What is the reality of ‘green’ packaging?

From the time that plastics materials were first used in packaging, back in the 19th Century, the debate has been over their effectiveness, and, in more recent times, has been directed towards their long-term effect on the world in which we live. Bioplastics are not new. They were first produced more than 100 years ago and, with added new compounds, are now seen as direct replacements for their pure petrochemical rivals in certain applications.

Today, bioplastics can be categorised in two distinctly different ways, which are often erroneously confused. They can be biodegradable (and possibly, but not necessarily, compostable), or they can be produced from a renewable source. Biodegradation, technically speaking, is a natural process, and is measured by the production of carbon dioxide. Non biodegradation requires the use of additives.

The second type of bioplastics is that which is manufactured from renewable resources, which themselves are not necessarily biodegradable. An example of this is Bio-PE.

The major growth in the use of bioplastics film in recent years, currently running at around 30% year on year, has been in the food packaging industry, where the product’s biodegradability is perceived to be of value by the consumer. The food manufacturers and retailers have been quick to link the ‘good for you – good for the environment’ message in their promotions, and this is driving demand.

Other areas of growth are waste bags, agricultural products, and the personal hygiene sector. Demand is also growing for the renewable resource based bioplastics – this is in the perishable goods market too.

Public perception is a key driver here, and has moved the criteria for consumer spending. Price is no longer paramount, and an awareness of other factors, such as recyclability, sustainability, and health issues all add pressure to consumer choice, though, as with higher priced organically grown foodstuff, an economic recession that puts less spending money in shoppers’ pockets, tends to stall the upward trend in ‘green buying’.

In general, though, the public enjoys the opportunity to shop for packaged goods, where the packaging has an ‘after-life’ in terms of secondary use.

So-called raw bioplastics are unsuitable for certain applications, and it is only by modifying them with compounds and additives that they become easy to process and suitable for the application intended. PLA and PHA fall into this category.

One German company, FKuR Kunstoff, has developed special resins that, when added to the raw plastics, make the hybrid product ready to use, with improved stability. The company’s Bio-Flex and Biograde are manufactured from renewable resources and can be converted normally on standard equipment.

Improved performance

Another company working on development in this field is Henkel. Mindful of the dwindling reserves of fossil fuels, and aware of the ready market acceptance of bioplastics, it has teamed up with Tecnaro to develop new high performance polyamide additives to improve the performance of bioplastics. Moreover, the additives are based on renewable resources. The natural raw materials in ‘Macromelt’ are based on the fatty acids in rapeseed and tall oil. The additives are claimed to reduce processing temperatures and stress on the fibres, which improves stability and appearance. Arboform, Arboblend, Arboflex, and Arbofill are the brand names to look out for.

The issue of how to improve existing materials by using biopolymers was discussed recently at the SPF 2010 conference in Düsseldorf. These included details, from the Fraunhofer Institute for Process Engineering & Packaging, of a project called ‘Wheylayer’, which is EU sponsored, and replaces existing polymer coatings with whey extract produced by the dairy industry. Results to date are promising, with over 150 blends already trialled on PLA and PHA bases.

Another technique discussed, by VTT Technical Research (Finland), was ALD (Atomic Layer Deposition), in which, for example, an ultra thin layer of metal oxide is coated onto the film to provide oxygen and vapour barriers. Trials of the process have been sufficiently successful for it to be adopted for high volume applications, including high barrier coatings in biopolymer films.

A third technique for PLA recycling is Loopla, a process based on chemical treatment of PLA, using lactic acid. Pretreating used PLA, prior to processing, to produce virgin material, has shown yields of almost 100% in volume and similar success in terms of quality. Although PLA is biodegradable, a better use of its original production cost (and effect) is re-use. The process is said to be robust, low on energy consumption, and tolerant of high levels of contamination. One company in Belgium, Galactic, is already producing 2,000 tonnes per year using the Loopla process.

The conference also offered opportunities for manufacturers and users to compare notes. Film producer, RKW, vouched that, from its own experience, PE bags were often more environmentally friendly than a biodegradable polyester alternative, or even a paper sack with a PE liner.

Using diaper backsheet, shrink sleeves, and flow wraps to illustrate the point, the company concluded that conventional technology, if managed correctly, can still offer the best solution to packaging and sustainability demands.

