Recycling and/or using regranulate is a major factor to cut down on film production costs. In addition, producers can reduce their energy consumption, and consequently their carbon footprint.

Recycling and reuse of film production scrap

Cost-efficient and sustainable production is a must nowadays. Economic criteria, but also new legal requirements force the plastics industry to put a critical eye on production practices. Many states have introduced plastic collection and recycling rates to deal with the growing waste quantities, and one of the next steps will be to reduce land-filling to zero. In addition, brand-owners are taking advantage of the positive marketing effect of “green” packaging and increasingly look for packaging that includes recycled content. Also, individual initiatives for sustainable dealing with waste are emerging. One of them is ERDE, the “Erntekunststofferecycling Deutschland”, which helps farmers to dispose of agricultural plastic waste and recycles it for use into various different plastic products.

Benefits for film producers

How can film producers benefit from these developments? Recycling the production scrap in-house is one of the answers. Dealing with production scrap is necessary throughout the entire film production chain, no matter if the production process is for blown film or cast film. The scrap occurs continuously as edge trim, and discontinuously as solid start-up lumps, loose film, off-spec reels and cut outs, and can be either mono-polymer or a mixture of polymers.

A variety of economic factors like rising resin prices, pressure to reduce costs, and stronger competition have led to higher awareness concerning the costs of production scrap. In-house film waste is a valuable secondary resource for producing first-class products. For fast ROI, it requires a simple and cost-effective setup of the recycling equipment.

Recycling production scrap: maximising profit in-house

Recycling of production scrap contributes considerably to cost savings by avoiding waste disposal costs and replacing virgin resin. The choice of the right equipment is fundamental if the goal is to increase the regranulate content in the primary product up to 100 %. The result: higher competitiveness, resource conservation, and a high-quality end product.

For film recycling, Starlinger recycling technology offers a spectrum of innovative machinery solutions for the efficient recycling of all kinds of films. The types of film produced range from mono-layer and multi-layer films, bi-axially oriented films, same polymer or blended films, films with varying MFI to heavily printed and metallized films. In the best case, the scrap is clean and dry; in reality it might have become humid through outside storage, or be contaminated with paper labels or metals.

Polymers (and their blends) such as PE (LDPE, HDPE, LLDPE, mLLDPE), PP (BOPP), PA (BOPA), PET (BOPET), PS, PLA, etc. can be processed with a choice of pre-treatment, extrusion, filtration and pelletising modules.

Heavily printed film requires efficient degassing solutions; highest efficiency is achieved with the Starlinger C-VAC module. Optionally, the line can be equipped with CaCO3 flushing for increased machine uptime.

Multi-layer film is composed of a variety of materials. Thorough homogenisation for high melt quality is achieved with customised design of the extruder screw.

BOPP, BOPET and BOPA production scrap, on the other hand, requires sophisticated material logistics as it is discontinuous production scrap and has low bulk density.

In stretch film production it is recommended to recycle the various trims in-line. The high automation of the Starlinger recycling lines – e.g. automatic stand-by/restart mode – ensures that the operator can pay full attention to the main process.

In addition to all that, the technology must be flexible – not only because different and varying input streams have to be processed, but also because of the unpredictable future. High automation and optimised maintenance procedures are needed to fulfil the high up-time rates. Also, up-cycling through adding additives plays an increasingly important role.

A new generation of recycling technology

Ecological, economic and energy-efficient recycling was in the focus during the development of Starlinger’s new recoSTAR dynamic recycling lines. The successor of the successful recoSTAR basic series has been launched in spring 2015 and is characterized by its high degree of automation as well as its flexibility regarding input materials and material conditions. The machine features make this new generation of recycling lines perfect for recycling film scrap from production and post-industrial and -consumer collection.

Equipped with the Dynamic Automation Package the recoSTAR dynamic line achieves higher outputs and extraordinary flexibility in regard to types of input materials, as well as reliable and constant operation. Machine uptime and productivity are increased while the overall energy consumption is reduced by up to 10 %. Automatic temperature regulation based on the speed-controlled SMART feeder drive and the self-regulated filling level in the SMART feeder ensures ideal material preparation, while an actively controlled input slider regulates the extruder load and throughput.

