In development: innovative food packaging
In development: innovative food packaging
Biobased plastics are not currently widely used in injection-moulded food packaging, such as salad trays or butter dishes. A new research project focusing on the realisation of price-competitive food packaging from biobased plastics should change this. The challenge within the project is to be able to injection-mould transparent biobased plastics that are actually too viscous for this as thinly as possible.
Food producers are interested in packaging made from biobased plastics. Nevertheless, there are no biobased plastic tomato buckets or butter tubs on the market on a large scale yet. 'Interest in biobased packaging decreases drastically as soon as you start calculating what a switch to such materials costs,' argues senior researcher polymers Gerald Schennink of Wageningen Food & Biobased Research. Niels L'Abée, director of SFA Packaging, has exactly the same experience. 'We get limited questions from customers. But at the same time, everyone thinks that more environmentally friendly packaging should actually be there. Especially among consumers, this trend is clearly visible.'
Thin-walled injection moulding of biobased plastics
L'Abée therefore took the initiative together with Wageningen Food & Biobased Research to find out whether biobased plastics can be made more suitable for these kinds of applications. Recently, a public-private research consortium within the Top Sector Agri&Food was started for that purpose, in which, besides SFA Packaging B.V. and Wageningen Food & Biobased Research, Arburg B.V. and TN Plastics B.V. also participate.
There are now many bio-based plastics on the market and most of them are perfectly suitable for making films. Schennink: 'Food packaging films should preferably be strong and rigid. Lactic acid (PLA), which is naturally biobased, possesses these properties. But complex-shaped food packaging is not made from film, and alternative production methods place very different requirements on a material.' Injection moulding is one method of producing this type of food packaging. This involves injecting molten plastic into a mould and then cooling it in the mould. Commercially available biobased plastics flow relatively difficult by themselves, so it is not possible to replace a conventional plastic one-to-one with a biobased plastic.
Thinner and cheaper
A simple technical solution is to make the packaging product slightly thicker-walled. But because the material costs of biobased plastics are higher than those of conventional plastics and biobased plastics also have a higher density per unit volume, such a solution is cost-prohibitive.
The project focuses on three innovations. First, it will investigate whether the flow behaviour of bio-based plastics can be improved by smart additives. Secondly, the project partners will find out whether the production process can be improved. The idea here is not to close the mould completely, but to inject the plastic into it first and only to close it completely once it is well distributed in the mould. This so-called compression injection moulding technique already exists, but it needs to be investigated whether this leads to the desired effect with bio-based plastics: food packaging with thinner walls than conventional plastics, so that less plastic is needed and the packaging becomes cheaper. Schennink: 'This is where the mechanical properties of biobased plastics work in their favour again; they are often very stiff by themselves.' A thin wall is essential in this project, as this is the only way to save on the amount of material.
Extra layer
A third innovation focuses on the barrier effect of packaging. A tray for biscuits not only keeps the product clean but also fresh. That's because it barely lets water vapour through. 'We're not going to achieve that with PLA, because it has a limited barrier to water,' argues L'Abée. 'But we want to see if we can add an extra layer in such a container that does have the right barrier properties.' That sounds complicated, but food packaging is often layered. This involves printing the imprint on a pack onto a wafer-thin film, which one presses into the mould along with the plastic and fuses with it. This technique - in mould labelling - is already used for marketing purposes because, once the packaging is moulded, it is difficult to print on it.
The ultimate goal of the project is to arrive at cost-effectively producible biobased packaging that results in about half the CO2 emissions per unit of material and production compared to conventional plastics. This will give consumers the opportunity to choose a "greener" alternative. L'Abée: 'Now consumers don't have that choice, because an alternative is simply not available. Soon, a product might cost a bit more, but then the market will show whether consumers are willing to pay that extra price for the environment.'
