Stand-up pouches are not new. The technology was first developed some 40 years ago. Japan has been prominent in the use of stand-up pouches for well over a decade, spurred on by developments in film technology by leading packaging companies such as Toppan, Mitsubishi and Dai Nippon says Amcor Flexibles Europe business development director for processed food Jonathan Fowle
The European market is reckoned to be worth in the region of 6bn units and growing at least 10% per annum. Acceptance began to accelerate in the mid 90s following the introduction of wet pet food in this format.
With a shelf life comparable to a can, portion control, lightweight packaging and a perception of high quality, it is not difficult to understand why consumer acceptance was positive. Since then significant developments in pouch filling speeds and laminate performance have enabled a more cost-effective supply chain.
Historically, steel cans and glass jars have been used to pack food products as diverse as pet food, baked beans, fish, soups, fruit and vegetables. The combination of a sterile product, a long shelf life under ambient conditions and a good, consistent product quality has proved a winner with consumers. Reliability and safety have been the watchwords.
In the same way with canning, sterility is achieved for pouched products through a retort process. Typically, after filling and sealing, products are placed in a closed chamber (autoclave) and subjected to elevated temperatures for a sustained period.
Pack pressure is carefully controlled to prevent bursting. To be fully effective in achieving the desired level of sterility, retort temperatures generally kick in at around 120 deg C and for some demanding products 130 deg C is exceeded. Retort cycling times vary from a few minutes to up to an hour and even beyond.
For the converter, the retort process places heavy demands upon laminate performance. Aluminium foil provides the core protection against ultra violet light, oxygen and moisture transmission.
For the most demanding applications, a four-ply specification is utilised where the alufoil is protected on both sides by an oriented film such as polyester or BO Nylon. The act of ‘burying’ the foil improves puncture resistance and flex strength, so vital to limit pin-holing and prevent product deterioration.
Due to its heat tolerance, cast PP is used almost exclusively as the sealant layer. Recent developments have focused on down-gauging without sacrificing rigidity, improving pouch-making performance and introducing easy tear characteristics. Selection of substrates, inks and adhesive types are all of decisive importance in the retort cocktail, as are the conversion conditions.
What appears to be a very solid bond can change into a de-laminated package post-retort if due care is not exercised. Inks also tend to lose their performance if they are not thermally stable.
Many canners have shown reluctance to embrace the new technology due to the inferior speed of pouch sealing compared with canning lines, which typically operate in excess of 1000/min.
This snapshot fails to embrace the supply chain benefits to be derived.
Steel can walls are typically many times thicker than the 9-micron aluminium foil used in flexible laminates. This means that heating up of the product in the centre of the pouch pack is achieved much faster.
In other words, sterility is obtained with less energy consumption. The gentler retort process may also be decisive for product quality. Add to this the undeniable logistical benefits such as reduced transport costs and less warehousing space for pre-filled packaging. Fig. 1 details a comparison of the number of lorries required for empty rigids versus pouches.
Packing machinery manufacturers such as Toyo and Thimonnier have not been dragging their heels. In the last five years there have been significant developments in operating speeds of filling and sealing machines as illustrated in Fig. 2. November’s Pack Expo in Chicago highlighted that this trend is set to continue.
At this point we should pause to consider why filler/packers should wish to opt for buying pre-made stand up pouches rather than using laminate in reels which can be formed, filled and sealed on reliable equipment such as Volpak, Bossar and Laudenberg.
The Chicago show illustrated that such companies are also being pro-active in the rigids replacement market, with R A Jones unveiling their new Pouch King, capable of producing up to 500/min. While dry products only are possible today, wet applications are envisaged.
Manufacturing pre-made pouches with bottom gusset – to enable the ‘stand up’ effect – is not a simple process. Typically the fronts and backs are made from one reel of laminate and the narrow gusset material is fed in from another reel.
The two reels are fed through intermittently and sealing is effected through heat and pressure. Depending upon pouch size, four-lane pouch machines are typically used for 100g and two-lane for 400-600g sizes.
Constant focus on cost-effectiveness means that modern stand-up pouch machine cycling speeds have ramped up to greater than 100 strokes/min.