The recycling line starts up and shuts down automatically, and when the material feeding is stopped, the SMART feeder switches into stand-by mode without requiring operator interaction. The automatic temperature controller allows the processing of input materials with different moisture levels and varying bulk density, all the while maintaining consistent product quality. This makes it possible to process post-consumer regrind or fluff that has varying moisture levels. The recycling line automatically adapts to the requirements of the input material and can even process material with a moisture content of up to 10 % with additional equipment. In addition, the increased capacity of the large SMART feeder results in a much larger operating window, while the self-regulating material feeder allows the extruder to process a wider range of input materials, giving recyclers greater flexibility in the marketplace.

For degassing, a variety of systems, ranging from a conventional vacuum unit, high-vacuum and double-degassing to cascade degassing, is available depending on material properties and process target. Filters include double-piston backflush filters for in-house and post industrial/post consumer scrap with a degree of contamination of up to 0.5 %. For materials with higher degrees of contamination and/or very fine filtration requirements others systems are available. Regarding pelletising systems, water ring, strand and automatic strand and underwater pelletizers are available.

Up-cycling is possible by compounding during the recycling process. Additives can be fed directly into the extruder through a side feeding unit, while the output feedback loop ensures total process control.

Increased energy efficiency with the new rECO package

Starlinger’s trendsetting concept for improving the energy efficiency of recycling lines is called rECO. With this package, the overall energy consumption (kW/h) is reduced by approximately 10 %. The benefit for the client: reduced costs; the benefit for the environment: reduced carbon footprint. The energy savings are achieved by a new drive concept for the extruder main drive, barrel heating with infrared heaters, and heat sealed adaptors. Also, all motors of the recycling line are IE3 standard/Nema Premium – i.e. the most energy efficient motors available. In addition, energy recovery solutions can be integrated into various process steps.


Case studies with LLDPE film


Case study 1: inline edge trim – stretch film



  • production scrap: stretch film (LLDPE/mLLDPE/VLDPE/LDPE); melt embossed film (LDPE/MDPE/HDPE/LLDPE); edge trim
  • contamination: none (inline)



• output optimization for OEM projects


Findings & comments

  • machines: recoSTAR basic 65-105 without degassing and filter
  • specials: output optimization up to 550 kg/h with screw diameter 85 mm, high automation, stand-by and automatic start procedure regulated by output of film line; one button start/stop
  • reuse: inline cast film production
  • > 35 lines installed since 2009


The challenge consisted in the number of gels found in film made of 100 % virgin LLDPE compared to film containing 15 – 30 % recycled LLDPE. In the analysis of a test film of 16 µm thickness that contained rLLDPE, the number of gels counted by external experts was comparable to virgin film and even lower.



Case study 2: inline edge trim – breathable film



  • production scrap: LLDPE breathable film (up to 50 % CaCO3); edge trim
  • contamination: none (inline)



  • output optimization for OEM projects


Findings & comments

  • machines: recoSTAR basic 65-105 VAC
  • specials: special screw design at degassing section (avoiding material purge), water-bath heating; high automation, stand-by and automatic start procedure regulated by output of film line, one button start/stop
  • reuse: inline cast film production

Case study 3: BOPP and multilayer film, heavily printed



  • production scrap: BOPP and LDPE, LLDPE multilayer film; reels /loose film / start-up lumps; adding of post-consumer washed flakes (film)
  • contamination: heavy printing


Findings & comments

  • machines: 2 x recoSTAR universal 125 D-VAC
  • specials: double degassing to avoid gassing of colour content (no “air bubbles” in the pellet, which affects the film), adding of 5 % CaCO3 masterbatch for screw cleaning (hermetic powder bag unloading)
  • in operation since 2005



Case study 4: multilayer film, production waste



  • Production scrap: various blends (e.g. mLLDPE & LDPE, HDPE & thermoplastic elastomer & mLLDPE, HDPE & mLLDPE & PA, etc.), laminated (e.g. 32 μ PET coated with silicone on one side); rolls, loose, start-up lumps
  • Contamination: paper and metal labels (barcode, RFID); some with additives (TiO2, CaCO3, colour masterbatch)


Findings & comments

  • Machine: recoSTAR universal 85 VAC (production capacity up to 350 kg/h)
  • Specials: bigger vacuum pump due to PET content, hydraulic backflushing filter, water bath heating for optimized start-up, special screw design for better plasticising and homogenization of PET
  • In operation since 2012