Materials

There is something of the Jekyll and Hyde in current consumer perceptions of packaging materials, particularly plastics. In some people’s eyes rigid plastic makes convenient and safe packaging, while others think it is wasteful and polluting.

But it is not just in consumers’ minds that plastic has a poor reputation; some parts of the packaging industry still see it as a ‘bad’ material, even while it continues to win ground in new markets and formats.

Plastic has been successfully competing against other materials on a range of fronts, and barrier polypropylene (PP) has been a particular success story. By incorporating an ethylene vinyl alcohol (EVOH) layer into clear PP, converters such as RPC have helped to transform the long-life fruit sector, despite some real performance disadvantages. The pack used by sector giants such as Dole is a great example of logic-defying marketing. Despite price premiums of 50% and over, compared with the longer-life tinplate alternative, use of these plastic packs has been directly credited for the recent 3-4% growth in this sector.

Vince Dean, sales and marketing manager at RPC Corby, asks: “Why would people buy a plastic jar rather than a can, when it costs more and is more difficult to process and recycle?” He might have added that the shelf-life is shorter too, since even barrier PP is unlikely to stretch to more than two years.

The answer lies in the fact that many consumers see plastic packaging as a safe and convenient format, and associate it more closely with fresh, healthy food. They like to be able to see the product through the pack without having to worry about the fragility of glass.

As health concerns continue to threaten parts of the children’s soft drinks market, Dean even sees potential for plastic-packed fruit products in the vending sector. And the same type of barrier structure already has its foot firmly in the door of the ambient protein-based salads and snacks sector.

Significant challenges
In the beverages sector, plastic is doing battle with glass and metal, the established materials for beer packaging, but cost and performance, rather than environmental concerns, are the sticking points.

Advocates of glass and metal point to the problems that PET has with light and oxygen degradation, arguing that the problem of oxygen ingress worsens as unit sizes come down. This means the small bottle sizes favoured in Western Europe will either have to have a short shelf-life or will require prohibitively expensive barrier solutions.

Naturally, no one in the industry can discount the possibility that more effective and affordable barrier solutions will be developed, but bottle and can manufacturers are not panicking just yet. John Hayes, president of Ball Packaging Europe, predicts: “Among those discriminating consumers who understand their beer, PET is unlikely to be of great significance.”

Peter Davis, director general of the British Plastics Federation, disagrees. He says the “long-awaited beer bottle revolution”, where rigid plastic replaces glass, still hasn’t happened in the UK, but that doesn’t mean it won’t. For sporting events, festivals and outdoor drinking, he says the police and waste authorities would prefer plastic to be used to bottle alcohol.

Other countries are already doing it, he says. In Denmark, Carlsberg has established a reusable beer bottle chain where customers receive credits for returning bottles to be industrially cleaned and refilled.

In many ways, retailers have followed consumers in their often violently conflicting views of plastic packaging. Adam Barnett, marketing manager at Linpac Plastics, points out one specific clash between the environment and profitability: the current publicity given to stores selling loose fruit and vegetables. “There’s always going to be a requirement for loose fruit,” he admits. “But if you choose not to package premium fruit, then it won’t stay premium for long.”

He believes the market for punnets and trays that offer protection for fresh produce will continue to grow, but using packaging and materials which are seen to be sustainable.

Like other converters of rigid plastics, Linpac has felt the need to offer biodegradable polymer options to customers. But as Barnett is quick to admit, as a recycler, the company also recognises some of the potential pitfalls with this new generation of materials. “We can supply polylactide (PLA), but our own recycling division would be seriously damaged by the emergence of PLA in the waste stream,” he explains.

Linpac’s own preference would probably be for options such as its R-Fresh range, PET that incorporates food-grade recyclate. By combining virgin polymer and post-consumer recyclate (PCR) in primary and secondary packaging, says Barnett, converters, brands and retailers can create “a true closed loop”.

Niche growth
There are other examples of growth for rigid plastics, many of them in niche rather than volume applications. For instance, a few months ago Linpac introduced its Linfreeze blended polymer range for categories, such as parts of the baked goods industry, which require blast freezing. The blend, originally developed for a UK frozen food customer, can withstand temperatures down to -40°C.

In a very different sector, Surlyn serves as a prime example of the way in which specialist plastics are transforming the cosmetics and personal care markets. This particular material offers the aesthetics of glass with none of the disadvantages. But RPC Beauté France points out that it also lends itself to several types of special effects and finishes, from multicolour co-injection moulding to overmoulding and electroplating.

However, once plastic stops being packaging and becomes waste, consumers find it harder to see it as a super-hero.

Consumer acceptance
If there is slightly less doom and gloom today about plastic packaging waste in the UK, it is down to battles being waged by the likes of the Waste and Resources Action Programme (Wrap) and its supply chain partners. Separate projects for PET and HDPE recycling are well advanced, with capacity in both polymers promised for the first half of next year.

Wrap has also collected research which shows that consumers have no objection to recycled content, says plastics technical manager Paul Davidson. For instance, only a negligible proportion of consumers were concerned about PCR content in baby food packaging.

Perhaps most importantly, Wrap reports evidence that recycled content in plastics packaging is likely to have a cumulative impact on the level of participation in further recycling.

Davidson takes a longer-term view: “Glass containers have been seen as environmentally friendly because they are easily recycled. But plastics could challenge that and win.”

Measured against any criterion, whether performance-based or aesthetic, plastics continue to prove that they can challenge traditional materials. But increasingly, and importantly, in many cases sustainability is being added to that list of criteria.

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CARTON-FREE CARTONS
Board-orientated purists may prefer the term ‘boxes’ to ‘cartons’, but applications for clear plastics – particularly polypropylene (PP) – in this format are increasing, largely due to a combination of improved material clarity and higher quality in print and other converting processes.

Simon Lewis, marketing director at Arjo Wiggins company Priplak, says there was little enthusiasm a decade ago for using offset litho printing on clear PP. “Even five years ago, it would have been considered a difficult substrate. But since then, the polymer itself, press technology and inks have all improved.”

Lewis says that developments with large-format presses have been particularly impressive. In fact, these materials will run on most offset presses equipped with UV drying. “Having a corona treatment option at the front end of the press will help with ink key, depending on the age of the material,” he says. “A lot of the big packaging houses are gluing PP, and corona treatment can help to prepare the surface for that, too.”

Neal Whipp, an experienced converter and consultant to the British Printing Industries Federation (BPIF) carton group, believes that volumes of plastics for cartons may have increased in recent times. But he says: “A number of carton converters have found the printing stage to be the least contentious part of the process with plastics. But all of them have underestimated the issues of cutting and creasing the material.”

Applications have come in both food and non-food areas. In recent years, Tesco has been among those using a rigid, clear PP sleeve to differentiate its products in the ready-meals sector. Wines and spirits have also benefited, from French Champagne to Johnnie Walker whisky.

High-profile non-food uses of printed, clear PP cartons have included GlaxoSmithKline toothpaste brands, and others where the ability to incorporate a Euroslot has been an important consideration. A high concentration of this distinctive format is to be found, for instance, in any Marks & Spencer (M&S) underwear department.

Having made a very public commitment to sustainability, in packaging as elsewhere, M&S may have other reasons for appreciating the polymer, not least its relative lightness. “After all, for chains intent on reducing the overall weight of their packaging, being able to use up to 35% less PP than alternative polymers for a given pack can make a huge difference,” says Lewis.

In the sustainability stakes, oil-derived polymers also face competition from bioplastics. Mead Westvaco company AGI/Klearfold has its NatureSource PLA folding cartons. The format has been available for over a year.