Why do cans have a plastic liner?
When you pop open a can of your favorite soda or sparkling water, the last thing you might think about is what is happening inside that shiny aluminium shell. You might be surprised to learn that many drink cans contain a hidden plastic liner. This seemingly simple feature plays a crucial role in preserving the quality and taste of your beverage while ensuring safety. Let us dive into the science, reasons, and implications behind this invisible yet essential component.
The purpose of the plastic liner
Prevents corrosion: Aluminium, though highly resistant to oxidation, can still corrode when exposed to acidic substances like soda. The plastic liner acts as a barrier between the acidic drink and the metal can, preventing any chemical reaction that could compromise the integrity of the can or alter the taste of the beverage.
Preserves flavour: Have you ever noticed how some drinks taste different from a can versus a bottle? The plastic lining helps maintain the intended flavor profile by preventing the drink from absorbing any metallic taste from the aluminium. This ensures that each sip tastes just as the manufacturer intended.
Ensures safety: Without this liner, the reaction between acidic drinks and aluminium could potentially produce harmful substances. The liner serves as a safeguard, ensuring that what you are drinking is safe and free from contaminants.
Material and manufacturing
The plastic liner is typically made from a type of polymer such as epoxy resin. This material is chosen for its durability, flexibility, and ability to form a seamless barrier. During the can manufacturing process, the inside of the can is sprayed with the plastic coating before the can is filled and sealed.
Watch this Rubbish Snooker experiment removing the outer aluminium to reveal the plastic liner.
Environmental considerations
While the plastic liner is beneficial for preserving the quality and safety of the drink, it also presents challenges in terms of recycling. Here are some key points to consider:
Recycling process: The presence of the plastic liner complicates the recycling process. When cans are recycled, they need to be melted down, and the plastic must be burned off. This step requires additional energy and can release harmful emissions if not managed properly.
Sustainability efforts: Manufacturers and researchers are continuously looking for ways to improve the sustainability of drink cans. Innovations in biodegradable linings and improved recycling technologies are on the horizon, aimed at reducing the environmental impact while maintaining the benefits of the plastic liner.
Consumer choices: As consumers become more environmentally conscious, there is growing demand for eco-friendly packaging. Some companies are exploring alternatives like plant-based polymers or even cans with no plastic liner, though these solutions are still in the development stage.
Conclusion
The plastic bag inside drink cans is an unseen yet vital component that ensures the safety, flavor, and longevity of your favorite beverages. While it presents challenges for recycling, ongoing advancements in materials science and recycling technology hold promise for more sustainable solutions. Next time you enjoy a cold soda or beer, you will know a bit more about the science and care that goes into delivering that perfect sip.
Learn more about Rubbish Snooker and view the litter art here.