Cardboard is renewed as a functional and sustainable material



Paper and board have traditionally been the most widely used materials in the packaging sector. According to Eurostat data, in 2018, 40.9 of the total packaging waste generated in Europe, being a total of 31.8 million tonnes, were paper and board. A value far from 19.0 for plastic waste, 18.7 for glass, 16.1 for wood and 5.0 for metal

Cristina González and Rafael Sánchez - ITENE


Considering that high amount of packaging waste generated and its corresponding environmental impact, the European Union has focused on improving the packaging waste management with a view to protecting, preserving and improving the quality of the environment, as well as protecting human health and promoting the principles of the circular economy. To this end, in 2018, the European Commission amended the directive on packaging and packaging waste (Directive (EU) 2018/252), establishing that 65% of packaging waste will have to be recycled by 2025, and 70% by 2030. For plastics there is a special plan, since the European Plastics Strategy adopted in 2018 stablishes that by 2030 all plastic packaging must be recyclable.



In addition, following this strategy, the European Commission adopted Directive 2019/904 on reducing the impact of certain plastic products on the environment by which Member States will ban, from July 2021, the marketing of certain single-use plastic products (single-use plastic cutlery and plates, straws, ear sticks, balloon sticks and polystyrene food containers and cups) and of products made of oxo-degradable plastic.

These regulatory restrictions on plastic packaging, together with the constant demands of consumers who are increasingly aware of the need to care the environment, are the main motivation for companies to look for alternative materials to plastic, which are renewable, recyclable, biodegradable and low-carbon, such as paper and board. In fact, according to the study "Packaging: society's perception" carried out in 2017 by the Spanish Association of Corrugated Cardboard Packaging Manufacturers (AFCO), cardboard packaging enjoys the highest environmental reputation among Spaniards. Compared to other materials, it is the most sustainable with a percentage of 41.7, compared to glass (28.4), wood (13.9), plastic (5.7) and, finally, aluminium (2.3). This figure shoots up when put face to face with plastic: a majority of 76.7 say that cardboard is the most sustainable, compared to 10.7 who prefer plastic.

There is growing interest in corrugated packaging in traditional sectors and markets, such as the fruit and vegetable sector, as well as increasing investment in new materials that contribute to reducing raw material consumption, saving energy and improving the efficiency of logistics processes.

Cardboard is undoubtedly one of the key raw materials in the circular economy. Its versatility is combined with a series of social and economic factors that underline the growth of the sector and provide good prospects for the future: the improvement in production and digital printing techniques, the consolidation and expansion of consumption through e-commerce, the incorporation of new consumer profiles into the market and, in addition, the growing demand from customers and end consumers for alternative, sustainable and environmentally friendly packaging solutions.

Alongside these improvements in production, there are various possibilities to provide cartonboard with functional properties, which by nature are not present, and which make cartonboard-based packaging an alternative to plastic-based packaging. Some of these possibilities are:

· Application of reinforcements, either mixed directly with the fibres (in bulk) or in the form of coatings, to provide the board or paper with certain improvements in its mechanical properties or barrier properties (hydrophobicity, oleophobicity, oxygen barrier or water vapour barrier).

· Laminations of cellulosic substrates (cardboard, paper, moulded cellulose, etc.) with different biodegradable and/or compostable film sheets, with the consequent improvement of barrier properties and without altering the sustainable character of the final products.

· Application of surface treatments, mainly aimed at improving the barrier properties, which are based on the surface modification of the cardboard or paper by anchoring chains of compounds -mainly fatty acids- providing the surface of the paper with a hydrophobic and sometimes oleophobic character.



At ITENE, taking advantage of these interesting possibilities offered by cellulosic materials, different European projects are being developed to improve the barrier properties of different types of cellulosic packaging.

An example of this type of project is the PULPACKTION project, which has received funding from the "Bio-Based Industries Joint Undertaking" action within the European Union's Horizon 2020 research and innovation support programme under agreement no. 720744.

Among the main objectives of the PULPACKTION project is the improvement of wet moulded cellulose packaging by adding different mass reinforcements, one of them being microfibrillated cellulose, improving both its mechanical and barrier properties.  This project also envisages the improvement of the production technologies of this wet moulded cellulose, increasing the production capacity of the equipment and the quality of the final products.

Achieving these targets will reduce the energy consumption of the wet pulp moulding process by 20% compared to solutions based on fossil raw materials. In addition, it will allow the reduction of CO2 emissions by more than 50%, leading to a considerable increase in the competitiveness of the European pulp, board and paper industries.



CELLUWIZ project

Another example of a project that seeks to improve the functionalities of cellulosic materials is the CELLUWIZ project, which is also funded by the Bio-Based Industries Joint Undertaking under the EU Horizon 2020 programme under agreement number 838056.



The main objective of CELLUWIZ is to develop two processes for the production of a cellulose packaging material that can compete in functionality with multilayer and multi-material plastics currently on the market, while being renewable, biodegradable and recyclable within the paper value chain.

The processes developed in CELLUWIZ are:

1. Wet lamination of paper with a microfibrillated cellulose film (MFC) without the use of adhesives. This MFC layer makes the paper stiff, light and provides a barrier to air, grease and oxygen.

2. Coating and grafting process using "Chromatogeny", a technique that consists of the chemical surface modification of cellulosic materials to create a water-repellent barrier. In this technique, a fast, effective and solvent-free chemical grafting of hydrophobic groups to the paper surface confers a hydrophobic character to the paper surface, improving its barrier to liquids and water vapour.

The performance of the proof-of-concepts developed at CELLUWIZ (clamshells, trays and cups) will be at least equivalent to market references and will also be bio-based, recyclable in the paper value chain, biodegradable in compost and in the marine environment.


The processes developed in the projects mentioned in this article, together with continuous R&D&I of cellulosic materials, offer the possibility to give cellulosic materials (paper and board) new functionalities that did not seem achievable so far and thus give an important boost to this sector.

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