Molding sustainability into the bottle

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Cola-Cola Co. Coca-Cola's plant bottle, made using bio-based resins, is one example of the renewable resources available for traditional plastics.

Pittsburgh — One size does not have to fit all when it comes to sustainability in plastics.

That’s because blow molders have a variety of ways to improve their sustainability and recycling efforts, according to one official with the Association of Plastic Recyclers.

John Standish, APR’s technical director, gets paid to think about and analyze this kind of stuff. He shared his thoughts at the Annual Blow Molding Conference recently held in Pittsburgh.

“When we look at rigid plastic packaging and sustainability, there’s four strategies that I’m aware of that can be used to address sustainability,” he said.

“One is package lightweighting,” Standish told attendees. “And you are all aware that not too many years ago we packaged laundry detergent products in high density polyethylene bottles that were fairly large volume. And because of sustainability, the brand companies started to concentrate their formulations, allowing smaller packaging to be used. So there’s an example of lightweighting.

“But we’re starting to reach the point of diminishing returns that can be achieved in lightweighting and weight reduction,” Standish said. “So biosourcing of polymers is a strategy we might be interested in.

“Some of you might know that in polyethylene, you can make the ethylene used in polyethylene from natural resources. Or in PET plastics, you can make the ethylene glycol used to make PET from bioresources. But in today’s market, making polymers directly from traditional petroleum sources is by far more economical so as appealing as this strategy is, it’s not economically practiced very much today,” he said.

Beyond lightweighting and bioplastics, Standish said the use of recycled content in new products also is a way to improve sustainability.

“The energy required to make recycled resin is about half that required to make virgin resin. And directly tied to that, the greenhouse gas generation from making recycled resin is about half of that associated with making virgin resin,” he said. “So including recycled content is an important sustainability effort.

“And then, finally, we can design projects so that they are recyclable. Because if a product goes to landfill, that doesn’t help sustainability. If a product goes to waste-to-energy, that might be better than landfill, but it’s not as good as designing it so that it’s suitable for a next use,” he said.

While the technology exists to use a high percentage of recycled content in blow molded products, market conditions are preventing that on grand scale.

“We’re not able to use recycled content at these high levels widely because, frankly, the demand for post-consumer resin far exceeds the supply of post-consumer resins. So the availability of post-consumer resins today limits its use,” Standish said.

But arguments for recycling and sustainability, the APR technical director said, have grown over the years.

“In the past, when we talked about recycling and ‘let’s recycle more,’ we did it terms of warm and fuzzy feelings,” he said. “We said, ‘Let’s recycle because it conserves resources or it prevents litter or it will make the world a better place for our grandchildren.’

“All of those things are very true and all of those are good reasons to recycle. But what I want to emphasize to everybody in the room is the most important reason to recycle is that it’s simply good business,” Standish said.

The annual conference is sponsored by the Blow Molding Division of the Society of Plastic Engineers.