Since polyethylene is the same polymer as the package body, closures and dispensers made of it will be captured and processed with HDPE. This increases the reclaimers yield and reduces possible waste. The APR encourages the industry to innovate toward widespread use of same-polymer closures on bottles. While the blending of fractional-melt bottle-grade HDPE with high melt index resins used in closures will alter the MFI of the blend, this is a minor issue today given the limited use of HDPE closures and dispensers on bottles and the relatively low recycling rates for HDPE bottles. In the future these impacts may need more study.
Closure systems without liners
Due to size and thickness, most liners are lost in the recycling process thereby slightly decreasing yield. Closures without liners do not experience this loss.
EVA and TPE liners
EVA and TPE float in water and will not be separated in the recycling process. However, they are compatible with HDPE and in fact enhance its properties so they are preferred.
Closures or safety sleeves made of polymers with density >1.0 that sink in water
(Specifically, PS, silicone, nylon, acetal, thermosets)
Silicone, polystyrene, thermoset plastics, nylon and acetal are expected to sink in the float-sink tank, thereby separating from the HDPE. They also do not damage or wear cutting machinery in the recycling process. Small amounts of these materials that make it through the float-sink process can be melt filtered from the recycled HDPE in the extrusion step. However, these materials are lost to the waste stream in the recycling process and are considered less preferable than an alternative floating attachment that is compatible with HDPE.
Shrink film safety sleeves that are designed to be completely removed before the package can be opened
Regardless of material, designs that require complete removal by the consumer of the safety sleeve are Preferred, as the material will not be introduced into the recycling stream.
Polyethylene or polypropylene tamper evident safety sleeves
HDPE safety sleeves are the same polymer as the final product, and PP at the very small levels expected from safety sleeve residue has a very minimal negative impact. Such attachments that remain with the HDPE throughout the recycling process increase yield and have minimal negative quality impact for the reclaimer.
PETG or PLA tamper evident safety sleeves
PETG and PLA both sink in the float sink tank where they are removed from the HDPE. Unlike PVC, small amounts of PETG or PLA entering the extrusion process with the HDPE are not catastrophic since both can be removed in the melt filtering stage.
The APR recognizes that polypropylene is perhaps the most commonly used material for closures. Complete HDPE packages with PP closures are considered recyclable (as long as all other components are Preferred), but with a Detrimental feature. Since polypropylene floats in water like polyethylene it is not separated in the reclaimers float-sink tank. When blended with HDPE it negatively affects the impact properties and can render the material brittle. Although very small amounts of PP, such as that contributed by labels, are regularly accepted by HDPE reclaimers, closures and dispensers comprising a larger weight percentage of the package have a greater negative affect.
Closure Liners that are composites of Aluminum and Paper
These materials will contaminate wash water, will contribute to waste disposal costs, or will stick to the valuable HDPE and reduce quality and value of the final products.
Closures containing floating silicone polymer
This material passes through the float-sink tank along with the HDPE and is difficult to remove with other methods, thereby causing contamination in the final product. Sinking silicone does not experience this issue.
PVC closures and PVC tamper evident safety sleeves that are not completely removed when package is opened
PVC is relatively easy to remove in the float-sink tank since it sinks while the HDPE floats. However, the float-sink tank is imperfect and even a very small amount of PVC with the recycled HDPE renders large amounts of it unusable as the PVC degrades at lower temperatures than those at which HDPE is processed.
REQUIRES TEST RESULTS
Dispensers, closures or lidding with metal components
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 contamination is highly undesirable in recycled HDPE. Metals create wear in process machinery, increase operation costs and yield loss, and are a primary source of defects in products made with recycled HDPE. MRFs and HDPE reclaimers use magnets, eddy current separators and metal detectors to keep packages with metal components out of the process stream. Any metal components, such as pump springs, valves, safety sleeves, or lidding that trigger the metal detector will cause the entire plastic item to be removed from the stream and not recycled.
Although metal is easily removed in the float-sink process, most reclaimers have metal detection equipment designed to protect their cutting machinery. Therefore, the container never makes it to the float-sink tank. Large metal items attached to HDPE packages may cause the package to be directed to the metal or waste stream in the recycling process, causing yield loss.
Shrink film safety sleeves that are NOT designed to be completely removed before the package can be opened
Shrink film safety sleeves that are NOT designed to be completely removed before the package can be opened. If a shrink film safety sleeve is designed such that pieces of it may not detach from the package when opened, the material must be tested to determine its compatibility with HDPE recycling. Specifically, such materials should either sink and be separated from the HDPE, or if they float, they must be compatible with HDPE.