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Packaging Goes Green
Source reduction means consuming less material through lightweighting or downgauging a package or eliminating one of its components. Redesigned closures are one lightweighting strategy. Short-skirt closures, which are particularly popular in the beverage industry, reduce the amount of plastic in the closure itself and in the neck finish of the bottle. It is common to save about 1.5 g per container–closure. This reduction might not sound like a lot, but it adds up quickly during a production run and cuts resin use by thousands of pounds and packaging costs by thousands, if not millions, of dollars per year.
Another way to remove weight from packaging is by switching to a lighter material. In the past 30 years, many food products have been switched from glass to polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene, or multilayer plastic containers. With the high-barrier coating and oxygen-scavenger technologies now available, more oxygen-sensitive products such as beer and wine are being packed in PET instead of glass. Compared with traditional glass containers, PET bottles consume less energy in production, distribution, and recycling and result in a smaller carbon footprint.
Sutter Home Winery (St. Helena, CA) has added a 187-mL size to its PET container lineup. The custom-designed bottle features an internal silicon-oxide barrier coating to protect product shelf life (Plas-max PET bottles, Ball, Broomfield, CO).
Although it requires measures to ensure that the product is adequately protected, reducing the use of corrugated in distribution packaging is a common source- and cost-reduction strategy. In a survey by the Packaging Machinery Manufacturers Institute, 51% of respondents said they intend to reduce corrugated consumption by replacing regular slotted cases with bliss boxes or overwrapped trays. Respondents already using overwrapped trays are achieving additional material savings by adopting overwrapped pads or overwrap alone.
Another source-reduction tactic, eliminating a packaging element, not only saves material and reduces package weight and transportation costs, but also may reduce package size, thereby enabling more product to be stacked per pallet.
Incorporating recycled content from postconsumer or postindustrial sources into packaging reduces the amount of virgin material needed and lowers greenhouse-gas emissions. Primary, secondary, and distribution packaging can all be made with recycled content. Companies should perform tests, however, to determine whether recycled-content packaging will reduce their costs or perform as well as virgin materials.
A range of 100% recycled PET (RPET) containers for liquid prescription drugs is available in 2–16-oz sizes. The bottles meet standards set by the US Pharmacopeia for virgin PET bottles, including limits on light and water-vapor transmission. The range of containers also is designed to meet child-resistant and senior-friendly protocol requirements set by the Consumer Product Safety Commission (RPET containers for liquid pharmaceuticals, Rexam Prescription Products, Perrysburg, OH).
Although containers made of 100% RPET are feasible, blends of virgin and recycled material are more common because of relatively limited supplies of food-grade RPET. The percentage of RPET used is likely to rise during the next decade, however, because the number of suppliers of food-grade RPET and their capacities are increasing (Food-grade RPET resin, Phoenix Technologies, Bowling Green, OH).
RPET may require companies to fine tune the container-production process through adjustments such as increasing the level of melt filtering on preform equipment and modifying the bottle-blowing machine. Additives may be needed to impart desired properties and duplicate the viscosity of the virgin material. Regardless of whether 100% recycled content or a recycled–virgin blend is chosen, the resulting containers should perform the same as virgin PET containers on the filling line.
Recycled-HDPE (RHDPE) containers also offer filling-line performance equal to that of their virgin counterparts, although their color may differ slightly. A washing and devolatilization process converts postconsumer, food-grade HDPE bottles to food-grade recycled resin by removing impurities such as volatiles and fragrances to levels approximately 50% below FDA's maximum threshold. Sample quantities of RHDPE are currently supplied from a research and development line, but a full-scale production line is scheduled to start operations before the end of 2009. Although as much as 100% RHDPE can be used, a recycled–virgin blend will be more cost-effective until the price of scrap material declines (EcoPrime RHDPE, Envision Plastics, Reidsville, NC).
Another way to incorporate recycled content is as a layer in a multilayer package. One common application is laundry detergent bottles, but the technology is feasible for smaller containers and tubes.
Some suppliers offer inserts and folding cartons with recycled content. One firm's recycled content for inserts is typically 20%, of which 10% is derived from postconsumer sources, and its folding cartons may contain as much as 50% recycled content (Recycled-content inserts, folding cartons, Cortegra Group).
One option for recycled-content distribution packaging is an air-filled cushioning made of monolayer linear-low-density polyethylene (LLDPE) or coextruded LLDPE–nylon with as much as 40% recycled LLDPE. The material is made of roughly equal amounts of postconsumer recycled resin and industrial scrap (Astro-Bubble Green cushioning, Pregis, Deerfield, IL).
Interest in packaging derived from renewable sources such as trees and corn is growing because of these materials' perceived advantages over materials derived from finite resources such as oil. Packaging derived from renewable resources offers a smaller carbon footprint and is seen as a way to meet corporate sustainability objectives. In addition, renewable materials often are biodegradable and may be compostable.
