HITOX®
TiO2 Pigment
Adding Value To Color Formulations
Introduction
A natural colored
beige TiO2 pigment, called HITOX®
add value
to many formulations by replacing some of the more expensive
colourants.
HITOX®
colored pigment has
a TiO2 content of about 95% and can be used as partial
or full replacement for white TiO2. In products which
require opacity and color, the cost savings is achieved from
the reduction of more expensive TiO2 and colorants,
such as phthalo blues and greens.
The main differences
between white TiO2 and the natural-colored pigment
are particle size, oil absorption and iron oxide (Fe2O3)
content.
Particle Size
The absence of
a surface treatment combined with the pigment's larger particle
size and slightly higher oil absorption require that extra care
be taken to ensure that the pigment is properly wetted and dispersed
into the vehicle system.
Iron Oxide Content
HITOX®
TiO2 pigment
contains between 1.5% and 2.0% residual Fe2O3,
which partially gives the pigment its natural beige color. The
natural beige color is inherent in the pigment's crystal structure.
Performance
HITOX®
TiO2 meets ASTM
D-476-84 ( Standard Specification for Titanium Dioxide Pigments)
Type II and Type III as a chalk-resistant, rutile pigment.
Exterior-exposure
and accelerated-weathering studies have shown that natural-colored
TiO2 used as a color pigment in conjunction with
other color pigments performs similarly to treated white TiO2
on chalking and color shifts.
Substantial improvements
over the past several years in color quality, lot-to-lot color
consistency, and a uniform particle size over a narrow range
have allowed the pigment to be used in most coating systems.
Fig.
1 : Comparison of the Typical Properties of HITOX®
STD, HITOX® ULX
| Property |
HITOX®
STD |
HITOX®
ULX |
WHITE
TiO2 |
| Color |
Beige |
Lighter
Beige |
White |
| Crystal
Structure |
Rutile |
Rutile |
Rutile |
| TiO2
Content |
95% |
95% |
94% |
| Refractive
Index |
2.73% |
2.73% |
2.73 |
| Fe2O3 |
1.7% |
1.7% |
N/A |
| Al2O3 |
0.4% |
0.4% |
2.0%-4.5% |
| SiO2 |
1.25% |
1.25% |
0%-3.0% |
| Median
Particle Size, microns |
1.5 |
0.75% |
0.2-0.3 |
| Specific
Gravity |
4.1 |
4.1 |
4.1 |
| Oil
Absorption, ASTM D-281 |
23-28 |
26-28 |
13-20 |
| Moisture |
<0.5% |
<0.5% |
0.5%-1.0% |
| 325
Mesh Retention |
<0.01% |
<0.01% |
0.01% |
| Hegman
Grind |
7.0 |
7.0 |
7.0 |
| pH |
6.5-7.5 |
6.5-7.5 |
6.5-
8.5 |
Color Properties
HITOX®
TiO2 is used as a partial or full replacement for
white TiO2, but the advantage of formulating
with HITOX® TiO2 pigment is its color
properties and thereby reduce the amount of the more costly
color pigments.
In Figure
2, the color value of HITOX®
colored TiO2 is
demonstrated by the reflectance properties over the visible
range of the spectrum as compared to a white TiO2.
The HITOX®
colored pigment's ability
to absorb the light in the visible spectrum differentiates it
from a white TiO2 and places it in a color-pigment
category. The tinting color pigments used in a formulation with
white TiO2 are thereby reduced when HITOX®
is inserted as a color pigment.
Paint Formulation
A blue industrial
alkyd gloss enamel coating with and without HITOX®
comparison is as shown. The
paint prepared with HITOX®
TiO2 resulted in
a reduction in the amount of Hansa Yellow, Phthalo Blue, and
Carbazole Violet color pigments used to obtain the desired color.
The white TiO2 loading was reduced from about 3.7
kilos to about 2.0 kilos.
The Color
difference between the two blue enamel is 0.23 DE*. Significant
cost savings are achieved by using the HITOX®
TiO2 pigment as
a partial replacement for white TiO2, but more so
by reducing the amount of the more expensive color pigments,
This savings is obtained by taking advantage of the color properties
of the HITOX®
TiO2.