Lightening the load

C&I Issue 21, 2007

  • Flexible packaging currently accounts for 21% of the European thermoplastics market, or around 8m t/year
  • Most of these polymers are used in multilayered films produced in the form of laminates or through co-extrusion systems
  • Biopolymers and metallocene polymers are the two classes of polymers in flexible packaging with the fastest growth rates – each with average double digit gains. Metallocene catalysts have simplified the process of resin manufacture by providing versatile polymers suitable for a range of flexible packaging tasks
  • Co-extruded polymers are now increasingly preferred by converters rather than laminates, because they tend to use less polymer, sealants and other additives, and require fewer processing steps

Much seems to be working in favour of the flexible packaging sector at the moment. Pliant polymer films are able to respond to the need for convenience, ready-made meals, safer food and smaller packs because of more single-person households. They are also helping to reduce energy consumption, lower emissions of carbon dioxide, reduce waste and increase productivity among film producers, logistics firms and retailers.

Flexible packaging sales have been growing particularly strongly in Europe where it now amounts to around 8m t/year or 21% of the thermoplastics market, according to UK-based market research organisation, Applied Market Information (AMI). Its popularity has been maintained even in the face of steep rises in the cost of polyethylene and polypropylene, because resin producers and converters have provided films that curb packaging volumes.

‘The Western European flexible packaging market is far more sophisticated than that in the rest of the world,’ says John Thompson, marketing manager for film and fabric at Borealis, one of Europe’s leading polymer resin producers.

Large parts of the flexible packaging market in Europe, the US and Japan have become specialty segments with growth rates well above those of GDP. In Europe, the flexible packaging market has been expanding by value at around 4-5%/year but parts of the sectors for shrink and barrier films have been surging ahead at double digit levels. In relation to the average rise in GDP, it has been growing at the same rate or even faster than in the emerging economies of India or China.

‘The strongest market trend has been downgauging,’ says Gloria Vendrell, Total Petrochemicals’ European marketing manager for polyethylene film. ‘It has resulted in less packaging and more convenience for the consumer, and has allowed the meeting of weight reduction targets according to environmental and sustainability challenges.’
For retailers and manufacturers, it also means less weight to transport. ‘Bottles, cans, and paper and board are much heavier to carry in trucks than flexible packaging,’ says Nicolas Kokel, responsible for Catalloy film development at Basell.

Because of the diverse requirements in flexible packaging, a wide variety of polymers and combinations of polymers are used. Most of them are employed as multilayered films produced in the form of laminates or through co-extrusion systems. ‘With monolayers you do what you can, while with multilayers you can do what you want,’ says Vendrell.

German film packaging company Kloeckner Pentoplast uses over 20 different mono- and multilayer films for barrier food packaging, with 15 different polymers. These range from individual applications of polypropylene (PP) and polyethylene terephthalate (PET) to single combinations of PP, polyethylene, polyamide, polystyrene and ethylene vinyl alcohol (EVOH).

Multilayered films allow sealant and adhesives producers to reinforce or add to the properties of the packaging barrier. DuPont has recently introduced a sealant for meat packaging that improves its breathability for gases while giving clarity to the film. It also has environmental benefits since 30% of the sealant comes from renewable sources.
Nanotechnology is also becoming a feature in multilayered film. Basell, for example, has recently developed a resin allowing vacuum deposition of uniform nanoscale aluminium particles on biaxially oriented polypropylene (BOPP) film, providing a big improvement in barrier properties.

Due to its tendency to use less polymer, sealants and other additives, and to require fewer processing steps, co-extrusion is now being preferred by converters rather than laminates.

‘Laminated systems are tending to be replaced by co-extruded structures which require fewer processing steps for the converter and are generally cheaper, easier and less time consuming,’ explains Andreas Goeldel, responsible for polyolefins solutions and product development at Basell.

‘Overall in flexible packaging the current priority is to raise efficiency but at lower costs. This means simplifying the whole process for producing films,’ he adds.