In response to rising demand, one maker of polylactic acid (PLA) bioresin doubled its production capacity and installed an applications laboratory equipped with a sheet-extrusion line, commercialsize thermoformer, and injection molder to help drug manufacturers develop packaging made from the biodegradable material. The expanded production capacity has been accompanied by process improvements that reduce PLA's carbon footprint by cutting energy consumption by 30% and carbon-dioxide emissions by 60%. With this change, PLA production generates 77% less carbon dioxide per kilogram of resin and consumes 56% less energy compared with PET. It also has a smaller carbon footprint than RPET (Ingeo PLA, NatureWorks, Minnetonka, MN).
But as demand for PLA rises, so do concerns about its postconsumer fate. Because few US consumers have access to industrial composting facilities and no municipal recycling infrastructure currently exists for PLA, containers are likely to end up in landfills or mixed with traditional plastics such as PET. Unfortunately, biodegradation generates methane in landfills, and small amounts of PLA contaminate RPET.
Although testing by NatureWorks and Primo Water shows it's possible to sort PLA from PET containers using near-infrared technology, the National Association for PET Container Resources (NAPCOR) contends that the cost of such systems precludes widespread installation by recyclers. In addition, these systems tend to sort out too much PET with the PLA and do not capture enough PLA to prevent contamination problems. "The reality is that the PLA container becomes a contributor to PET bale yield loss, which is already a big concern for PET reclaimers," says Dennis Sabourin, executive director of NAPCOR.
One answer to some of the criticisms leveled at bioplastics may lie in using renewable sources to make polymers ordinarily derived from oil or natural gas. With a 30:70 blend of plant- and petroleum-based feedstock, the Plant-Bottle, recently introduced by Coca-Cola for Dasani water and sparkling brands, employs this tactic. Byproducts of sugar production, sugarcane and molasses, are converted into a key component of PET.
According to a life-cycle analysis by the Imperial College of London, the plant-based component is responsible for a 25% smaller carbon footprint, but has no ill effect on PET recycling. "The PlantBottle represents the next step in evolving our system toward the bottle of the future," says Scott Vitters, director of sustainable packaging for Coca-Cola. "This innovation ... moves us closer to our vision of zero waste with a material that lessens our carbon footprint and is also recyclable."
Degradable PET controversy
Another material receiving lots of attention, degradable PET, sounds like an ideal choice for green packaging because so much PET packaging ends up as litter, ocean pollution, or in landfills. Three trade associations have reservations about this PET, which includes additives to make it degradable. The associations fear that the material could cause problems for PET recycling and recycled-content PET products.
NAPCOR contends that suppliers of degradable PET need to substantiate claims of degradability, investigate the effect of degradable additives on the quality of the PET recycling stream, examine the effects of degradable additives on products made of RPET, and learn how the material changes the service life of these products.
"We don't yet understand the impacts that these additives could have on the quality of the PET recycling stream, let alone the impacts on the safety and functionality over time of next-use PET products like recycled-content PET packaging, carpeting, or strapping," explains Sabourin.
EurPR (Brussels), a trade association for plastics recyclers, echoes NAPCOR's concerns and is particularly worried about whether oxo-biodegradable PET will pose problems in recycling operations.
European Bioplastics (Berlin) also has issued warnings about oxo-biodegradable plastic containers, claiming that no evidence shows that these materials meet international standards regarding biodegradation and compostability such as the International Organization for Standardization's ISO 17088 Specifications for Compostable Plastics or European Norm 13432 Requirements for Packaging Recoverable through Composting and Biodegradation. "If certain products that claim to be biodegradable or compostable are proven not to fulfill acknowledged standards, this is liable to impact negatively on our own members' products, even though they do fully comply," explains Andy Sweet-man, chairman of the board of European Bioplastics.
But a maker of oxo-biodegradable additives argues that its material complies with the degradability, biodegradability, and nonecotoxicity requirements of the American Soceity for Testing and Materials's D6954-04 Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation (Symphony Environmental Technologies, London).
Another maker of a degradable additive also claims compliance with ASTM standards for biodegradability and recyclability and has confirmed results with third-party testing and validation. This additive is not classified as oxo-biodegradable, but enables the PET to degrade in anaerobic and aerobic environments by attracting microbes that convert the resin into humus and gases such as carbon dioxide and methane. Because it does not chemically bond to the PET, it reportedly has no effect on bottle weight or properties. Testing also has shown that the material has no negative effect on the PET recycling stream (EcoPure degradable additive for PET, ENSO Bottles, Phoenix, AZ).
Hallie Forcinio is Pharmaceutical Technology's Packaging Forum editor, 4708 morningside Drive, Cleveland, OH 44109, tel. 216.351.5824, fax 216.351.5684, firstname.lastname@example.org