Metal packaging: can sealants

Aluminum cans take just 60 days from being consumed to be recycled into a new can. In addition to this fast turnaround time, 100% of it can be recycled over and over again. And when new cans are created from recycled aluminum, it can reduce greenhouse gas emissions by 95%.

Aluminum is one of the most eco-friendly materials out there, but those food and beverage cans we rely on every day wouldn’t exist if it wasn’t for their invisible enabler.

Almost all food and drinks cans, from beer cans to canned vegetables, require a sealant. This attaches the body of the can to the lid, preventing leakages and contamination. 

Most cans sit on people’s shelves for weeks or months, so a seal is important to ensure the shelf life of a can’s contents for as long as possible.

Aluminum is one of the most circular economy friendly materials in existence, which is why there’s a renaissance occurring. Growth is estimated to be about 6% for the next 3-5 years, driven by the sustainability of aluminum cans.

Brand owners of new drink categories are choosing aluminum cans over alternative packaging, and we foresee further shift from beverages using PET to aluminum in the next few years.

But, once the aluminum has been produced and used as a can, approximately 80% of that is recycled in most developed economies.

The carbon footprint of an average can is therefore very low because it requires less energy to recycle it, re-roll it, and reuse it, than it does to extract it from the earth and process it to create new rolled aluminum.

This popularity is feeding the growth of the sealants that are also needed to ensure the success of aluminum cans. Sealants are flowed-in rubberized gaskets applied during the manufacturing process of the ends. A small amount of material is applied by high-speed equipment while ends rotate on a chuck, forming a gasket in the internal perimeter of the end. This process happens at incredible speeds, making the application almost invisible to the human eye.

These invisible enablers usually don’t come into direct contact with the food or beverage itself – there’s usually some gap or headspace between the food/drink at the top of the container.

But it’s important to formulate all sealants with FDA and EU approval just in case there’s any incidental contact, or potential migration of monomers from the sealant into the food or beverage, such as when the can is upside down.

Ingredients therefore need to be non-toxic and pose no danger to human consumption. This makes choosing the raw materials for these compounds an important task.

Our DAREX technology was invented over 100 years, but it has evolved to keep up with the increasing production speeds in the industry.

However, little has changed about formulations because the original product was so efficient. The evolution of the materials has been focused primarily in making application faster and cleaner. The focus of our innovation in the past few years has shifted toward ensuring the ultimate food and beverage safety of our sealants.

At Henkel, we’ve implemented a Triple Safety program for our can sealants products which goes beyond what the regulations require us to do.

Sustainability and food safety are closely linked. We pay special attention to any substances used to formulate our products to ensure no substances of concern are used in our can sealants.

Our analytical department looks into potential chemical reactions which may happen when we formulate and dry-up the compound from liquid to solid gasket form. They then investigate any reaction products that may be created and check that those monomers are safe, too.

Food safety is incredibly important to us. We proactively monitor the latest information from brand owners, the industry, and the public on the substances used in our products to keep an eye out for potential substances of concern. This monitoring is also something we’ll continue to do going forward.