“PE film” is not one uniform recycling feedstock. Stretch wrap, shrink film, shopping bags, agricultural film and heavy-duty sacks can differ in polymer grade, thickness, printing, labels, moisture, soil and multilayer construction. Those differences determine how the material should be opened, sorted, washed, separated and dried. Line design should begin with representative bales and a target product specification instead of a generic moisture or recovery promise.
Common PE film categories
| Film type | Typical characteristics | Recycling implications |
|---|---|---|
| LDPE packaging film | Flexible, often printed or labelled; may include shrink and bag film. | Check ink, adhesive, paper, food residue and non-PE attachments. |
| LLDPE stretch film | Thin and elastic, frequently collected from transport packaging. | Can wrap around shafts and hold labels or dirt; controlled feeding and cutting are important. |
| Film HDPE | Stiffer bags or liners with different melt behaviour from LDPE/LLDPE. | May be recycled separately when the buyer requires a defined polymer stream. |
| film agricole | Often wet and contaminated with soil, stones, crop residue and agrochemical packaging. | Needs strong pre-cleaning, grit removal, water management and wear planning. |
| Printed or laminated film | Heavy inks, coatings, barrier layers, metallisation or bonded polymers. | May be unsuitable for a high-purity mono-PE product; identify the structure before setting the process. |
| Post-industrial film | Usually more consistent and traceable, but may contain edge trim, labels or mixed production scrap. | Often needs less intensive washing, although the actual contamination must still be verified. |
Sorting is the first washing decision
Washing cannot convert every multilayer film into clean mono-PE. Remove incompatible polymers, paper, metals and problematic structures as early as practical. Where LDPE/LLDPE and HDPE must meet different downstream specifications, separate collection or sorting may be more reliable than trying to correct a mixed stream later.
Packaging design also influences recyclability. The Association of Plastic Recyclers’ PE flexible guidance and CEFLEX’s recyclability guidelines explain how inks, labels, adhesives and barrier structures affect a flexible-PE recycling stream.
Match washing intensity to contamination
Clean post-industrial trim may need size reduction and limited cleaning, while agricultural film can require bale opening, pre-cleaning, repeated friction and rinsing stages, heavy-particle removal and careful sludge handling. Food packaging may carry oils, product residue and odour that require a different wash strategy.
Hot washing and chemicals should be justified by trials and the output requirement. More temperature or chemistry is not automatically better: it changes energy, rinsing, wastewater and material-handling needs. Document dosing, residence time, water quality and how wash performance will be measured.
Wet crushing versus dry size reduction
Introducing water during size reduction can begin surface cleaning, reduce certain airborne dust and help move material, but it also changes wear, water load and the condition entering separation. Dry crushing isolates water from that stage but may require stronger dust and material-flow controls. The right choice depends on soil, labels, film toughness, downstream tanks and water-treatment capacity. Our article on wet crushing versus dry crushing covers this decision in detail.
Separation and water management
Float-sink separation can remove many dense contaminants from floating PE, but it cannot distinguish all PE grades or remove bonded layers. Tank geometry, agitation, residence time, skimming and bottom-discharge design should match the film form and dirt load.
Water circuits should be designed around contamination and local discharge requirements. Screening, settling, dissolved or suspended solids control, oil management and sludge dewatering may all be relevant. “Closed loop” should not be treated as zero treatment or zero discharge; water quality must remain suitable for the cleaning stage it serves.
Dewatering and drying are feedstock dependent
Thin film carries water in folds and has low bulk density. Mechanical dewatering, squeezing, agglomeration or thermal drying may be combined depending on the downstream extruder and storage plan. State the moisture measurement method, sampling point and test feedstock before accepting a guaranteed value.
A squeezer can densify washed film to improve handling and stabilize feeding. It is not a substitute for upstream contaminant removal. For a complete process layout, see the Ligne de déchiquetage et de densification des films PP/PE.
Define the feedstock before specifying equipment
- Identify polymers, multilayer structures, colours, printing, labels and attachments.
- Measure dirt, moisture, metals, paper, organics and other contamination across representative loads.
- Define the required flake or densified-product specification and downstream process.
- Separate input rate from saleable output and include expected reject and water loads.
- Run trials when feedstock is highly variable or the product specification is demanding.
Foire aux questions
Can LDPE and LLDPE film be washed together?
They are often processed together when the downstream specification permits it, but the decision should be based on melt properties, additives, contamination and the buyer’s requirements.
Why is agricultural film difficult to wash?
It can carry large and variable loads of soil, stones, moisture and organic residue. These increase wear, water-treatment demand, rejects and the difference between input mass and saleable output.
Can washing remove barrier layers from multilayer film?
Usually not when the layers are bonded. The structure should be identified during sorting and evaluated against the intended recycled-product specification.
Sources et lectures complémentaires
- Association of Plastic Recyclers : Guide de conception flexible PE
- CEFLEX: Designing for a Circular Economy Recyclability Guidelines
- RecyClass : Protocoles d'essai
Test the actual film stream
Energycle can review film samples, contamination data, target output and downstream use before recommending a washing and drying sequence. This reduces the risk of specifying a generic line for feedstock it was not designed to handle.
