"Our goal is to use recycled plastic with few processing steps.”
Stories
01.06.2022
97

"Our goal is to use recycled plastic with few processing steps.”

Circular Economy
It is not that simple to use recyclate in plastics extrusion. Dr. Tim Pohl, Director of Sustainability and New Business Development at Reifenhäuser, rates the opportunities and obstacles and explains why more flexible and robust lines are needed to process recyclate.

Tim, there is an increase in social and political pressure to produce plastic products on a more sustainable and resource-conserving basis. For example, the EU has adopted a strategy for plastics that calls for a substantial increase in the proportion of recyclate by 2030. Do you think a quota for the use of recyclate in plastic products is needed?

Yes. And this is happening already. All the major brands, such as Coca-Cola and Nestlé, have committed themselves to using appropriate amounts of post-consumer waste in their packaging. This will result in a change in the demand and availability of high-quality recyclate. Collection and sorting are complex and therefore expensive. Quotas hopefully succeed in decoupling the recyclate market from the virgin market.

- 60%

A product made from 100% recyclate has a carbon footprint that is approximately 60% lower than a product made from virgin material.

Product Carbon Footprint

The Product Carbon Footprint (PCF) is a method of determining the climate impact of a product over its entire life cycle. The PCF helps to quantify and analyze this impact. The carbon footprint is not only about carbon dioxide emissions, but also about other greenhouse gases.

I expect the price of the recyclate will rise higher than the price of virgin material for comparable qualities, at least in the near future. This is where we engineers are called upon to develop solutions that make a good circular economy affordable. And I am confident we will succeed.

Can you already give an example of this?

It is costly and resource-intensive to process waste plastic by washing, drying, and regranulation. Our goal is to reduce the number of processing steps for second live plastic to a minimum, and preferably to use fractions that are only presorted. Reifenhäuser offers suitable solutions. For example, we can extrude thermoforming film directly from shredded PET bottle flakes or we can extrude blown film directly from film fluff. The second process is a particularly challenging one from an engineering point of view since luctuating raw material input might influence the bubble stability and final film quality. 

Why is this so?

It starts with the fact that film fluff comes in different thicknesses, shapes, and rigidity. In addition, the input moisture of the material often changes within the same batch, not to mention the fact that a bunch of different polymers is usually processed. Continuous extrusion is very challenging and sensitive in this respect, especially when production involves very thin film or fine nonwovens.

It is a well-known fact that the quality of recyclate can vary greatly...

Exactly! The greater the demands placed on the product and the general conditions, the more crucial it is to have good quality raw material - in other words: what is the history of the recyclate and what is its previous life? But once you know the quality of the recyclate and once you have applied the line designed to a particular application, then the recyclate is just another raw material fed to the extrusion line.

Dr. Tim C. Pohl
Dr. Tim C. Pohl
Dr. Tim C. Pohl, born in 1974, studied mechanical engineering at RWTH Aachen University and received his doctorate in extrusion from the University of Paderborn. After holding various management positions in another company, he joined the Reifenhäuser Group in 2010, where he now heads Business Development, and closely supports developments in the fields of strategic and technological sustainability.

What is recyclate?

Recyclates are secondary raw materials that, depending on their condition, can be sorted, cleaned, reprocessed, and recycled in production. A distinction is made between recyclates from industrial waste (Post Industrial Recyclate) and from end-user waste (Post Consumer Recyclate).
For more information: Recyclate Guidelines of the Recyclate Forum

However, processors need not venture into uncharted territory alone. They have a very experienced partner at their side – Reifenhäuser. We have the required expertise and the right pilot lines available in our Technology Center. Of course, it is also very helpful that many of the lines we sell have long been processing industrial plastic waste. In the case of thermoforming lines or spunbond lines, this has been going on for more than 15 years.

What are the line engineering requirements for processing recyclate?

You have to design the system to be more flexible and more robust. This may mean extending an extruder or changing the screw diameter. Or the raw material feed may need more space. At the same time, more customization is necessary because every customer works with different raw materials or procures them from different sources. Our task is to design the machine technology so that our customers can process the widest possible range of materials today and in the next months.

What adjustments do you make to achieve this?

Companies that process waste plastic with the associated impurities require screws and barrels that have greater protection against abrasive wear. What's more, it's not always possible to prevent corrosive particles from migrating into the extruder together with the feed material, so the line needs greater corrosion resistance. This is the basic requirement for the components with melt contact.

Another aspect is melt processing. To process different polymers, you need a plasticizing system, i.e., an extruder that homogenizes different fractions as well as possible. And the flow channel should be designed to be as material-independent as possible to ensure uniform distribution for fractions with different flow behavior.

Three requirements for line engineering

  • Protect components from wear and corrosion.
  • Design the extruder to homogenize different polymer fractions.
  • Design the flow channel to be material-independent.

“For extrusion, there should be a certain consistency in the rheological and physical properties.“

Dr. Tim Pohl
Director Sustainability at Reifenhäuser

Would you say there are no unsuitable recyclates - provided the line is good enough to process it?

No. We are already capable of processing heavily contaminated recyclate now, but we’re not magicians. There should be a certain consistency in the rheological and physical properties. According to the raw material variation, it is then determined for which end products the recyclate is suitable. This may range from thick construction film to a comparatively sophisticated thin stretch film.

What does this mean for film producers?

First of all, film producers need access to the right type of recyclate. To increase its quantity, we need a functioning circular economy extending from the recycled plastic product to the new plastic product. Beyond that, in my opinion, processors should keep closer scrutiny on the quality of the starting raw material in the future. In other words, what raw material quality is sufficient for what requirement? A shampoo bottle with a wall thickness of 1 mm requires different recyclate quality than a thin 50 µm film with 30% recycled content. I also think it will increasingly be a matter of tapping into new raw material sources - and preferably at regional level to keep transport routes short.

Reifenhäuser is happy to assist film and nonwoven producers as a partner in the processing of recyclate. And we advise our customers so that they neither do too much or too little when it comes to line and process engineering. So, in the end, everyone gets a customized system based on proven extrusion technology.