Material Analysis
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Insufficient Heat Seal Strength of High-Density Polyethylene Film
Problem Phenomenon
After heat sealing of the film, the seal strength is low, and the seal cracks when stressed.
Insufficient heat seal strength affects the packaging sealability and causes leakage in food packaging films.
Cause Analysis
（1）The heat seal temperature is low, and the melting is insufficient
（2）The heat seal pressure is insufficient or the time is not enough
（3）The film thickness is uneven, and the heat seal area is thin
（4）The film surface is contaminated or has additive precipitation
（5）The heat seal material is improperly selected
Solution
（1）Adjust the heat seal temperature according to the melting point of high-density polyethylene, generally 10-20°C higher than the melting point
（2）Increase the heat seal pressure to 0.2-0.4MPa and the heat seal time to 0.5-2s
（3）Ensure the film thickness is uniform, especially at the heat seal part
（4）Control the additive dosage to avoid surface precipitation affecting heat sealing
（5）Use heat seal layer materials (such as LDPE, EVA, etc.) when necessary
Key Takeaway
Insufficient heat seal strength is caused by improper temperature, pressure, or time settings, and the heat seal process parameters need to be optimized.
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