Where to now for dual-ovenable packaging?

Where to Now for Dual-Ovenable Packaging?

Dual-ovenable trays for packaging frozen foods have been an unpredictable, roller-coaster for plastics processors, who found they could have a 100-million-tray market one day and none the next. That happened to china-like thermoset polyester frozen dinner trays, which all but vanished in 1988 after eight years of growth, and with them a slew of big compression molding ventures set up to exploit the burgeoning market for microwavable and ovenable foods. Thermosets lost out to thermoforming of CPET and a smattering of other materials. CPET alone zoomed from nothing to 630 million units between 1983 and 1989. Then injection molded nylon appeared on the horizon in 1988, but its death knell was sounded last month, abandoned by customers after growing to 60 million units.

So thermoforming appears unchallenged for the present, but recent trends leave the future of the whole dual-ovenable packaging market in doubt. Complaints about food quality have hurt these products, industry sources say. And frozen dual-ovenable meals are competing with less-expensive fresh-refrigerated and shelf-stable foods, at a time when the limited amount of commercial freezer space has never been tighter. Because of the expense of maintaining such space, "Frozen foods can't grow, they can only cannibalize each other," says packaging consultant Harry Rubbright of the Rubbright Group, St. Paul, Minn.

Nonetheless, some tray thermoformers remain optimistic, encouraged in part by continuing development of new thermoforming technology and materials, which are discussed below.

RISKY BUSINESS

The risks of participating in such a large but fleeting market have been all too evident. GE Plastics' Atlanta-based GEPAX unit, set up to develop trays thermoformed of coextrusions based on GE's Ultem polyetherimide (PEI) and Lexan PPC high-heat polycarbonate, made trays only for Stouffer Foods Corp., Solon, Ohio, and disbanded in 1987 when Stouffer switched to Eastman Chemical's less expensive PCTA polyester thermoformed trays (and more recently to injection molded nylon for some products). Campbell Soup Co., Camden, N.J., also switched its Swanson and Le Menu product lines from thermosets and aluminum--first to thermoformed CPET and injection molded nylon, and now all to CPET.

"There aren't many materials to look at now besides CPET," Campbell packaging source says. "CPET is part of the recycle stream, so it doesn't make sense to go anywhere else." Campbell had about 60% of its dual-ovenable entrees in CPET, 25% in nylon, and 15% in paper trays, before the switch from nylon.

Price is usually the determinant. For instance, when thermoset polyester was supplanted in 1988 by four or five brands of CPET and filled nylon, thermoset trays cost 20 [cents] apiece, filled nylon trays 13 [cents], and CPET 12 1/2 [cents]. A more subtle reason, says consultant Robert Schiffmann of R.F. Schiffmann Associates, N.Y.C., was that once people had an extra set of thermoset dishes, they stopped buying the product. However, some thermoset molders, like BMC Inc., St. Charles, Ill., are still holding onto a sizable niche serving some airlines and the Amtrak railroad with hot entree dishes, because of a perceived safety advantage from the less easily ignitable thermoset.

The latest dual-ovenable demise is also the most recent entry--10-25% mica-filled nylon 66, introduced just two years ago by Du Pont Canada, Inc., Mississauga, Ontario, which molded plates of its own material. The only other molder was Du Pont's joint venture, Tru-Clean Plastics Inc., Toronto. Du Pont cancelled the product just last month, citing weak market demand. Nylon had lost all three of its original applications--Stouffer's Dinner Supreme, a Nestle's U.K. entree, and most recently Campbell's Le Menu. One of nylon's unfulfilled promises was a lidding system that was expected to save 3 [cents]-4 [cents]/package, but which never worked on high-speed filling lines (200 trays/min). This apparently proved fatal, even though Du Pont sold trays at less than half the nylon resin price, competitors say.

Du Pont Canada, which equipped the two plants to make the trays, plans to sell its specially modified Toshiba and Husky injection presses (with hardened-steel molds, barrels and screws because of the abrasive mica) to Tru-Clean. General Mills, which was testing filled nylon on plates (see photo) for its Bringers pilot project in Minneapolis (an upscale meals-on-wheels venture with refrigerated vans and microwaves), is looking for thermoformed or injection molded PP plates now. Du Pont Canada is also looking to license its recently developed shelf-stable barrier nylon tub design, but plans to sell resin, not tubs next time. (CIRCLE 87)

Another dual-ovenable tray developed after the demise of thermosets was coated aluminum, developed by Pittsburgh-based Aluminum Co. of America (Alcoa) and others. Tom Brown, Alcoa marketing manager for foil products, who developed a twice-coated aluminum tray (epoxy and vinyl), says the market grew steadily from local vending machines to 10 major accounts. He doesn't expect much further growth, but says coated aluminum will hold its niche with pies because of the need to brown crusts.

