Processing Machinery
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Difficult EVOH Purging
Problem Phenomenon
EVOH purging takes 2-3h, time-consuming and affecting changeover efficiency
Cause Analysis
EVOH has strong adhesion forming a firm adhesive layer on screw and barrel; EVOH has poor thermal stability, becoming sticky at high temperature and harder to remove
Solution
1) Before purging, flush with high-viscosity PE to carry away EVOH residue; 2) Reduce purging temperature below EVOH softening point to reduce adhesion; 3) Use dedicated purging compound
Key Takeaway
Purging difficulty is caused by EVOH's strong adhesion; PE flushing and temperature reduction are key
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