Small steps in material science can lead to great leaps for packaging

Everything in its place

Martin is careful to qualify his comments on paper – just as paper isn’t the solution to every problem, there are just as many applications where it works just as well. “We need a clear understanding of where these materials fit, how they’re used, and their practical limits. If I had to wrap a chocolate bar, I could put it in paper tomorrow—no problem. A cereal bar could also be in paper, but that paper would need to be coated with plastic. If it’s a pouch for liquid hand soap? Not a chance.”

There are no heroes and villains in this story – just complex compromises. That applies to exciting new innovations as much as it does to the existing technologies that the industry is working hard to improve. “Take biopolymers,” he says. “They have their benefits, but to a certain point. For Europe, they’re a nightmare because Europe and the UK are taxed based on recyclability and recycled content. Unless a biopolymer can be recycled through mainstream processes, it’s not as useful.

“We’ve evaluated them all, and there are issues. PLA, for instance, is often praised, but it contaminates the waste stream. PVOH and PVA are alternatives, but they’re still polymers, regardless of their feedstock. What we’re finding is that biopolymers are great at the front end but problematic at the back end. Only certain types really work well, and they are good for replacing plastics in specific applications, like components within components – coating trays, or coatings on boxes, for example. They work well in these cases because they get washed away in the recycling process at paper mills, which use chemicals like alcohol and acids to break things down.

“In my opinion, biopolymers have their place, but only for very specific products that can’t be recycled.”

A solution for every market

At this point, it’s easy to start questioning what the ideal solution actually is – or if it even exists at all. But as Martin argues, looking for one magic bullet solution is the wrong approach. “I always tell my team, don’t approach everything with blinkers on. Look at it in terms of what is the best material for the specific product, the solution, and the market you’re targeting because not everything will work in every market. It’s as simple as that.

“So, we have to balance all these factors. You have to keep an open mind, with no preconceptions, because there’s always something new and unexpected. We’ve even seen old technologies like casein [milk protein-derived polymers first introduced in the early 1900s] make a comeback because it’s a natural source that can replace synthetic polymers in glues for laminating bottles, labels, etc.

“We also look at polymers derived from other natural sources, like chitosan, which is made from crustacean shells, the second most abundant polymer source in the world. A company in Scotland has developed a process to turn it into a usable material that’s now going commercial. It’s great, but the price is still high, and everyone’s testing to see where it could be used.”

Does Martin think this is likely? “It’s a promising story if used in the right way. The first thing we would ask any innovator is, ‘What’s the end-of-life solution for this material?’ If it creates a waste profile we can’t manage, we’re not interested. You have to think about both the business needs and the environmental impact. It’s great if a startup offers something better than what we have now, but if the end-of-life solution doesn’t align, there’s an imbalance, and the material’s application becomes limited. This is why, while many bio-based materials may look fantastic, the key question is: what’s the end of life?”