Workhorse additives historically used without issue
Most PE film contains some form of additives. The “workhorse" additives commonly used have not been shown to cause significant issues with the recycling process or further uses of the recycled PP. Commonly acceptable workhorse additives include:
- Thermal stabilizers - These additives typically enhance the further processing of the polymer and are therefore preferred for recycling.
- UV stabilizers – These additives typically enhance the further processing of the polymer and are therefore preferred for recycling
- Nucleating agents
- Antistatic agents
- Slip agents
- Fillers – note that many fillers are dense, so particular attention should be paid to the overall blend density
- Impact modifiers
- Chemical blowing agents
Additive usage should be minimized to maintain the best performance of recycled PP for future uses.
See “Requires Test Results" section
PVC and PVDC layers and coatings
PVC and PVDC degrade at low temperatures rendering large portions of the recycled PE unusable.
Additive concentration that causes the material to sink, when recycled in a wet wash system
Many of the additives and fillers used with PE are very dense and when blended with the polymer increase the overall density of the blend. When their weight percentage reaches the point that the blend density is greater than 1.00, the blend sinks in water rather than floats. Density is an important property and float-sink tanks are critical separation tools used by film reclaimers who use a wet wash process. Therefore, a sinking material will be considered waste by such a film reclaimer. Film reclaimers using a dry process are normally able to process this material but there is no way to determine if a particular film will be processed by a dry or wet system.
Also see “Requires Test Results" section
REQUIRES TEST RESULTS
Metalized layers are extremely thin layers of metal deposited on the film as a vapor. They should not be confused with actual metal layers addressed as “foil" in this document. Metalized layers are not removed in the recycling process and are melted and blended with the PE. This may cause material discoloring. In many cases a metalized film will be detected early in the recycling process by metal detectors designed to protect machinery from catastrophic damage. Metal detectors are unable to differentiate between a metalized film and a solid metal part so the entire package is normally discarded rather than accept the risk.
Degradable additives (photo, oxo, or bio)
Recycled film is intended to be reused into new products. The new products are engineered to meet particular quality and durability standards given properties of typical recycled film. Additives designed to degrade the polymer by definition diminish the life of the material in the primary use. If not removed in the recycling process, these additives also shorten the useful life of the product made from the recycled film, possibly compromising quality and durability.
Degradable additives should not be used without testing to demonstrate that their inclusion will not materially impair the full-service life and properties of any product made from the recycled film that includes the additive. Testing must show that these additives will either separate and be removed from the film in the recycling process or have no adverse effects on the recycled film in future uses. When used, their content should be minimized to the greatest extent possible.
Non-PE additives, layers, or coatings not listed
A growing number of innovative materials are being used as additives in PE film packaging. These materials must be tested to determine their impact on PE film recycling processes and the PCR produced.