Plastic attachments with a density > 1.00 except for PVC
These items sink in the float-sink tank where they are removed from the HDPE and small residual amounts do not severely affect the final product since many of them are melt filtered. PVC is detrimental as discussed elsewhere in this document.
The HDPE reclamation process involves a wash step that removes adhesives and other components. This process renders paper into a pulp which is very difficult to filter from the liquid, adding significant load to the filtering and water treatment systems. Some of the small individual paper fibers will remain with the HDPE and carbonize when the material is extruded, causing unacceptable quality degradation.
PVC sinks in the float-sink tank where the majority of it is removed from the HDPE. Because the float sink tank is imperfect and even a very small amount of PVC entering the extruder causes sever quality and yield problems, this material is detrimental. PVC degrades at HDPE extrusion temperatures and renders large amounts of the recycled HDPE unusable.
Because polypropylene floats in water, it is not separated in the reclaimers float-sink tank. When blended with HDPE it negatively affects stiffness and impact properties. Although very small amounts of PP, such as that contributed by labels, are regularly accepted by HDPE reclaimers, some attachments comprise a larger weight percentage of the package and therefore a greater negative affect.
RFID’s (radio frequency identification devices) on packages, labels or closures
RFID’s are printed on silver metal, which may create costly waste disposal issues. While RFID’s are small, they may affect HDPE recycling in the same ways as metal labels or other attachments. The use of RFID’s is discouraged as may limit HDPE yield, introduce potential contamination, and increase separation and waste disposal costs.
REQUIRES TEST RESULTS
Testing must show that these attachments are not adhesively bonded to the package and are made from materials that sink in water so they readily separate from the package when ground and put through a float-sink separation. If adhesives are used to affix attachments, their selection should consider the adhesive criteria within this document.
HDPE Benchmark Test *This test is currently being developed.
Metal, metalized and metal-containing attachments
Sortation testing for metal components will result in either a Detrimental or a Renders Non-Recyclable ruling. Metal components cannot be Preferred at this time.
Metal or metal-containing attachments may cause NIR sorters in MRFs to misidentify a HDPE container as metal and direct it to a metal stream, from which it is then discarded. Sorting equipment in the reclaiming process is designed to detect and eliminate metal from HDPE in order to protect cutting machinery. Large items, or items adhesively bonded to the HDPE, can damage the machinery and render the entire package non-recyclable. If small, not detected, or allowed to pass, metals, when used with wash friendly or no adhesive quickly sink in the float sink tank where they are removed from the HDPE.
A certain amount of a welded attachment cannot be separated from the HDPE in the recycling process. These attachments may cause recycled HDPE contamination and yield loss issues in both cases: when the ground section containing both polymers sinks and carries the HDPE with it, or when the ground section floats and carries an incompatible material with the HDPE into the extrusion process. Testing must show that the blend is of a density less than 1.0 so that it floats along with the HDPE in the float-sink tank, and that it is compatible with HDPE in the extrusion process.