Adapted thermoforming process for the production of detachable cardboard-plastic composites

Research Project

Pack4Sense

Challenges

  • An uneven sealing edge of paper mouldings, caused by forming due to material compression, results in leaky sealing seams
  • Damaged barrier layers during forming of coated materials in the processes of deep drawing and pressforming
  • Processing of particularly thin films in the thermoforming process is complicated due to the lower heat capacity and reduced elongation capacity
  • Air-impermeable containers, such as moulded parts made of paper, negatively affect the forming process during thermoforming

Research results

  • Development of a method to complement paper forming techniques based on material compression.
  • The film of the barrier layer covers the uneven sealing edge and enables the production of tight sealing seams.
  • Thermoforming allows thin films to be formed into a desired geometry without causing defects due to abrasive tool contact

Benefits

  • Reducing the amount of plastic used in food packaging with high barrier requirements.
  • Production of separable cardboard-plastic composites suitable for recycling
  • Achieving higher process reliability in the production of packaging primarily made of fiber material
The graphic shows how a 3D-molded cup made of fiber-based material is constructed with the subsequently inserted barrier layer.

Protection of sensitive products with minimal use of plastics and full recyclability

 

To achieve a circular economy, the "Pack4Sense" project is dedicated towards the development of a packaging concept, which ensures easy separability of the packaging components while fulfilling the barrier requirements of sensitive food products with minimal usage of plastic.

Fiber-based materials such as paper and cardboard are increasingly used as a substitute for plastics made of fossil resources. Besides the advantage that renewable raw materials are used for the production, recycling infrastructures are also established worldwide.

Due to the fact that paper and cardboard have limited barrier properties, for example against oxygen, plastic barriers are still commonly used. However, the barrier is laminated, which makes it difficult to separate the composite. As a result, full recyclability cannot be achieved because the components cannot be added to the intended recycling chain.

In order to solve this problem, a new approach has been developed which enables the coating of paper mouldings by forming a thin film into the moulding using the thermoforming process. This allows the production of packagings with a high fiber proportion and reliable barrier properties, which can be disassembled into their individual parts after usage.

 

High quality barrier layers and secure sealing seams for fiber-based packaging

 

The forming methods used are based on the compression of excess material, which results in the characteristic wrinkling of the moulded part. As a result, the sealing edge causes leaky sealing seams, because the unevenness cannot be completely sealed with the melted material. When using the thermoforming process for coating, the film lays over the uneven sealing edge and allows a tight seal of the packaged goods.

Another advantage is the prevention of unwanted material damage. When forming coated fibre materials, the abrasive contact between the packaging material and the forming tools can result in significant damage to the barrier layer. When the film is formed separately, the applied process forces and tool contacts are significantly lower, which prevents damage to the barrier layer.

The forming of the thin films results in process-related challenges, which are mainly due to the specific thermomechanical properties of the thin films. The Fraunhofer IVV Dresden is developing solutions to drastically improve the forming of thin films in the thermoforming process.

 

Individual design of the shape and barrier properties of food packaging

 

The project results have shown that the thermoforming process can be used to apply a thin barrier layer to the inside of fibre-based packaging. This results in a new method for reducing plastic waste, which complements the three-dimensional paper forming process. Good barrier properties and stable process designs can be achieved while maintaining sustainability, as separation of the components is possible after usage.

Do you have any questions or require further information about this project? Please get in touch with us!

 

EIT Food is supported by the European Union

Project term January 1, 2021 to December 31, 2021
Project partner
Colruyt Group [Belgium], Strauss Group [Israel]; Syntegon Technology GmbH [Germany], University of Reading [UK]
Project management
/funding:
European Institute for Innovation and Technology EIT Food