the project SUR3D, coordinated by the association INNOVATE with the participation ofOIMO Bioplastics, the Foundation Eurecat, the Foundation Catalan Institute of Cork (ICSuro) and the Cluster MAV, has developed a new biodegradable material from used corks. This is a project that was approved by the Ministry of Industry, Commerce and Tourism (MINCOTUR) as part of the call for Innovative Business Associations (AEI) 2022. The project has a budget of 173,458 euros.

Currently, around 4,000 tons of corks are used in Spain. Cork stoppers are widely used by wineries for their oenological properties and environmental and social sustainability, contrary to plastic and screw caps. Although the cork dust that is generated during the production process of these caps can be considered a waste, it can be used, mainly, for the generation of energy.

The SUR3D project, which has been developed between August 2022 and April 2023, has used this waste to obtain a new material with high added value that will open up a new market field and become a clear example of the application of a circular economy and bioeconomy model.

In this project, the OIMO company has been responsible for developing a new bioplastic formulation suitable for 3D printing with a cork granulated base obtained from used corks. The polymer developed by OIMO is biobased in a higher percentage than 80% and 100% biodegradable under natural conditions. This aspect distinguishes it from other biopolymers on the market, such as PLA, one of the most popular biomaterials in 3D printing due to its cost and ease of printing, since it is a biodegradable material in the industrial field but not in natural conditions.

In turn, cork is a natural, renewable and biodegradable material with a combination of properties that make it unique and versatile. Among these properties it is worth noting the low density, the high mechanical and fire resistance and the low thermal and electrical conductivity, in addition to being a good thermal and acoustic insulator and possessing great elasticity.

Parts of the process

• In the framework of this project, it was intended to adapt the OIMO polymer formulation by incorporating cork to obtain a new biomaterial for 3D printing that incorporates the multiple properties of cork (Figure 1).

• Figure 1. From left to right: cork by-products (3 types of dust) shipped, compound of OIMO material and cork powder and test tubes.
  • ICSuro has contributed its knowledge and experience in the uses of cork by being in charge of obtaining cork granules from used corks with the desired characteristics to be used as raw material to form a compound for a 3D filament (Figure 2).

• Figure 2. Determination of the apparent density of the samples, according to the protocol based on ISO 2067. Source: ICSuro.
  • The production of the biomaterial with cork was carried out through the process of compounding. After correcting some problems that arose, the compound with cork load (Figure 3).

• Figure 3. Grain obtained by OIMO through the process of compounding. On the left, unloaded material. On the right, material with cork.
  • Once the grain was obtained, the Eurecat Foundation was responsible for studying the printability of the materials with and without cork, and determining the optimal parameters for use, and thus being able to compare them (Figure 4).

• Figure 4. Extrusion temperature tests for OIMO material.
  • By carrying out the printability tests, it was verified that the new biomaterial developed in the SUR3D project is compatible with additive manufacturing technology by extrusion. Finally, test tubes were made of the material loaded with cork and without load, for mechanical and thermal characterization (Figure 5 and 6).

• Figure 5. Left, flow test for OIMO + cork material. On the right, mechanical characterization test tubes made with the material OIMO + cork.

• Figure 6. On the left, test tubes for the thermal characterization of the OIMO material. On the right, test tubes for the thermal characterization of the OIMO + cork material.

Compete with plastic 

The new biomaterial presents physical properties similar to cork, such as low thermal conductivity, and maintains the natural biodegradability of the polymer. On the other hand, the incorporation of cork in the formulation has made it possible to obtain a compound for 3D printing with mechanical properties superior to cork-free polymer.

Therefore, the improved properties of this new biomaterial can bring a lot of versatility in terms of 3D printing technologies and compete directly with other plastic-based products that have a greater environmental impact.

In the coming months, the consortium will decide how to continue the project. Mainly, the following steps will be based on looking for applications of the new biomaterial related to thermal insulation and optimizing the formulation of compound for use in other processes, such as injection.