Cycloolefin Copolymers (COC): Key Component for Recyclable Minimal Packaging Solutions

Advantages for packaging development

1. Mechanical properties

What makes COC interesting for use in packaging is its high rigidity - a key property when it comes to reducing material without sacrificing stability. The grade TOPAS 8007 has a tensile modulus of over 2,000 MPa. Even small quantities, around 10 % in a blend with PE, can significantly increase the stiffness of a material. This enables the use of thinner films - so-called "downgauging" - without mechanical losses. A stronger, stiffer sealing layer also leads to better sealing behavior and enables high-speed packaging processes.

2. Temperature resistance

Various COC grades remain dimensionally stable almost up to the respective glass transition temperature (Tg). Compared to PE or PP, which significantly lose rigidity at higher temperatures, the high Tg grades TOPAS 5013 and 6013 are stable up to 130°C. This is particularly advantageous for applications such as hot filling, metallization, printing and sterilization, where thermal stress plays a significant role.

3. Barrier properties

COC offers an excellent water vapor barrier - up to five times higher than LLDPE - and also has a slightly improved oxygen barrier compared to standard polyolefins. Particularly notable is the protection against aroma migration and polar solvents. Here, the data show an improvement by a factor of 20 to 30 compared to pure LLDPE. COC can also be combined with polymers such as polyamide or EVOH, adding moisture protection to their good oxygen barrier.

4. Sealing behavior

The addition of COC into the sealing layer also brings advantages in this aspect. It increases stiffness without affecting the low sealing initiation temperatures (SIT) of the polymers. Friction is also reduced, which leads to better machine running properties. The weaknesses of a plastomer in terms of stiffness and tackiness are thus balanced out.

5. Thermoformability

COC significantly improves the thermoformability of PE films. A COC content of just 30 % leads to properties similar to those of rigid films with improved molding accuracy and reduced shrinkage. A concentration series with increasing COC proportions shows that the cavity shape improves and the puncture resistance increases, resulting in downgauging potential. 

COC-COC blends also allow the thermoforming behavior to be specifically adjusted or adapted by adjusting the Tg. The PE trays are also fully recyclable in the defined polyolefin stream.

6. Metallizability

Thanks to its high surface energy, COC has very good metal adhesion properties - ideal for aluminum metallization. Combined with high stiffness, gloss, foldability, and barrier properties, this results in high-quality films with high functionality and full recyclability.

7. Corona treatment

Films with COC content also require pre-treatment to ensure that the ink adheres during printing. COC requires less energy for pre-treatment than PE or PP. The surface energy remains stable on the surface over a longer period of time, which leads to energy savings and more consistent printing results.

8. Recyclability

A key advantage of COC is its excellent recyclability in the polyolefin stream. Even if the mechanical properties in terms of stiffness and amorphous structure differ greatly from polyethylene, COC is chemically very close to PE-LLD and therefore has good recycling properties. These have been confirmed by cyclos-HTP and RecyClass.

Application examples

1. Twist wrap

Traditional materials such as PET or PVC are difficult to recycle and standard PP often does not offer the required stiffness for twist wrap. A structure of PP and COC provides a 100% polyolefinic, recyclable monomaterial solution that also offers the necessary stiffness for the dead-fold effect. The film can be produced on standard equipment, can be metallized and provides effective protection against aroma and moisture loss.

2. Shrink sleeves

Another area of application is shrink sleeve film, which has so far mainly been made of PVC or PET. COC-based alternatives represent a purely polyolefinic solution. They offer comparable shrink rates of over 70 %, high rigidity, excellent printability and a low density. The low density is important for separation in flotation processes and therefore for unmixed recycling - for example in the case of beverage bottle labels. 

3. Pharmaceutical blister

Blister packs with COC in the core (embedded between two PP layers) are a sustainable alternative to PVC/PVdC. They are easy to thermoform, offer a high water vapor barrier and can be produced as a co-extrudate or laminate. In combination with metallized COC films, there is also the possibility of replacing the aluminum lidding film in the long term, with the aim of enabling a fully recyclable monomaterial solution based on polyolefin.

Conclusion and outlook

Cycloolefin copolymers combine high performance with sustainability. Whether higher stiffness, better barrier or optimized sealing and thermoforming properties - COC helps to specifically improve the properties of conventional polyolefins. At the same time, recyclability is maintained in existing PE and PP streams. COC therefore offers not only a technical, but also an ecological upgrade for modern packaging solutions.

The capacity expansion in Leuna from 2026 will increase industrial availability and facilitate industrial use. In view of stricter EU recycling requirements, COC can play a central role in the transformation of the industry - away from complex multi-material structures and towards intelligent, highly functional mono-material solutions.

Dr. Dirk Heukelbach studied chemistry with a focus on chemical engineering at the Technical University of Darmstadt. After holding positions at REHAU, TICONA and RENOLIT, he joined TOPAS Advanced Polymers in Raunheim in mid-2020. He currently works in Technical Sales & Marketing, specializing in film applications of the plastic COC.