Material Drying
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PET bottle-grade drying 165-175℃
Fenómeno do problema
White haze and silver streaks appear in the preforms, and the AA acetaldehyde value exceeds the standard, leading to complaints about beverage taste change
Análise das causas
Insufficient drying of bottle-grade PET makes moisture aggravate acetaldehyde generation and IV decline; AA affects taste, and IV decline causes the bottles to have insufficient pressure resistance and break easily, both directly manifested as customer complaints
Solução
①Drying temperature 165-175℃ with a residence of 4-6 hours; ②feed opening temperature above 160℃ and dew point below -30℃; ③drying air flow 3.7 m³/h per kg/h
Conclusão principal
Bottle-grade PET drying parameters are a precise combination: the four elements of temperature, time, dew point, and air volume are all indispensable, and AA and IV are the verification indicators; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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