Resins as additives

Plastic avoidance remains a component of environmental protection. Nevertheless, a balancing act cannot be avoided. After all, yogurt pots, fruit bowls or the precisely fitting interior of a box of chocolates rarely manage without plastic.

In the case of foodstuffs, the films used for this purpose have to meet stringent requirements. But even despite such intricate interrelationships, environmental protection does not have to fall by the wayside. The German Federal Environment Foundation (DBU) has therefore provided technical and financial support for a project to produce so-called thermo films.

EU Commission goal: All plastic packaging recyclable by 2030

The DBU has provided around 303,000 euros in funding for a process developed by the North Rhine-Westphalian company Constab Polyolefin Additives in Rüthen in the district of Soest together with the Institute of Plastics Technology at the University of Stuttgart: To produce such films more sustainably, the two partners have devised a process that uses special plastic resins to save energy and materials.

On the one hand, plastic causes problems when it enters the environment: several million tons of plastic waste enter the sea via rivers worldwide every year, adversely affecting ecosystems. On the other hand, plastics are among the most versatile materials due to their material properties and meet high requirements, especially in the food sector. They are hygienic, stable, lightweight and durable, and reduce the passage of oxygen and water vapor to keep sensitive goods fresh and thus prevent food waste. The European Commission’s goal is for all plastic packaging to be recyclable by 2030. „In the future, plastics will increasingly be about saving materials and consistently keeping resources in the cycle,“ says DBU Secretary General Alexander Bonde. The project by Constab and the University of Stuttgart pursued both goals, he said.

Film: Better, denser, stronger and yet thinner

The innovative aspect: For the first time, resins with special properties were used as environmentally friendly additives, with which Constab and the University of Stuttgart succeeded in lowering the so-called forming temperature by 20 degrees. This saves energy. In addition, the films can be processed better with the additive. The effect: they are both denser and stronger – but still thinner. „The film thickness can be reduced by about 25 percent, and the heating power by 20 percent,“ says project manager Dr. Andreas Strunk-Westermann. „These material and energy savings would mean that the new process would save around 200 metric tons of carbon dioxide per year for the customers who purchase plastic granules from us for the production of thermal films alone.“ Optical properties could be improved, while mechanical properties remained the same.

Material recycling of the products is possible without any problems, as the new material can also be used in monofilms. Unlike composite materials, which are difficult to recycle, such as milk cartons, here there is only one material. Strunk-Westermann can therefore imagine a broad use for the new thermal films: „The trend is toward single-layer films instead of composite materials. Our new material could replace composite films.“ The new environmentally friendly additives are already available as a ready-to-sell product.