J. Rommens, A. Verhaege, G. Michiels, Chemours, Belgium; M. Diebold, Chemours, USA
Abstract
Titanium dioxide pigments play an important role in protecting
white and light colored paints against the influences of weathering.
Careful pigment design enables the best protection and guarantees
maximum coating lifetime. During the development of pigments
and paints it is important to study and measure weathering influence in the most representative way. In this paper, a comparison is
made between accelerated methods for studying weathering and
outdoor exposure of several industrial paints. The impact of titanium dioxide on weather resistance, as well as the correlation between the testing methods, is evaluated and discussed.
Introduction
Titanium dioxide is a well-known white pigment; but beyond its
exceptional whitening power, it can also increase the durability
of a paint. TiO2 has a positive effect on the weather resistance
of a coating due to its UV absorbing capacity. TiO2 absorbs UV
light, which provides protection from UV degradation to the un-
derlying resin molecules. After UV absorption, however, the en-
ergy of the UV photon must be transformed to another form of
energy. In the clear majority of UV light absorption events, the
energy absorbed by the TiO2 is changed into heat, without dam-
aging the paint film. However, the UV light energy is sometimes
changed into chemical energy in the form of chemical radicals.
These radicals form on the TiO2 surface, but are mobile enough
to travel to resin molecules, where they initiate a series of degra-
dation reactions that ultimately lead to film failure. This process
is called photocatalysis. Proper treatment of TiO2 pigments can
reduce photocatalysis to a great extent, thereby turning the pig-
ment into an efficient UV protecting agent without the negative
photocatalysis effects. Such TiO2 grades are referred to as “du-
rable” grades. The efficiency of this treatment can vary between
A comparative study between test methods.
TiO2 Impact on
Paint Weather Resistance
