Extrusion & Post
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Metallocene linear low density polyethylene MLLDPE high extrusion torque/high energy consumption
Fenómeno del problema
During MLLDPE extrusion, the screw torque is large, the main motor current is high, and output is limited.
MLLDPE has a narrow molecular weight distribution and high melt viscosity, and its processing energy consumption is significantly higher than conventional LLDPE.
Análisis de la causa
（1） Metallocene-catalyzed MLLDPE has narrow molecular weight distribution and high melt viscosity\
（2） Screw design does not match, compression ratio or mixing section not suitable for MLLDPE\
（3） Extrusion temperature too low, melt viscosity high\
（4） Die resistance large, runner design improper\
（5） No processing aid used
Solución
（1） Select a screw design suitable for MLLDPE, generally L/D ratio above 30:1\
（2） Increase extrusion temperature to the higher value within the 190-260°C range （240-260°C）\
（3） Add PPA processing aid to the formulation （fluoroelastomer 0.05-0.2%）\
（4） Optimize die runner design to reduce pressure loss\
（5） Appropriately reduce screw speed, control at 30-50rpm
Conclusión clave
MLLDPE high energy consumption is caused by narrow molecular weight distribution and high melt viscosity, and needs to be solved by optimizing screw design, increasing temperature and adding processing aids.
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