Polyethylene mono-material flexible packaging
Pure polyethylene, bio-based or not, is compatible with flexible films collection streams and easily recycled into a variety of end use applications, including new flexible films, composite lumber, and other molded plastic products. As the supply stream includes a mixture of grades of PE, individual packages may also be comprised of various PE grades, as defined by ISO 472:2013 – HDPE, LDPE, LLDPE, MDPE, VLDPE. Special grades of PE available in the industry like plastomers, mLLDPE, ULDPE and others are also included as “Preferred”.
Based on APR company data and evaluation by the APR Film Committee, EVA copolymers designed for film extrusion are included in the “Preferred” category at any weight percent, provided the VA (vinyl acetate) levels are 5% or less of the total package weight.
One company has received Critical Guidance Recognition for a branded ionomer copolymer intended for use in film extrusion. Based on the chemical similarity of ethylene copolymer ionomers and this data, it has been demonstrated that ethylene copolymer ionomers do not affect recyclability performance when used up to 20% in PE formulations. For that reason, ethylene copolymer ionomers designed for film extrusion are also listed as “Preferred” when used below 20% in weight of the total package.
PB (polybutenes) are also typically used in small fractions on PE “easy peel” film formulations that are currently recycled in the industry with no adverse effects. For this reason, PB is accepted in the “Preferred” category up to 5% in weight.
A minimum of 90% PE and copolymers by weight of the total packaging structure is preferred for full compatibility with a PE mechanical recycling process, in order to maintain the quality and value of the final recyclate. This is the guideline threshold to be strived for, but not an absolute rule. Ethylene copolymers like the ones mentioned above or even other-than-PE materials can be listed in this category above 10% after proper recyclability testing based on the APR Critical Guidance Protocol.
Postconsumer PE content
The use of PCR PE in all packages is encouraged to the maximum amount technically and economically feasible.
Less than 90% PE
Structures with 80-90% PE and copolymers by weight of the total package may present technical challenges for the recycler’s yield, productivity, or final product quality. They are considered detrimental until tested and film designers should refer to the other sections of this document for more specific guidelines.
PET, PVC, PVDC, Paper, Aluminum foil or degradable polymers
These polymers lead to the contamination of polyolefin recycling streams. They drastically reduce the quality of recycled polyolefins and they can disturb the recycling process.
PET is incompatible with polyethylene and copolymers from the chemical and rheological standpoints. It melts at significantly higher temperatures and it is known to cause film defects (“unmelts”) that compromise film quality.
PVC and PVDC layers degrade at low temperatures rendering large portions of the recycled PE unusable.
Paper or aluminum-foil-containing materials are not suitable for recycling within the polyolefin stream and cause problems for the recycling process.
Degradable polymers (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. Polymers designed to degrade by definition diminish the life of the material in the primary use. If not removed in the recycling process, these polymers also shorten the useful life of the product made from the recycled film, possibly compromising quality and durability. Degradable polymers include PLAs, PHAs, PHBs, PHVs, PBS, cellulose acetate, starch-based polymers and others. They should not be confused with degradable additives, which are covered in another section of this document.
REQUIRES TEST RESULTS
Less than 80% PE
Structures with less than 80% PE of the total package will likely affect the overall yield of the respective PE mechanical recycling process and could negatively impact the recycled plastic quality. For that reason, they should be tested to determine the appropriate APR recyclability category.
Blends, coextrusion or lamination of PE and other resins designed to enhance properties in the intended first use with unknown residual effects in future uses of the recovered resin
Non-PE layers or blend components at any level (%) require testing to determine the appropriate APR recyclability category, since these layers are not removed in the film recycling process. They enter the extrusion stage of the process with the base material where they are either melted and blended with the PE or remain solid and are filtered from the melted product.
Testing must show that unfilterable layers have no adverse effect on the recycled PE in future uses. These include:
• Nylon (PA)
• Polypropylene (PP)
The above materials may be acceptable at small weight percentages of the total film but only testing can determine this.
Several compatibilizers are available on the market that may, if used correctly, allow a non-compatible material to blend with PE without negative effects. This has been successfully demonstrated for specifically formulated films including EVOH and nylon. Providers of these solutions must present evidence of effective compatibilization by testing the specific formulation of the film and pursuing critical guidance or benchmark validation from APR.
Any other material combination not mentioned above, with or without compatibilizers, at any level (%) needs further testing to qualify for recycling with the polyolefin stream. A few examples include:
• PB (above 5%)
• Engineering thermoplastics (PBT’s, PC’s, etc.)
• Crosslinked polymer layers (chemically, EBeam or UV)
• Elastomeric materials
• Nonwoven (Tyvek® and others)
• Other fiber-based materials
One company has received Critical Guidance Recognition for a multi-layer PE film including COC content.
Some PE additional copolymer categories also require testing, for example:
• Acid copolymers (EAA & EMAA)
• Ester copolymers (EMA, EEA, EBA)
• Ionomers (above 20%)
Tie resins/layers are typically grafted-polyethylene copolymers used to bond incompatible layers on coextruded or laminated films. They are not required to undergo testing independently, but only to validate recyclability of the incompatible-to-PE materials listed above.