Blown film strategies: with the right technology, you can go where the growth is.

Put away that crystal ball. When you're planning growth strategies for your company five years out, you need solid evidence to answer key questions: Which segments of the blown-film business will be expanding fastest? What sort of technology will you need to either penetrate those businesses or dominate them?

So instead of consulting a Ouija board, we asked a range of industry experts to help us come up with some answers. For the economic projections, we enlisted well-known extrusion market researcher Richard Mastio of Mastio & Co., St. Joseph, Mo., to pinpoint the fastest-growing markets for blown film through the year 2002. For the technological nuts and bolts, we asked major film machinery and materials suppliers to speculate as to what types of tools processors will need to become major players in these fields.

The five film sectors highlighted here aren't necessarily the biggest in volume. In fact, some are quite small. They are, however, five of the eight fastest-growing film segments Mastio identified. We took some editorial license and eliminated from discussion both cross-laminated film and geomembrane liners, reasoning that these products are highly exclusive to a handful of processors. We also omitted stretch film (though it's a huge and fast-growing business) because an estimated 40% of this type of film is cast rather than blown.

In looking at the five remaining sectors, two conclusions stand out across the board: Film processors looking either to expand in these business segments or to enter them for the first time probably should investigate coextrusion and become more familiar with the new-generation metallocene-catalyzed materials.

Grocery Sacks

Will Coex Become A Force?

Fewer than 10 years ago this was a business held mainly by single-layer LLDPE structures. Today, HMW-HDPE accounts for roughly 80% of the poundage, a shift explained by high-density's inherent ability to be downgauged. But a vast majority of grocery-sack film is still processed on monolayer lines. For example, industry leader Sonoco High Density Products Co. of Hartsville, S.C., runs nothing but one-ply products.

As they have for years, machinery suppliers seem convinced that this market will eventually go multi-layer. "I'm not talking about a stampede, but coextrusion is making inroads into grocery-sack production, and I suspect that will continue as older lines get replaced," remarks Steve Engel, president of Kiefel Inc. "Not necessarily for performance reasons," he adds, "but more for look and feel." A three-layer structure with LLDPE on the outside and inside and HMW-HDPE in the middle can be soft and glossy and yet stiff enough to be downgauged to 0.5 mils, Engel explains. He also points out that when the grocery-sack market was in oversupply last summer, processors with coex capacity generally got the business.

Despite all the advantages of multilayer structures, Engel cautions processors to be careful about layer set-ups: "LLDPE as a skin layer comprising 15% of total thickness can cause big problems at the bagmaker," he warns. "If the temperature of the sealing bars is too hot, the film will stick and not seal. If it's too cold, it won't stick, but it won't seal either."

David Nunes, president of Alpine American, also sees coextrusion becoming a major force in this business. "The trend will move toward coex simply because of the flexibility the process offers to make different and better products," he says. Adds Matt Bangert, general manager of Reifenhauser Inc., "The market has matured to the point where the supermarkets and other big customers recognize the superior performance offered by a coex bag."

But whether film processors opt for coex or stick with tried-and-true single-layer structures could depend on how successful resin suppliers are in addressing HMW-HDPE's main weakness - susceptibility to machine-direction tears. Equistar Chemicals LP has a number of ongoing "resin design" projects aimed specifically at improving MD tear strength, reports Norma Maraschin, director of PE product and technical service for the new company, which combines the polyolefin businesses of Lyondell Petrochemicals and Millennium Petrochemicals. "By changing or modifying the resin, we can improve dart impact and modulus," she says. "We can also improve MD tear by lowering the material's density, but that comes at the expense of stiffness."

SIZE MATTERS

Another trend to track is growing extruder size. Over the past few years, Alpine, Kiefel, Reifenhauser, and Battenfeld Gloucester all have introduced bigger machines aimed at this market. Output rates are now up to 800 lb/hr and more. The standard machine used to be 80 mm diam., now it's in the 100-mm range, says Kiefel's Engel. Dies, likewise, have stretched from 200 mm up to 275 mm typical diam.

