Fuels & Lubricants Magazine

carbonate = PC; hydrophilic PC =
HPC) had a relatively small effect on
defoaming performance compared
to the non-polar polypropylene
(P). However, the 3D-based defoamer
(HP753N; 0.2% in the MWF
concentrate) maintained superior
persistence even with the polypropylene
(P) filter, while the 2 OMS
products (0.4%) showed increased
foam. Other filtration studies that we
have performed have shown similar
trends.
Washability and Paintability
of 3D Siloxane Technology
Silicone-based defoamers can
cause defects such as craters in
painting operations due to silicone
residue adsorbed on the substrate
surface. Silicone oil droplets can
readily spread on metal surfaces.
This spread layer, which has a low
surface energy, can be particularly
difficult to clean, and even a monolayer
left on the surface can cause
retraction of the applied paint. On
the other hand, defoamers based
on the 3D siloxane technology have
good washability due to optimized
formulation parameters and the 3D
siloxane’s crosslinked nature, which
impedes spreading on the metal
substrate surface. To test this, we
immersed cleaned steel panels in a
semi-synthetic MWF dilution containing
various defoamers, and then
washed with tap water and dried (in
an oven at 50 °C) the panels. Then, a
water-based white primer paint was
applied using a #10 Myer rod. As
shown in Figure 5, the coatings on
the panels that were immersed in the
MWF containing the 3D siloxane
defoamer technology did not show
any defects, while a panel with a silicone
emulsion in the MWF showed
many defects. This observation is
consistent with the many years of
field experience that have demonstrated
the excellent washability
and paintability of the 3D siloxane
technology.
Figure 4. Effects of Filtration Media on Defoamer Performance
FOAM BAN HP753N
Figure 5.
FOAM BAN HP757
10% Silicone Emulsion
Summary and Conclusions
The most effective defoamer technologies
are based on polysiloxane
chemistries, because of their inherently
low surface tensions that are
required by the thermodynamics
of defoaming processes. For MWF,
the 3D siloxane technology provides
a superior level of initial and
persistent defoaming compared to
alternative technologies. In addition,
3D siloxane-based defoamers have
excellent concentrate compatibility,
filterability, and washability/paintability
characteristics.
6 Fuels&Lubricants No. 2 JUNE 2018