The goods have been shipped, and the customer reports back: the sealing film has detached, and the product leaked. This isn't a production issue — it's a problem that occurred on the road. Leadtra Packaging has encountered many such cases while serving customers, and the approach is usually "find the cause first, then determine the solution."

First, determine: is it "full detachment" or "edge lifting"?

The causes differ. Full detachment often indicates insufficient heat seal strength — the sealing temperature, pressure, or time didn't meet process requirements, and the film didn't form adequate bonding with the bottle mouth. Edge lifting is more related to temperature and humidity changes during transport — the film and bottle mouth have different thermal expansion coefficients, and repeated expansion and contraction in environments with large temperature swings can cause the edges to separate.

Next, look at transport conditions: temperature and humidity are the main variables

In summer, truck cabins exposed to the sun can reach temperatures above 60°C, and some heat-seal adhesives soften at high temperatures, reducing bonding strength. In winter, northern transport routes expose the film to low temperatures, making it brittle and prone to cracking during vibrations. The high-humidity environment inside shipping containers can cause the paperboard layer to absorb moisture and swell, indirectly affecting seal stability. If transport distances are long and involve many transshipment points, every loading and unloading is a test for the seal.

Solutions: start with the sealing process and film material selection

If heat seal strength is insufficient, it's recommended to specify transport conditions during the sampling stage and appropriately increase heat seal strength standards to ensure the seal can withstand transport vibrations. If detachment is caused by temperature differences, choose film materials with a wider temperature tolerance range, or use composite structures with cushioning layers to reduce the impact of temperature changes on the seal. For long-distance ocean freight or extreme climate transport, moisture-proof measures can also be added inside the outer cartons to control temperature and humidity fluctuations.

Additionally, conducting a simulated transport test before shipping — drop, vibration, stacking — can help identify potential problems in advance, which is far more proactive than waiting for customer complaints to remedy the situation.

Leadtra Packaging recommends that customers consider transport scenarios when customizing sealing film. We can also assist in evaluating film material options and providing sealing parameter recommendations to help you reduce the risk of transport-related detachment.