Sustainable cap connections in the beverage industry

AB InBev’s lightweight longneck bottle
(Photo: © AB InBev)

Sustainability remains at the forefront of the development of glass and PET bottles, drink cartons and cans. The demands placed on packaging by consumers and legislators vary depending on material, but all fall under this overarching, dominant topic. Caps that are firmly attached to the bottle or carton (for single-use plastics), reduced use of material (lightweight glass bottles) and increased use of recycled material (rPET) are important goals, and will continue to be in future. Let’s take a look at current projects.

When it comes to developing beverage cartons, the beverage carton industry currently appears to be focusing primarily on caps. This comes as no surprise – after all, the EU Single-Use Plastics (SUP) Directive requires all single-use beverage packaging to be supplied with an attached cap by July 2024 so that the cap can be disposed of and recycled with the rest of the pack.

The EU directive focuses on the environmental aspect of introducing tethered caps. But does this actually reflect the desires of consumers as well? According to a study commissioned by Sidel and conducted by Ales Research, in which consumers were asked to rate the attractiveness, functionality and environmental impact of caps attached to the bottle, sustainability is not the consumers’ main concern. Instead, the 3,200 European adults surveyed primarily valued the product safety and user friendliness.

87% of the participants did agree that plastic waste harms the environment and bottle caps contribute to this. However, only a small portion (26%) felt that attached caps would really help prevent plastic pollution. “Consumers have an extremely practical attitude towards bottle caps. As it turned out, they are mainly interested in product safety and user friendliness. They want to know whether or not a cap was opened before using the bottle and how easy it is to put it back on. In addition, the tightness of the cap is crucial for preventing the drink from spilling,” explains Simone Pisani, Portfolio Intelligence & Value Selling Director at Sidel. The survey concluded that the cap’s convenience and ease-of-use advantages are considered the most important criterion. “Of course, this perception may change once consumers realize the environmental benefits of caps attached to the bottle,” says Simone Pisani.

Benutzerfreundliche Verschlusslösung
Most consumers prioritize user-friendliness with cap solutions, according to a survey commissioned by Sidel. (Photo: © Sidel)

When developing caps that are attached to the packaging, leading manufacturers of beverage cartons and bottles are doing everything they can to offer customers from the beverage industry suitable solutions so that they can implement the EU requirements in time. There are already various options.

Ahead of the times: Tethered cap solutions with a robust double-hinge solution

Recyclebare Tethered Caps von SIG
Compatible with existing SIG filling machines and applications, SIG tethered caps can be recycled with the carton packs.(Photo: © SIG)

At the start of May 2021, SIG announced that they would launch carton packaging with caps that remain firmly attached to the packaging even after opening on the European market as early as the second half of 2021 – well ahead of the deadline of July 2024 set by the EU. According to the company, the new caps are compatible with the existing filling machines and cap applicators from SIG. Ali Kaylan, SVP Innovation and VP Global Marketing at SIG, says, “Thanks to our flexible and adjustable systems, we are able to use our tethered caps with existing SIG filling machines and cap applicators.”

Compatible with existing SIG filling machines and applications, SIG tethered caps can be recycled with the carton packs.

Convenient cap for consumers

The SIG tethered cap solutions use a robust double-hinge solution, which the company claims has turned out to be very suitable for consumers. When the packaging is opened for pouring, the cap can be fixed in the desired position by pressing it down until it clicks into place. This allows consumers to pour from the packaging conveniently without the cap getting in the way or having to hold onto it with their fingers. To close the packaging, the cap is lifted slightly and then closed as usual. Once the packaging is empty, the cap and packaging can then be recycled together.

For customers who choose Signature solutions, the tethered caps are made from polymers that are 100% linked to renewable, wood-based raw materials via a certified mass balance system – as are the polymers in the packaging itself.

Pure-TwistFlip – new closing solution

Competitor Elopak also has its sights firmly set on caps for beverage cartons and is launching innovative tethered caps solutions well before the mandatory introduction in summer 2024. The manufacturer presented its new Pure-TwistFlip tethered cap solution at the start of June 2021: The sealing cap remains reliably connected to the packaging throughout its entire service life. The cartons can be recycled together with the complete cap. According to the company, this is also the manufacturer’s lightest screw cap to date – which further reduces plastic consumption. All of this makes the Pure-TwistFlip a solution for brands that want to meet the growing consumer demand for sustainable packaging without sacrificing convenience or product integrity, the manufacturer claims. The new lid is compatible with all of the company’s Pure-Pak beverage cartons. Patrick Verhelst, CMO at Elopak, states: “We are very excited that our tethered cap solution is now ready for use. We always try to raise the bar with our innovations. Sustainability is a central driving factor at Elopak in this regard.”

Weight reduction – the credo for developing new glass beverage bottles

While the engineers developing new PET bottles or beverage cartons are currently concentrating on innovative caps, the experts in the development of innovative glass bottles are continuing to focus on reducing weight by saving material. This is not an easy task; the carbonation of beers or lemonades, for example, places particular demands on stability. Additional external factors also act on the bottle during filling or transport.

The lightweight bottle from AB InBev

AB InBev recently presented what they claim is the lightest longneck beer bottle in the world for commercial production, with a total weight of 150 grams. This represents a weight reduction of 30 grams compared to a similar standard longneck bottle (standard bottle 180 grams). According to the company, by reducing the weight, the CO2 emissions per bottle also drop by 17 percent.

This world premiere was developed in the brewery’s Global Innovation and Technology R&D Center (GITEC) in Leuven, Belgium, where they combined various innovative technologies to deliver a more sustainable bottle while keeping the packaging secure and ensuring the quality of the beer.

