UPM, Uteco and Siegwerk develop paper secondary packaging

UPM, Uteco and Siegwerk have developed a paper-based secondary packaging structure containing up to 90% paper, combining moisture and grease resistance with heat-sealing functionality. The companies have completed an industrial conversion trial using UPM barrier base paper, Siegwerk’s CIRKIT BAR SEAL coating and Uteco’s high-definition flexographic application technology.

The development is intended for secondary packaging, where a wrapper, sleeve or other outer structure provides additional protection and handling functionality around products already contained in primary packaging. The partners have deliberately retained the primary pack as the principal means of safeguarding product integrity, allowing the outer material to be redesigned without requiring it to perform every function of the packaging in direct contact with the product.

UPM provides the paper substrate, which forms the fibrous base of the new construction. Siegwerk supplies CIRKIT BAR SEAL, a functional coating intended to provide moisture and grease resistance alongside heat-sealing properties. Uteco’s equipment applies the coating through a high-definition flexographic process, bringing the material and machinery components together in a manufacturing trial rather than restricting the work to laboratory coating tests.

The combination addresses limitations associated with replacing conventional flexible plastic packaging with paper. Untreated paper contains a network of fibres and pores through which moisture or oils can penetrate, while its surface does not necessarily form a reliable seal under the temperatures and pressures used by packaging equipment. Functional coatings can change those properties, but must be applied consistently if the finished structure is to perform as intended.

In flexographic coating, material is transferred through a controlled application process onto a moving substrate. The quantity deposited, its distribution across the paper and the conditions during drying influence the resulting surface. Uneven coverage can leave areas with inadequate protection, while excessive coating may increase material consumption and interfere with subsequent converting or fibre recovery. Achieving the intended balance requires the formulation and application process to be developed together.

The partners report that the industrial trial integrated coating, printing and heat sealing within a coordinated single-pass arrangement. Uteco says this can reduce processing stages and associated time, energy and cost requirements. Those benefits have not been accompanied by published comparisons of energy consumption, operating speed or production cost, however, and should be treated as the equipment supplier’s reported advantages rather than independently measured savings.

Heat-sealing performance depends on the interaction between the coated surfaces and the equipment used to join them. Temperature, contact pressure and dwell time affect seal formation, while paper thickness and the coating’s properties influence how the material responds during the operation. The companies have not disclosed a minimum sealing temperature, measured seal strength or validated operating window for specific commercial packaging machines.

Moisture and grease resistance must also be considered in relation to the intended distribution conditions. Secondary packaging may encounter condensation, contact with other packs, changes in humidity and mechanical handling during transport. The level of protection required is different from that of a primary package responsible for maintaining a controlled atmosphere or preventing direct contact between food and its surroundings.

UPM says paper content can reach 90% in the tested packaging structure while retaining the required functionality. That percentage is a reported upper level rather than a specification necessarily achieved by every proposed format. The proportion of coating, printing materials and other components will vary according to the finished design, while the total package weight depends on dimensions and material thickness as well as composition.

The companies also describe the structure as compatible with conventional paper recycling streams under CEPI/4evergreen v2 assessment criteria. Fibre recovery depends on the behaviour of the complete construction during repulping and subsequent recycling operations. Functional coatings can influence how readily fibres are released and whether residual materials affect the quality of the recovered pulp, so the recycling characteristics of another version cannot automatically be inferred from the tested design.

Compatibility with a recognised recyclability assessment method also differs from acceptance by every local collection and recycling system. Regional infrastructure, sorting arrangements and the actual components of the disposed package influence whether the material can be recovered. The October release does not provide independently verified recycling yields for a portfolio of commercial packaging formats or establish that all additional inks, adhesives and closures would leave the assessment unchanged.

The industrial work has implications for the use of renewable materials in packaging groups that already depend on plastic primary packs. Replacing an outer plastic structure with coated paper may be technically simpler than redesigning the pack that controls the product’s immediate environment. Any reduction in plastic consumption must nevertheless be calculated from the actual materials removed and introduced, rather than assumed from a high paper percentage alone.

European packaging legislation provides part of the commercial context. The Packaging and Packaging Waste Regulation introduces requirements concerning material use and recyclability, with obligations taking effect according to the legislation’s implementation schedule. A structure designed for fibre recovery may help a packaging company investigate future compliance options, but the reported development does not establish that every application already meets all relevant requirements.

The project is distinct from UPM’s separate collaboration with Ingredion and Paramelt, also reported in October. That work examines starch-based grease barriers and heat-seal coatings for food packaging using specific UPM paper grades. The Uteco and Siegwerk programme instead demonstrates secondary packaging conversion with CIRKIT BAR SEAL, leaving the primary packaging responsible for the product’s principal protection.

The three companies displayed samples at PACK EXPO International in Chicago in October. No named food manufacturer has been identified as operating the new structure commercially, and the partners have not disclosed a production contract or installation timetable. Converters considering the material would still need to establish line compatibility, sealing performance, material use and the recycling behaviour of their intended construction.

The completed industrial trial demonstrates that barrier coating and heat-sealing functionality can be incorporated into a predominantly paper-based secondary packaging structure through established converting technology. The next evidence required concerns repeatable performance at specified commercial production rates, measured material and energy consumption, and the characteristics of finished packs supplied to individual customers.