PE and PP film recycling is not one fixed sequence. Clean factory edge trim may go directly to size reduction and pelletizing, while post-consumer packaging or agricultural film can require debaling, sorting, pre-washing, wet size reduction, intensive washing, mechanical dewatering and controlled extrusion. The correct route depends on resin, film construction, contamination and the specification for the recycled product.<\/p>\n
“Plastic film” describes a shape, not a single material. A project specification should identify:<\/p>\n
PE and PP are both polyolefins and often float in water, so a normal sink-float tank does not reliably separate them from each other. Processing them as a mixed stream should be a deliberate product decision supported by trials and an end-market specification\u2014not an assumption that all flexible plastics are interchangeable.<\/p>\n
Known, clean production scrap may need inspection, metal protection, controlled cutting or compaction, filtration and pelletizing. Washing can sometimes be omitted when contamination and product requirements allow it. The benefit is lower water use and fewer drying stages, but the supplier should still verify inks, additives, paper cores and mixed grades.<\/p>\n
Dirty film usually needs a complete washing route. A typical flow is:<\/p>\n
debaling and metered feeding \u2192 sorting and contaminant removal \u2192 pre-washing or grit removal \u2192 shredding or wet granulation \u2192 friction and separation washing \u2192 rinsing \u2192 mechanical dewatering or squeezing \u2192 thermal finishing where required \u2192 extrusion, filtration and pelletizing.<\/strong><\/p>\n The exact order can change. Heavily soiled agricultural film may need robust dry or wet pre-cleaning before a high-speed granulator. Some packaging streams place size reduction before the main wash to expose more surface area. Trials should determine where dirt is removed without causing excessive wear or fines.<\/p>\n Baled film must be opened and metered so that the line receives a stable load. A vertical debaler<\/a> can separate compacted material, but the following conveyor still needs surge control and access for inspection.<\/p>\n Sorting removes large non-plastic items, metals, paper, rigid objects and incompatible films. Optical, ballistic, air-based and manual methods can be combined according to the collection stream. The APR’s PE flexible packaging guidance<\/a> shows why layers, attachments, inks and other package components matter to recyclability; identifying only the dominant polymer is not always sufficient.<\/p>\n Metal protection should be placed where it can protect shredders, granulators and extrusion equipment. Document how oversize objects and rejects leave the line so that they do not repeatedly circulate.<\/p>\n Loose soil, sand and stones should be removed as early as practical because they abrade knives, screws, pumps and screens. The pre-wash design may use agitation, sprays, trommels or tanks depending on the material. Water and reject handling must be designed for the actual dirt load.<\/p>\n Film is difficult to cut because it is light and can wrap around shafts. The feeding system, rotor-end design, knives and screen must work together. A plastic granulator<\/a> produces a controlled flake, while a shredder may be used when bales, rolls or bulky film need lower-speed primary reduction.<\/p>\n Wet granulation can help manage heat and begin surface cleaning, but it adds drainage, corrosion and water-treatment requirements. The target flake size should suit washing and dewatering rather than follow a universal screen chart.<\/p>\n Friction washers apply mechanical action to remove loose paper, dirt and surface contamination. Detergent, temperature and residence time should be selected from wash trials and wastewater limits. Hot or chemical washing is not automatically required for every film stream, and one fixed temperature range is not a general recipe.<\/p>\n A sink-float separation tank<\/a> can remove many denser contaminants from floating PE\/PP film. It cannot, by density alone, create a clean PE-versus-PP split, and it may not remove low-density labels or other floating polyolefins. Sorting and feedstock control remain necessary.<\/p>\n Rinsing should remove loosened contamination and process chemicals to the downstream specification. Evaluate water recirculation, filtration, sediment removal and wastewater treatment as part of the line; the washing machine alone does not define total water performance.<\/p>\n Washed film holds surface water in folds and has a low bulk density. Mechanical dewatering removes free water, but a centrifugal dryer optimized for rigid flakes does not always produce the best handling result for flexible film. A film squeezing machine<\/a> combines water removal with compaction, creating a denser feed for extrusion.<\/p>\n Thermal drying can finish the material where the extruder or product requires it. Do not accept a universal residual-moisture promise. Test representative film at the intended throughput and report the sampling and moisture method. The film squeezer density and compaction guide<\/a> explains how to measure bulk density without confusing it with polymer density.<\/p>\n Loose film must be fed to the extruder consistently. Depending on the route, the system may use a cutter-compactor, agglomerator, force feeder or squeezed material. This is densification and feeding\u2014not contaminant removal.<\/p>\n The extruder melts and homogenizes the material. Venting handles residual moisture and volatiles within the equipment’s design range, while melt filtration removes solid particles down to the selected filter level. Neither step can restore a badly mixed resin stream or remove all odors, inks and degradation products.<\/p>\nStage 1: debaling, feeding and sorting<\/h2>\n
Stage 2: pre-washing and size reduction<\/h2>\n
Stage 3: washing and density separation<\/h2>\n
Stage 4: dewatering, squeezing and drying<\/h2>\n
Stage 5: extrusion, filtration and pelletizing<\/h2>\n