Thermoforming Film for Boiling and Retort: PA/PE or PA/PP?

Start with the heat treatment conditions

For boiling around 100 °C for about 30 minutes, we commonly suggest a suitable PA/PE grade. For retort around 121 °C, we normally recommend a retort-grade PA/PP or PA/EVOH/PP structure. A general-purpose film should not be selected for retort simply because its material name includes PP.

How PA/PP and PA/PE differ in use

PA/PE and PA/PP can differ in stiffness, handling and appearance as well as heat resistance. These properties depend on the grade, layer design and thickness. Compare samples when clarity or flexibility is important to the finished pack.

Where stronger oxygen protection is needed, we can consider PA/EVOH/PP. Barrier data should relate to the proposed film and its intended processing conditions.

Comparing sample data

When comparing films, look at the data for the actual sample specification, including sealing performance, mechanical properties and any barrier requirement. For a retort application, also consider how the finished pack performs after the intended heat treatment and cooling cycle.

Why retort packs leak

Seal contamination, sealing conditions, an unsuitable film grade or the retort cycle can all contribute to leakage. Note whether the failure is at the seal or in the pack body, and when it appears. Have the operator or equipment supplier review the retort and cooling conditions alongside the film specification.

Choosing samples for your process

• Process temperature and time: boiling or retort, and how long.
• The product, and whether it contains liquid, bones or sharp edges.
• Approximate pocket depth and pack size, plus the current film and lid specifications if available.
• Whether transparency or an oxygen barrier is required.
• Expected quantity.

With these details, we can suggest a suitable structure and thickness and provide samples. Test the forming film together with the intended lid on your line, including the actual boiling or retort cycle. Check the finished packs for sealing performance, leakage and visible damage, then share the results before confirming the specification.Explore our thermoforming films.