Extrusion & Post
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Slow curing of PU coating
Problem Phenomenon
PU coating cures at room temperature >24h, below the 8h requirement
Cause Analysis
Curing agent NCO/OH ratio too low <1.0; low ambient humidity <40%RH delays curing
Solution
1) Increase NCO/OH ratio to 1.1-1.2; 2) Control ambient humidity at 50-70%RH to accelerate curing; 3) Add 0.1wt% drier
Key Takeaway
PU coating curing speed is determined by NCO/OH ratio and humidity
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