THERMOFORMING WINS OUT

CPET is now the dominant dual-ovenable plastic tray, growing from 20 million units in 1984 to 250 million in 1986 and about 630 million in 1989, according to Cleveland-based Freedonia Group, a market-research firm (see chart). However, the Rubbright Group pegs CPET trays at only 390 million units in '89 and 533 million this year, after Stouffer used the last Ultem and switched to PCTA (a more heat-resistant polyester than CPET, trade named Kodar Thermx by Eastman Chemical Products, Inc., Kingsport, Tenn.). Con-Agra Consumer Frozen Food Co., Ballwin, Mo., also boosted CPET tray volume by going back to a divided plate with its Healthy Choice meals--thermoset entree plates had all been flat, so flavors mixed and little could be done with sauces or gravies.

Five large thermoforming operations--Mullinix Packages Inc. in Ft. Wayne, Ind.; Illinois Foam Products Co. in Atlanta; Illinois Tool Works, Glenview, Ill.; Therma-Plate Corp., South Plainfield, N.J.; and Campbell's in-house facility in Modesto, Calif.--now account for 80% of CPET tray-forming. All form from sheet except Therma-Plate, a joint venture of Penny Plate Inc. and Therma-Systems Corp., S. Plainfield, N.J., which uses Therma-Systems' patented melt-to-mold process (see PT, Dec. '87, p. 70).

Some dual-ovenable CPET is also being replaced by dual-ovenable paper set-up cartons, costing about 12 [cents] complete, half the cost of a CPET tray, including the lid and carton. Set-ups were developed by Westvaco in Loral, Md.; James River Corp., Kalamazoo, Mich.; and others. Sales of shelf-stable foods in CPET trays like General Foods' Impromptu product, not limited by freezer space, are also expected to grow strongly. CPET's recycability and cost/performance compared with other shelf-stable materials, like five-layer PP/barrier tubs, are major reasons cited.

WHAT'S THE OUTLOOK?

Dual-ovenable package growth has been dramatic (see chart), but perhaps deceptively so, because the percentage of households owning microwaves more than doubled from 33.3% in 1983 to 80% in 1989. So dual-ovenable sales per microwave household member may not have really risen. Many high-end products like Campbell's Le Menu are seeing falling sales, and some like Stouffer's Dinner Supreme have been withdrawn from the market. Dual-ovenable entrees are said to pay "slotting fees" of $500 to $3000 per product for retail freezer space at a supermarket, and only Con-Agra's Healthy Choice is said to still sell fast enough not to have to pay for display space.

So how stable is the outlook for dual ovenable products? Suppliers to that market say dual-ovenable food formulation is retreating. "Microwave-only makes more sense for the convenience of two-minute heating and because food companies can't make food that tastes good both ways," says Adrian Boon van Ostade, marketing manager for packaging resins at GE Plastics, Pittsfield, Mass.

Consultant Schiffmann says dual-ovenable food preparation will be gone altogether in three to five years, converted to one or the other ovenable formulation or shelf-stable. "The concept of going into two ovens will end, but you'll still have a need for high-heat plastics," he says. CPET will keep a share of the market for microwave-only, and there'll be a cost-driven shift to paperboard, he adds.

Consultant Rubbright thinks dual ovenability will decline, but not vanish. Food companies will hold onto dual ovenability for a while because research shows people like to heat multiple dinners simultaneously in the larger conventional ovens. Dual-ovenability will also continue to target particular foods like fish and chicken, research shows. Some dual-ovenable CPET will shift to microwave-only CPET with lower crystallization levels (safe to 350 F, not 450 F) as food recipes shift, thermoformers say.

The big problem for dual-ovenable food is taste. The head of one research lab fed dual-ovenable dinners to his lab people while testing the packages and said the food was so bad he wrote the manufacturer's chairman to say so. Taste suffers because food prepared for reheating methods as different as microwaving and radiant heating call for different ingredients and formulations, particularly moisture content. Ice and water absorb microwaves very differently, so frozen food in a microwave heats unevenly as its thaws.

Not everybody, however, thinks dual ovenability is disappearing. A 79-page research report, issued in August by the Freedonia Group (available for $1200), predicts 7.9%/yr growth for dual-ovenable trays over the next 10 years, to 5.2 billion units by 2000. And CPET tray makers agree that they are seeing continued growth. Product development manager Richard Freundlich says Therma-Plate is growing because of its melt-to-mold CPET technology, which reportedly makes a stress-free tray.

