Material Drying
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Silver streaks caused by moisture in PU processing
Fenómeno del problema
White silver streaks appear on the surface of PU injection molded products
Análisis de la causa
Raw material contains moisture >0.05%, which vaporizes during high-temperature processing to form bubbles that are stretched into silver streaks; insufficient drying or moisture condensation in the hopper
Solución
1) Dry raw material at 80°C for 3-4h to moisture <0.02%; 2) Increase back pressure 0.5-1MPa for venting; 3) Reduce injection speed to avoid air entrapment; 4) Heat the hopper to prevent moisture condensation
Conclusión clave
Silver streaks are caused by moisture vaporization and stretching; drying and venting are the main countermeasures
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