The "bigger-is-better" shift is driven by several factors. For one, most processors today want to extrude film "three-up," meaning they extrude at layflat widths to 60 in. and slit the collapsed tube twice to create three lanes. Such a system requires an extruder with more pumping capacity and a larger-diameter die.

Higher-output extruders, in turn, directly affect how you need to cool the film. Narrow tubes running one-up can get away with no internal bubble cooling, but IBC is a must for anything larger. "Anybody who continues to try to compete with non-IBC equipment is doomed to failure," states Bangert of Reifenhauser. "You won't get the rates without it."

A few established processors of grocery sacks have tinkered with four-up lines as a way to improve productivity. But machine builders, warn the uninitiated not to attempt it. "Four-up at 80-in. web widths is dead," Bangert states. "The wider you go, the stronger the winder shafts have to be. At four-up, you re talking about a 6000-lb, 76-in.-wide roll that s extremely difficult to handle." Alpine's Nunes agrees: "Some processors are doing it, but you better have great operators." With HMW-HDPE especially, the wider the bubble, the more likely the film is to wrinkle and sag, which wreaks havoc with printing and bagmaking, adds Engel.

Heavy-Duty Sacks

Open to Metallocenes

Heavy-duty sacks are used to hold everything from deicing salt to pet food to landscaping products to plastic resin. On a volume basis, Mastio reports that nearly 70% of the film made for these bags is monolayer. Processors are generally achieving the balance of properties they seek by blending different resins rather than by coextrusion. "Other than aesthetics and differential slip, which isn't a major consideration anyway, I don't know what you gain by coextrusion that you wouldn't get by blending," remarks Gus Garrett, a Dow Plastics senior PE marketing executive. If slip is an issue, film processors have the option of extruding a single layer of high-slip film and laminating it to a stickier film in-line.

Nonetheless, most equipment suppliers recommend coextrusion as the way of the future. "I think you need higher slip on the inside than on the outside to make the bag easier to fill and open," says Kiefel's Engel. "Besides, the way to make your mark in this and other markets is by being flexible. Coextrusion lets you take advantage of almost every resin combination out there." Adds Andrew Wheeler, extrusion sales manager for Windmoeller & Hoelscher Corp., "If you're interested in getting into the market, I would certainly recommend coextrusion. Otherwise, you'd just be a 'me-too' player with a monolayer line."

DON'T SKIMP ON COOLING

Film thickness for these sacks ranges from 4.5 mils up to 8 mils. The film bubble is rather narrow - typically 14 to 20 in. - so small-diameter dies from 5 to 7 in. are the norm. Small dies dictate relatively low outputs, but IBC is still a virtual prerequisite for cooling such thick films. "I don't know of a single line we've supplied to this market in the last five years that didn't have IBC," notes Dean Ward, v.p. of sales and marketing for Brampton Engineering.

Davis-Standard Egan recently developed an IBC die specifically for this process. It has a single 4-in. hole bored through its center, allowing for more air flow than typical multi-hole IBC dies, explains Ricky Keller, industry director for film systems.

MAKE WAY FOR METALLOCENES

LLDPE accounts for a whopping 75% of the material for heavy-duty sacks, according to Mastio's research. In applications such as pet food, where grease barrier is important, processors with single-layer capacity are inclined to blend LLDPE with small amounts of either HMW or MMW-HDPE.

Metallocenes seem destined to play a bigger role in the future. Exxon Chemical, for instance, reports that Poly Pak America in Los Angeles is extruding Exceed mLLDPE in the core and/or surface of its three-layer sack film. Compared with conventional LLDPEs, Exceed offers greater tensile strength, impact strength, and puncture resistance, says Exxon product manager Joe Devet.

