And Then There Is the Composite Paperboard Canister

Convolute-wound composite paperboard cartons are on a slow roll to dry foods packaging—with their bold entry for tea mix about three years ago, followed last year by Austin’s Dolphins fish-shaped snack crackers and now by SeAnimals, which appear to be a new version of our venerated Animal Crackers, I suppose.

Once upon a time, multiple layers of paperboard were wound around a mandrel and glued together to form a rigid rectangular-shaped structure to which a metal end was affixed for filling with such foods as cocoa powder and its kin. Closure was by single-seaming a metal end with a not-so-easy friction-fit plug metal closure to “close” the canister. Many consumers today recall spoon-prying the metal closure and manipulating the spoon into the opening to extract the powdered contents—with difficulty. These canisters were replaced by plastic—in, of course, rectangular shapes.

The engineers developed spiral overlap winding on a round mandrel so that the final shape of the canister was cylindrical—just like the metal can. The spiral wound composite paperboard/polyethylene/aluminum foil cylinder was—and, in some instances, is—the package of preference for dry foods as well as for refrigerated dough and frozen concentrated orange juice.

The paperboard canister is a “monolithic” package capable of being enhanced with laminated water and water vapor barrier layers. Whether the composite paperboard canister, with all its layers of materials, is really a monolith, or just another variant of multi-layer package with marginal economics and functionality is debated. The packager was compelled to acquire preformed empty canisters—a high space-volume proposition—even if the fabrication was a through-the-wall operation.

Then came the in-line fabricated convolute-wound composite canister, advocated by those who envisioned economic, highly functional semi-rigid packages. Instead of laminating multiple paper layers over mandrels, the paperboard could be pre-coated and pre-laminated with aluminum foil to provide functionality in truly monolithic constructions. These evolved gradually into round corner rectangles. The initial attraction was in-line fabrication analogous to flexible packaging’s form/fill/seal machines. But the convolute-wound composite can erecting machines were initially adaptations of paper cup manufacturing equipment. Although these lines were reliable and high-output, they were generally over-engineered and oversized for food plant production.

In-food-plant fabrication of convolute-wound composite cans introduced in the 1980s could use smaller equipment which led to production of simple canisters with relatively marginal seals and barriers suitable only for low-requirement contents such as soup starter, stuffing mix, croutons, and raisins. However satisfactory these canisters are in replacing the less demanding of spiral-wound composite paperboard canister applications, the packages are deficient in too many aspects of barrier and physical protection.

Round composite containers evolved into square and rectangular shapes. The key to barrier is the generous flow of polyethylene during heat sealing to caulk the openings at mechanical gaps in the crossovers of seams and closures. But the machines to fabricate these canisters with high barrier were precision engineered and therefore expensive—too costly to “save” costs for food packagers. Which led to a new strategy—target “value-added” foods—of which there are not yet enough in the dry foods sector.

The new target by the early 1990s was ice cream, formerly packaged in paperboard folding cartons that are difficult to open and impossible to reclose, or round paperboard tubs that have some difficulty. Some ice cream is definitely indulgence unlimited, i.e., value added. And thus was born the in-line manufacturing of round-corner single-ply paperboard tubs with paperboard bottoms for premium ice cream—with insert-injection-molded closures that could be opened and reset on the opening after scooping a generous dollop of too-rich dessert. For the second time in the checkered history of paperboard canisters, a viable application had been implemented.

The concept of round-corner rectangles with a paperboard bottom that was heat-sealed was appealing for marketing managers and technologists, but the impact of stand-up flexible pouches with their barriers and soon-to-be-good graphics demanded careful product applications. Ice cream cartons are fine, but do not require any special barrier or physical structure because it is frozen solid. To apply the fabrication and structural design to dry foods was a challenge.

The concept of convolute-winding multiple layers of paperboard incorporating aluminum foil lamination plus polyolefin internal coating plus skived and hemmed seams was resurrected to achieve moisture and fat barrier. The more difficult task of in-line fabrication was dropped in favor of preformed canisters. The result is the semi-rigid paperboard-bottom canister with flexible lamination closure with enough barrier and physical structure to protect even sensitive dry food contents. A molded plastic overcap serves as a reclosure feature.

We have come nearly full circle: from pre-fabricated convolute-wound multilayer paperboard canisters mechanically closed with metal ends; to spiral-wound composite paperboard canister mechanically closed with metal ends applied for dry foods; to in-line fabricated canisters heat-seal-closed for modest-requirement foods; to in-line fabricated ice cream cartons; to pre-fabricated heat-seal-closed convolute-wound paperboard canisters for moisture-sensitive contents.

PATENT
Patents may be downloaded at no charge at www.uspto.gov. A Boolean search on the site will permit locating patents by keywords, assignee, inventor, or patent number.

Microwave popcorn package. U.S. patent 6,126,976, filed 9/21/1999, issued 10/3/2000 to G.W. Hasse Jr. et al., assigned to Try-Way Industries, Inc. Describes a microwave popcorn package including a container having a bottom wall, an open top, and a tapered side wall extending from the bottom wall to the open top. The package also includes a variety of lids including a lid which has a substantially planar center portion. The lid is positioned within the container between the bottom wall and the open top to define a popcorn receiving region and to provide a support for the stacking of a plurality of containers. The invention further includes a pouch positioning collar and a method of making and assembling the above package. 

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Products & Literature
Web site offers surplus packaging. Packaging machinery and materials including aerosol components, PET preforms, can ends, and other such items are available for purchase on-line through a new Web site www.PackagingParade.com The new e-trading company offers second and third-generation packaging machinery and surplus stock at what they call “realistic market prices.” Products are sold by bids made by registered sellers and buyers. For more information, contact David King at DavidKing@Packaging Parade.com or call +44 1256 78426—or circle 311.

Filler line has touch screen. Clients for the packaging line report significant increases in productivity when they use the new screen item. The six-inch screen controls all product-filling parameters including speed, agitator speed, acceleration rate, and product programming. The screen system is easy to learn, with intuitive menus that are self-explanatory. For more information about these packaging lines, contact Spee-Dee Packaging Machinery Inc., 950 Durant Ave, Sturtevant, WI 53117 (phone 262-886-4402, fax 262-886-5502, or visit the website at www.spee-dee.com) —or circle 312.

Salsa shines in new PET container. The 64-oz, 63-mm, wide-mouth, heat-set container filled with Chi-Chi’s® salsa was shipped to club stores during August. The old container used by the Hormel brand was a multilayer, polypropylene/ethylene vinyl alcohol copolymer container, which served as an unbreakable club store container, but the product manager for Chi-Chi’s wasn’t happy with the transparency. The product is hot-filled, so until recently, the multilayer container was the only unbreakable option. The new PET container withstands the 200ºF fill temperature, and sports a wrap-around label with 30% more label space. For information about the container, contact Schmalbach-Lubeca Plastic Containers USA, 10521 S. Hwy M-52, Manchester, MI 48158 (phone 734-428-4515, fax 734-428-4622)—or circle 313.

by AARON L. BRODY
Contributing Editor