Blow Molding
2 views
EVOH extrusion '2079851475616104457 parison sag is severe
Problem Phenomenon
EVOH extrusion '2079851475616104457 parison sag 20-40mm, causing bottle bottom wall thickness of only 0.3-0.4mm
Cause Analysis
EVOH melt strength low, parison stretches and thins under gravity; slow parison extrusion speed increasing sag time; parison temperature too high with low viscosity aggravating sag
Solution
1) Add slight crosslinking agent 0.3-0.5wt% to increase melt strength; 2) Increase parison extrusion speed to shorten sag time; 3) Reduce parison temperature by 10-15°C to increase viscosity; 4) Wall thickness controller to compensate sag
Key Takeaway
Parison sag is caused by low melt strength; slight crosslinking and wall thickness control are key
Was this helpful?
0 people found this helpful
Thank you for your feedback!