Fibre-based packaging is at a technological turning point. For a long time, they were primarily discussed as a sustainable alternative to plastic. Today, technical criteria such as reproducible shaping, defined functional properties, stable product protection and safe integration into existing packaging and filling processes take centre stage. This has shifted the industry's central question from „Is it feasible?“ to „Is it industrially scalable and to what specifications?“.
Paper and cardboard have been established packaging materials for decades. What is new, however, is the claim to achieve functional levels with fibre-based materials that were previously reserved for plastic packaging, particularly in terms of barriers against water vapour, oxygen and grease, dimensional stability, format flexibility and cycle times in industrial production. This claim presupposes that material, process and quality are considered as a unit.
How is series capability created?
Modern fibre-based packaging is predominantly made from cellulose fibres, more precisely virgin fibres and recycled fibres, or from alternative fibre sources such as bagasse, grass or other plant-based raw materials. The origin of the fibre is less decisive for its industrial suitability than its properties in the process: fibre length distribution, fines content, moisture content, additives and binding properties directly influence the formability, strength of the surface quality and other properties.
New manufacturing processes such as dry moulded fibre or advanced paper forming technologies allow fibres to be precisely formed, thermoformed and manufactured with high precision. Compared to traditional wet moulding processes, there are advantages in terms of product and manufacturing costs, surface quality, decoration options and CO₂ emissions.
In addition to the material base and moulding, mastery of the process window is essential for series production capability. Typical control variables are
- Fibre preparation and additivation (maintaining the fibre length and precise separation of the individual fibres from the composite)
- Fibre distribution/lay-down (homogeneous fibre distribution and therefore constant basis weight)
- Pressing the fibres (compacting the fibres and forming hydrogen bonds)
- Tool design (durable tools, option for undercuts)
- Lamination (creation of a high barrier, constant film thickness, option for very thin films)
In industrial operations in particular, it is not enough to produce good samples in the laboratory, but to have the ability to produce over long running times with defined specifications - including tool life, maintenance windows and the lowest reject rates.
Barriers: Differentiation by application
Barrier properties are the key to scaling fibre-based packaging beyond traditional applications. Depending on the product, packaging must protect against water vapour (measured as WVTR (Water Vapor Transmission Rate - particularly relevant for powders, instant products, snacks, sensitive dry goods) and/or against oxygen, measured as OTR (Oxygen Transmission Rate - relevant for flavour protection, oxidation protection, e.g. for coffee and certain ready meals). In addition, protection against fat/oil (measured with a KIT test - central for food service, fatty foods, ready meals) or liquids and moisture (measured as Cobb value - for moist and liquid products such as soups, dairy, ready meals) may be required.
The clear differentiation according to requirement level (low/mid/high barrier) is technically decisive. In many cases, it is not the maximum barrier that is required, but a resilient, application-optimised level.
Nowadays, barriers from the low to the high segment are available for most products - naturally PPWR-compliant and suitable for international legislation. This means that high-barrier solutions can also be designed to be recyclable. Three technical aspects are often more decisive than the barrier material itself: surface and substrate quality, application process and layer uniformity as well as bond adhesion and long-term stability.
Process integration in filling and packaging lines
An underestimated bottleneck and a key success factor is integration into existing process chains. Brand owners and co-packers need packaging that can be processed in existing lines: Feeding, separating, filling, sealing, labelling, secondary and tertiary packaging. Typical integration issues are
- Handling and separation: friction coefficients, edge stability, dust, tendency to deform
- Filling: particle abrasion, hopper geometries, product contact surfaces
- Sealing/closure: sealing temperature window, pressure distribution, sealing surface
- MAP: Tightness and stability over running time, leakage rates, process capability
- Shelf-life performance: barrier over time, storage climate, transport
A test example has shown that fibre-based trays for ready meal concepts function stably with a good barrier, provided that the coating and the sealing edge are designed and produced correctly and with good quality so that sealing processes run reproducibly. In realisation, however, it is often the case that the seal seam is less „tolerant“ than with plastic: laminated cardboard trays often do not have the required seal edge quality, which leads to a high reject rate. In addition, the strongly angled corners of the packaging lead to leaks and the use of thick films. As an alternative, dry-moulded fibre trays offer high-quality sealing edges. The rounded corners do not stress the laminate, which means that much thinner films can be used.
Further practical experience makes it clear: low to mid-barriers can already be realised with inherent or top-coat spray coatings. Packaging solutions are laminated for high-barrier solutions. From a technical point of view, low, mid and high barriers are realised with different barrier technologies. It is fundamentally important that a fibre-based solution can also demonstrate its advantages with the different barrier solutions, for example in terms of haptic quality, printability, design freedom and recyclability.
In the high-barrier area (e.g. very oxygen-sensitive, very long shelf life, sophisticated MAP concepts), work is also being done on ever thinner barrier films and inherent solutions. Technically, it is less a question of „either/or“ and more a question of how thin the barrier can be in order to remain functional and how the system can still be utilised. At the same time, the barrier must be resistant to cracking and buckling, particularly in the case of deep-drawn moulds and under mechanical stress in line and logistics.
Large-scale serial production as a signal
The transition from pilot projects to large-scale industrial production is currently the biggest challenge and at the same time the area in which the industry is professionalising the most. Pilot plants are necessary to define and stabilise process windows, validate tool and service life concepts, test coating and laminating processes at realistic cycle times and generate quality data on large quantities.
Scaling is particularly important in the barrier context: a system that works on a laboratory scale or in small series can reach its limits at higher speeds and longer running times. Real production data and reliable series strategies are therefore crucial.
Optima will be showcasing its machine portfolio for the industrialisation of dry moulded fibre, paper forming and paper board forming at interpack. The company will also be presenting one of the machines in its in-house „Fibre Center“. This is relevant in the context of industrialisation because it demonstrates not only the feasibility, but also the ability to achieve stable quality and reproducible process windows at high output.
Such systems provide data on cycle times, energy and media requirements, reject rates, barrier process stability and the integration of finishing and quality assurance modules. This means that investment decisions can be based more on measured series parameters than on individual results from pilot or laboratory scenarios.
Part of a technically optimised material mix
In the long term, fibre-based packaging will not completely replace plastic, but rather expand the range of materials in a targeted manner. The decisive factor is the application-related choice of system, both technically and economically as well as from a regulatory perspective. Three criteria are central to market penetration: functional equivalence, cost and quality.
If barriers and processes can be industrialised in this way, fibre-based packaging will make the transition from a sustainable alternative to an industrially established solution - not as a universal solution, but as a technically robust option for clearly defined applications.
