Swedish RKW dairy cup for Lobetal

The latest yoghurt pack for Lobetal’s Bio range of dairy products – which was nominated among the Deutsche Verpackungspreis 2010 packaging innovation awards at the FachPack fair in Nuremberg last year – uses calcium carbonate filled PP and an eco-optimised production process to help minimise its impact on the environment.
The 150g capacity cup was developed in conjunction with packaging consultancy Carolina E. Schweig and film, sheet and compound producer RKW of Sweden. By using a 56% calcium carbonate filled PP material for the cup and lid it was possible to reduce oil-based fossil fuel content by almost 40%. The elimination of conventional aluminium lidding foils and use of printing, rather than labelling, of the cups also improved the ease of recycling.

Performance has not been sacrificed. The filled PP cup material is 2.5 times stiffer than unfilled PS, enabling a 33% thinner sheet to be used while still providing greater resistance to crushing and impact. Reducing the weight of the Lobetal cup also means 15% less energy is required during the thermoforming process for heating and cooling of the parts.

In addition to the down-gauging benefits, lower post-processing shrinkage and higher dimensional stability also enable material wastage to be reduced and closer tolerances to be maintained.

The PP film used for the project is thinner than aluminium alternatives and is more resistant to penetration – Schweig claims stacking ability is 25% better as a result.

The cup stands out from other products on the shelf due to what RKW describes as the “matt appearance and velvety feel” of the filled PP material. This characteristic is retained by replacing the conventional label with printing.

Packaging consultant Carolina Schweig says the chalk filler used in this project is sourced from a deposit in southern Norway that meets food contact purity requirements with little post treatment. She says German chalk deposits could only provide this with energy-intensive cleaning processes.

Schweig told European Plastics News that the project partners are working to lift the mineral content from 56% to 58% to make further energy gains.

Berlin-based Lobetal, which is a social enterprise employing both able and disabled workers, spent three months investigating material options for its ecological yoghurt cup, ultimately rejecting coated cardboard, conventional plastic and naturally-sourced bioplastic materials in favour of the mineral filled PP solution.

Lobetal’s dairy manager Michael Kuper told European Plastics News: “An alternative would have been corn starch [plastic] but then we would have never been able to exclude contamination by genetically modified material. It was out of the question.”

Fernholz Verpackung in Meinerzhagen extrudes the sheet and thermoforms the cups for Lobetal at the current time. Beucke & Söhne produces the printed PP lidding at its plant in Dissen am Teutoburger Wald.

Aside from the Deutsche Verpackungspreis 2010 nomination, the Lobetal yoghurt packaging application was judged as the most practical example of sustainable packaging within a research project granted to the BÖLW association for ecological food industry and the FIBL German/Swiss research institute for biological agriculture. It also won an International Dairy Foundation award last year.

The mineral filled PP is one of a range of materials that RKW produces as part of its Filled Polyolefin (FPO) product line. Aside from calcium carbonate, the company also uses talc for some other applications, improving sheet thermal conductivity and reducing heating capacity while also enabling faster processing and higher outputs. In thermoforming applications this means a higher stroke rate, while in injection moulding it results in faster cooling cycles and in profile extrusion quicker stabilisation. In blow film extrusion, RKW says that higher extruder output is obtained along with a more stable bubble that cools faster.

Barrier to light, oxygen and water vapour are also said to be superior to unfilled polyolefins, enabling FPO compounds to be used as an alternative to more complex PE/paper laminates.

Helsingborg, Sweden based RKW Sweden was founded in 1987 as Tetra Pak’s Filltech R&D development centre and was acquired by Worms, Germany headquartered RKW Group in 1998. The Swedish subsidiary’s turnover amounts to €14m. It manufactures its FPO materials as ready-to-use compounds, high concentration masterbatches and as sheets. The latter can be supplied in standard 1,400mm widths and in thicknesses from 170 to 1,200 microns.

Source.