Extrusion & Post
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HDPE film gel (fisheye)
Problem Phenomenon
HDPE blown film has gel spots and fisheyes, and the film surface of high-strength shopping bags is defective.
Cause Analysis
Unplasticized particles, degraded crosslinked material or impurities; HDPE has high molecular weight and is difficult to plasticize, and gel is more obvious when the screen is insufficient.
Solution
①Increase plasticization temperature and mixing (barrier screw + mixing section); ②densify the screen; ③clean the dead corners of the head; ④control regrind quality.
Key Takeaway
Plasticization of high molecular weight material is the foundation of gel prevention and control.
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