How to avoid yellowing of bottle preforms during PET injection molding?
During PET injection molding, the bottle preform turns yellow, mostly due to the high temperature during the injection molding process.
Based on our analysis, the main reasons for the yellowing of PET bottle preforms are as follows:
1. Drying time is too long or drying temperature is too high;
2. The barrel temperature is too high;
3. The processing temperature is too high.
The solutions to this series of problems are as follows:
1. Release the excessively dried raw materials and re extract them for drying;
2. Reduce the temperature of the barrel (increase the temperature of the bottle blank from 2-5 ° C to the normal temperature without producing white mist);
3. Reduce the processing temperature to an appropriate temperature of 275-280.
