Processing Machinery
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Insufficient heat seal strength of metallocene linear low-density polyethylene film (variant: material or color changeover scenario)
Problem Phenomenon
After heat sealing, the seal strength of the film is low, and the seal cracks under stress.
Insufficient heat seal strength affects packaging sealability and causes leakage in food packaging film.
Especially when changing materials or colors, this problem is more prominent and requires focused attention.
Cause Analysis
(1) Heat seal temperature is on the low side and melting is insufficient
(2) Heat seal pressure is insufficient or time is not enough
(3) Film thickness is uneven, and the heat seal area is on the thin side
(4) The film surface is contaminated or additives have migrated out
(5) Heat seal material selection is improper
(6) When changing materials or colors, process parameter fluctuations or equipment condition changes aggravate this problem
Solution
(1) Adjust heat seal temperature according to the melting point of metallocene linear low-density polyethylene, generally 10-20°C above the melting point
(2) Increase heat seal pressure to 0.2-0.4MPa, with heat seal time of 0.5-2s
(3) Ensure uniform film thickness, especially at the heat seal position
(4) Control additive dosage to avoid surface migration affecting heat sealing
(5) Use heat seal layer materials if necessary (such as LDPE, EVA, etc.)
(6) And do a good job of transition material cleaning; pay special attention to parameter stability when changing materials or colors
Key Takeaway
Insufficient heat seal strength is caused by improper temperature, pressure or time settings; heat seal process parameters need to be optimized.
In different production scenarios, targeted preventive measures need to be taken.
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