Material Drying
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PVC Drying 75-90℃
Fenómeno do problema
Silver streaks and bubbles on PVC product surface, extruded profile surface bubbling, appearance unqualified
Análise das causas
PVC pellets absorb little water but not zero; surface-attached moisture and low-molecular volatiles vaporize at processing temperature; soft PVC plasticizer system absorbs moisture more obviously, bubbles and silver streaks increase with moisture content
Solução
①Pellets dried at 75-90℃ for 1.5-2.5 hours; ②Moisture-affected material extended drying and verified; ③Soft PVC pay attention to moisture management of plasticizer system
Conclusão principal
PVC drying requirement is lower than nylon but cannot be omitted; 75-90℃×1.5-2.5h is the general specification, moisture-affected material must be re-dried; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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