Metallocene catalysts have simplified the process of resin manufacture by providing versatile polymers suitable for a range of flexible packaging tasks. First discovered in the 1950s, metallocenes have only begun to find a significant role in flexible packaging in the past few years. These sandwich-shaped molecules catalyse the synthesis of plastics with the sort of combinations of properties needed in today’s packaging films - in particular, stiffness, transparency, a high melting point and flexibility. Furthermore they can be designed for specific polymerisation processes so that highly customised resins can be produced.

In the packaging film sector, metallocene polymers, predominantly polyethylene, account for well under 10% of sales. But demand is growing rapidly in some key segments. The use of metallocene resins for collation shrink film, for example, used to bring together products like beverage containers in single packs, has been growing at rates of over 60% a year in Europe, according to AMI.

Metallocene polymers are being used in the outer layer of co-extruded shrink films in order to provide a high gloss surface for printing graphics as well as improved transparency so that shoppers can see the products inside the package. AMI predicts that the share of printed collation film will rise from 12% in 2006 to 19% by 2011.
European demand for metallocene resin in flexible packaging will be boosted by the entry of Ineos Polyolefins into the sector this year and of Sabic Europe, scheduled for 2009. Currently the metallocene market is shared by ExxonMobil Chemicals and Total Petrochemicals, both of whose metallocene catalyst technologies date back to R&D work in the 1980s.

Ineos highlighted the difficulties of developing metallocene technologies. The launch of its new metallocene product range in September had been the culmination of a lengthy period of plant trials and customer testing. ‘Our metallocene polymers are not me-too products,’ says Richard Cudd, film sector technical services manager at Ineos. ‘They offer advantages to converters over current commercial grades, particularly in the area of processability. We can demonstrate this value in a wide range of end-uses.’

Because of the long time it takes to commercialise new catalyst technologies, metallocene polymers are likely to have a competitive edge in some key parts of the flexible packaging market for the foreseeable future. As a result their share of the sector could rise well above 10%.

‘There is a lot still to be done in realising the full potential of metallocene technologies in flexible packaging,’ says Vendrell. ‘We are learning more all the time about metallocene polymers, particularly in our partnerships with downstream users on improving existing products and developing new ones to keep a competitive advantage.’
While converters and film producers are seeking ways of raising the efficiency of their processes, consumers are looking for more eco-friendly packaging. Retail chains have responded to the wishes of their customers by pledging to make greater use of renewable materials in packaging of materials like polylactic acid (PLA), which is made from corn or sugar beet.

‘Consumers do not like packaging but they have a positive view of   biodegradable packaging,’ says Malcolm Cohn, marketing manager  for the Americas at Innovia Films, Wigton, UK, a maker of biodegradable cellulose-based films. ‘It makes them think they have done their bit for the environment.’

Even producers of petrochemical-derived flexible packaging are now aiming to diversify into biopolymers. Total Petrochemicals and Galactic, a Belgian producer of lactic acid, have just agreed to set up a 1500 t/year joint venture pilot plant for developing an improved grades of PLA plastics.

‘We want to enhance the properties of PLA is areas like temperature resistance and mechanical processability,’ says Jean-Michel Brusson, biopolymer R&D manager at Total Petrochemicals Research, Feluy, Belgium. ‘We don’t
  see PLA matching the qualities of   major polymers like polyethylene   and polypropylene but it can be   complementary to them with its own specific properties.’  In some retail chains, compostable films have already found a niche in the packaging of fresh fruits and vegetables because their permeable structure allows moisture to pass in and out of the pack.

The two classes of polymers in flexible packaging with the fastest growth rates – each with average double digit gains – will be biopolymers and those based on metallocene catalysts. They will each reflect two contrasting needs:greater efficiency at lower costs and preservation of the environment. The flexible packaging sector will need to continue to reconcile both if it is to maintain its strong growth.

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