Extrusion & Post
3 Aufrufe
Metallocene linear low density polyethylene blown film poor transparency（Variant: Startup Commissioning Scenario）
Problembeschreibung
The film haze is high and transparency does not meet requirements.
Poor transparency affects product appearance and display effect, especially important in packaging films and optical films.In particular, during new machine commissioning or the initial startup period, this problem is more prominent and requires key attention.
Ursachenanalyse
（1） Metallocene linear low density polyethylene has high crystallinity, crystalline regions scatter light causing high haze\
（2） Melt temperature too low, plasticization insufficient\
（3） Cooling rate slow, crystallinity high\
（4） The raw material contains impurities or gel\
（5） Film surface rough\
（6） During new machine commissioning or the initial startup period, process parameter fluctuations or equipment status changes aggravate this problem
Lösung
（1） Appropriately increase the extrusion temperature to the higher value within the 190-260°C range, fully plasticize\
（2） Improve air ring cooling efficiency, speed up cooling to reduce crystallinity\
（3） Select grades with good transparency or add a nucleating agent to refine grains\
（4） Strengthen filtration, use 80-120 mesh filter screen to remove impurities\
（5） Polish the die to improve film surface finish\
（6） And do well in parameter recording and archiving, paying special attention to parameter stability during new machine commissioning or the initial startup period
Wichtigste Erkenntnis
Poor transparency is caused by high crystallinity or impurities, and needs improvement by increasing temperature, speeding up cooling and selecting suitable materials.Targeted preventive measures need to be taken in different production scenarios.
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