WHAT ARE YOU MADE OF?
Choosing the right titanium dioxide to enable the durability performance of other coating components

Choosing the right titanium dioxide to enable the durability performance of other coating components

The Central Roles ofPaints are to Beautify
and Protect.

While individual tastes may vary and beauty is very much in the eye ofthe beholder, we can all agree on what we want in terms of protection.
No one wants their paint to discolor, peel, lose gloss or become chalky,
and consumers expect their paints to resist these appearance andphysical changes as the paint ages.

2Choosing the right titanium dioxide to enable the durability performance of other coating components

The Complex Nature of Durability.
Formulating a highly durable paint is complex. Doing so requires asystems approach—all components of the paint must be optimized.
The most important of these is the resin chemistry—some resins areTiO2 Manufacturing Processes

more resistant to weathering than others. Generally speaking, thecosts of the most durable resins are many times higher than the costof their non-durable counterparts. Because of this, it is importantthat all other paint components are optimized for high durability—
otherwise some of the value of the expensive, high durability resin
will be lost.
After resin, titanium dioxide (TiO2) is the next most importantcomponent of a highly durable coating. TiO2 has two opposing
effects on paint durability, both of which are due to its very highultra-violet (UV) light absorption efficiency. The first effect has to dowith what happens when the resin is exposed to the high energy of
UV light. Most resins will degrade through the absorption of UV light
photons. These photons are energetic enough to break chemicalbonds in the resin and initiate changes in both appearance andphysical performance (for example, peeling). Formulators can lessen
the damage from UV light by adding UV light absorbers to the paint.
These materials tend to be costly, and the level that they are added
to paints tends to be limited by these costs.
TiO2 also absorbs UV light, and in fact is such a strong absorberof UV radiation that essentially all of this component of sunlightis removed after striking a single 0.25 micron TiO2 particle. This3

Choosing the right titanium dioxide to enable the durability performance of other coating components

provides protection from UV degradation to the underlying
resin molecules. The ability of TiO2 to protect paints is

Opacification of a Filmdetermined primarily by how well it is dispersed in the film, withgood dispersion giving higher paint durability. Therefore it isincumbent on the TiO2 manufacturer to provide a pigment thatdisperses easily and is completely for durable paint applications.
The second impact of TiO2 on durability has to do with what
happens after a TiO2 particle absorbs a UV light photon. Sinceenergy must be conserved, the energy of the UV photon mustbe transformed to another form of energy. In the vast majorityof UV light absorption events, the energy absorbed by the TiO2
is changed into heat, and the film get warmer. However, theUV light energy is sometimes changed into chemical energy inthe 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 degradation reactions that
ultimately lead to film failure.
The rate at which radicals form and attack the resin is not thesame for all grades of TiO2. Super durable grades have a layerof silica, alone or in combination with other materials, on theirsurface that prevents these radicals from

A: Complete Hiding—Light Scattering

B: Complete Hiding—Light Absorption

C: Incomplete Hiding“The ability of TiO2 toprotect paints is determinedprimarily by how well it isdispersed in the film, withgood dispersion giving
higher paint durability.”

forming. This silica layer is applied by the TiO2 manufacturerduring production of the pigment. The fact that different gradesof TiO2 have different radical formation rates is reflected by
the labeling of TiO2 grades as being “non-durable”, “durable” or4Choosing the right titanium dioxide to enable the durability performance of other coating components“super durable”. Note that these designations do not apply tomentioned above, well dispersed TiO2 particles offer the best

the pigment itself—TiO2 is titanium metal rust and as such isprotection to resin from UV light. This two pronged strategy—

thermodynamically stable—but rather to the effect that thebetter dispersion and low radical formation rates—provides

TiO2 grade has on film durability.

a high level of durability, particularly with regard to gloss

Not all super durable
pigments are created equal,
and the paint formulator
can choose between two
pigment types.

retention. These grades also have the advantage of being
faster and easier to process, since they have been designed
to disperse easily and completely. While these grades do nothave the decades long durability track record that the legacy
grades do, they are finding widespread acceptance in thecoatings industry. This is particularly true in applications that
require excellent gloss retention, since, all else being equal,well dispersed TiO2 particles have a higher gloss (and glossretention) than poorly dispersed particles.
The formulator has a choice of ingredients when developing

The first type consists of well-known traditional or legacy
grades. These are grades that have been in the market for
decades and offer well known, consistent performance.They
achieve their durability by greatly slowing the rate at whichradicals form (i.e. the second mechanism listed above). Paint
formulators are generally quite familiar with these grades
and with the durability performance that they provide, andas such these grades offer familiarity and confidence to thea new super durable paint or modifying an old one. The first
choice is the correct resin, and super durable paints must use
highly durable resin. Since these resins tend to be quite costly
compared to their low durability counterparts, it is essentialthat the formulator select the other ingredients in a way thatmaximizes the durability performance and value of the resin.
Using the right super durable TiO2 grade is a critical aspectof this, and in this regard formulators have the option of using

paint formulator.

familiar legacy grades of TiO2 or newer, more advanced

The second type of super durable pigment are newer grades

degree of dispersibility. In either case the result is the same—

that, in addition to retarding the rate of radical formation,

the maximum value of the highly durable resin is maintained

also provide for easier and more complete dispersion. Asor even improved upon.

pigments that combine low radical formation rates and a high5Choosing the right titanium dioxide to enable the durability performance of other coating components

Dr. Michael Diebold, Chemours Research Fellow
Dr. Michael Diebold is an inorganic chemist with a B.S. degree from the University of Illinois
and a Ph.D. from Texas A&M University. He also served a year-long postdoctoral fellowshipat Cambridge University before joining DuPont as a research chemist in the titanium dioxidegroup in 1988. In his current position as Research Fellow, Dr. Diebold is involved in productsupport, new product and process development, and the study of fundamental propertiesof TiO2 and light scattering in coatings.
Dr. Diebold is a recipient of Surface Coating International’s Stern Award and a past FSCTDistinguished Lecturer. He was the ICE 2003 Technical Focus Keynote Speaker and a2005 European Coatings Conference plenary lecturer. He has authored numerous papers
for coatings journals and holds 10 patents on TiO2 pigment technology. He has recently
published a book on the application of light scattering in coatings.

Titanium Technologies
The information set forth herein is furnished free of charge and based on technical data that Chemours believes to be reliable. Chemours makes no warranties,express or implied, and assumes no liability in connection with any use of this information. Nothing herein is to be taken as a license to operate under or arecommendation to infringe any patents or trademarks.
©2016 The Chemours Company FC, LLC. Ti-Pure™ and any associated logos are trademarks or copyrights of The Chemours Company FC, LLC. Chemours™
and the Chemours Logo are trademarks of The Chemours Company.
C-103706