What it the Tinting strength of titanium dioxide

Tinting strength of titanium dioxide is the opacity or strength of a titanium dioxide solution in regard to its ability to form a thin film on a surface that the solution is dissolved in. It is the measurement of light reflection from an object coated with coloured-solvent paint film with white titanium oxide as pigment. The higher the tinting strength, the more opaque the paint will be. The amount of titanium dioxide pigment in paint determines its opacity, resulting in a glazing effect and a covering power (CP).

It is measured by ASTM D1003-02a and ISO 2813; test methods for the determination of tinting strength of titanium dioxide pigments by reflectance measurements. The instrument is a spectrophotometer based on ASTM E308-97. The color change of the paint film is measured with an optical color spectrophotometer (spectrometer) based on ASTM E308-97.

The average tinting strength of white titanium dioxide pigments used in paints is about 93%. The highest value is as high as 98%. In addition to the pigment concentration, the other factors influencing tinting strength are the rheology, solids content and viscosity of paint.       

Structure of titanium dioxide        

Titanium dioxide is a white, inorganic, hydrated oxide of titanium. It is a naturally occurring mineral. It is the second most abundant element in the Earth's crust and the third most abundant element in Earth's oceans.

The nature of natures' titanium dioxide has formed a wide variety of industrial applications over time, including paints, table salt, pigments, plastics and other coatings. In its pure form it is as strong as steel, but it can be dissolved in either water or organic solvents such as alcohol which tend to melt at lower temperatures than water.

The strength of titanium dioxide depends on the pH, temperature, and the concentrations of the solution. Its strength is dependent on other factors such as pH, solubility and molecular structure of the compound. At low concentrations, it is insoluble in water but it becomes soluble in a wide range of organic solvents.

Compared with other chemicals used in paints and coatings titanium dioxide has characteristics such as quick cure, high mechanical hardness and good adhesion to most substrates. These characteristics make it more valuable than other pigments in paints because they are used to prepare highly resistant materials for industrial applications where paint coatings would normally fail.

Physical features of titanium dioxide

1. High melting point

Titanium dioxide is a semiconductor and the melting point of the solid is 1970Fs(3135K). Titanium dioxide has a high melting point and high hardness, which makes it not easy to melt.

2. High boiling point and high viscosity

Titanium dioxide does not dissolve well in water but it can remain stable in hot water for a long time. The boiling point of titanium dioxide is about 3113K (2650F), which is higher than that of most other chemicals. The viscosity of titanium dioxide solutions is relatively large due to the fact that its molecular structure is strong.

3. White color

The light absorbance of titanium dioxide is 8.5%. At high temperatures, lithium ions within titanium dioxide (Li3Ti) are transformed into the ionic form by heating; with the direction of the displacement being from the more hydrophilic side to the less hydrophilic side. When this happens, one lithium ion on one Ti center is replaced by three sodium ions, and another sulfur and two sodium ions are transformed into sulfate ions. The color of titanium dioxide becomes white because of this process; its color also varies significantly based on pH and concentration.

4. High refractive index

The refractive index of titanium dioxide is 2.55 in the visible light region. The higher the refractive index, the more light it will absorb. Because titanium dioxide has a high refractive index, it can absorb light at high levels without much damage to itself and can also be used as a white pigment due to its transparency at low concentrations.

5. High hardness and good chemical resistance

Titanium dioxide does not strongly adsorb water-soluble organic materials such as phosphates, but it can strongly adsorb many types of water-insoluble substances such as oxygen in air because of its high hardness and relatively good chemical resistance.

Chemical features of titanium dioxide

1. High solubility in water

The solubility of titanium dioxide is related to the pH and the concentration. It can dissolve in a wide range of organic solvents. In addition, it is relatively soluble in cold water, which makes it well-suited as a paint pigment.

2. High hardness and good chemical resistance

Titanium dioxide has a high hardness and good chemical resistance (except for titanium alkoxide). It does not strongly adsorb water-soluble organic materials such as phosphates, but it can strongly adsorb many types of water-insoluble substances such as oxygen in air because of its high hardness and relatively good chemical resistance.

3. High temperature resistance

The decomposition of titanium dioxide at a temperature of about 1000 ℃ (1773K) will result in the transformation of the TiO₂ molecules into TiO, which is burned and turned into a white powder. In addition, titanium dioxide can be heated without producing harmful substances.

4. It does not emit toxic gases when it burns or decomposes, which makes it safe to use in paints; however, it should be stored in containers with thick walls or other such materials to avoid fire hazards.

In conclusions, tinting strength of titanium dioxide is extremely important. Its quick curing time, high hardness and good chemical resistance make it more valuable than other pigments in paints.