Reclaiming waste plastics
AssigneeMonsanto Company
InventorEugene P. Baldyga
Life of this patent
Estimating the term…
Abstract
Molecular orientation stress is relieved in thermoplastic articles being prepared for reclaiming in order to shrink the article and decrease volume. Shrinkage is sufficient to cause separation of labels when the latter are present. When the articles are containers, each shrunk-back mass has the appearance of an individual, grotesquely distorted container, which, because of its reduced volume, is especially useful as feedstock to a reclamation system.
Claims11
In a process for delabeling molecularly oriented thermoplastic articles having labels adhesively bonded to surface portions thereof, the step of relieving orientation stresses beneath the labels to the extent of reducing the surface area of such portions by at least about five percent, thereby causing the thermoplastic material and labels to separate.
In a plastics reclaim process which includes the step of:
- grinding used thermoplastic containers at a grinding station to form particulate material for further processing,
- the improvement wherein such containers are molecularly oriented and including steps comprising:
- heating such molecularly oriented containers at a heating station to at least about the glass transition temperature range of the thermoplastic material forming the containers prior to said grinding to relieve molecular orientation stresses therein and for a period sufficient to reduce the volume of such containers by about 70 to 90%;
- and
- transporting said containers from such heating station to said grinding station after said heating;
- whereby the transport bulk of such containers is substantially reduced as a result of such volume reduction.
Dependencies are inferred from the claim text.