PET BOTTLES: Pushing the boundaries of LIGHTWEIGHTING
"You can never be too thin" -- it's a slogan many people seem to live by these days, and also a maxim the PET drink bottle industry is testing in its own way.For bottlers of both carbonated soft drinks (CSDs) and water, these are golden days...
“You can never be too thin” — it’s a slogan many people seem to live by these days, and also a maxim the PET drink bottle industry is testing in its own way.
For bottlers of both carbonated soft drinks (CSDs) and water, these are golden days for shedding weight, with more and more grams of material being carved from necks, sides and bases.
The catalyst for recent innovations in lightweighting began prior to the Great Recession, when PET resin prices were rocketing upwards with no end in sight.
Case in point: In December, Nestlé Waters launched a new version of its Eco-Shape half-litre PET bottle. Weighing an average of 9.3 grams, the bottle contains 25 per cent less plastic than the original launched in the mid-’90s. Company CEO Kim Jeffrey predicted that shaving bottle weight down to 9.5 grams would cut Nestlé’s volume purchase of PET resin by 95 million lbs. per year, delivering an annual saving of up to US$62 million.
With the stakes this high, every part of the bottle is a target for being lightweighted. “In CSDs, the biggest recent developments centre around the bottle necks, which are responsible for the largest share in material consumption,” said Ottmar Brandau, president of OB Plastics Consulting. Shedding weight became simpler late last year, when a new neck finish standard for CSD containers was introduced. PCO 1881, approved by the St. Paul, Minn.-based International Society of Beverage Technologists in 2009, applies to containers 0.5 to one litre in size, the bulk of CSD bottles made from PET. It creates thinner and smaller neck finishes — only two screw threads against three in the past — and lighter-weight polyolefin closures, decreasing the amount of material used in preforms by 1.3 grams and in standard 28-mm closures by 0.5 grams, for a total savings per bottle of 1.8 grams. “Multiply that amount by the billions of bottles molded worldwide every year and it translates into hundreds of millions of dollars saved annu ally for major brand holders like Coke and Pepsi,” Brandau said.
Bottle sides are another obvious target, and have inspired some creative lightweighting approaches. “Amcor’s current hot-fill offerings use the vacuum to create structures and designs such as hand grips, instead of the old approach of fighting the vacuum by adding geometry and material,” said Fred Beuerle, senior manager, strategic innovation for Amcor Rigid Plastics. “As a result, we reduced our 20-ounce single serve beverage containers from 38 grams three years ago to 30 grams today, and we’re working on 20-ounce containers that are 24 grams and potentially less.”
Bottle bottoms have been getting thinner for years — and as with other sections, developments are accelerating. Some of the newest lightweighting approaches also embrace the vacuum. Graham Packaging’s Escape hot-fill PET bottle, for example, is 6.5 grams lighter than previous offerings; production is topped off when, after filling and capping, the bottle goes through a CMA — continuous motion activator — that inverts the base, which takes up the vacuum in the bottle and creates a slight overpressure.
BIG GAINS IN WATER
Particularly dramatic lightweighting results are being seen in water bottles. “Because of the non-carbonation factor, the water industry can go further in reducing the neck to smaller dimensions,” said Werner Amsler, president of blow molding machine maker W. Amsler Equipment Inc. “Modern 500-ml PET water bottles have been reduced to a standard weight of less than 10 grams, compared to a standard weight of 17 grams just a few years ago.”
Statistics from the Alexandria, Va.-based International Bottled Water Association (IBWA) support this: One recent IBWA study estimated that over the past eight years the gram weight of the 16.9-ounce single serve bottled water container has dropped by a whopping 32.6 per cent.
For the drinker, at the opposite end of the spectrum from water is alcohol. Although PET has nowhere near the market penetration here as in CSDs and water offerings, it’s been around long enough for first generation PET liquor bottles to be replaced by seriously lighter designs. “Over the past few years, Westbridge PET Containers has reduced the package weight in this market by approximately 10 per cent,” said Dave Birkby, company president and CEO. “Most recently, we designed a port and sherry package in PET that went from 86 grams down to 70 grams, using a PET preform that could ideally optimize the distribution of thickness to meet customer requirements for look, feel and performance.”
REACHING THE LIMITS
A comment from Amcor’s Fred Beuerle sums it up nicely: “In the past, we made incremental progress lightweighting PET bottles; now we’re progressing in leaps and bounds.” Just so. But there’s always been awareness that lightweighting would eventually reach the point at which it creates more problems than it solves. That marker might be approaching fast. “Many PET bottle suppliers are already hitting the practical limit for lightweighting,” said Jamie Pace, vice president-general manager at Nissei ASB Company. “If they continue beyond that, they could end up with products too flimsy to survive the rigors of the distribution chain.”
This reality was just acknowledged by UK supermarket giant Tesco. In 2007, the company had pledged to reduce packaging weight by 25 per cent by this year, but recently reduced the target — a concession that cost savings through weight reduction can’t remain the sole driver.
The second big lightweighting driver — trimming environmental waste — has also run head-on into reality, at least for now. “Currently, PET bottles are being lightweighted to the point of requiring an added nylon oxygen scavenger as a barrier,” said Fred Beuerle. “The problem is, some of the currrent barrier materials might contaminate the recycling stream when present at above certain levels, and consumers don’t want the industry to lightweight to a less recyclable product. A big part of our current development projects involve creating an enhanced barrier that will have no impact on the recycle stream, and also support very thin, light containers. The industry is now making rapid progress in this direction.”
Amcor Rigid Plastics (Manchester, Mich.); www.amcor.com; 734-428-9741
Nissei ASB Company (Atlanta, Ga.); www.nissei-asbus.com; 404-699-7755
—— Plastics Machinery Inc. (Newmarket, Ont.); 905-895-5054
OB Plastics Consulting (Wasaga Beach, Ont.); www.blowmolding, org; 705-429-1492
W. Amsler Equipment Inc. (Richmond Hill, Ont.); www.amslerequipment.net; 905-707-6704
Westbridge PET Containers (Calgary, Alta.); www.westbridge.ca; 1-800-650-2454