As a plastic factory owner in Lagos, Kano, or Onitsha, you are likely mixing more recycled materials into your blown film machine today. With the current Naira exchange rate and the skyrocketing cost of imported virgin resins, using local recycled plastic pellets is often the only way to keep your production costs competitive.

However, recycled plastic brings heavy technical headaches. Your operators will constantly complain about black spots, fish eyes, frequent film breaking, and sachet water film leaking at the sealing machine.

Running recycled materials requires different settings than virgin raw materials. Here is a practical, low-cost engineering guide to fixing these recycled material defects and keeping your blown film machine running smoothly.

Recycled pellets in Nigeria often contain heavy sand, dust, paper stickers, and unground ink particles. If these impurities go directly into your blown film machine die head, they will block the die lip gap and cause immediate film tearing or tiny pinholes.

To solve this, you should immediately stop using a simple single-layer mesh screen. We highly recommend upgrading your extruder breaker plate to a manual quick-change double-screen filter or a hydraulic screen changer.

For the best filtration, you should use a combined mesh screen setup consisting of an 80 mesh, a 120 mesh, and another 80 mesh placed together. The middle 120 mesh stops the finest dust, while the outer 80 mesh layers support the high pressure. You must train your machine operators to change this screen filter every two to three hours when running heavy regrind, rather than waiting for the pressure gauge to alarm.

Recycled plastics absorb moisture incredibly fast, especially during the high-humidity rainy season in West Africa. When this trapped moisture enters the heated barrel of your blown film machine, it turns into high-pressure steam. This steam causes water marks, silver streaks, bad odors, and sudden bubble popping.

Many local factories still dry their raw materials manually on the concrete factory floor under the sun, which actually introduces more dust. The correct solution is to install a dedicated Hopper Dryer directly on top of your blown film machine feed throat.

You should run the hopper dryer at 75°C to 85°C for at least 1.5 to 2 hours before feeding the recycled material into the screw. This continuous heating eliminates internal moisture, removes a large percentage of the recycled chemical smell, and ensures a stable film bubble that does not pop.

When using a blown film machine to produce film for pure water sachets, recycled materials can degrade the polymer chains. This makes the final film weak and very difficult to seal tightly on automatic liquid packaging machines.

First, you need to adjust the die lip gap. If you are using a high percentage of local recycled material, you should slightly widen your die gap to about 1.0mm or 1.2mm to reduce the shear stress on the weak recycled polymer melt.

Second, you must control your Blow-Up Ratio. Keep this ratio strictly between 2.0 and 2.2 because over-stretching recycled film makes the molecular orientation weak, leading to easy punctures during transit.

Finally, we suggest upgrading to a dual-lip air ring on your blown film machine. Recycled melt has lower hot-strength and requires rapid, uniform cooling. A dual-lip air ring cools the film immediately at the die exit, which prevents the film layers from sticking together and significantly improves the final heat-sealing strength.

Running high percentages of recycled materials on a standard blown film machine will quickly wear out your machinery due to sand abrasion. To maintain a stable film thickness and prevent continuous business losses, you need a tougher screw and barrel with specialized bimetallic or nitriding treatments.

If you are facing continuous film breaking, thick-thin variations, or need to upgrade your current extruder setup to handle local Nigerian materials, we are here to help.