3 plastic recycling challenges and how to solve them

Recycling plastics is a crucial step on the road to a more sustainable future, despite 3 central plastic recycling challenges:

Moisture
Printing inks used on plastic film
Contaminants entering the recycling process

Each of these challenges can have an adverse effect on the efficiency of recycling and reduce the quality of the end product.

However, there is an innovative approach to solving them: TVE technology.

Challenge 1: How does moisture affect plastic recycling?

Tolerance limits of various recycling machines

Each recycling machine has its own processing tolerances with regard to the moisture content of the input material. At best, these range from

0-6 % as for example with the UMAC READYMAC 1109 TVE
up to max. 12 % on INTAREMA type systems with a special configuration.

These tolerances are crucial, because materials that have already been pre-washed have to be dried prior to the recycling process.

Energy-intensive drying

Timely and effective drying stabilizes the recycling process. This prevents plastic recycling challenges during the later stages of processing.

However, the drying process is carried out using energy-intensive methods involving heat sources such as gas turbines or drying systems. The materials often need to be heated up to temperatures of over 90 to 95 degrees, because that is the only way that the moisture can evaporate effectively.

Moisture due to insufficient drying prior to processing can be eliminated in the preconditioning unit (PCU), although this may lead to a longer dwell time and reduce output.

The unique PCU technology and patented TVE technology, however, enable processing at a high level. Learn more about that later in the article.

Costly consequences of inadequate moisture control

Moisture that passes into the extruder screw or, in the worst case, into the degassing and into the pellets, can lead to gas inclusions. These present a major plastic recycling challenge and affect the downstream processing of the pellets produced. This is because inclusions carry the risk of the material tearing when the pellets are made into film or bin liners. The reason for this is that the moisture evaporates during the film blowing process.

These kinds of material defects not only lead to increased costs and waste, but also to an increased demand for personnel.

Challenge 2: How does printing ink influence the recyclability of plastic film?

Challenges due to ink deposit incrustations

Printing ink sticking to components often leads to ink incrustations and deposits that are difficult to remove. These lead to a reduced throughput rate, as less material can be transported efficiently through the extruder screw.

That is why printed film causes the following problems

Technical plastic recycling challenges.
A direct loss of production output.
Impaired costeffectiveness of the recycling process.

Adding calcium carbonate

Additives such as calcium carbonate are often used to prevent the inks from sticking. While this is one solution, it leads to further plastic recycling challenges:

It can change the physical properties of the recycled plastic, which leads to a reduction in the strength and elasticity of the end product.
Adding calcium carbonate requires precise dosing and thorough mixing with the plastic, which increases the amount of work involved during processing. The result is longer production times and higher costs.
Some recycling processes depend on the purity of the input material, so additives can make reprocessing more difficult and reduce the quality of the recyclate.
Although calcium carbonate is considered to be relatively environmentally friendly, it may have negative effects on the environment. Adding it to the feed material can also influence the overall balance in terms of energy consumption and carbon footprint.

Challenge 3: Why do contaminants cause plastic recycling challenges?

Accelerated wear due to sand and soil

Abrasive contaminants present a major plastic recycling challenge. They have a similar effect to using sandpaper on the machine components and cause increased wear. The result is high maintenance and repair costs with parts needing to be replaced before the end of their normal service life.

Loss of efficiency and reduction in throughput

Contamination can also significantly reduce the throughput and efficiency of the machines. This is because processes have to be interrupted or slowed down to prevent damage or correct quality defects in the end product.

Challenges in preparing materials

Non-metallic inclusions such as wood, sand and paper can cause additional plastic recycling challenges because they impair purity and cause defects in the end product.

Solution: The patented EREMA extruder system with TVE technology

What is TVE technology?

TVE technology is a patented extruder system. What is special about it is that the melt filtration takes place upstream of extruder degassing. Thanks to the improved process sequence, even contaminated, moist and printed materials can be processed in an ideal way.

How does it solve the 3 biggest plastic recycling challenges?

Moist materials: The preconditioning unit is the heart of the extruder system. Here, materials are shredded, mixed, pre-compressed, buffered and homogenized, as well as dried.
Printed materials: The optimized sequence mentioned above efficiently removes contaminants such as printing inks. This prevents incrustation due to ink deposits so that there is no need to use calcium carbonate.
Contaminated materials: Wear, reduced throughput and inclusions are no longer an issue thanks to ultra-fine filtration upstream of degassing.