The Return of Convolute-Wound Canisters

It may seem like a million or more years ago, but actually it was only a quarter century or so back that in-line-manufactured, convolute-wound paperboard canisters were the packaging sensation—destined to replace spiral-wound composites, bag-in-box, lined cartons, gable-top coated paperboard cartons, and even some metal cans and glass bottles for dry granular foods, powders, chips, and a few liquids. Roaring out of the starting blocks from International Paper, Continental Can, Seal-right, Heraus, Container Corp. of America, Paper Machinery Corp. (PMC), Akerlund & Rausing, and others whose names have faded from memory, were a new generation of containers fabricated from paperboard laminations and sealed at their peripheries by fusing polyethylene to polyethylene. Thrown at food products as diverse as breakfast cereals, stuffing mixes, soup starters, roasted peanuts, raisins, roasted and ground coffee, ice cream and fabricated potato crisps, these in-line-manufactured packages appeared to be the low-cost response to the perpetual search for the perfect package.

Defining the Concept
The concept was deceptively simple. Start with a roll or sheet of a paperboard-based barrier or non-barrier structure occupying little space volume in the package-material supply chain. In continuous or discontinuous fashion, form the material into a cylindrical or square-round (round-corner rectangle or square) shape. Seal the longitudinal edge by skive and hem, or overlap with polyethylene melting into a web structure, or even butt joint with a compatible film. Affix a sheet of paperboard structure to the interior of one end on a mandrel or equivalent, and voila—an open-end, three-dimensional container heading for a filling station. All of the operations can exist in a single line—without the inconvenience of pallet loads of factory-converted, open-ended spiral-wound canisters from Sonoco or through-the-wall containers when the numbers warranted or, occasionally, converted convolute-wound paperboard canisters. Does anyone recall Nestlé Quik with the pry-open lid? The idea was especially appealing since so many convolute-wound paperboard cups were manufactured so that the converting operations were well established from an engineering perspective.

The History
But, as with so many of our overhyped food packaging developments, in-line convolute canisters resisted rapid implementation by virtue of escalated-cost equipment, slow speeds, and a deficiency of universal barrier. Almost as rapidly as the concept burst upon the scene, the growth of in-line-fabricated, convolute-wound composite-paperboard canisters diminished to an intriguing niche system.

Organizations vied for the remaining niches, while simultaneously developing alternatives to fulfill the expectations of the concept. Despite a high materials cost and relatively slow output speed, the noted Cekacan from Europe was installed for packaging Maxwell House coffee filter packs in a square round, while several Sealright machines plied at dry soup mixes and the like. Sealright further developed the concept for large, square ice cream canisters intended for retail/foodservice applications like Baskin-Robbins and their ilk, and then was acquired by Huhtamaki, which continued the development.

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Smurfit Stone (www.smurfit-stone.com), successor to Container Corp., in conjunction with Paper Machinery, made "The Big Easy," a large, convolute-wound square round engineered to replace the lined paperboard carton for breakfast cereals. The closure was an injection-molded split top that sealed to the top opening so that consumers could repeatedly open and close it. For reasons that escape us, this major project was abandoned to history nearly 10 years ago. Possibly the threat of stand-up flexible pouches—which still has not materialized in this food category—dulled the enthusiasm of the tonnage-oriented paperboard company.

A major break for the convolute-wound package came about a decade ago, sparked by the legendary Gerry Meier of PMC (www.papermc.com), who dared to propose a dual innovation: a wide-mouth square round paperboard container to be closed with a Double H Plastics (www.doublehplastics.com) snap-on insert injection-molded lid for premium ice cream. Defying the accountants who subscribed to the rule of "cheaper is better," the two-piece paperboard and plastic container was embraced by ice cream aficionados, who truly appreciated the convenience in opening and reclosing. Who wanted the difficult-to-open and almost-impossible-to-reclose single-wall box or all-paper-board, tapered-round units favored by environmentalist advocates? Gerry pushed the injection-molded polyethylene frames plus printed paperboard inserts as closures for graphic appeal and ease of fit over the rolled upper edges of the base canister—and once again, voila—a new category of ice cream flourished in a new category of packaging.

Enter the Stand-up Flexible Pouch
Meanwhile, however, the realm of the in-line-fabricated, polyethylene-coated single-wall round for dry powders and granules and dry fruits became vulnerable to the stand-up flexible pouch because of better barrier function, new zipper-lock reclosure, flat display, and lower cost (once again making the accountants happy).

