Which resin is sustainable? It depends on the application

By Mike Verespej | PLASTICS NEWS STAFF

There’s no single magic bullet when it comes to determining what plastic resin is most suitable for a particular product or packaging application.

“We began to develop a comprehensive program seven years ago because not one single technology is suitable for all applications,” said Roman Forowycz, group president and chief marketing officer at Clear Lam Packaging Inc. in Elk Grove, Calif.

“We have three mutually exclusive approaches in our Project EarthClear program,” he said: renewable raw materials, packaging with recycled content and light-weighting. Each approach is designed to reduce the impact of the package on the environment.

‘We believe a portfolio approach is appropriate for executing appropriate sustainability solutions,” Forowycz said.

David Clark, director of sustainability for Amcor Rigid Plastics, agreed.

“We try to use a system approach to packaging development, looking at the next generation of materials and the increased use of recycled materials where it is available,” Clark said at the Sustainable Plastics Packaging 2010 conference in Atlanta, organized by Plastics News Global Group. “We look at polypropylene, high density polyethylene, extruded PET and barrier technologies to determine what’s best for a particular package.”

Amcor Rigid, based in Ann Arbor, Mich., changed its name from Amcor PET Packaging in March when its corporate parent, Amcor Ltd. in Melbourne, Australia, acquired parts of Alcan Packaging and reorganized into seven operating units. That restructuring moved Amcor into materials beyond PET and into other processes, such as extrusion blow molding. The company now includes the former Amcor PET packaging, the plastic container unit of Alcan’s global pharmaceutical business and a plastics closures joint venture.

“It has given us the opportunity to look at the environmental impact of different materials and which is best for a particular need,” he said. Amcor, for example, has developed — for sliced fruit sold under the Libby’s brand by Seneca Foods Corp. — a 24-ounce round and a 26-ounce square PP container that is 80 percent lighter than glass and has a higher thermal stability than heat-set barrier PET.

Similarly, Clear Lam developed new polylactic acid containers for Stonyfield Farms multi-pack yogurt cups.

‘We wanted to move into the renewable area and felt we needed to find a suitable partner,” said Forowycz, whose company manufactures flexible films, rigid rollstock and thermoformed containers. “We felt that this was a transformational technology for the next decade” that can be used for products such as single-use butter cups, coffee and tea pods, and dairy products such as margarine, cottage cheese, sour cream and ice cream containers.

He also sees opportunities outside the food industry for Clear Lam’s Renew 910 PLA film that is used for the Stonyfield yogurt cups in blister packaging, clamshells, cases, bags and pouches for electronics, personal care products and health care products.

Forowycz said Stonyfield and Clear Lam are focusing the marketing of the new PLA yogurt cups on the fact that they are made from a renewable, non-petroleum-based resin made from plants, and emphasizing the improved barrier properties, the lower carbon footprint and the reduction in energy use because of the lower temperatures at which PLA melts.

“The decision was made not to talk about recycling and composting because we don’t do that [compost] in the United States [or recycle] except for PET and HDPE containers,” Forowycz said. “We don’t advertise those points because it would convey a benefit that doesn’t exist.”

That is also the case with other films and packages Clear Lam makes that are a combination of PLA and other resins — whether it is packaging for single-serve bags of pretzels, mixed nuts, clear pasta, lettuce and egg containers or single-use shampoo caps. “None of those products today are recycled, so we focus on the front-end message,” Forowycz said.

As companies ponder material changes to improve the sustainability of packaging, it is important that they take into account and understand the equipment and the processes involved, Forowycz added.

“To change technologies, you need to understand the current process and the limits of the existing equipment,” he said. “It is difficult to change a mindset and say there is a new way to do this as it requires changes in operating processes.”

Bill Goldfarb, president of Universal Dynamics Inc. in Woodbridge, Va., which manufactures everything that handles resins from blending, drying and granulating equipment to material handing equipment, also pointed out the importance of working together with fabricators and processors to understand how to process materials such as PLA.

“There are challenges in processing and reprocessing PLA bioresins, and advantages and disadvantages,” Goldfarb said. “You have to work together to achieve new approaches.”

But he emphasized that the changes needed to switch from using PET to PLA are simple, and involve the use of proper drying temperatures, removal of all traces of PET to remove contamination, lower melt temperatures for the PLA resins and remembering the any PET contaminates will come through the extruder unmelted.

“The advantages of PLA are that it is renewable and there is an energy savings because of lower processing temperatures,” Goldfarb said. “It melts at temperatures more than 100° lower than PET so the energy you need is only one-fourth of what you need when you use PET. But you need to move it at a steady state process flow so it doesn’t clog up the process.”

The disadvantages, at this point, is that that are applications limitations from a temperature and durability standpoint, and that PLA must be handled and processing differently — through slight modifications of existing equipment, he said. In addition, PLA must be dried differently as it requires dehumidifying hopper dryers with low-temperature process options.

‘There is a handling/processing paradigm shift that must occur, and there is a learning curve whether it is extruded or whether you do injection molding,” Goldfarb said. “You need a new mindset, but the capital equipment costs will be the same or less than when you run PET.”

SOURCE: PLASTICS NEWS

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