Plastic cans with aluminum pop top lids

At COPAK, we pride ourselves on the versatility of our clear PET cans. They are perfect for cold brew coffee, craft beer, sparkling sodas, and chilled juices. However, there is one specific application where standard PET cans are not suitable: Hot Filling.

If you are producing pasteurized juices, teas, or syrups that need to be bottled at high temperatures (typically above 85°C / 185°F), standard PET cans are not the right choice. Here is the science behind why.

The Glass Transition Temperature (Tg)

The primary reason lies in the chemical structure of Polyethylene Terephthalate (PET). Every plastic has a "Glass Transition Temperature" (Tg). This is the point where the polymer chains begin to move freely, transitioning the material from a rigid, glass-like state to a soft, rubbery state.

For standard PET, this transition temperature is approximately 65°C to 70°C (149°F - 158°F).

What Happens During Hot Filling?

Most hot-fill processes require liquid temperatures between 85°C and 92°C. If you pour liquid this hot into a standard PET can:
1.Immediate Deformation: The heat exceeds the Tg of the plastic. The can will immediately lose its structural integrity, shrinking and warping into an unrecognizable shape.

2.Vacuum Collapse: Even if the can somehow survived the initial heat (which it won't), physics causes another problem. As the hot liquid cools down inside the sealed can, the liquid volume shrinks. This creates an internal vacuum. Without special vacuum-absorbing panels (like those seen on hot-fill tea bottles), the PET can will be crushed inward by the atmospheric pressure.

The "Cold Fill" Advantage

Our PET cans are specifically designed for Cold Fill or Ambient Fill (room temperature) processes (< 60°C). This makes them ideal for:
● Fresh-pressed juices (HPP processed)
● Carbonated beverages
● Cold brew coffee and tea
● Alcoholic beverages
● Dry snacks and confectionery

Is There a Solution for Hot Drinks?

If your production line relies strictly on hot filling for sterilization, standard PET cans are not compatible. You would typically need:

● Heat-Set PET Bottles: These are specially manufactured with thicker walls and vacuum panels to withstand heat, but they rarely come in a "can" shape.

● Aluminum Cans: Aluminum can withstand high temperatures, though handling hot metal cans requires specialized safety equipment.

Conclusion

To ensure your product looks premium and professional, always fill our PET cans at temperatures below 60°C (140°F). By sticking to cold or ambient filling, you preserve the crystal-clear transparency and perfect cylindrical shape that makes your product stand out on the shelf.