Injection molding and thermoforming to produce deep-draw tubs similar to the ice cream square rounds arose slowly to compete vigorously for food packaging minds for powders, granulates, and even large solids such as hard or chewy candies. Polypropylene could offer very good water-vapor barrier, and the precision molding allowed for excellent closure and reclosure when coupled with internal flexible lidding. For practical purposes, in-line manufacture was not applied, and so cost was a deterrent on many potential applications.

Gerry countered with Barrier Plus™, a system applying a preprinted, mineral-filled polypropylene sheet in place of paperboard. PMC developed machinery capable of producing canisters of 32–170 oz capacity at output speeds of up to 225 cpm. Obviously, the all-plastic structure could achieve a higher moisture barrier using less plastic per unit area of package. If necessary, the material could be combined with ethylene vinyl alcohol to impart oxygen barrier. All of this was possible without the very high cost of injection molds or the thinning from thermoforming. But within the universe of food packaging, Barrier Plus has not become a blockbuster hit—yet.

And so the in-line fabricated paperboard canister chugged along as a bit player on the food packaging scene, applicable occasionally for premium products but not truly considered part of the mainstream.

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The Return of Cekacan
Was it just last year that some bold professionals associated with Target and Sonoco hammered together a Linearpak to apply the technology to the chain’s private-label breakfast cereals and analogous foods? Convolute-wound rectangular rounds of recycled paperboard with hinged plastic reclosures dotted the shelves—and, evidently, consumers’ tables—not replacing traditional lined paperboard cartons used for major national brands, but offering a more-convenient alternative.

In Europe, in-line blank-formed composite canisters were not some footnote in history. A&R Carton (www.ar-carton.com), the new name for Akerlund & Rausing, arose like a Phoenix and addressed markets across the board with its accrued experience. Cekacan has returned in Europe for packaging flour, baby formula, sugar, chocolate milk mix, tea, peanuts, dietary supplements, and a variety of nonfood powders and granules, winning a host of awards, including the Gold Starpack in the United Kingdom. With the development of new, state-of-the-art machinery, A&R Carton is relaunching Cekacan with equipment capable of running 120 packs per min and handling larger sizes.

Most of the new European entries are square rounds for dry products with molded polypropylene hinged Toptainer reclosure devices. The Toptainer is a molded frame with a hinged closure, coupled with an easy-open aluminum foil lamination heat-sealed to the body interior. With roasted and ground coffee, valves to release carbon dioxide are affixed to the aluminum foil closure. The plastic top may also be perforated to permit sprinkling of the contents. The packages represent transitions from multi-wall paper sacks with their propensity to split and spill, paperboard folding cartons, and lined paperboard cartons. The reclosure devices are configured to provide a small enclosed headspace, which is used to contain a spoon or recipe folder or even adjunct foods such as dry creamer for tea, all separated from the product contents. Containment is sufficiently tight to provide for both moisture barrier for hygroscopic powders and for reduced oxygen for oxidation-vulnerable products such as infant formula. Induction heating of aluminum foil is employed to melt adjacent polyethylene coatings to flow the plastic in to close the seals.

Machines that are unitary, i.e., in-line, are modular and servo-driven, reportedly with relative ease of changeover, a problem with past equipment. Thus, the unit that fabricates canisters is linked to the filler, which is linked to the can sealer, which is linked to the lid applicator, but they may be interchanged as needed. The can maker begins as usual with the flat blanks being formed into the body, followed by affixing the bottom to create a three-dimensional, open-top canister ready for filling. Output speeds range up to 120 canisters per min per line.

When Canisters Make Sense
In-line convolute canisters will not revolutionize food packaging because they are more complex than stand-up flexible pouches, but the high-barrier option offers gas-tight packs for a wide range of products, including infant formula and roasted and ground coffee. So they can occupy a role in the delivery of some foods because they are semi-rigid, stiff, and easy to access, with the possibility of unique shapes for specific brands. Further, when the output requirements are not great, canisters have a purpose.

Their convoluted chronology from paperboard companies seeking to dramatically escalate mill volumes to machine companies trying to place their monster equipment through hyperbolic selling suggests that even the best of concepts can be hidden in rhetoric. The concept truly began when the canister was integrated with rational closure mechanisms. When packaging is the objective, reality emerges. In-line-fabricated, convolute-wound paperboard-lamination canisters warrant serious consideration when it fits—as it does in so many situations.

Aaron L. Brody, Ph.D.,
Contributing Editor
President and CEO, Packaging/Brody Inc., Duluth, Ga.,
Adjunct Professor, University of Georgia
[email protected]