Molds & Tooling
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PET Acetaldehyde AA Content Exceeding Standard
Fenómeno do problema
The AA value of preforms or blown bottles exceeds the standard in headspace gas chromatography testing, and after filling drinking water, the water has an odor and sweet taste.
Análise das causas
AA is generated by PET thermal degradation; melt temperature too high, barrel residence time too long, local overheating of the hot runner or excessive screw shear all aggravate degradation; high AA in the raw material itself is also directly brought in.
Solução
①Control melt temperature at the lower limit of the 270~290℃ window; ②shorten barrel residence time and match the machine model with the injection volume; ③calibrate the temperature of each hot runner point; ④switch to low-AA grade resin and test incoming material AA.
Conclusão principal
AA exceeding the standard is a food safety risk, and the requirements for mineral water bottles are particularly strict; temperature control and shortening residence time are the fundamental means, and headspace GC sampling must be done before filling to confirm qualification.
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