NEW FORMS OF CPET

Therma-Plate was experimenting with lightweighting trays, but instead discovered a unique resin morphology produced with its proprietary system. "At first we thought we'd made some mistake," Freundlich says, but sending samples to resin companies for lab tests confirmed that they had created a new structure with very small crystal size. Crystallization from the melt state creates lots of tiny crystals, which fuse together to form a diffusion barrier, whereas crystallization from reheated solid sheet creates fewer large crystals with plenty of room for oxygen to pass between them, he explains. Freundlich, who announced the discovery at the Future-Pak conference in Atlanta last month (sponsored by Ryder Associates, Whippany, N.J.), expects the new development will yield improved barrier performance.

Mullinix also makes a shelf-stable barrier CPET package by coextruding with an amorphous PET inner layer, which hermetically seals to PET film lidding before retorting. The Mullinix system has been test marketed with General Foods' Impromptu entrees since 1986. Mullinix president George Lueken agrees that the CPET market is still increasing. Much will be microwave-only, he says, once CPET trays become more competitive through a combination of resin and machinery modifications.

The most recent dual-ovenable tray material in development is low-density foamed CPET sheet, being developed at the Polyester Div. of Goodyear Tire and Rubber Co., Akron, Ohio, Hoechst Celanese Corp., Spartanburg, S.C.; and Eastman (see PT, Aug. '90, p. 13). Goodyear calls the material Petlite, which has been extruded from flat die but could also probably be produced with an annular die like PS foam sheet, according to a company spokesman. Goodyear says Petlite will cost 25% less than a CPET tray (6 [cents] vs. 8 [cents]). Foamed CPET retains dual ovenability but isn't economical for frozen food applications, because the foam insulates against cold, retarding commercial freezing. Like CPET, it needs the support of a cookie sheet when heated above 212 F. Eastman and Goodyear see foamed CPET going after deli clamshell packs, currently made of PS, paper, and GE's Noryl PS/PPO blend.

Goodyear senior research engineer Walter Johnston says processors who want to run Petlite will have to modify their extrusion equipment to introduce an "inert gas" blowing agent, but can use standard CPET thermoforming equipment. Foamed CPET products are expected to become commercial in early 1991. (CIRCLE 88)

FDA SCRUTINIZES SUSCEPTORS

CPET could find increasing competition from paper in microwavable trays, owing to the growing popularity of so-called microwave "susceptor" technology to achieve a browning or crisping effect. The susceptor, which locally concentrates microwave energy, is a metallized plastic film laminated to paperboard or sandwiched between paper layers. (There is also one brand-new flexible susceptor package on the market, a bag made of metallized PET film.) Apparently, susceptors aren't used with thermoformed packages because of cost and possible package deformation during forming.

However, FDA has become concerned about the high temperatures--over 400 F--generated locally by the susceptor, and about possible migration at such high temperatures of monomers, oligomers, plasticizers, or chemical decomposition products from the paper, plastic or adhesives into the food contents of the package. FDA has been studying migration of volatile and nonvolatile substances from microwavable and dual-ovenable packaging for over a year.

In a late-August meeting of the American Chemical Society in Washington, D.C., FDA chemist Timothy Begley presented FDA's early findings in a paper called "Application of a Single-Sided Migration Cell for Measuring Migration Through Microwave Susceptor Films." Begley reported 10-times-higher levels of migrants coming off PET susceptor film that off PCTA, PEN (polyethylene naphthalate, a developmental high-heat TP polyester), or PEI. PET-coated susceptor trays, designed for microwave use only and rated to 220 F, were observed to reach temperatures well above 400 F, locally destroying the effectiveness of the PET layer as a barrier to migration from the paper or adhesives, Begley said.

"We found PET is the worst film to use as a barrier. According to present FDA regulations, PET is supposed to act as a functional barrier between adhesive components and food, but that is absolutely not the case. The barrier loses its properties," Begley reported, adding that FDA is now rewriting the rules for high-temperature susceptor applications.

Researchers say improved susceptor technology, now in development, could eliminate migration from adhesives by doing away with a susceptor film altogether, and incidentally make a better microwave dinner. The idea is printing a susceptor ink directly onto paper, says William Heikkila, head of R&D at Chase Packaging Corp., Asheville, N.C. Heikkila thinks microwave-only trays with "pattern-applied susceptors, configured to optimize cooking of a particular food" will be a big growth area, though it's about 18-24 months from commercialization.

PHOTO : Now you see it, now you don't! This mica-filled nylon plate from Du Pont Canada was

PHOTO : announced in June, cancelled in Sept., the latest in a long line of tray experiments, from

PHOTO : thermosets to GE's Ultem (PEI), which had 100-million-tray markets one day and none the

PHOTO : next. (General Mills' plate will likely switch to PP.)