 |
 |
| 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. |
 |
|
| 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 www.bryair.com |
| |
 |
|