Innovia Films, the manufacturer of bioplastics made largely with wood pulp from managed forests, listed the ways in which its new NatureFlex films are designed to meet user criteria.

Citing raw materials, manufacturing process, functionality, and end of life treatment as the four pillars of sustainability, Innovia claimed the key issue is functionality, which highlights the wastage of the package contents. This is especially the case in the perishable goods market (food), and the latest NatureFlex NK caters for this with a vapour barrier capability similar to BOPP.

While the drive is on to develop new packaging films, and particularly ones that cater for specific applications, the existing technology continues to be used and needs to be accommodated in society. Nowhere is this more clearly thrown into focus than in Italy, where, at the beginning of the year, the Government banned the retail trade from handing out plastics carrier bags to shoppers. Roundly condemned both inside Italy and out, the ban poses an awkward question other regulatory bodies will need to consider carefully before taking action.

In Italy’s case, the situation is brought into sharp focus because of its high level of plastics bag consumption – thought to be around 20% of the total for the entire EU, and also because the manufacturing plants for these bags are located in the south of the country, where unemployment is already high, and due to go higher as workers are laid off. The knock-on effect is both commercial and social.

Other regions involved in some kind of restrictive legislation include: the UAE, which is proposing a ban on plastics carrier bags by 2013; China, where, since restrictions on plastics bags came into force in 2008, usage has dropped by 40 billion bags, saving the equivalent of 1.6 million tonnes of crude oil; and Ireland, Mexico City, and several states in the USA, where individual charge per use, or fines on retailers have significantly curbed the use of plastics bags.

Assessing ‘impact’

The situation, however, is far from clear and straightforward with regard to ‘impact on the environment’. An independent study carried out in the UK, for example, reported that the conventional HDPE bag has the lowest impact of all lightweight bags in use, while the cotton bag, often seen and cited as the replacement, has a far greater impact. The statistics relate to ‘full life cycle’, and compute all costs and impacts from raw material, through manufacture, to usage and re-usage, and all elements associated with each phase of the bag’s life.

To quote the figures used, a cotton bag needs to be re-used 174 times to have less environmental impact than the average HDPE bag. So, who gets to count? A life cycle study by a German institute showed similar results, with PE bags having less impact than biodegradable bags in general. The study compared virgin and recycled PW resins with their bio-counterparts, and in every case, the conventional technology proved the winner. What defines their usage appears to be their respective properties, with the bio versions seemingly less appropriate for high performance packaging, but holding a distinct advantage on the fresh food market.

Affordability

Inevitably, price is also an issue, and it’s often a case of ‘how green can we afford to be?’ more than ‘how green can we be?’ Recent estimates put Europe’s potential use of bioplastics at 85%, but despite an annual growth rate of 15-20%, market share is still low – and in the current economic climate is likely to stay that way if the natural laws of supply and demand remain.

Currently being held aloft as a beacon is Oxo-biodegradability, which according to one industry expert, ‘will not only survive competition from other plastics, including bioplastics, but looks set to increase its worldwide share dramatically’. The statement, from Michael Stephen of Symphony Environmental Technologies Group, said that no other plastics was as suitable for solving the problem of plastics that finds its way into the environment, and would otherwise lie or float there for generations without degrading.

He commented: “It has the same strength and versatility as a normal plastics but is specifically designed to address the problem of degradation, because at the end of its pre-determined lifespan, it converts in the open environment into a material with a completely different molecular structure. At that stage, it is no longer a plastics, and is inherently bio-degradable in the same way as a leaf.”

Stephen insisted that this core value was appealing to food companies and retail groups who are desperate to protect their brands, and see this as a way of combining ‘green credentials’ with little extra cost. “The industry is beginning to realise that it needs to protect itself from allegations by environmental groups, and governments that are keen to impose legislation,” he added.

Perhaps the final word should go to a leading UK converter of flexible packaging, whose comments on ‘green films’ are not directly repeatable! But, to paraphrase his thoughts: “The opportunity to punish packaging converters with ‘green issues’ is a useful diversion from the socially and economically unacceptable levels of waste that occur every day in the food retail chain. Until the quest for perfect packaging is replaced by a more realistic attitude from the brand owners, the damage to the environment will continue, irrespective of the packaging material used!”