Processing Machinery
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Metallocene linear low density polyethylene MLLDPE excessive gel/gel particles（Variant: Startup Commissioning Scenario）
Problem Phenomenon
There are many gel particles and gel granules in the MLLDPE film, affecting the film appearance and mechanical properties.
The gel particle problem is particularly prominent in transparent films, reducing the product grade.In particular, during new machine commissioning or the initial startup period, this problem is more prominent and requires key attention.
Cause Analysis
（1） MLLDPE has a narrow processing temperature window, and is not fully plasticized at low temperature\
（2） The barrel temperature is too low, and the high molecular weight fraction is not melted\
（3） The screw mixing section design is insufficient to fully plasticize MLLDPE\
（4） The raw material itself contains gel\
（5） The filter screen mesh count is too low\
（6） During new machine commissioning or the initial startup period, process parameter fluctuations or equipment status changes aggravate this problem
Solution
（1） Increase barrel temperature to 240-260°C, ensure full plasticization\
（2） Optimize the screw mixing section design\
（3） Increase the filter screen mesh count to 100-150 mesh\
（4） Select MLLDPE grades with few gel particles\
（5） Regularly clean the screw and die\
（6） And do well in parameter recording and archiving, paying special attention to parameter stability during new machine commissioning or the initial startup period
Key Takeaway
MLLDPE gel particles are caused by insufficient plasticization, requiring increased processing temperature and strengthened filtration.Targeted preventive measures need to be taken in different production scenarios.
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