Material Analysis
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PE Film Poor Heat Sealing
Problem Phenomenon
PE bags have low heat seal strength, cannot be sealed or are falsely sealed, the packaging leaks air and liquid, and the heat seal window is narrow and difficult to adjust.
Cause Analysis
The three elements of heat seal temperature/pressure/time do not match the PE melting point; slip agent blooming or contamination on the film surface and insufficient heat seal layer thickness also reduce the seal strength; LLDPE has a higher melting point than LDPE, and the heat seal temperature must be increased accordingly.
Solution
①Optimize the heat seal temperature/pressure/time according to the grade melting point; ②clean the sealing knife and film surface; ③evaluate the effect of slip agent migration on sealing; ④thicken the heat seal layer or laminate easy-seal materials; ⑤conduct heat seal strength and hot tack strength testing.
Key Takeaway
For PE heat sealing, first determine the temperature window according to the grade melting point, then check the film surface condition and heat seal layer thickness; slip agent is a double-edged sword, requiring both opening and sealing performance, and the dosage must be weighed.
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