Research & Innovation
The paper coffee cup that can be recycled
May 25, 2018 - Unless you’re one of those overachiever types who brings his or her travel mug to the coffee shop every day, you probably carry your caffeine fix away in paper cups. Chances are you drank from a takeout cup this morning.
May 25, 2018 By BASF Dispersions & Resins Business Unit
If so, you’re in good company. More than 136 million Americans will drink from a paper coffee cup by the end of the day, and more than 50 billion cups by the end of the year. Another 50 billion next year, and the year after that, and so on.
That’s a lot of cups. More pressingly: that’s a lot of waste. And, contrary to what most consumers believe, coffee cups are not even widely recyclable – not in North America, anyway. (In their defense, inaccurate labels are everywhere, including on the cups themselves). Alas, once used, paper cups become garbage that piles up by the hundreds of billions in our landfills.
The reason paper cups aren’t recyclable
Paper cups have two basic parts — paper and polyethylene. Comprising only 5 per cent of the whole container, the polyethylene liner is what brings the muscle – the liquid barrier that keeps heat in and prevents the cup from getting soggy – but it’s also a contaminant in the paper waste stream.
Most contaminants can be removed and paper mills can easily filter out unwanted substances, like dirt, dyes and other residue, during the re-pulping process. What makes the plastic liner different from other contaminants is that it breaks up into large flakes that pass through coarse pulping screens and clog the fine screens. The filter clogs are so disruptive to the equipment that most paper mills send the cups to the landfill automatically.
We put a man on the moon, but we can’t deal with a few clogs?
It’s not that recycling paper cups isn’t possible — it is. The technology exists. In fact, there are two Material Recycling Facilities (MRF) in the U.K. that can do it. It’s also not for lack of wanting change.
“Brand owners have long been under pressure from increasingly eco-conscious consumers to improve their environmental stewardship,” said Katherine Grisson, Industry Marketing Manager for Printing, Packaging & Adhesives, BASF. “I’ve talked to several brand owners who are actively trying to address this problem.”
Just ask Starbucks; they are up front about it: “We are working to shrink our environmental footprint and meet the expectations of our customers by reducing the waste associated with our business, increasing recycling and promoting reusable cups.”
The problem? Recycling is complex, and it goes beyond technical ability. There’s the question, for example, of responsibility. If cups need to be made differently, who pays for material or mechanical upgrades? Who pays to retrofit MRFs with the necessary equipment? Who ensures that cups are sorted properly and arrive at the right MRF in each municipality?
“Consumers and taxpayers don’t feel like they should have to foot the bill; they feel it’s the brand owners’ job,” Grisson added. But as specialists in coffee – not cups – brand owners turn to their cup suppliers to solve the problem. These suppliers turn to their converters who turn to their ink formulators, and so on.
Everyone in the value chain is feeling the pressure, but pressure doesn’t pay the bills.
Designing for consumer whims and industry realities
Interestingly, the same consumers who demand sustainability are seemingly unwilling to sacrifice their own convenience for the cause. Just ask the coffeehouses that offer incentives to show they’re serious about waste. “Starbucks has implemented a program where customers can save 10 cents every time they bring in their own mug,” said Grisson, but less than 2 per cent of customers actually take them up on the offer.
“What we can take from this is that people still want paper cups, so the solution can’t venture too far outside the box. Designers are up against tight parameters: paper cups have to be recyclable, but they also have to be affordable, and work within existing infrastructure, and meet performance standards.”
Not surprisingly, it has been difficult for the industry to find such a cup. Several companies will claim that salvation has arrived, but with every solution it seems that one criterion is always amiss.
Take polylactic acid (PLA) liners; they’re made from plant-based resins that can be composted. At face value, composting seems like an even better solution than recycling. But in practice, not only is PLA more expensive, most retail locations also aren’t equipped to compost.
“Unless the PLA-lined cup finds its way into a controlled compost facility, it will pollute, just like any other non-degradable cup,” added Grisson. “And just like PE-coated cups, it is not a wanted recyclable by the paper industry. So what sounds like a great idea isn’t necessarily viable for most brands.”
Another strategy that is gaining attention is a method that uses the same PE liner, but applies it differently, by lightly gluing it onto the fibre, instead of extruding it. The idea is a good one, but it assumes that MRFs have the equipment to process the cups correctly. If they don’t, it is functionally the same as trying to recycle existing cups on the market.
It seems that no matter how advanced the design, the problem is always buried in the liner.
The U.K.-based Paper Cup Recovery and Recycling Group (PCRRG) concurs: “One could argue if cups were made out of a single material then they could be simply sorted with other paper in the MRF. However, no such pure single material cup exists, since the cup has to be able to hold a hot drink safely without going soggy or leaking?”
The PCRRG is both right and wrong.
Water-based polymers: Fighting liquid with liquid
“The two-part cup model is a problem,” said Grisson. “But thanks to innovative polymers, there is now a solution that can combine paper and performance. BASF found the answer in water-based polymers.”
Here’s how it works:
“The polymer acts as heat-sealable, block-resistant, liquid barrier,” explained Grisson. “It performs like polyethylene, so the cup still does what it needs to do, but at the end, the cup can be sorted with regular paper.” The novel water-based technology does not interfere with the paper repulping process. There are no additional contaminants that have to be separated-just valuable paper returned to the material stream.
“It’s a practical alternative for formulators and converters, because they don’t need any additional equipment,” she concluded. “It’s applied during the converting process at a comparable cost-in-use pricing; they can use their existing gravure printing or rod coating processes. It also eliminates the extrusion or liner gluing step required for polyethylene coated cups.”
Making our well-caffenaited future a responsible one with water-based-polymer technology on the horizon, it’s only a matter of time before landfill-bound paper cups – frozen yogurt cups, and takeout noodle containers – are a distant memory.
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