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Kenplas Forum ==> Injection Molding (Machine) ==> Vacuum Dryer -- Newest Drying Solution
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Please send me more detail on Vacum Drying.
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Instead of blowing hot, dry air over the pellets to draw out the moisture, the newest type of dryer on the market uses vacuum to reduce the boiling point of water, literally pulling the water vapor from the resin pellets. Makers of these units boast of using only 20% as much energy and 17% as much drying time as other dryers. They also permit much lower drying temperatures—e.g., 300 F for PET vs. the usual 350 F. Vacuum dryers can reportedly dry most hygroscopic resins.
Polycarbonate can be heated within 20 min and then vacuum dried for another 20 min, for a total of 40 min vs. 4 hr recommended for desiccant drying.
Vacuum drying reportedly uses 70% to 80% less energy than desiccant drying because it eliminates regeneration heating and cooling.
Eastman's Boochard has found vacuum drying to be very effective with polymers that have a high glass-transition temperature (Tg of at least 100 C or 212 F), such as PET, PC or ABS; but he does not see vacuum drying as viable for polymers with Tg of under 160 F, such as PETG.
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