Research & Innovation
The Increasing Significance of Old Corrugated Containers
By Pulp & Paper Canada
As a significant source of wood pulp fibre, old corrugated containers (OCC) have become an increasingly valuable commodity which benefits both the paper packaging industry and this country’s economy.David Andrews, executive director of...
By Pulp & Paper Canada
As a significant source of wood pulp fibre, old corrugated containers (OCC) have become an increasingly valuable commodity which benefits both the paper packaging industry and this country’s economy.
David Andrews, executive director of the Canadian Corrugated and Containerboard Association (CCCA), says the importance of OCC to our recycling paper mills cannot be understated. “For both domestic use and export revenue, the supply of recycled wood pulp fibre from collected OCC is critical to corrugated containerboard supply. It impacts the long-term viability of recycling and fibre reclamation processes that bolster our industry’s manufacturing capability.”
On a global scale, the economics of OCC transactions are impressive. A general shortage of OCC coupled with growing demand by the US and China, along with other countries, is making Canadian OCC a viable export commodity. Countries outside North America need it to cost-effectively produce new paper for new board and new containers. Notable is China – the highest among other net-importing countries – which cannot supply its packaging industry requirements with wood fibre from domestic sources.
Robert Lanthier, Norampac’s vice-president of sales, marketing and innovation for the firm’s containerboard and boxboard divisions, observes that China is growing at a very fast pace but their recycling is far behind North America’s. “They are creating a widening gap between demand for OCC and domestic availability and the ‘loop’ is turning faster and faster.”
Every year it becomes harder to get
North America is a net exporter of OCC, with the “tiger’s share” of shipments going to China, followed by Latin America – Brazil and Mexico primarily. Composed mostly of scrap cuttings from boxes made of double liner kraft, OCC is the basic material for making corrugated linerboard. As worldwide demand for OCC increases, so does its world market price per tonne. The resulting global supply situation is summarized by Serges Desgagnes, paper product specialist for Kruger Inc. “Somewhere in the world there’s a shortage of OCC, and every year it becomes harder to get.”
Unlike the situation a few years ago, most of China’s manufactured goods now arrive in Canada already boxed and China wants that used corrugated returned for recycling into new containers. China adds nearly four million new tons of containerboard capacity per year, with 90% of that volume coming from recycled material.
Kruger’s Desgagnes emphasizes why the collection of Canadian OCC for re-use is so important: “The more OCC we can acquire locally, the more raw material we have immediate access to. That’s why we must ensure that little or no used corrugated gets dumped into landfills. It’s valuable, and we need it for both manufacturing and export.”
He goes on to explain the economics of shipping OCC for Canadian paper packaging manufacturers and their customers. “Ordered in bulk by recycling paper mills, most of the pricing [for OCC] is FOB point of delivery. If we take a shipment of OCC from Texas, for example, its actual delivered price to our Quebec mill could be doubled due to freight costs. If we can get if from Toronto or Montreal, the cost per tonne is far cheaper. When OCC is not readily available in Canada, we have to obtain it elsewhere. Essentially that means importing from the U.S., and freight becomes a problem.”
Longer hauls not only add cost but bring environmental concerns into play. Although the carbon footprint of transportation is not easily quantifiable, it is a constant consideration as the thrust of this industry’s effort in OCC reclamation and re-use in new paper and board is based on environmental benefits coupled with cost efficiencies.
Technical hurdle: wax-free coatings
According to Robert Lanthier at Norampac, it’s vitally important for the corrugated packaging industry to recycle as much OCC as it can. “Achieving that optimal goal will require wax-free moisture barrier coatings and treatments that permit corrugated containers used for shipping produce in crushed ice to be recycled for repulping and milling into new paper.”
One example of innovative wax-alternatives is Norampac’s new Norshield process. “We want to send as little OCC as possible to landfills. To that end, this company has been working for more than four years developing a new water-based moisture-barrier process,” states Lanthier. “Compared to traditional wax-coated containerboard, the Norshield wax-alternative product is at least 80% effective for packers and 100% effective for OCC recycling by retailers.”
How old corrugated board becomes new paper
“There’s a lot more to making paper than meets the eye,” says Joe Zenga, manager of Norampac’s OCC recycling paper mill in Mississauga, Ont. “People generally don’t realize how complex and complicated it is. There’s a lot of science involved in our mill operation and the processes are getting more scientific every year.”
At the ‘wet end’ of the mill, arriving shipments of collected OCC are mixed with municipal water and slowly churned to create a coarse mixture – about the consistency of wet cement – which undergoes mechanical separation to remove all foreign matter.
Once liquified, the slurry can be washed and treated. It is pumped through several filtration stages that remove minuscule particulate matter and any chemical contaminants, leaving a residue of extracted wood-pulp fibres that can be processed and milled into new packaging-grade paper.
Gerry Murray, vice-president of mill operations at Atlantic Packaging’s OCC paper mill in Scarborough, Ont., emphasizes that at the end of the initial reclamation stage, “Wood pulp from recycled OCC comes out as clean, or even cleaner, than pulp made from virgin wood. Those fibres can be controlled to create a sheet of paper.”
After emerging from the pulper head-box, the mixture is composed of 96% water and 4% wood fibre. The fibres are randomly cross-aligned to maximize paper strength, then held in position through the addition of polymers in a process that includes ‘fibrillation’ of individual polymer strands to increase fibre bonding affinity at the cellular level.
Murray, who is a chemical engineer, details the science of the process: “Envision a myriad of little curled microfibres of polymer at the hydrogen-bond level. The polymer strands are fibrillated—vibrated and abraded—until their microscopic fibrils link and stick tightly together, rather like Velcro.”
That induced physical affinity between fibres enhances the strength of the mechanical bonds within the paper sheet. For some applications, starch may be used in place of polymer to enhance bonding strength.
Norampac’s Joe Zenga comments on how fibre orientation affects the performance of the finished paper sheet: “Everyone in this industry is fine-tuning their fibre alignment and basis-weight, constantly striving to create lighter weight paper with higher stacking strengths to satisfy our customers’ evolving needs. It’s a delicate balancing act.”
After the head-box, the wet mixture enters a multi-step drying and rolling process which extracts water from the mix until its moisture content is reduced to less than 8% (92% percent fibre).
When it reaches 50% water and 50% fibre, the sheet becomes strong enough to be conveyed unsupported along rollers, then accelerated to 914 metres (3300 feet) per minute through the dry-end milling processes. To remove most of its remaining water content, the bonded and formed pulp is compressed between hardened-steel rollers. It passes through a serpentine run that heats both faces of the paper sheet simul
New paper created from recycled OCC is “at least as strong” as paper made from virgin fibre, its performance enhanced by internal polymer bonds. Atlantic’s Gerry Murray describes milled OCC as the perfect paper for corrugating and converting. “Strong, sterile and absolutely clean, you couldn’t ask for a better paper.”
Using our recycled wood fibre wisely and well
The Paper & Paperboard Packaging Environmental Council (PPEC) recently called for a ban in Ontario on dumping used corrugated boxes into landfills. PPEC’s executive director, John Mullinder, emphasizes that OCC is far too valuable a commodity to simply waste. “From every aspect including social, economic and environmental, it is an ecological travesty for old used corrugated containers to be buried in landfills rather than “re-harvested” and recycled.”PPC
Freelance photojournalist Jerry Scott Mills has covered the paper packaging industry for more than a decade.