The areas where the bottom gusset material is sealed to the body of the pack are the most vulnerable. Choice of polypropylene sealant with good ‘hot tack’ strength and appropriate melt flow index is crucial if micro-leaks are to be avoided where multi-layers of material are being fused together. Zero defects are essential to ensure product safety.
Marketeers are attracted to the all-over graphics that stand-up pouches can offer, even having the option of utilising the bottom gusset for random printed text. They are not shy of full frontal graphics within a solid ink border.
This not only places great demands on the pouch-maker to maintain stand-up pouches made with perfect print registration but also the con-verter to maintain extremely good inter-ply adhesion. Add to this the vigilance of avoiding seal contamina-tion with liquids [such as soups and sauces] and pastes [say pet food] and it is not difficult to understand why packer/fillers opt to make only the top seal [pre-made stand-up pouches] rather than undertake the complete form-fill-seal cycle.
Flexibility also plays a part, particularly as product life cycles become ever shorter and brand proliferation intensifies. Global reach increases the size of the prize but often at the expense of many and frequent print changes and different pack sizes to accommodate diverse cultural tastes.
Pre-made pouches tend to confer faster changeovers and lower waste.
The ability of the pouch maker to offer add-on features such as drinking spouts, pouring taps, handles and shapes is assuming greater importance. Improved consumer convenience is on the wish list of most marketeers.
The dynamics of the European retort pouch converting market [table 1] are rather interesting.
Companies such as Pactiv, Frantschach, Cellpack, Fruh, Goglio and LPP are also believed to be active.
Strategic considerations revolve around in-house or outsource to pouch making specialists and whether to pouch on the same site as mainstream flexibles conversion or have a dedicated, stand-alone business unit.
Amcor has chosen the latter course, believing that the quality assurance, technical and engineering disciplines that are required for highly efficient pouch making should not be compromised. It is striking that, in a relatively labour intensive manufacturing process, none of the mainstream pouching sites are in any so called ‘low cost’ countries. Furthermore, the specialist pouching contractors are located in Germany and Switzerland.
It is not surprising that companies such as Alcan and VAW have utilised their downstream foil-rolling capabilities to develop retort business. Their proposed alliance will make them a major player in the wet pet food sector.
While this market continues to exhibit double digit percentage growth, dramatic increases are being seen in the transparent retort pouch market.
From its present relatively low Western European base of 250-300M units, widespread consumer accept-ance is likely to rapidly push sales to the 1bn level, the key driver being microwavability in the pack.
No can opener, no messy saucepans to wash and easy pack disposability has prompted the launch of soups, cooking sauces and rice meals. Well known brands packaged in this format convey trust and reliability, spiced up with mouth-watering graphics.
Japanese converters were the first to capitalise in Europe, taking advantage of the learning curve from their home market. Developments with high barrier coatings have been highly successful and such technologies are now being developed rapidly in Europe.
Traditionally, alufoil has been regarded as virtually absolute in protection afforded against UV light, moisture and oxygen.
This is why a shelf life of more than 12 months under ambient conditions is possible with an alufoil laminate. Comparable shelf life is now being achieved from transparent barrier specifications.
The main applications are inorganic coatings of aluminium oxide or silicon oxide, both applied by physical vapour deposition.
A typical barrier coating substrate is polyester. Although, achieving a super barrier that will be sufficiently robust to withstand the high temperature and humidity of the retort process is far from straight-forward.
These very thin coatings are easily damaged and great care must be exercised during printing and lamination.
Typical oxygen barrier achieved post-retort (121 deg C, 30 minutes) is around 2cm3 [m2 dbar] at 23 deg C, 75% relative humidity, derived from a 3-ply laminate incorporating Alox or Siox coating, two layers of oriented plastics films and a cast PP sealant.
The European leaders in this market are believed to be Amcor and Alcan. Following its acquisition of two former Rexam businesses in 2002, Amcor is now capable of offering CamClear, an Alox-coated Polyester. It combines this with further conversion to offer HeatFlex, a range of heat processable laminates. Alcan has invested in Siox coating, marketed as Ceramis.
