Material Drying
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Gel particles and fisheyes on PET sheet surface
Problem Phenomenon
Transparent or opaque tiny particles appear on the PET extruded sheet surface, affecting appearance and subsequent processing.
Cause Analysis
Material mixed with high-melting impurities or crosslinked gels, material stays too long at screw dead corners forming gels, drying temperature too high causing solid-state polycondensation.
Solution
Clean screw and barrel to eliminate dead corners; control drying temperature ≤175°C; appropriately increase processing temperature to melt gel particles; use filter screens.
Key Takeaway
PET gel particles originate from impurities, degradation, or excessive drying.
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