Another processor, Union Camp Corp. in Wayne, N.J., reports similar benefits from moving to Dow's Elite mLLDPE from a 0.920-g/cc LLDPE. Union Camp says the switch allowed it to downgauge 19% - from 6.3 mils to 5.5. "But there are practical gauge limits defined by performance," warns Dow's Garrett. He also cautions that filling machines may be unable to work with films below a certain thickness.

Besides higher strength, metallocene PEs are also said to be better in sealing performance. As a result, Union Camp says it reduced its heat-seal temperature settings by 15-25 [degrees] F and consequently increased its line speeds.

As other processors move toward higher bagmaking and filling speeds, tighter film specifications - especially on roll uniformity - could follow. This, in turn, could make gauge-randomizing systems such as oscillating haul-offs more essential in the future.

Fresh Produce

No Room for Low Tech

Film for fresh-cut, ready-to-eat produce is a relatively new business driven by consumer demand for convenience. In the minds of many, this is a business driven by metallocene plastomers, such as Dow's Affinity and Exxon's Engage resins, due to the outstanding clarity and oxygen transmission they provide.

Researcher Mastio says processors now use mainly LLDPE and fractional-melt LDPE, but most of them expect metallocene plastomers to take over eventually. Today, most fresh-produce films are single-layer structures, Mastio notes, but that too is likely to change, according to machine builders.

"Plastomers do give clarity, but to control respiration rate you should coextrude with a 0.92-g/cc LLDPE," advises Javier Noguchi, senior product manager for Battenfeld Gloucester. "Coextruding plastomers with a material having a higher secant modulus also provides extra stiffness necessary for converting," he adds.

Noguchi's comments suggest that processors wanting to get into this business need to brush up on material science. Jim Stobie, marketing manager for Macro Engineering, agrees: "Film structures have to be engineered to control the respiration rate of the product being packaged. Different products respire at different rates, so you have to do a lot of tailoring. You can predict properties by knowing the melt index, molecular weight, and density of the materials you're using." Adds Jeff Wooster, global technical leader at Dow Plastics, "You have to know how to match the oxygen transmission rate to the type of produce being packaged."

YOU'LL NEED TIGHT CONTROL

As is the case with most consumer packages, overall film quality is critical. Film-thickness control is important because variations can foul up bagmaking and printing steps, notes Wheeler of W&H. That means film lines with oscillating haul-offs (and perhaps even automatically self-adjusting dies or air rings) could become the norm. Quality demands could also require processors to pay more attention to winding. To minimize wrinkles, it is important to be able to control tension between the primary and secondary nip and between the secondary nip and winder, says Reifenhauser's Bangert, who recommends center-assist type surface winders.

What's more, layer-to-layer integrity is vital in coextrusions to control respiration rates and clarity, so streamlined, low-residence dies are important, adds Bill Hellmuth, Gloucester's senior product manager. Gels and unmelted resin also influence clarity, and can contribute to poor mechanical properties and thickness variations. Therefore, processors should specify screws that promote melt homogeneity, states Addex president Rick von Kraus.

Since scrap cannot always be reused in these products, Wheeler of W&H emphasizes the importance of bubble-control systems that cut down on edge trim. And don't forget that you'll need an IBC system to achieve competitive output rates.

You may not need all of these line components to compete in this market right now, but it won't hurt to be prepared for stiffer challenges ahead. "The bar is getting raised in terms of film quality all the time," explains Brampton's Ward. "As the market matures, packagers will want to print and fill at higher speeds. That will put more of a premium on film quality."

Even though the competition may get tougher, Bangert thinks there is room for more processors to get into this application. "There's been some consolidation in this business lately," he says, referring to the purchase by Sealed Air Corp. of Cryovac and other packaging units of W.R. Grace & Co. "When that happens, converters get nervous. They don't like their choices being limited."

Envelopes

Going Multi-Layer

Plastic is nipping at the heels of nonwovens in this business. Federal Express and the U.S. Postal Service are the only small-package haulers that don't offer plastic sacks, according to market-researcher Mastio. Although non-woven pouches are generally considered superior in stiffness, especially when stacked up against monolayer LLDPE or blends of LLDPE with HMW-HDPE, they are also more expensive. Mastio estimates that the Postal Service would not have needed to raise the first-class postage rate from 29[cents] to 32[cents] had it been using plastic sacks.

