THE BASICS OF BIOPLASTICS
Is your company thinking of moving over to PLA or PLA-based materials? Here's your primer!
September 1, 2008 by Umair Abdul, Assistant Editor
Peterborough, Ont.-based Harco Enterprises Ltd., a custom molder of promotional materials primarily for the restaurant and nightclub industries, recently ventured into the green bioplastics market. The company started offering alternative products made of compostable plastics to its existing client base late last year.
“We’re offering it as an option right now on most of our line items, and we’re hoping to get into some custom molded items,” said vice president Terry Harris.
Since then, Harco has been selling items like custom stir sticks and other promotional and premium impact items under the NaturesPlast name. Harris noted that although the increase in sales has been nominal thus far, NaturesPlast has created a lot of interest and the company is doing a lot of quotations.
Harco is one of several processors that have added bioplastic capabilities to their plant. And polylactide (PLA), a biodegradable resin made from renewable feedstocks such as cornstarch, has become the leading material of choice for processors looking to diversify.
MAKING THE MARKET
PLA is available to North American processors through Minn.-based NatureWorks LLC, which sells the biopolymer under the Ingeo brand name. There are 14 grades of Ingeo designed specifically for different applications, taking processing requirements and end product performance into account.
PLA from Ingeo is also being used in certain starch-based Cereplast Compostables resins produced by Hawthorne, Calif.-based Cereplast Inc. Companies like Peterborough’s Harco have opted for Cereplast’s formulations, which replaces petroleum-based feedstocks with materials like corn, wheat, tapioca and potato starches.
Since their introduction and commercialization, Ingeo and Cereplast Compostables have attracted a significant amount of attention from the plastics community. Although some other compostable resin types such as polyhydroxyalkanaoates (PHAs) are slowly moving towards commercialization, PLA has made the biggest splash and forged the largest market for bioplastics.
“It’s the fastest growing segment in our business,” noted John Moisson Jr., founder and president of Jamplast Inc., an Ellisville, Mo.-based distributor of both Ingeo and Cereplast Compostables. However, Moisson is careful to note that the two resins are starting from a very low volume base, and are relatively recent entrants into the market.
THE TAKE UP
When NatureWorks was first introducing PLA to the market, the fibres and sheet extrusion markets were seen as the biggest segments for the biopolymer. To date, those anticipated markets have been the strongest for Ingeo. Currently, the food-service industry is making extensive use of PLA, producing everything from thermoformed trays to clamshells to cups using the biopolymer.
However, several non-consumer industries have also experimented with PLA, using it in unique and innovative applications. For instance, electronics manufacturer recently announced that it had used PLA-based materials in the housing of the FMV-BIBLIO notebook series. Additionally, Samsung Electronics unveiled two new cellphone handsets made of corn-based polymers at the World IT show earlier this year.
Although more sectors are experimenting with PLA and other starch-based resins, Jamplast’s Moisson notes that the materials need to be modified to fit the application. “You can’t do it with pure polymer, you really have to use modifiers to get there, and the challenge is you want to stay green so you don’t want to use traditional materials like impact modifiers,” he explained.
WORKING WITH BIOPLASTICS
One of the benefits of working with Ingeo and Cereplast Compostables is that they require very few changes to your plant’s equipment and tooling. At Harco, Cereplast’s compostable polymers are being run on the plant’s existing presses, with only small tooling modifications such as different gating to accommodate the new material.
Cereplast’s compostable resins process in a very similar way to Ingeo’s straight PLA. Both polymers are hydroscopic, so they require drying prior to being processed. Additionally, the materials require a lower temperature profile, in the 365F to 385F (185C to 196C) range.
“It’s a lower temperature, but it’s not dramatically less,” said Moisson. “Also, the shrink rate for PLA is similar to polystyrene, the cycle times are a bit longer, and the part has to be cooled for a bit longer before it can be pulled out of the mold.”
According to NatureWorks’ technical director Jeff Smith, Ingeo is most similar to polystyrene — a stiff, clear material. As a result, polystyrene molds should work fine and processing will likely be comparable or slower depending on the part design.
However, the material is very different from polypropylene, which is softer, less clear, and lower in density. Processors will encounter difficulties if they try to process PLA in a system or molds designed for polypropylene (PP).
“If Ingeo is replacing polyethylene terephthalate (PET) for injection molding, then cycle times are similar and molds do not need to change,” noted NatureWorks’ Smith. “If Ingeo is replacing polystyrene, cycle/ cooling times on thicker parts is longer, and thinner parts become more closely aligned. If we are replacing PP, times are longer and molds need to change due to the difference in shrinkage.”
LOOKING TO THE FUTURE
Suppliers note that despite the increase in demand for materials like PLA, there is no shortage when it comes to meeting the market’s needs. Nature- Works, for instance, constructed a facility in Blair, Neb. in 2003 with a nameplate capacity of 300 million pounds, making biopolymers a worthwhile gambit for high-volume, commercial processors.
Additionally, recent fluctuations in the price for petroleum-based resins have virtually eliminated the premium that was previously attached to PLA and other biopolymers.
Cereplast Inc. (Hawthorne, Calif.); www.cereplast.com; 310-676-5000
Jamplast Inc. (Ellisville, Mo.); www.jamplast.com; 636-238-2100
NatureWorks LLC (Minnetonka, Minn.); www.natureworksllc.com; 1-800-664-6436