solvent and this simplifies extn.. Contacts with this solvent need only be brief e.g. if paper labels have to be freed from the polymer 5-30 mins. are enough at room temp. or less at elevated temp.. Removal of cyclohexane from the plastics fraction is best achieved by heating and evaporating, as its b.pt. is only 80 deg C. The evaporated solvent is recovered. ADVANTAGE - Polymer is recoverd in a clean state suitable for recycling e.g. by fusion. In some cases the residues of the contents can also be obtd. in reusable state. The process is suitable for use with non-food types of packages. Washing with solvent instead of water has several advantages e.g. removal of grease, etc., aq. portions are sepd., satd. hydrocarbons are less reactive and hence not liable to react with the residues concerned, deep penetration, low energy consumption by low b.pt./vapour pressure, solvent recovery, residues concerned are partly recoverable. (3pp Dwg.No.0/0)