Unpigmented (Natural) PE
Natural material has the highest value as a recycled stream since it has the widest variety of end-use applications. It is the most cost-effective to process through the recycling system.
White, buff, or lightly colored film
It is not common for film to be sorted by color in the recycling process. Therefore, the resulting recycled material is a blend of all the colors present. Light colors blend well with little effect.
While dark colors are not considered Preferred, they are nonetheless readily accepted by recyclers even if technically Detrimental (features that present known technical challenges for the MRF or recycler’s yield, productivity or final product quality, but are grudgingly tolerated and accepted by the majority of MRFs and recyclers). Darker colored PCR manufactured from darker color feedstock may be used for inner layers, and there is evidence that the marketplace is becoming more accepting of darker colored material if it can help them meet recycled content goals.
It is not common for film to be sorted by color in the recycling process. Therefore, the resulting recycled material is a blend of all the colors present. Dark colors have a great effect on a lot of material. Since the standard material is a light blend and dark colors are relatively rare, the reclaimer normally hand selects dark colors and processes them separately. In some cases, the dark colors are discarded.
REQUIRES TEST RESULTS
Pigments designed for a visual metallic appearance on plastic films are not removed in the recycling process and are melted and blended with the PE. This may cause material discoloring. In many cases a metallic 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 metallic film and a solid metal part, so the entire package is normally discarded rather than accept the risk. There is also some evidence that metallic inclusions can be captured in ultra-fine laser filters and potentially cause equipment problems.
Test Methods (in order):
Pigments concentration where density approaches 0.996
Many pigments like TiO2 (titanium dioxide) and others are very dense and when blended with the polymer increase the overall density of the film. When their weight percentage reaches the point that the film density is greater than 0.996 g/cc, the film sinks in water rather than floats. Density is an important property and float-sink tanks are critical separation tools used by reclaimers. Therefore, a sinking material will be considered waste by a film reclaimer and any PE in the blend will be lost.