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Process for delamination of multilayer film

Country of Origin: Spain
Reference Number: TOES20200327001
Publication Date: 27 March 2020

Summary

A Spanish university has developed a procedure for the delamination of the multilayer film. It uses a mechanical method, rather than a chemical dissolution, to facilitate access to the area between layers of the laminates. As the reactant accesses the interlayer, it eliminates the adhesive that joins these films, thus producing their separation. Companies interested in the commercial exploitation of this technology through licence agreements and/or technical cooperation are sought.

Description

Sometimes, a single type of plastic alone is not capable of reaching the characteristics demanded by the industry. Still, it is necessary to use a combination of plastics glued together to form a multilayer composite material (laminated plastic). 



Another use of laminates is as barrier for printing pigments. In this case, printing is done first at one of the plastic sheets, and a layer of the same plastic is added over to protect the food from the ink.



Although laminated materials have many technical advantages, they suppose a significant problem when it comes to recycling due to the differences in melting points between the polymeric materials that make them up, restraining them from being reprocessed by extrusion. 



The traditional methods used for delamination are based on selective dissolution, in which each layer is solved using organic solvents. These solvents present environmental and safety problems since they are toxic and flammable. On the other hand, because of the price of the chemicals, these methods are not feasible for most laminated materials. 



In this sense, a Spanish research group has developed a procedure for removing the adhesive that holds the laminated plastic sheets (Figure 1) together, and the subsequent removal of the ink. This procedure facilitates the recycling of each of the plastic materials in the composite material.  



This procedure consists of the following steps (Figure 2): 



1. Conditioning and crushing of the laminated plastic material previous treatment (optional).

2. Micro-perforation of the laminated plastic material.

3. Removal of any ink or adhesive.

4. Separation of water from the plastic material in a centrifuge. 

5. Removing of any ink or adhesive from water in a clarifying centrifuge, by adding flocculants and coagulants before the centrifugation.

6. Separation of plastic materials by wet-phase decantation based on the difference in density between the various plastics, through the use of hydrocyclons or any other separation technique available on the market.



The innovation of this technology takes place in step 2, where the micro-perforation of the laminated plastic material is carried out using micro-needles in a micro-perforation device, comprising at least a pair of double rollers rotating in opposite directions. The crushed laminated plastic material coming from the mill falls into the hopper and, due to its weight, is forced to pass between the rollers, where the micro-needles produce perforations in the material that allows the reagent to access the interlaminar area.



The micro-perforated laminated plastic material is introduced into a reactor so that chemical agents can access the interlaminar zone of the laminated plastic material and remove the ink and adhesive.



This procedure could be useful in the plastic recycling sector since it can be applied to different types of laminates from plastic waste of both industrial or domestic origin.



The research group is mainly looking for companies interested in acquiring this technology for its commercial exploitation through license agreement. The company should be responsible for the development of the industrial prototype, the validation of the technology, its installation and its introduction into the market. The university will be ready to provide technical assistance in each step, if required.



However, the research group would be also interested in establishing technical cooperation agreements to further develop the laboratory-scale prototype, to find new applications or to adapt it to the company’s needs. The goal of this type of collaboration would be increasing the technology readiness level for a future commercial exploitation of the patent. The university would offer its support based on their know-how; while, the partner sought would provide its expertise to help improve this invention. The university would offer this partner a preferential option to acquire this technology in exclusivit

Advantages and Innovations

The removal of any ink and adhesives from laminated materials is very complex, as the plastic itself prevents access to the reagent. The principal innovative aspect of this technology is the fact that micro-perforations are made in the laminated plastic material, which allows the access of reagents to the interlaminate area. In this way, ink and adhesive can be removed at later stages.



This technology has the following advantages:

• It reaches an efficient plastic delamination for the vast majority of multilayer plastics, allowing them to be recycled.

• It allows eliminating the printed ink present in the interlayer. 

• The technology is simple and easy to implement. 

• Environmentally friendly procedure. 

• No need to use organic solvents. 

• It is not necessary to cut material below 5x5 cm2.

Stage Of Development

Under development/lab tested

Stage Of Development Comment

The technology is developed on a laboratory scale. It has been tested with different types of laminates: polyethylene /polyethylene terephthalate, polypropylene /ink/ polypropylene, polypropylene /aluminum/ polyethylene.

Requested partner

- Type of partner sought: Industry.

- Specific area of activity of the partner: Recycling of plastic waste; Manufacturers of plastic containers; Producers of virgin raw material.

- Task to be performed: 

* In the license agreement: to buy a license for the technology, to further develop it to the industrial scale and to introduce it into the market.

* In the technical cooperation agreement: to provide their expertise in order to collaborate with the scientists on further development and improvements of the technology. The company should identify technical requirements and/or market and client’s needs in order to carry out further technical development so that the market readiness will be increased and the technology could be commercially exploited.