The dried pet food market is rapidly moving out of paper based materials into plastics. While reel fed materials are widely used, pre-made stand-up pouches with features such as carry-handles and re-sealable zippers are being adopted for multi-serving packs. Bennington Foods recently introduced such a 1.4kg pack in a 2-ply poly-ester/PE laminate.
One of the latest developments to meet the demands of convenient and efficient resealability is slider tech-nology. The slider is self-explanatory to consumers. It adds significant cost but is already finding applications in Europe for soil compounds.
Peel Plastics of Ontario, Canada, has several pouch/bag-making machines fitted with SlideRite applicators [Fig. 3], including Pactiv’s slider version.
Amcor Flexibles Europe is teaming up with Peel to serve the European market with AFE distributing pre-made pouches and bags manufactured in Canada. This is a stepping stone to full-scale production in Europe.
In the early days the US military was one of the first to exploit the benefits of lightweight flexibles for long-range exercises where keeping qualities for ready meals is fundamental to nutritional needs.
Technology has come a long way since then, with improved pouch security, more sophisticated food processing, faster running filling/ sealing lines, high barrier transparent solutions and differentiation through add-on features.
More consumer attractions are essential if stand-up pouch penetration is to increase. Fun, interactivity and personalisation will be key differen-tiating features.
Pouches must be easier to open and, in some instances, be reclosable. Shaping is compelling if relevant, evocative of the brand image and imaginative. The Zap yoghurt from Yoplait is a very good example [Fig. 4].
Microwavable stand-up pouches require creativity to make them cooler to touch, easier to handle and to pour. Packs, which self-vent to prevent bursting, will become increasingly popular.
Compared to cans and jars, filled stand-up pouches are not easy to stack. Nor are they space friendly due to their tapered shape, a point increasingly emphasised by retailers.
To meet these concerns, Amcor is launching a liquid version of its FlexCan, targeting 250ml upwards [patent pending].
The first generation of FlexCan liquid is based on a pre-made pouch so as to secure seal integrity and die cutting of special shapes. To provide easy opening, a number of features have been developed and two of these are illustrated in Fig. 5 and 6.
Fig. 5 [patent pending] details an integral spout formed by the laminate. This could be used as a drinking or pouring device for beverages, soups and sauces or for detergent, motor oil and anti-freeze applications, either single shot or refills. The neck design can be altered to improve handling and security.
Fig. 6 [patent pending] shows a peelable FlexCan. The pack has been designed to withstand strong forces, even a high internal over-pressure in a retort chamber. The peelability is created by sealing in a 10mm laminated strip during pouch production. This makes a fusion seal on one side and a controlled peel on the other.
In order to build in opening features in the top of the FlexCan, it is necessary to fill from the side. The objective was to develop a filling process to provide an efficient fill level with hardly any head space.
The Amcor project team has rebuilt a conventional fill/seal line in order to test the feasibility [patent pending]. This process is now complete with very encouraging results. Potential Euro-pean customers are showing strong interest in this concept.
It is thought stand-up pouches are most unlikely to replace traditional, mature products.
They are increasingly finding niches for product line extensions where marketeers see the opportunity to satisfy the consumer’s insatiable appetite for more choice and convenience. For example, prepared ethnic meals and sauces provide ample opportunity.
The total supply-chain cost equation, including distribution, stor-age, packing speeds, processing time, energy consumption, waste and cost of capital, must be considered.
Environment credentials for various packaging formats is a complex subject beyond the scope of this particular paper.
Flexibles comprise layers of material with inks and adhesives, not easily separated and not suitable for food use in a re-processed form.
Resource minimisation, de-layering, less energy consumptive processes and materials from renewable resources are just a few of the ways in which the highly responsive flexible packag-ing industry is addressing all these concerns.
A decisive factor in the growth of stand up pouches will be the ability to stream-line the industry’s supply chain.
Print changes can be managed in the twinkling of an eye for wrap around paper labels, facilitating new designs and promotional packs for rigid con-tainers.
It remains to be seen how nimble flexibles converters can become, faced with a complex and demanding manufacturing process with attendant curing times for high performance adhesives. Surface printing on finished laminate is an option but more work needs to be carried out before there is sufficient confidence in this solution. Above all else, food safety must not be compromised.