Extrusion & Post
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Poor transparency of low density polyethylene blown film
Problem Phenomenon
Film haze is high, transparency does not meet requirements.
Poor transparency affects product appearance and display effect, especially important in packaging film and optical film.
Cause Analysis
(1) High crystallinity of low density polyethylene; crystalline regions scatter light causing high haze
(2) Melt temperature too low, insufficient plasticization
(3) Slow cooling rate, high crystallinity
(4) Impurities or gels in raw material
(5) Rough film surface
Solution
(1) Appropriately increase extrusion temperature to the higher value within the 160-220°C range, full plasticization
(2) Improve air ring cooling efficiency, speed up cooling to reduce crystallinity
(3) Select grades with good transparency or add nucleating agents to refine grains
(4) Strengthen filtration, use 80-120 mesh filter screens to remove impurities
(5) Polish the die, improve film surface finish
Key Takeaway
Poor transparency is caused by high crystallinity or impurities; it needs to be improved by increasing temperature, speeding up cooling, and selecting appropriate materials.
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