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Toyo Seikan’s solution to venting off steam
By Stuart Hoggard   
25 July 2006

Japan - Vapour pressure build-up has always been a problem with microwavable packaging, but Toyo Seikan has used its weakness to deliver a solution to today’s pressurised urban lifestyle.

 

 


toyoseikan1

Standing at one of the many confusing exits at downtown Tokyo’s Shinjuku station, salary men, and more importantly salary women, rush past with hardly a second glance at the slightly lost foreigner waiting at the wrong exit.

This hectic pace of life is impacting on their spending behaviour and is a well-known formula governing the packaging supply chain.

It goes like this: with more salary-women (or office ladies – OLs as they’re known in Japan) the family shopping expedition is reduced to a mad dash to the convenience store, which means the role of the package in promoting and preserving food becomes a vital part of the product lifecycle rather than serving as a humble product container.

The development of vacuum packs, aseptic packs, high barrier and oxygen scavenging packs have all been a response to the brand owner’s demand for greater shelf life and presence. toyoseikan2Rarely, however, does one come across a pack which actually pre-empts the formulaic demand drivers in this industry and creates demand in a market which did not exist. However, as one of Japan’s largest container makers, Toyo Seikan has done just that with the development of the ERP, the quirkily named Electronic oven available Retortable Pouch.

It’s actually a retortable pouch that enables curry sauces, pre-cooked rice and (presumably) roast beef in gravy to be taken straight from the supermarket shelf and microwaved in the bag - for salary men and women who have no time to cook.

Ahead of the pack

With net sales in excess of Y6,670 million (US$58 million) and more than 12,000 staff, the Toyo Seikan Group comprises seven core divisions: canmaking, plastics, glass, laminated paper cups, aerosols, closures and food processing equipment.

The plastics division, Toyo Seikan Kaisha, contributes more than half or the corporation’s total sales. It is primarily in the beverage packaging business with more than 67 per cent of sales, while food packaging contributes 19 per cent.

Toyo Seikan Kaisha maintains a highly sophisticated research and development programme to keep ahead of the pack and maintain its position as market leader.

It is an R&D programme which Hiroto Watanabe, general manager, general plastic container development, is justifiably proud: We take a holistic view of package design. It is a combination of pure science, market knowledge and cost accounting with just an occasional dash of inspiration.

Quotation We take a holistic view of package design. It is a combination of pure science, market knowledge and cost accounting with just an occasional dash of inspiration. Quotation


Rarely is Toyo Seikan content to allow the market to lead it: “We constantly have to challenge the market and ourselves. Why is a pack like that? Can we do this differently? Better? Cheaper?”

Taking the vapours
Boil-in-the-bag retortable pouches have been around for more than 30 years, and have been eating market share from glass and metal cans for many years; in 2002 Japan’s retortable pouches held 30 per cent market share with more than 280,000 tonnes.

A barrier to further growth has been the speed and convenience of the microwave. The main difficulty with microwave cooking has been the rapid build up of scalding steam inside the pack which causes it to expand and explode dangerously.

toyoseikan3Toyo Seikan’s solution was to develop a high burst strength multi-layer pouch as a composite of CPP, ONY and PET and use the problematic steam build-up as a positive property of the pouch.

In effect, the boiling steam turns each pouch into a pressure-cooker in a bag, yet with no risk of explosion due to its multi-layer structure, also quirkily named ‘SCOOP’ (which stands for Stress Concentrate Opening). Essentially, this is an automatic vapour release valve built into the pouch.

When the liquid contents of a bag are subjected to heat in a microwave, steam is created, which expands in the bag in a uniform manner; the bag itself expands like a balloon.

“This creates a stress concentration circle with pressure building up uniformly in all directions simultaneously,” according to Watanabe. “If the steam is allowed to continue its build up, the bag will rupture at the weakest point (the middle of the seam), away from the stronger corners.

“What was needed was a valve which would open to release the steam when the pressure reached a critical level. But it also had to remain inexpensive; since it is a single use pouch which gets thrown in the recycling bin after opening there would be no budget for additional expensive valves.

toyoseikan4 “We achieved this by developing a process which crimps one corner of the pouch and punches a hole completely through. This deliberately weakens the barrier to create a reduced stress focal point.”

Despite the apparent simplicity of SCOOP, the science goes well beyond what one would normally expect of a container maker’s commercial offering to the brand owner.

The high strength properties of the combination of substrate (CPP, Nylon, and PET), creates a high pressure-resistant pouch sealed along all four edges. However, at the weak point - the crimped and flattened corner - the punched hole means that the only actual barrier is the CPP without the nylon and PET reinforcement, which at the critical point of steam build-up minutely ruptures to release the steam.

It is an ingenious system that uses the microwave to heat and cook the contents under high pressure. By building in a controlled point of rupture, steam is expelled to prevent pressure build up.
Quotation It is an ingenious system that uses the microwave to heat and cook the contents under high pressure. By building in a controlled point of rupture, steam is expelled to prevent pressure build up. Quotation

Once the microwave’s timed cooking cycle is over, the pouch can be removed and cut open with no danger of scalding the user, and with the pressure removed the bag reverts to its previously limp state which is safe to open.

Available either as a flat pack or stand up pouch, Toyo Seikan’s ERP has already found commercial application and market acceptance in Japan, in products such as cooked rice, a variety of soups and sauces, and specialty cuisine packs, such as Korean dishes, demonstrating that with today’s pressurised urban lifestyles the package can be the demand generator for the product.


Stuart Hoggard
About the author:

Stuart Hoggard, is a 12 year veteran of the packaging media and a member of IPPO (International Packaging Press Organisation) - the professional body representing more than 84 editors and journalists worldwide. IPPO is affiliated with the World Packaging Organisation (WPO).

He has been a journalist and publisher since 1971, and has written on a wide range of topics from the Music Business to Computers and general news reporting. He is the author of a number of books including biographies of Bob Dylan and David Bowie.

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