Is the shade of the pigment poor? These factors affect it!

 The ability of pigment to cover the surface of the coated object no longer can be exposed through the coating is called the hiding power of the pigment.

The factors affecting pigment hiding power include refractive index, light absorption ability, crystal structure and dispersion.

(1) the hiding power of refractive index pigment depends on its refractive index and its high refractive index. In the film containing pigment, the refractive index of the pigment is the same as the refractive index of the base material. The pigment is transparent in the film and does not cover the pigment. The pigment is called the transparent pigment. The greater the refractive index of the pigment and the refractive index of the substrate, the stronger the hiding power of the pigment. For example, the refractive index of titanium dioxide is about 2.5, and the refractive index of polymer is about 1.3. Therefore, titanium dioxide is a pigment with strong covering power to polymer.

(2) the hiding power of pigments that absorb light is also determined by the absorptive capacity of the pigment to the light above it. If carbon black does not reflect light, it absorbs all the light on it, so it is highly pigments.

(3) the stronger the crystal structure of the crystal structure, the stronger the hiding power. The crystal structure of Li crystal is not strong or obviously the amorphous pigment has lower covering power. For example, the crystalline form of rutile titanium dioxide and sharp titanium dioxide is different, and the covering power is different. The former is higher than the latter.

(4) dispersion. When other conditions are same, the hiding power of pigments depends on their dispersity. The higher the degree of dispersion, the stronger the covering power. But there is a limit to this relationship. When the size of the pigment particles is equal to half of the wavelength of the light, that is to reach the limit of the covering force, the light will penetrate the particles and not be refracted. Such particles are transparent, such as nanoscale titanium dioxide.