Don't let moisture
Moisture is a major menace while processing Polyethylene terepthalate or PET. PET is one of the most popular packaging materials today but is extremely Hygroscopic. Soitisvery important to dry i t thoroughly and properly to ensure quality finish. It is estimated that more than 80% of the problems associated with PET manufacturing is because of improper and inaccurate drying. Improper and inaccurate drying leads to loss of structural strength, impact strength, tensile strength, cosmetic defects and many other moisture related defects and deficiencies.
Moisture must be less than 0.003% prior to moulding
Proper drying of the PET resin is the first critical step towards the final required quality of the moulded product. The resin must be dried so that it may contain less than 0.003% moisture prior to moulding. In the presence of moisture hydrolysis occurs causing reduction of molecular weight. This is responsible for several defects in PET preform like decrease in clarity and haziness Of these parameters, dew point plays the most critical role. Dew point plays a very critical role in creating a lower vapor pressure around the surface of the resin. This lower vapor pressure forces the moisture in the molecular chain of the resin to dissipate out to its surface. Parameters for PET Resin Drying
The PET resins dried at -20ºC dewpoint retain 10 times more moisture than PET resins dried at -40ºC dewpoint. Only Bry-Air Honeycomb Resin Dryers can guarantee -40 ºC to -65ºC as consistent dewpoint.
Methods of drying
The dehumidified drying can be done through honeycomb wheel technology and molecular bead technology. Due to the advantage of honeycomb wheel technology on energy saving (25%), better dew point (up to -65ºC), less maintenance, no contamination and lower cycle cost, generally they are preferred over molecular bead technology. For more information on Bry-Air solution to the problems while drying, moulding and conveying visit our PET application page after logging on to
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