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At left is the giant 7-in. extruder that puts out 4000 lb/hr of PLA sheet. It carries a UnaDyn insulated hopper and additive feeder for blue toner to mask the yellowness of PLA. At right are the PLA regrind receiver with cyclone separator and ample filter capacity because of PLA regrind’s dustiness.
Fabri-Kal’s Greenware-brand PLA cups are a runaway hit for Fabri-Kal, says marketing v.p. John Kittredge.
PLA regrind from thermoforming (left) must be crystallized under carefully controlled conditions before reuse. UnaDyn redesigned its crystallizer (in the background) specifically for PLA. In the foreground are UnaDyn pump filtration dust collectors that convey the dust to a single collection point.
Kittredge is v.p. of marketing for Fabri-Kal in Kalamazoo, Mich., the sixth largest thermoformer in North America, specializing in foodservice and consumer-goods packaging. F-K is also a leading processor of today's plastic with the biggest market "buzz"—polylactic acid, or PLA. The best known "green plastic," PLA is not only 100% compostable but it's also 100% bio-based, made by bacterial fermentation of cornstarch.
"It was stressful when we started working with PLA five years ago," recalls senior process engineer David McIntosh. "There are a more nuances to learn with this material than with PET or PP. our first production trial in late 2004 ran one week and produced zero cases of usable product."
But PLA proved to be worth the sweat and tears. Fabri-Kal (or F-K for short) commercialized its Greenware brand of PLA drink and portion cups at the start of 2005. "For two or three years, customers were skeptical of PLA and held off," says Kittredge. "Back then, PLA was a dollar-plus material in a 50¢/lb market." But then the "green" wave arrived. Greenware is now 6% to 7% of F-K's business and the company's fastest growing product—even during the recession, and despite being a premium-priced product. "It's the clearest cup we make," says Kittredge. Annual sales growth for Greenware cups was 55% before the recession and is holding onto a sparkling 15% growth rate even now. Cups with the Greenware logo are now 40% of the company's stock printing business.
The customers for Greenware are mainly restaurants, cafes, and college cafeterias. "We did a consumer survey six months ago," Kittredge notes. "Ninety percent of respondents saw sustainability as a value in a foodservice establishment, and 50% said they would return to a restaurant serving Greenware." And new frontiers beckon: One of the biggest makers of computer software is taking a look at PLA clamshell packaging, according to Kittredge.
'SEND US A GAYLORD'
Executive v.p. Rob Kittredge, like his younger brother John, is a son of owner Bob Kittredge, who co-founded the company in 1950. Seven years ago, it was Rob's idea to give PLA a try. "I saw PLA had a certain public-relations panache, it would reduce dependence on foreign oil, and it would help us and our customers differentiate our products." He saw corn-based plastic as way to get off the oil-price rollercoaster. "We could go longer than month to month on fixed pricing with PLA. The big benefit came in 2007 when oil prices spiked. That was our biggest growth year for Greenware, which has been growing every year."
Back in 2002, Rob Kittredge asked PLA supplier NatureWorks (then called Cargill Dow) to "send us a couple of gaylords and let us test it." By the time F-K commercialized Greenware in 2005, he was so enthusiastic that he told NatureWorks, "We want to be your first carload customer." Today, F-K does bring in PLA by railcar for transfer to a silo.
The move to PLA, as Dave McIntosh noted, was hardly painless. The Hazleton plant was given the task of learning to run this new material. McIntosh recalls, "What we did with PLA was like what we did with HDPE 35 to 40 years ago and PP 25 years ago. Remember that forming PP was tricky in the beginning. Or bringing PET into a plant that was used to PS—that was tricky, too."
Early on, F-K had problems with PLA's brittleness and tendency to "gum up" when crystallizing regrind. PLA crystallizes at a much lower temperature than PET and gets much stickier during the transition phase from amorphous to crystalline, according to McIntosh. "If you know only PS or PET, your whole mindset has to be erased to run PLA," he warns. "PLA has a narrower process window. Those first few months at Hazleton, we were making mountains of regrind, much more than we could ever reuse."
Right away, the Hazleton team focused on issues of crystallizing regrind, since thermoforming produces lots of it even under normal circumstances. Since the plant already had equipment for crystallizing and drying PET from Universal Dynamics, "We went to UnaDyn and it became a mutually beneficial learning experience," McIntosh recalls. The first step was to understand the thermodynamics of crystallizing PLA. Says McIntosh, "UnaDyn put a thermocouples and a datalogger on the crystallizer so we could record what was going on." What they found was that PLA experiences higher exotherm during crystallization than does PET, and that necessitated careful temperature control.
UnaDyn made a number of equipment modifications as a result of this experience. Notes UnaDyn president William Goldfarb, "We redesigned our crystallizer so it can be cleaned thoroughly with no trap points for dust, as PLA can be very dusty. We added special heating systems and more access points, as well as a solid cone air diffuser instead of a perforated metal cone to facilitate cleaning." UnaDyn also came up with a new "lump catcher" at the bottom of the crystallizer to trap and remove PLA agglomerates, which can occur even with good temperature control.
