Husky helps bottle preform producers lightweight their packaging

Strategies to promote sustainability continue to evolve for bottle preform producers, who are finding new ways to lightweight the products and tether caps to them.

“As a strategy, lightweighting has been around for a long time,” Carson Kim, business advisor for rigid packaging at Husky, said during a recent webinar on the Plastics Machinery & Manufacturing website. “It’s a very simple principle – every gram of resin used in the packaging makes a direct impact on your bottom line.”

Reducing the weight of plastic bottles makes it possible to achieve savings without compromising performance or the customer’s experience, he said.

Lightweighting is a good way to compensate for the extra costs of recycled PET (rPET), which Kim said typically is 70 percent to 100 percent more expensive than virgin PET. With bottle manufacturers under pressure to use rPET, especially in Europe where use of the material is mandated, they're more motivated than ever to reduce the weight of their products.

Methods targeting four different areas of the bottle can help manufacturers reduce the weight of typical PET bottles, Kim said.

The first strategy involves trimming the neck finish through small modifications that reduce unnecessary material.

The second method involves lightweighting the neck and adopting a new closure design.

“This approach delivers greater savings when compared to the previous case simply because you’re changing both the neck and the closure together,” Kim said, with designs that reduce the amount of plastic required for each.

The third approach is optimizing the body of the bottle to reduce the amount of resin required.

“We can help to improve stretch ratios by consulting and working with our blowing OEM partners for ongoing technology improvements,” Kim said. Improvements in blow molding technology allow for thinner body walls.

Design changes from top to bottom

Redesigning the base of a bottle also can reduce its weight.

“There are a number of options that we provide you depending on how aggressively you want to lightweight your base,” Kim said. This option can reduce bottle weight by up to 2.5 percent.

“Of course, these four methods can be implemented individually or in combination to achieve greater savings,” Kim said.

Kim cited a project in which Husky helped one of its customers redesign a 0.5-liter bottle for carbonated soft drinks. Husky worked with other OEMs, including downstream OEMs, to redesign the preform to maximize lightweighting without compromising bottle performance. Part of the savings was achieved because Husky and its customer determined the bottle was oversized for the application.

“We were able to bring the part [overall preform weight savings, including neck finish, diameter under support ledge, overall length and base] down by more than 2 grams, or more precisely, 2.24 grams,” Kim said. “This was a very comprehensive approach where we were approaching every aspect of the preform. We had extensive piloting and validation before the customer went to full production, and, of course, the results were very positive. The customer was able to save a lot of resin consumption, as well as a huge cost benefit.”

Outlining the business benefits, Kim said resin savings amounted to 1.48 grams for the dispensing system (when looking at the neck finish and closure only), with total resin savings of 1,958 tons per year, and a cost savings of $1.51 million per year based on a production of 1.2 billion dispensing systems (bottles and caps) per year. Carbon savings amounted to 4,979 tons per year.

Caps also seeing innovations

Another recent trend in bottle manufacturing involves using redesigned caps that are tethered to the bottle neck.

“What is really driving this whole tethered closure phenomenon is back about two years ago, the European Union (EU) Parliament passed a single-use plastic strategy,” said Michael White, director of business development, closures for Husky.

Part of a wide-ranging piece of legislation, the requirement states that by July 2024 brands that sell into the European Union must have closures tethered to bottles with volumes of up to 3 liters. That means the closure must still remain affixed to the bottle after it’s opened to help boost recycling and reduce plastic litter.

White described the EU requirement as “the first domino to fall.” Canada and Australia are looking at similar requirements, and California and Maine have also discussed it.

Adoption of tethered closures allows companies to reinforce the message that they support sustainability initiatives, White said.

Husky highlighted several tethered cap designs, with some designed for noncarbonated water and others designed for carbonated beverages. Husky also has developed what White referred to as a premium tether that allows the consumer to lock the closure in place.

“It’s a way of differentiating your brand,” White said. “This approach helps us to actually lock the shell in place on the neck finish.”

The premium tether serves several purposes, White said.

“It’s not flopping around. It’s not hitting you in the face when you’re going to take a drink or when you’re going to empty the contents out of the package. You want to make sure that it’s not interfering with the flow or the stream of the beverage as it’s being emptied out of the container itself,” White said.

The case for simplicity

It’s also important, when adopting a tethered closure, to ensure that it’s simple and intuitive for consumers to understand how to put the cap back on the bottle and not cause them to take any additional steps in closing the bottle.

Husky is developing a variety of options for tethered closures, White said.

“It’s not a one-size-fits-all – there are little tweaks,” White said. However, it’s important that the tethered designs promote a positive consumer experience and don’t add extra weight, he said.

While Husky is largely focusing on designs that meet EU requirements, interest in the designs is not limited to that geographic area.

“The first customer of ours with a tethering design was actually based in Southeast Asia,” White said. “They looked at it as a means of promoting their brand as a sustainable alternative to their competitors.”

Husky can help its customers design lighter-weight bottles while at the same time adopting new tethered closure designs, White said.

Readers seeking additional information can visit:

Bruce Geiselman, senior staff reporter

[email protected]

Contact:

Husky Injection Molding Systems Ltd., Bolton, Ontario,
905-951-5000, www.husky.ca/en/