The “beer lightweight” is the result of a collaboration with external glass partners who have worked together on new lens coatings, lens mold coatings and state-of-the-art processing to strengthen the glass. “When reducing the weight of the bottle, we found ourselves confronting the challenge of stability,” says Frederik De Graaf, Global Director, Packaging Technology Development at AB InBev De Graaf. “Beer is a naturally carbonated beverage and pressure can build up inside a bottle because glass expands under certain temperature conditions. We also had to consider the speed of our filling machines as they exert high impact forces on the bottles. Ultimately, a combination of state-of-the-art facilities, trained professionals and process improvements helped us develop this innovation.” 

Leichteste Bierflasche der Welt
While the classic longneck beer bottle weighs 180 grams, the newly developed longneck beer bottle is a real lightweight with only 150 grams and 17% lower CO2 emissions. (Photo: © AB InBev)

AB InBev is now examining how the new bottle can initially be introduced in Europe as a one-way bottle. Returnable bottles are the next challenge for the GITEC team of scientists. This involves developing the technologies for the lightweight construction of these bottles, which have to withstand many cycles. AB InBev has committed to offering 100 percent of its products in reusable packaging by 2025..

Granini and KHS: 100 percent rPET – from planning to implementation

The Hohes C brand from Eckes-Granini has also worked together with the KHS Group to make its 1-liter PET bottle more environmentally friendly. As of May, the bottles have been manufactured from 100 percent rPET.

Hohes C rPET Flasche
Collaboration between Granini and KHS: As of May, the 1-liter bottle of the Hohes C brand has been made from 100 percent rPET. (Photo: © Eckes-Granini)

“In view of the EU’s plastics strategy and the related increase in quotas for recycled materials, we have now decided to switch completely to recycled PET. We want to be a pioneer in the field of closed-loop economy and lead by example in the beverage industry,” explains Hermann Naumann, plant manager from Eckes-Granini in the town of Bad Fallingbostel in Lower Saxony. “Our goal is to continue to reduce the CO2 footprint within production and in our packaging. This involves both reducing material consumption and closing the material cycle.” 

In the case of Eckes-Granini, the specifications for KHS were clear: Switching to 100 percent rPET with homogeneous and consistent container quality. Eckes-Granini claims the conversion of the 1-liter bottles from Hohes C saves more than 4,000 tons of new PET every year. According to the bottler, this reduces its CO2 emissions by around 8,000 tons per year.

The ambitious project didn’t just focus on saving resources. It was also necessary to check the implementability on the InnoPET FreshSafe block already in use. The InnoPET FreshSafe System from KHS sets itself apart with an integrated coating technology which grafts a wafer-thin layer of glass (SiOx) onto the interior surface of the PET bottle. By doing so, the contents are to remain fresh and last longer. “Among other things, it was a matter of whether adaptations to the preform or the system were necessary,” explains Matthias Kruse, Head of PET Technology at KHS. “To do so, we assessed the quality of the recycled PET materials. This is crucial because large variations in color, molecule length and inhomogeneity quickly reduce production efficiency.” 

Minimal adaptations to the oven of the stretch blow molding machine were necessary to optimize bottle manufacturing. There was no need for major changes to the system or to the geometric properties of the blanks. “With this method, we have achieved a very high level of process efficiency while maintaining the same container quality, thereby fully meeting our customer’s specifications,” says Kruse. 

The advantages of the barrier protection of FreshSafe PET can continue to be used even after switching to 100 percent rPET. The coating on Eckes-Granini bottles can easily be washed off during the recycling process. The sustainable packaging alternative therefore enables single-origin bottle-to-bottle recycling. “By combining rPET and forward-looking product protection, Eckes-Granini and KHS are once again demonstrating their pioneering role for the circular economy,” says Kruse. 

By the end of 2022, Eckes-Granini Deutschland intends to only use PET bottles made from 100 percent rPET for all its brands, thereby saving a total of around 9,000 tons of new plastic per year.


Cap solutions are currently the main focus in the development of beverage cartons and PET containers. In light of the EU directive, which stipulates the use of caps permanently attached to the bottle by July 2024, the packaging industry has done its homework and is offering its customers a wide variety. Depending on the provider, they can be attached to the existing, flexible filling lines with only minor adjustments.

Lower material usage and the associated weight reductions remain the dominant theme in the development of glass bottles. Engineers are continuing to walk a fine line between weight reduction and stability. The construction of lightweight returnable glass bottles, which have a longer life cycle and are exposed to more intensive loads in processes such as logistics and production, proves to be particularly challenging. The goal of using PET bottles is still achieving a closed-loop economy. While the proportion of recycled PET has been gradually increased in recent years, beverage manufacturers are gradually switching to using only recycled PET to manufacture their bottles. The respective contents are no longer a limiting factor. Thanks to sophisticated coating technologies, it is now even possible to fill 100 percent recycled PET with sensitive beverages such as juices or milk. The goal is therefore to achieve a closed-loop economy as soon as possible.

Would you like to find out about current trends on the beverage market and exchange professional information? Then we invite you to take part in the next drinktec, which will be held in Munich from September 12 to 16, 2022.

This article is powered by Verlag W. Sachon.

Verlag W. Sachon

The publishing house W. Sachon, headquartered at Mindelburg Castle, publishes nine established trade journals that regularly provide their readers with exciting and interesting information. The emphasis lies in the brewing and beverage industry. The specialized publications are published in German, English, Spanish and Mandarin. A national and an international newsletter as well as an SMS Executive Flash complete the print offer digitally.