In terms of volume, this is a relatively small market. But it also might be among the most attractive to processors. The business would boom if FedEx and the Post Office move to plastic sacks. "There are about 25 million lb worth of spunbonded envelopes in the supply chain now that could conceivably shift to plastic," Mastio notes.

Experts agree that this is yet another business that will make more use of three-layer structures and metallocene resins as it matures. "The very nature of the product lends itself to coextrusion," Bangert says. "For one thing, you need someplace to bury scrap. For another, you need slip differential. You want the outside of envelopes to be glossy, the inside matted. The inside also should be a dark color so you can easily see any documents inside." Multi-layer structures also let processors use fillers such as talc and calcium carbonate on the outside layer to write on the envelope, notes Brampton's Ward.

At this point, the role metallocenes play is negligible, according to Mastio. He estimates they account for about 5% of envelope film today. The lion's share is currently held by LLDPE, with some HMW-HDPE typically blended to improve bag stiffness.

But this is another market seemingly ripe for the metallocene revolution. Mastio says metallocene materials are used now primarily in a core-layer blend to improve sealing. An example is the use of Exxon's Exceed mLLDPE in three-layer film made by Poly Pak of Los Angeles. What's more, Poly Pak uses Exxon's Exact plastomer on the outside layer of its envelope film to provide a nonslip surface with impact and puncture resistance.

QUALITY BEFORE SPEED

Major processing issues in this sector include roll flatness and uniformity in order to speed up envelope forming (which is a type of bagmaking), notes Hellmuth of Gloucester. These quality considerations suggest a need for thickness profiling and/or gauge-band randomization systems. "Lines for this market are not necessarily engineered first for output," says Stobie of Macro Engineering. "Quality and gauge uniformity are even more important."

Snack Foods 

Wide and Varied Opportunity

This is perhaps the most of the fast-growing markets for blown film because it represents a wide range of products. The requirements on monolayer films for laminating and metalizing are somewhat different from those on coextrusions for cereal and crackers.

But regardless of the number of layers, overall film quality is a requirement. "In a multi-component lamination, the least important component is the film," says von Kraus of Addex. "You might say the film is a commodity. But you can't think of it that way. Lamination is a capital-intensive operation, so you need to supply film with consistent gauge to keep the line running and the seal integrity consistent."

More than 80% of the material now going into snack-food films is LDPE for its sealability, according to Mastio. But again, watch out for metallocenes. Kip Thompson, Dow's manager for flexible food packaging, reports that more processors are evaluating materials such as Affinity plastomers because of their improved sealing. Dow will soon make available Affinity compounds containing slip, antiblock, and range of other additives.

Another trend to watch is the move toward stand-up pouches, Thompson says. Film made for pouches needs extra stiffness, which could translate into more use of HDPE in blends or coextrusions.

Since this market is so varied, machinery suppliers think coextrusion is a wise investment. "It makes sense to go with a five-layer line," von Kraus argues. "Since the structure will depend on the shelf-life requirements of the particular snack, such a line gives you maximum flexibility. You can also produce three-layer or even single-layer structures on it." For coex structures based on temperature-sensitive barrier resins like EVOH and nylon, von Kraus and others recommend dies that keep residence times low.

"Coextrusion is where this market is going - even above five layers," predicts Ward of Brampton. "The food people are constantly improving the quality of their products and demanding more shelf life and more barrier against odor and water."

But if you prefer monolayer film, keep in mind that current single-layer LDPE structures contain up to 28% vinyl acetate, making the film sticky. You'll need to worry about film blocking, so von Kraus recommends zero-tension gap winders. Friction-reducing bubble stabilizers and non-contact haul-offs are recommended by other suppliers.