you got your flakes washed and all dirt
is gone, you may find out you need to
remove the media you did use to remove
the contamination itself.
- In other words, when you use chemicals,
surfactants, detergents or anything
like this, you should remove it as well.
- Sometimes it is more difficult to
get rid of a chemical media than the
dirt itself because it can be even more
- One example for all is caustic soda
used to remove glue from PET bottle
- After the flakes has been deeply
washed, and caustic did make its job
to remove glue, you flake is shining
and you're smiling because you finally
got it completely clean.
- Then, you go to extrusion and your
pellets come out black or very close
- What did happen ?
- The few PPM of caustic left on the
surface of the flake did react with the
Polyester chain and oxidised the whole
- And you're in damn trouble.
- Rinsing is an important step of
the washing line, specially if you use
any kind of chemicals.
- Some of them require only a short
step into little water, always together
with friction, and everything will be
gone while, for some other application
where the final product needs to be
absolutely pure, rinsing should be as
deep as the washing itself.
- To be continued...........