'KEEP IT CLEAN'
"PLA is very sensitive to contamination—even more than PET," cautions McIntosh. "You must keep it clean. All the more so if you run a PET or PS line right next to a PLA line or switch between materials on the same line." Early on, Hazleton shifted back and forth between PET and PLA on one extrusion/thermoforming line. "That's a killer," says McIntosh. PET and PS won't melt at the low temperatures used to process PLA. A speck of unmelted PS will show up white in a clear PLA cup. And a bit of unmelted PET will appear like a dimple. "We had to get everybody on board about this. Workers must learn that this clear cup is not the same as that clear cup, so regrind doesn't get mixed. Putting regrind into a clear product is challenging enough as it is."
When McIntosh talks about getting "everybody on board," he includes the packers of finished cups. PLA is very brittle and tends to shatter into very sharp fragments. McIntosh remembers how his work clothes were shredded by broken shards of PLA in those early days at Hazleton. "The problem was that we started out thinking we could handle PLA after forming just like PET, which is a much more robust material." PLA trims easily because of its brittleness, but finished product must be handled gently. Dustiness of the brittle material remains an issue. "We're even talking with sugar mills to see how they handle the dust," says Dave Grinage, manufacturing development manager.
The Hazleton team did find some positives in working with PLA. McIntosh says PLA has better melt strength than PP, and energy consumption in processing is much less than for other materials, owing to the low melt temperatures (390 to 430 F). PLA also can run on the same extruder screw and thermoform tooling as PET.
F-K's Greenware volume grew sufficiently to dedicate a line at Hazleton to PLA full time. After two years, a line in Greenville, S.C., began extruding and forming PLA lids on a part-time basis. But Fabri-Kal needed still more capacity. So in May of 2009, Line 5 was installed at Kalamazoo, dedicated to inline extrusion and forming of PLA. (The other four lines there process a range of rollstock for short runs.) This is the largest line operated by Fabri-Kal and is reportedly the largest used for PLA anywhere. It has a 7-in., 30:1 extruder capable of 4000 lb/hr. Built by PTi/Processing Technologies International, it extrudes 53-in.-wide sheet, which goes into a 50-in.-wide mold that has 80 cavities for cups of 12 to 24 oz. (The line at Hazleton runs 48-in.-wide PLA sheet on a 6-in. Welex extruder at under 3000 lb/hr).
"We started up a brand-new line with a new mold and a new crew of people," recalls McIntosh. Thanks to the experience gained at Hazleton, "It was actually a better startup than any we've had with PS. It took two weeks, which is normal, and we were running zero scrap within six weeks."
"It's one of the best lines in the plant in uptime efficiency," says senior process technician Ray Torres. Workers on Line 5, like Torres, Don Drenten, and Clemente Vigil wear T-shirts that jokingly proclaim, "Survivor of Line 5 Launch, May 2009."
"We're proud of them," sums up plant manager Lisa Shincariol.
The PTi extrusion system feeds a thermoformer from Thermoforming Systems, a trim press from Brown Machine, and a Brown lip roller. The lip roller had to be fine-tuned for running PLA at high speeds. "We had to find the right balance of heating and cooling and the right auger screw design," says McIntosh.
A granulator under the trim press sends PLA regrind to a surge bin and then to a Maguire blender, where it is combined with virgin PLA pellets. The mix is conveyed 4000-lb/hr UnaDyn crystallizer with a cyclone separator to remove the dust. After the crystallizer comes a UnaDyn dryer, and then material is conveyed to an insulated hopper atop the extruder with a UnaDyn color concentrate feeder to add a blue tint to mask the yellowness of PLA. Quality engineer Mike Saunders notes that color checks are a new QC task for the plant since PLA was brought in.
Fabri-Kal now has two dedicated PLA extrusion/forming systems in Hazleton and Kalamazoo, plus an additional line at each plant that can run PLA part-time and the part-time PLA lid line in Greenville. After a slow period late last year, the Kalamazoo plant is back to running three shifts five days a week. Continued growth seems assured, as customers appreciate both the "green" angle and the prospect of greater price stability than with petro-based plastics, notes supply-chain director Craig Bashore.
What's next? McIntosh says crystallized PLA for higher heat resistance (analogous to CPET) is being developed. "CPLA might get the product to withstand 180 F, versus 105 F now. But we'd like to go higher for microwaveability. And get more impact strength."
Fabri-Kal is also looking at the new Mirel PHA bioplastic from Telles (the Metabolix-Archer Daniels Midland joint venture), which is due to be commercialized this month. It has more heat resistance and ductility than PLA, notes McIntosh, but the cost is not yet competitive with PLA. F-K is also experimenting with thermoplastic starch polymers, which still have to overcome limited draw capability and heat resistance, in McIntosh's view.