Spotlight: Making the move to bio-plastics

Materials World magazine
1 May 2018

Materials World talks to Nigel Flowers, UK Managing Director at Sumitomo (SHI) Demag, about injection moulding with bio-plastics.

For more than 50 years, global production and consumption of plastics has continued to rise. In 2016, 335 million metric tonnes were produced. However, support for the introduction of bio-based products continues to gain momentum, suggesting that wider market penetration is around the corner. Market data shared at the 12th European Bio-Plastics Conference in November 2017 indicated that global production capacities of bio-plastics are expected to grow by 20% in the next five years.

According to probiotics research and development company ProBI, Sweden, 85% of plastics could technically be substituted with bio-based plastics, reducing our dependency on plastics derived from fossil-based resources. Yet, right now bio-plastics represent around 1% of annual plastics production. Making a difference is a joint effort that requires industry stakeholders, manufacturers, suppliers, and consumers being better informed and educated about the challenges, and having legislative and regulatory frameworks that actively promote sustainable development and support innovation.

Until recently, the focus has been on bio-based PET. However, the scale of adoption has not been as rapid as previously anticipated. In Europe, the focus is now shifting to the development of PEF (polyethylene furanoate). Expected to enter the market in 2020, this new polymer is said to feature superior barrier and thermal properties, making it comparable to PET and therefore suitable for the packaging of drinks, food, and non-food products.

With the number of brand owners applying bio-plastics to their solutions growing, it poses an important question for injection moulders. 

Application depending

‘Manufacturers do not necessarily need to invest in new equipment,’ says Nigel Flowers, UK Managing Director at Sumitomo (SHI) Demag. ‘In theory, you can run bio-plastics through an injection moulding machine just as you would any other polymer. The main issue lies in how that plastic performs as an end product, which will dictate what applications it can be considered for.’

Drop-in plastics, such as bio-based polyethylene, PET, or polyamides typically have the same technical and functional properties as their conventional counterparts. Used in high-demand and durable applications such as electronics, building and construction, automobiles, and consumer goods, they can, for the main part, be processed and recycled in the exact same way. However, other innovative bio-plastics, including polylactic acid or starch-based plastics, desired for food packaging and in agricultural applications, have different properties, such as improved barrier or compostability. 

‘If the bio-plastic material’s properties differ from the material it’s intended to replace, it can impact production costs of the article in question,’ says Flowers. As a result, careful consideration should be given to the selection of the material and products chosen.

Meeting requirements

Some bio-plastics are yet to fully meet the performance requirements needed to lend themselves to more durable goods. That’s not to say it won’t happen. Heat resistance, enhanced moisture barriers, greater rigidity and flexibility, and durability are continuously improving. 

Automobile companies are making great strides. Bio-based or partially bio-based commodity plastics such as PE or PET are already being used for applications such as car dashboards. Currently, packaging is the leading segment, accounting for almost 60% (1.2 million tonnes) of the total bio-plastics market in 2017.

Bio-plastics are also good for jobs, with a recent EuropaBio study suggesting a more than tenfold increase in European employment opportunities by 2030, which would boost the development of rural areas, says the report.

Flying the green flag, although highly commendable, needs to be evaluated. If you break it down, switching to bio-plastics is not so much a machine dilemma, but a question of commercial viability and cost effectiveness. 

Although 80% of European consumers want to buy products that have a minimum impact on the environment, when it comes to packaging especially, cost constraints and what the consumer is prepared to pay for throw-away items will play a key role in future developments. All of this needs to be offset against the cost benefit of boosting a company’s ecological and sustainability profile. 

Discussions with bio-plastic material suppliers

Most questions at the outset should be put to the company supplying the bio-plastic materials, advises Flowers. Among them, moulders need to understand:

  • How will the material perform in use? How close this is to the material it’s replacing? Will the quality of the component be compromised or altered significantly?
  • How will the material be processed? In production, the quality of the end component is reliant on controlling the melt during the injection moulding process, so moulders need to fully understand the conditions. This question about bio-plastic melt stability would therefore need to be discussed with the materials supplier.
  • How do the processing conditions vary? Ask the material supplier to provide comparison data, such as cost variations, mouldability, look and feel of components, strength, and load weight. Equipped with this information, a moulder can make a more informed decision about the feasibility of switching to bio-plastics. At this phase you may progress to a process trial to see how the material performs in your existing injection moulding equipment.